EP4143856A1 - Electrode structure for guiding a charged particle beam - Google Patents

Abstract

The invention relates to an electrode structure for guiding and, for example, splitting a charged particle beam, for example an electron beam, along a longitudinal path, having multipolar electrode assemblies which are mutually spaced along the longitudinal path and which comprise DC voltage electrodes. The electrode assemblies are designed to generate static multipolar fields which are centered about the path on transversal planes oriented perpendicularly to the longitudinal path, wherein the field strength of each of the static multipolar fields on the transversal planes has a local minimum at the location of the path, and the field strength increases as the distance to the location of the path increases. Field directions of the static multipolar fields vary periodically along the path with a period length such that the particles propagating along the path are exposed to a non-homogenous electric alternating field on the basis of the inherent movement of the particles and are subjected to a transversal restoring force in the direction of the longitudinal path, averaged over time.

Description

Electrode structure for guiding a charged particle beam

The present invention relates to an electrode structure for guiding a charged particle beam, for example an electron beam, a system having such an electrode structure and a method for guiding a charged particle beam. In particular, the invention relates to an electrode structure, a system and a method with which a beam of charged particles can be guided along a longitudinal path in a transversely enclosed manner.

Electrode structures, which lead a beam of charged particles transversely enclosed along a path, are used, among other things, in mass spectroscopy, laser spectroscopy or to realize quantum computers. Typically, such electrode structures are designed as linear Paul traps, which enclose charged particles transversely in a time-oscillating inhomogeneous electrical field. The electric field used for the transverse inclusion is generated by longitudinally extended electrodes, for example longitudinally extended rods, to which a high-frequency alternating voltage is applied.

As long as the particles can only follow the high-frequency oscillations of the electric field with a delay due to their mass inertia and the gradient of the electric field in the transverse directions does not become too large, the charged particles in the inhomogeneous alternating field of a Paul trap lead to a fast oscillation (micromotion, micromotion) with the frequency of the applied AC voltage and a significantly slower drift movement (secular motion) in the inhomogeneous electrical field, with the slow secular movement dominating on average over time. The secular movement always takes place in the direction in which the magnitude of the electric field decreases the most, so that the charged particles can be included in all transversal directions at those locations where the magnitude of the inhomogeneous alternating field is at a minimum.

If the permissible amplitude of the micromovement and thus the stability of the entire particle movement is determined, the strength of the transverse inclusion of the charged particles in a linear Paul trap is proportional to the frequency and amplitude of the alternating electric field. A strong transverse confinement therefore requires high frequencies and amplitudes. This applies in particular to light particles, such as electrons, which react quickly to changes in the electrical field over time and therefore require even higher frequencies for stable confinement than heavier particles, for example ions.

A stable inclusion of light particles is therefore only possible with great technical difficulties and requires alternating fields with frequencies in the high gigahertz range and powers of several 100 W. Such alternating fields can only be technically high due to the power losses occurring in the trap structures and the associated thermal load Effort can be used for entrapping charged particles.

It is an object of the invention to provide an electrode structure for guiding a charged particle beam, a system with such an electrode structure and a method for guiding a charged particle beam which strongly enclose the charged particle beam transversely. It is also a goal of the present invention to be able to deflect the beam in a simple manner over a small area.

These objects are achieved by an electrode structure, a system and a method according to the independent claims. Further developments are given in the dependent claims.

An electrode structure for guiding a beam of charged particles, for example an electron beam, along a longitudinal path has multipolar electrode configurations with DC voltage electrodes that are spaced apart from one another along the longitudinal path. The electrode arrangements are designed to generate static multipole fields centered around the path in transverse planes oriented perpendicular to the longitudinal path, the field strengths of the static multipole fields in the transverse planes each having a local minimum at the location of the path and with increasing distance from the location of the Increase path. Field directions of the static multipole fields vary periodically along the path with a period length, so that the particles propagating along the path are exposed to an inhomogeneous alternating electric field due to their own motion and experience a transverse restoring force in the direction of the longitudinal path on average over time.

The present invention is based on the knowledge that a transversal inclusion of charged particles can be generated not only with an alternating electric field, but also with static electric fields if the static electric fields vary periodically along the path and the particles move along the path move. In the rest system of the particles, the static electrical fields that change spatially along the path generate a temporally oscillating field which, on average over time, can create a transverse confinement in the same way as a dynamic alternating field of conventional multipole traps. An effective frequency with which the alternating field resulting from spatially successive static fields is given by the ratio of a longitudinal speed of the particles along the path and the period length with which the multipole fields vary along the longitudinal path.

Since the electrical multipole fields used for the transverse confinement are generated solely by static electrode voltages in the electrode structure according to the invention, the technical requirements for generating the trap fields are considerably reduced compared to alternating fields. In particular, no expensive and complex high-frequency sources and amplifiers are necessary for operating the electrode structure. Instead, the electrode voltages can be generated with simple DC voltage sources. Since the operation of direct voltage electrodes does not require an impedance-matched load, the electrical power losses on direct voltage electrodes are significantly lower than when using alternating voltage electrodes, and high electrode voltages can be generated with the direct voltage electrodes according to the invention in a much simpler way than with alternating voltage electrodes. For example, for an electrode voltage of 1 kV, which can be generated with open direct voltage electrodes with a conventional high voltage source with little effort, an alternating current output of 20 kW would be required with an impedance-matched termination with 50 ohms.

In order to generate a periodic variation of the field directions of the static multipole fields, the electrode structure can have direct voltage electrodes of the individual electrode arrangements arranged one behind the other along the longitudinal path. The electrode structure can include at least one row of DC voltage electrodes running along the longitudinal path. In particular, the electrode structure can comprise four or six rows of direct voltage electrodes running parallel to the path. The DC voltages of the individual rows applied to the individual DC voltage electrodes can vary periodically, for example change periodically. Within the period length, for example, two DC voltage electrodes can be arranged per row, which are alternately applied with a first and a second electrode voltage and have opposite polarities with respect to a reference potential, for example with respect to ground. DC voltage electrodes, which are arranged transversely next to one another in parallel rows, can also alternately have the first and second electrode voltage. A mean value of the first and second electrode voltages can be 0 V, so that the first and second electrode voltages have different polarities and the charged particles are exposed to an alternating field oscillating around the ground potential of 0 V due to their own motion. Alternatively, the mean value of the first and second electrode voltage can also be different from zero.

The DC voltage electrodes of the individual electrode arrangements can be arranged opposite one another in a first direction around the path. In this case, it is particularly possible for no DC voltage electrodes to be arranged laterally next to the path in a second direction oriented perpendicular to the first direction. This makes it possible to offset the DC voltage electrodes of successive electrode arrangements laterally in the second direction and thereby bend the path in the second direction. As an alternative, the DC voltage electrodes can also be arranged on only one side of the path or surround the path on all sides.

The DC voltage electrodes can each have the same longitudinal electrode length parallel to the longitudinal path. A base area of the direct voltage electrodes, which is formed in the conductor layer, can along the longitudinal path in each case through sides running parallel to the path be limited. Furthermore, the base areas can be delimited in the longitudinal direction by two opposite sides oriented perpendicular to the path. The base areas of the direct voltage electrodes of individual electrode arrangements can, for example, be rectangular, for example in sections in which the longitudinal path runs straight.

The electrode arrangements can generate multipole fields in the transverse planes, the dominant portion of which corresponds to a quadrupole field or a hexapole field or multipole fields of a higher order. The dominant portion of the generated multipole fields can also vary along the path, which enables a particularly pronounced structuring of the potential transversely enclosing the particles. The generated multipole fields can also be designed as mixed fields in which multipole components of at least two or more multipole orders are essentially equally strong and differ from one another, for example, by less than 20%, less than 10%, less than 5% or less than 1%.

In general, the individual multi-pole electrode arrangements each form multi-pole lenses with a longitudinally periodic, for example longitudinally alternating, polarity. The multipole lenses can be, for example, quadrupole lenses or hexapole lenses. The electrode arrangements accelerate the charged particles in the transverse planes each along at least one spatial axis in the direction of the path and along at least one further spatial axis away from the location of the path. Due to the periodic variation of the electrode voltages of the direct voltage electrodes along the path, the polarity of the multipole lenses produced changes in each case, so that the charged particles experience periodically changing accelerations in each spatial direction.

In order to create a stable inclusion of the charged particles perpendicular to the longitudinal path, the electrode voltages can be adjusted to the dimensions Solutions of the DC voltage electrodes and the speed of the charged particles must be adapted so that a stability parameter derived from a harmonic component of the electrical alternating field defines an operating point within the stability range of a linear multipole trap, for example a linear quadrupole trap.

The stability range of an ideal linear quadrupole trap is described, inter alia, in Section II. A. of the publication Leibfried et al. : "Quantum dynamics of single trapped ions", Rev. Mod. Phys., Vol. 75, p. 281 ff., 2003. According to this, the stability parameter derived from the alternating electric field results in an ideal linear quadrupole trap where Q is the charge of the particles, M is their mass, 2UAC is the amplitude of the alternating voltage applied to the electrodes, W is the frequency of the alternating voltage and R is the distance between the quadrupole electrodes and the location of the longitudinal path.

The stability parameter q _AC is derived from an ideal transverse quadrupole field with field amplitudes where x, z are the coordinates in the transverse plane and y are the coordinates along the longitudinal path. Such an ideal quadrupole field is generated by the linear quadrupole trap sketched in FIG. 1 with hyperbolic electrodes.

In the context of the invention it was recognized that this stability parameter can be transferred to the present electrode structure if U _{AC is} replaced by half the voltage difference U _{DC of} the static electrode voltages and the frequency W is set as W-2p-. I denote? _J the longitudinal le velocity of the particles and L _{P is} the period length with which the electrode voltages of the direct voltage electrodes vary along the longitudinal path. In addition, scaling has to be carried out with a geometry factor h <1, which describes the deviations of the multipole field generated by the DC voltage electrodes from a longitudinally homogeneous ideal quadrupole field.

For the present electrode structure, the stability parameter of the alternating field generated by the intrinsic movement of the electrons then results where R is the minimum path distance of the longitudinal path from the DC electrodes.

If the charged particles were accelerated with an acceleration voltage U _A before being fed into the electrode structure, their longitudinal velocity is v ₁ In this case the stability _{parameter q DC can} also be written as

To calculate the geometry factor h, the square of the amount of the electric field that the DC voltage electrodes generate in the transverse planes oriented perpendicular to the path is averaged over a period length L _P and with the square of the time-averaged field amount of the electric field E _x , E _y , E _z compared to the ideal linear quadrupole trap. In addition, the square of the magnitude of the electric field of the direct voltage electrodes averaged over the period length L _P in transverse planes oriented perpendicular to the path around the location of the longitudinal path with a quadratic function of the shape 2 4 U ²

El ² = h ( ² + z ² ) i? ^{4 can be} approximated.

In order to produce a stable transverse confinement of the charged particles, in the electrode _{structure according to the invention the period length L p} , the minimal distance R of the path from direct voltage _{electrodes and the direct voltage U DC} applied to the direct voltage electrodes are adapted to the longitudinal velocity v / of the guided particles that the stability parameter q _DC assumes a value that defines an operating point within the stability range of a linear quadrupole trap. The stability range and its dependence on q _DC are, inter alia, in Section II. A and FIG. 1b) of the above-mentioned publication by Leibfried et al. described. For electrode arrangements that generate a pure alternating field on average over time without a superimposed direct voltage field, the stability range includes all values 0 <q _D c - 0.92.

The transverse movement of the charged particles in the vicinity of the path can also be described by a ponderomotive restoring force in the direction of the path. In general, such a ponderomotive force describes the time-averaged drift movement of charged particles in an oscillating inhomogeneous electromagnetic alternating field. It is given by the low-frequency component of the force that a spatially inhomogeneous high-frequency electromagnetic field exerts on a charged particle. The ponderomotoric force is proportional to the transverse gradient of the time-averaged field amount and can be determined by a scalar ponderomotor potential be described, where (E ² ) denotes the field strength of the electric field averaged over an oscillation period. For the electrode structures according to the invention, (E ² ) is for each point that is oriented perpendicular to the path transverse planes given by an average value of the square of the absolute value of the electrical field, the average values being formed in the longitudinal direction over a period length L _P.

A stable inclusion of the charged particles along the longitudinal path is then achieved in the electrode structure according to the invention in that the field amount or the field strengths of the static multipole fields generated by the electrode arrangements have a local minimum at the location of the path. As a result, the ponderomotive potential also has a local minimum at the location of the path, in which the charged particles are enclosed by the transverse restoring force oriented in the direction of the path.

The ponderomotive potential is independent of the sign of the charge of the charged particles. In this respect, the charged particles guided in the electrode structure can be both negatively charged particles, for example electrons, and positively charged particles, for example ions. The electrode structure can in particular be used in an electron microscope for guiding an electron microscope beam.

The multipole fields generated by the electrode arrangements can also have a higher order multipole component instead of a quadrupole component in the lowest order. For these cases, the stability parameter of the alternating field can be used, as in D. Gerlich: "Inhomogeneous RF fields: a versatile tool for the study of processes with slow ions" in Advances in Chemical Physics: State- Selected and State-to-State lon- Molecule Reaction Dynamics. Part 1. Experiment, vol. 82, John Wiley & Sons, 1992, pp. 42, generalized to where n is the order of the multipole field. For an alternating field, which according to the invention is generated by the proper movement of the particles, then results

Consequently, with the electrode structure according to the invention, the period length L _P , the minimum distance R of the path from direct voltage _{electrodes and the direct voltage U DC} applied to the direct voltage electrodes can generally be adapted to the longitudinal velocity v / of the guided particles in such a way that the stability parameter q assumes a value , which defines an operating point within the stability range of a linear multipole of the nth order. Here, n can be the lowest or dominant multipole order of the static multipole fields generated by the electrode arrangements.

The electrode arrangement can be designed to enclose in a transversely stable manner all charged particles whose longitudinal energy E _kin = QU _{A of} an acceleration voltage U _A between 0 V and 500 kV, for example between 0 V and 100 kV, 0 V and 50 kV, 0 V and 30 kV, 0 V and 10 kV, 0 V and 5 kV or 0 V and 1 kV. Alternatively or additionally, U _A can also be at least 1 V, at least 10 V, at least 100 V or at least 1 kV.

The electrode arrangement can enclose the charged particle beam transversely over a length of at least 0.1 mm, 1 mm, 10 mm, 50 mm or 100 mm and / or at most 300 mm, 500 mm or 1000 mm.

The electrode arrangements can be designed to include the charged particle beam transversely over the entire length of the electrode structure. The electrode arrangements can guide the beam as a single beam. In this case, all charged particles, which travel along the lon- The longitudinal path is guided out of the electrode arrangement at the same point. The longitudinal path can, for example, be curved in one or two transverse directions.

Alternatively, the electrode arrangements, in particular the shape and / or the spacing and / or the number of DC voltage electrodes of the individual electrode arrangements, can change along the longitudinal path in such a way that the transverse potential generated by the electrode arrangements exhibits structural changes along the path. For example, the number of local minima of the electric field strength of the multipole fields can change along the path, so that the path splits transversely into two or more partial paths and the charged particles entering the electrode structure are divided into at least a first and a second part for example emerge from the electrode structure at different points

The multipole fields can change in particular in transversal planes spaced apart by the period length along the path, with, for example, a lowest and / or dominant order of the multipole fields and / or a strength of the multipole fields varying. This enables a particularly simple structural change in the transverse potenti as generated by the electrode arrangements. The change in the multipole fields in transversal planes, which are spaced apart with the length of the period, is superimposed on the periodic variation of the field directions of the static multipole fields. The change can take place via a change length which is greater than the period length with which the field directions of the static multipole fields vary periodically. For example, the length of change can be at least five times, at least ten times, at least 20 times or at least 50 times greater than the period length. Alternatively or additionally, a radius of curvature of a curvature of the longitudinal path resulting from the change can be greater than a minimum radius of curvature, with a The centrifugal force acting on the surface corresponds to the transverse restoring force in the ponderomotive potential, which acts on the charged particles on average over time.

According to one embodiment, the electrode structure comprises electrode arrangements formed as a fork, the electrode arrangements of the fork varying along the path in such a way that the path can be split into a first partial path and a second partial path, so that a first part of the charged particles along the first Partial path and a second part of the charged particles can be performed along the second partial path. By means of the bifurcation, the charged particles are guided, in particular trapped transversely, along the first and second partial paths, so that a loss-free splitting of the particle beam is made possible. Since the transversal inclusion of the charged particles is effected by static electric fields and such static fields have no effect on the quantum mechanical coherence of the particle beam, the charged particle beam can also be split up coherently.

The partial paths can be split at an angle of at most 1 °, at most 0.6 °, at most 0.1 °, at most 0.05 °, at most 0.01 ° or at most 0.005 ° in the area of the fork. The smaller the angle at which the partial paths split, the lower the excitations that the charged particles experience in the transverse ponderomotive potential, and the lower the losses in the area of the fork.

According to one embodiment, a dominant multipole component of the static multipole fields of the electrode arrangements is formed by a quadrupole component on an input side of the path and / or on the respective output sides of the partial paths in the transversal planes. The dominant multipole component can be caused by a multipole development of the electric field in the transversal planes and is given by the lowest non-zero multipole tensor, in the case of a quadrupole component that is, by the quadrupole tensor of the multipole expansion. Since the transverse curvature of the electric field and thus also the strength of the time-averaged restoring force of the ponderomotive potential decreases with increasing multipole order and a quadrupole field is the field with the lowest multipole order with a field minimum in the center, the charged particles become trans with a dominant quadrupole component Versal particularly strongly included.

According to one embodiment, the electrode arrangements each comprise three direct voltage electrodes arranged next to one another in a transverse direction with an inner electrode and two outer electrodes arranged on both sides of the inner electrode, the inner and outer electrodes of the individual electrode arrangements forming three rows of electrodes running along the longitudinal path a transverse width of the inner electrodes is increased along the longitudinal path.

With such electrode arrangements, a transverse trap minimum centered on the input side about the longitudinal path can be split in a simple manner into two separate transverse trap minimums centered about the first and second partial path. The increase in the transverse width of the inner electrode leads to a continuously increasing transverse distance between the partial paths.

According to one embodiment, the fork is set up to split the entering charged particles simultaneously into the first and second parts of charged particles and at the same time to guide the first part of charged particles along the first partial path and the second part of charged particles along the second partial path. Such a fork thus forms a beam splitter for the charged particles guided along the path. With such a fork For example, the charged particle beam can be split evenly into a first part and a second part.

Since the fork is completely realized by static electric fields, the particle beam can be split up in a quantum-mechanically coherent manner, so that the quantum-mechanical wave functions of the charged particles propagating along the first and second partial paths have a fixed phase relationship to one another. In addition, from a quantum mechanical point of view, such a fork can form an amplitude beam splitter in which the quantum mechanical wave functions of the particles in the two partial paths, in particular their amplitudes and phases, are determined solely by the geometry of the transverse ponderomotive potential and the wave functions of the exiting particles are determined independently of the Coherence properties of the particles entering the fork are.

In order to maintain the quantum mechanical state of motion of the particles in the transverse ponderomotive potential during the splitting of an amplitude beam splitter, the angle at which the partial paths split can be selected, depending on the longitudinal speed of the particles, in particular in such a way that the energy of the transverse excitation in the area of the fork is smaller than an energy difference of quantum states in the transversal ponderomotive potential, for example smaller than an energy difference between the two lowest-energy quantum states of the ponderomotor potential.

A fork that splits the charged particle beam into the first and second parts at the same time can be implemented, for example, with the electrode arrangements whose DC electrodes are arranged in the three rows of electrodes running along the longitudinal path and in which the transverse width of the inner electrodes is aligned along the longitudinal path enlarged. For this purpose, the outer electrodes of the individual electrode configurations can each have the same electrode voltage, the electrode voltage of the outer electrodes differing from the electrode voltage of the inner electrode.

According to a further development of the fork, a dominant multipole component of the static multipole fields of the electrode arrangements is formed in at least one transversal plane by a hexapole component. A hexapole field is the lowest order multipole field with which a point of intersection of the ponderomotive potential can be realized, at which the longitudinal path splits into the first and second partial path. As a result, the charged particles in a fork realized by means of a hexapole field are particularly strongly transversely enclosed and therefore stimulated particularly little transversely during the splitting in comparison to a fork which is based on multipole components of a higher order.

According to one embodiment, the fork is set up to guide the charged particles entering selectively either as the first part along the first partial path or as the second part along the second partial path. The fork can therefore be operated as a kind of switch. In this case, the first part of the charged particles guided along the first partial path and the second part of the charged particles guided along the second partial path are formed by parts of a beam of charged particles entering the electrode structure propagating one after the other along the longitudinal path. A fork designed as a switch makes it possible to guide the charged particles along the first or second partial path in a targeted manner. The partial paths can be components of a larger, branched network of individual paths along which the charged particles are guided and interact with one another, for example interact quantum mechanically. Such ge Targeted interactions are required, for example, to implement quantum computers.

If the electrode structure has the direct voltage electrodes arranged next to one another in three rows, the fork in the form of a switch can be implemented, for example, in that the inner electrodes of the individual electrode assemblies are optionally connected to the direct voltages of the outer electrodes on a first side of the inner electrodes or to the DC voltages of the outer electrodes can be applied to a second side of the inner electrodes which is opposite the first side.

According to a further development, the static multipole fields generated by the electrode arrangements vary along the path in such a way that only first charged particles and not second charged particles experience stable inclusion along the path, the first charged particles having a longitudinal first velocity and the second charged particles have a second longitudinal speed different from the first speed. The electrode arrangements thus act as an energy filter, which only allows the first charged particles to pass. In this respect, the present invention also relates generally to a use of the electrode structure described or its developments as an energy filter for charged particles guided along a longitudinal path.

As follows from the above representation of the stability parameter q _DC =, the stability of the particle trajectories, unlike conventional multi-pole traps, does not depend on the charge-to-mass ratio of the charged particles, but solely on the acceleration voltage U _A and thus on the longitudinal energy of the charged particles. The electric multipole fields can alternate along the longitudinal path about an average multipole field of zero. In this case, the electrode arrangement acts as a high-pass filter, the high-energy, but does not conduct low-energy charged particles. The electrode arrangements only conduct charged particles with energies that result from acceleration voltages U _A for which q _DC <0.92 applies.

In a further development, the multipole fields alternate along the path by a mean multipole field that is different from zero, so that the particles guided along the path, in addition to the inhomogeneous alternating electric field, are exposed to an inhomogeneous static overlay field defined by the mean multipole field and only the first charged particles and the second charged particles do not make stable transverse oscillation along the path. The mean multipole field can in particular be a quadrupole field as a first approximation.

In the case of a linear multipole trap, such a static superimposed field would correspond to a bias voltage of the longitudinal electrodes with a static multipole voltage, for example with a static quadrupole voltage in the case of a linear Paul trap. At high particle energies, such a bias reduces the value range of q _DC in which the charged particles perform stable oscillations around the center of the trap. An electrode arrangement in which the multipole fields oscillate around a multipole field other than zero therefore acts as a bandpass filter which only transmits charged particles with longitudinal energies from a value range limited on both sides.

A first stability parameter derived from the alternating field and a second stability parameter derived from the superimposed field can define an operating point for the first charged particles within the stability range of a linear multipole trap, for example a linear quadrupole trap, and for the second charged particles an operating point outside the stability range of the linear multipole trap . The first corresponds to the stability parameter the stability parameter q _DC , while the second stability parameter derived from the superposition field for a quadrupole trap is given by

U ₀ denotes the mean value by which the electrode voltages alternate along the longitudinal path.

The second stability parameter a _{DC of} the quadrupole trap can be generalized to an nth order multipole field in the same way as the first stability parameter q _DC , and is then given by

With given values for U _DC and U ₀ , the stability parameters and thus the operating point of the electrode structure depend only on the longitudinal energy of the particles or the acceleration voltage U _A. All operating points for a given ratio U ₀ / U _DC lie on a straight line through the origin in the stability diagram. By adapting the ratio U ₀ / U _DC , the slope of this straight line and thus the transmission range of the implemented energy filter can be varied. The values of U _DC and U ₀ can be selected in such a way that the _{degree of origin given by the ratio U 0} / U _DC intersects the stability range only over a predetermined length or, within the scope of the measurement accuracy, only in a single point. In the case of, for example, multipole fields designed as quadrupole fields as a first approximation, this point is at q _DC = 0.706 and a _{DC max} = 0.237. This then leads to the fact that only charged particles, the longitudinal energies of which are in a predetermined value range or correspond to a predetermined value, pass the electrode structure along the longitudinal path. The specified range of values or the specified value can be changed by varying the ratio U ₀ / U _DC .

According to one development, the period length of the longitudinal variation of the field directions of the static multipole fields is less than 60 mm, for example less than 10 mm, 6 mm, 1 mm or 0.1 mm. The smaller the period length, the smaller the stability parameters q _DC , a _DC or q _n , a _n , which leads to less micromovement and thus to more stable trajectories. In addition, a small period length enables the charged particles to be guided in a stable manner even at high longitudinal energies.

According to a further development, a longitudinal distance between the individual electrode arrangements is less than 10 mm, for example less than 1 mm,

0.5 mm, 0.1 mm, 0.05 mm or 0.01 mm. The smaller the distances between the individual electrode arrangements, the greater the field amount averaged over a period length of the multipole fields generated by the electrode arrangements. A reduction in the distances therefore leads to an increase in the ponderomotive potential and thus also to a stronger transverse confinement of the charged particles.

According to a further development, the electrode arrangements are arranged directly adjacent to one another along the longitudinal path. As a result, the distances between the individual electrode arrangements can be particularly small and the transverse ponderomotive potential can be particularly large. In the case of electrode arrangements directly adjoining one another, the DC voltage electrodes of adjacent electrode arrangements can be arranged next to one another, in particular without intervening spacer electrodes, for example without intervening ground electrodes. According to a further development, the electrode arrangements have the same distances from one another along the longitudinal path. In the rest system of the charged particles, the alternating electrical field generated by the DC voltage electrodes then varies regularly along the path and approximates a harmonic oscillation particularly well.

According to a further development, a longitudinal length of the electrode structure along the path is at least 1 mm, 10 mm, 50 mm or 100 mm and / or at most 300 mm, 500 mm or 1000 mm. As a result, the electrode structure is on the one hand compact enough to be used in conventional electron microscopes or mass spectrometers, on the other hand it is large enough to allow sufficient deflection of the beam along the longitudinal path and, for example, complete splitting of the particle beam.

According to one development, the DC voltage electrodes are formed in at least one conductor layer oriented parallel to the path and structured along the path. This enables simple production and alignment of the DC voltage electrodes relative to one another. The arrangement of the DC voltage electrodes in such a conductor layer also allows the potential generated by the DC voltage electrodes to be structured in a small area.For example, the longitudinal path can be curved in one or two transverse directions or the path can split transversely into two or more partial paths . In this respect, a fork or a beam splitter for splitting a beam of free charged particles can also be implemented in a simple manner with the present electrode structure.

The conductor layer for forming the electrodes consists of an electrically conductive material, for example a metal or semiconductor material. The conductor layer can for example comprise gold or copper, in particular at least on a surface facing the charged particles. The conductor layer can have minimum structure sizes of at most 1 mm, 100 gm, 50 gm, 10 gm or 1 gm. For example, the width of the insulating gaps between individual DC voltage electrodes can correspond to the minimum structure sizes mentioned. The conductor layer can for example have been structured by means of a microfabrication technique such as lithography, laser processing or electron beam cutting.

According to a further development, the DC voltage electrodes are formed in two conductor layers arranged at a distance from one another, the conductor layers being aligned, for example, parallel to one another. Compared to a conductor layer arranged only on one side of the path, which is basically also possible within the scope of the invention, stronger multipole fields and thus also a stronger transverse ponderomotive potential can be generated with two conductor layers spaced apart from one another. The conductor layers arranged so as to be spaced apart from one another can be arranged, for example, on two opposite sides of the longitudinal path.

According to one development, the DC electrodes of the electrode assemblies in the two conductor layers are mirror-symmetrical to one another, DC electrodes lying opposite one another in the two conductor layers having, for example, opposite polarities. Such electrode arrangements generate a particularly uniform and strong multipole field. Direct voltage electrodes lying opposite one another in the two conductor layers can generally also have different electrode voltages, the electrode voltages being able to be of the same polarity as well as of different polarity.

For example, the individual electrode arrangements in each conductor layer can have two direct voltage electrodes arranged transversely next to one another have, with different electrode voltages, for example different electrode voltages of the same amount and opposite polarity, have within the individual conductor layers transversely next to one another arranged DC voltage electrodes. In such electrode arrangements, the generated multipole field forms, as a first approximation, a quadrupole field which generates a harmonic transverse ponderomotive potential.

Alternatively, the individual electrode arrangements in each conductor layer can also have three direct voltage electrodes arranged transversely next to one another, with different electrode voltages within the individual conductor layers having different electrode voltages, for example different electrode voltages of the same amount and opposite polarity. In this case, the generated multipole field can, in a first approximation, form a hexapole field, by means of which a point of intersection for splitting the particle beam can be realized.

In a further development, the structured conductor layer is arranged on a surface running parallel to the longitudinal path, the surface being, for example, a flat surface or a surface curved around the longitudinal path. This allows a particularly simple production and relative alignment of the direct voltage electrodes formed in the structured conductor layer. Likewise, a further conductor layer opposite the structured conductor layer can be arranged on a further surface running parallel to the longitudinal path.

In a further development, the structured conductor layer is arranged on a carrier structure, for example on a carrier plate or carrier film. The carrier structure can, for example, form a substrate to which the conductor layer is applied. Coating methods with which the conductor layer can be applied to the substrate include, for example, a chemical or physical vapor deposition, doctor blade coating, electroplating or the like. The carrier structure stabilizes the conductor layer and, in addition to the conductor layer, can also comprise further conductor structures, for example feed lines for making contact with the DC voltage electrodes.

In a further development, a feed line which contacts individual DC voltage electrodes of the electrode arrangements is formed in a further conductor layer of the support structure that runs parallel to the conductor layer and is connected to the DC voltage electrodes via through-contacts running through the support structure. As a result, direct voltage electrodes arranged in the vicinity of the longitudinal path can be contacted without disturbing or deforming the multipole fields generated by the direct voltage electrodes by the electrical field of the supply lines.

In a further development, several supply lines in the further conductor layer run parallel to one another along the longitudinal path, the supply lines being connected alternately to the DC voltage electrodes of the individual electrode arrangements, for example. As a result, DC voltage electrodes arranged longitudinally one after the other, for example arranged longitudinally in a row, can be acted upon in a particularly simple manner with DC voltages whose electrode voltages vary periodically along the path.

In a further development, the DC voltage electrodes of the individual Electrode arrangements can each be acted upon with two oppositely polarized DC voltages. The multipole generated by the electrode arrangements can then be designed as symmetrical with respect to a common ground potential of the two oppositely polarized DC voltages, so that the longitudinal path is then also at ground potential. The charged particles can then be field-free along the longitudinal path Space areas lying at ground potential enter the electronic structure without being excited transversely.

A system with the electrode structure according to the claims and an acceleration device is also specified, the acceleration device being set up to accelerate the charged particles with a predetermined acceleration voltage and then to feed them along the longitudinal path into the electrode structure and with the acceleration voltage and on Electrode voltages applied to the multi-pole electrode arrangements are matched to one another in such a way that the accelerated charged particles, on average over time, execute stable transverse oscillation around the location of the longitudinal path. In particular, the acceleration voltage and the electrode voltages can be matched to one another in such a way that the stability _{parameters q DC} and a _DC define an operating point within the stability range of a linear multipole trap, for example within the stability range of a linear quadrupole trap.

To generate the at least one electrode voltage applied to the DC voltage electrodes, the system can also include one or more DC voltage sources, for example high voltage sources.

According to a further development, the acceleration device is set up to accelerate several types of charged particles, for example simultaneously, to the acceleration voltage and to feed them into the electrode structure along the longitudinal path. Since the stability of the particle trajectories along the longitudinal path depends only on the acceleration voltage U ^ with which the charged particles were accelerated before entering the electrode structure, but not on the mass or the charge-to-mass ratio of the individual charged particles the electrode structure is designed to transversely load simultaneously charged particles of different mass and / or charge to lead closed. As a result, chemical reactions at low particle energies or quantum mechanical interactions involving various types of charged particles can be carried out with the present electronic structure.

According to one development, the system is designed as an electron microscope and the charged particle beam is an electron microscope beam for irradiating a microscope object. The present invention therefore relates in particular to the use of the electrode structure according to the claims in an electron microscope. In this respect, all the advantages and developments that are disclosed in connection with the electrode structure according to the claims also relate to the use of the electronic structure in an electron microscope and vice versa.

The electrode structure according to the claims makes it possible, for example, to improve a conventional electron microscope in such a way that the electron beam can be easily deflected or split transversely. If the electron beam is split up, the microscope object can be examined with two separate coherent electron beams, for example, and in particular an interaction of the microscope object with one of the coherent electron beams can be detected on the basis of changes in the other coherent electron beam.

Several of the electrode structures according to the claims can also be cascaded, so that charged particles emerging from a preceding electrode structure enter a subsequent electrode structure. The electrode structures can each include bifurcations designed as beam splitters, so that a particle beam entering the cascaded electrode structures is split into a plurality of partial beams, in particular into more than two partial beams. A method for electrostatically guiding a beam of charged particles along a longitudinal path is also specified, the method comprising the following steps:

Providing the electrode structure according to the claims;

Applying the DC voltage electrodes of the electrode arrangements with electrode voltages which vary periodically along the longitudinal path, so that charged particles propagating along the path are exposed to an oscillating inhomogeneous alternating field due to their own motion and experience a transverse restoring force in the direction of the longitudinal path on average over time;

Feeding the charged particles along the longitudinal path into the electrode structure; and

Guiding the charged particles along the longitudinal path by means of the transverse restoring force.

All advantages and developments which are disclosed in connection with the electrode structure according to the claims also relate to the method according to the claims and vice versa. In particular, the method can include accelerating the charged particles with a predetermined acceleration voltage. The specified acceleration voltage and the electrode voltages arranged on the DC voltage electrodes can be coordinated with one another in such a way that the stability _{parameters q n} and a _n or q _DC and a _DC an operating point within the stability range of a linear multipole trap, for example within the stability range of a linear quadrupole trap, define.

The invention is explained below with reference to figures. In each case show a schematic representation: 1 shows a linear quadrupole trap according to the prior art;

Fig. 2 shows a system for guiding a charged particle beam with an electrode structure;

Fig. 3 is a perspective view of a first embodiment of the electrode structure;

4 shows a plan view of a first conductor layer of the electrode structure;

5 shows a section through the electrode structure in one of the transverse planes;

6 shows a ponderomotive potential generated by the electrode structure;

7 shows a plan view of a conductor layer of an electrode structure according to a second embodiment;

8 shows a plan view of a further conductor layer of the electrode structure according to the second embodiment;

9 shows a detailed view of supply lines on an input side of the electrode structure according to the second embodiment;

10 shows a detailed view of leads on an output side of the electrode structure according to the second embodiment;

11 shows experimental detector signals for detecting electrons on the output side of the electrode structure according to the second embodiment;

12 shows experimental detector signals for the detection of helium ions on the output side of the electrode structure according to the second embodiment;

13 shows an intensity of the detector signal of a guided beam of electrons as a function of an acceleration voltage and an electrode voltage;

14 shows an intensity of the detector signal of a guided beam of heli umionen as a function of the acceleration voltage and the electrode voltage; 15 shows a plan view of a conductor layer of a third embodiment of the electrode structure;

16 shows a contacting of DC voltage electrodes of the electrode structure according to the third embodiment;

17 shows a stability diagram of the electrode structure according to the third embodiment;

18 shows a plan view of a first conductor layer of a fourth embodiment of the electrode structure formed as a fork;

19 shows a transverse section through an electrode arrangement of the fork treatment;

20 transverse sections through ponderomotive potentials of the gift;

21 shows detector signals for detecting electrons on the exit side of the fork;

22 shows a contacting of direct voltage electrodes of a first conductor layer of an alternative embodiment of the fork;

23 shows a plan view of a first conductor layer of a further alternative embodiment of the fork;

24 shows a use of the bifurcation in an electron microscope.

2 shows a system 1 for guiding a beam 10 of charged particles along a longitudinal path 20. The system 1 comprises an accelerator 60 for accelerating the charged particles with a predetermined acceleration voltage 62 and an electrode structure 100 with a planar structure arranged along the path 20 Conductor layer 212. After the charged particles have been accelerated in the acceleration device 60 with the acceleration voltage 62, they enter a ponderomotive potential generated by the conductor layer 212 along the path 20 on an input side 150 of the electrode structure 100, which the charged particles along the path 20 in directions perpendicular to the path 20 transversely a closes. After the charged particles have crossed the transversely enclosing pondromotor potential along the path 20, they leave the potential on an output side 152 of the electrode structure 100. The electrode structure 100 shown in FIG deflect transversely along a curve.

The system 1 also includes a DC voltage source 75, which is connected to the electrode structure 100 and provides all of the electrode voltages 51, 52 necessary to generate the ponderomotori potential for the DC voltage electrodes of the electrode structure 100 (not shown in FIG. 2). Furthermore, the system 1 comprises an acceleration voltage source 73 which is connected to the acceleration device 60 and which provides the acceleration voltage 62.

The direct voltage source 75 and the acceleration voltage source 73 are connected to a control device 70, which specifies the acceleration voltage 62 and the electrode voltages 51, 52 applied to the direct voltage electrodes of the electrode device 100 and coordinates them in such a way that the charged particles along the path 20 have stable trajectories within of the ponderomotive potential.

3 shows a section of a perspective illustration of a first embodiment of the electrode structure 100, in which the path 20, along which the charged particles 11 are guided at a longitudinal speed 16, runs straight in a longitudinal direction 101. The electrode structure 100 comprises a planar first conductor layer 212 and a planar second conductor layer 222 arranged opposite one another of the first conductor layer 212 in a height direction 103 oriented perpendicular to the longitudinal direction 101. hen direction 103 a distance 201 of 1 mm from each other. The conductor layers 212, 222 extend along the longitudinal direction 101 and along a transverse direction 102 oriented perpendicular to the longitudinal direction 101 and the height direction 103.

In alternative embodiments of the electrode structure 100, the distance can generally also be less than 10 mm, less than 5 mm, less than 1 mm, less than 0.5 mm, less than 0.1 mm, less than 0.05 mm or less than 0 .01 mm.

The first conductor layer 212 comprises a first row 251 of direct voltage electrodes 120 running along the longitudinal direction 101 and a second row 252 of direct voltage electrodes 120 running parallel to the first row 251 in the transverse direction 102 longitudinal direction 101 arranged alternately as first DC voltage electrodes 121 and DC voltage electrodes 120 formed as second DC voltage electrodes 222. In the transverse direction 102, the first and second DC voltage electrodes 121, 122 are each arranged in pairs next to one another. The first and second DC voltage electrodes 121, 122 each have opposite polarities with respect to ground, the first DC voltage electrodes 121 being acted upon by a first DC voltage 51 provided by the DC voltage source 75 and the second DC voltage electrodes 122 being acted upon by a second DC voltage 52 provided by the DC voltage source 75 . The DC voltages 51, 52 are polarized in opposite directions with respect to ground and have the same amount of voltage U _DC with respect to ground, so that the first _DC voltage 51 + f / DC and the second DC voltage 52 -U _DC .

In the second conductor layer 222, the DC voltage electrodes 120 are also if in a first row 251 and a second row 252 along the longitudinal Nal direction 101 arranged, wherein the first and second rows 251, 252 of the first and second conductor layer 212, 222 are opposite one another in the device 103 height direction. In the rows 251, 252 of the second conductor layer 222, direct voltage electrodes 120 formed alternately as first counter-electrodes 123 and second counter-electrodes 124 are arranged in the longitudinal direction 101. In the height direction 103, the first counter electrodes 123 lie opposite the first DC voltage electrodes 121 of the first conductor layer 212 and the second counter electrodes 124 lie opposite the second DC voltage electrodes 122 of the first conductor layer 212. The first counterelectrodes 123 have the second direct voltage 52 and the second counterelectrodes 124 have the first direct voltage 51 applied to them.

4 shows a plan view of the first conductor layer 212. The direct voltage electrodes 120 are arranged in the two rows 251, 252 at a distance 111 of 1.4 mm from one another and have an electrode length 141 of 1.3 mm in the longitudinal direction 101 on. The DC voltage electrodes 120 are formed in a ground area 125 of the first conductor layer 212 and are electrically insulated from the ground area 125 by insulating gaps 129. A period length 112 with which the direct voltages of the direct voltage electrodes vary along the longitudinal direction 101 is L _P = 2.4 mm, two direct voltage electrodes 120 being arranged one behind the other in the longitudinal direction 101 within the period length 112. Overall, the electrode structure 100 has a length 105 of, for example, 100 mm in the longitudinal direction 101.

Direct voltage electrodes 121, 122 arranged next to one another in transverse direction 102, together with counter-electrodes 123, 124 lying opposite one another in height direction 103, each form electrode arrangements 110, which are arranged in transverse planes 30 running centrally through electrode arrangements 110 and perpendicular to longitudinal direction 101 around generate the path 20 centered static quadrupole fields. Between the individual electrode arrangements 110, the ground surface 125 forms ground electrodes which separate the DC voltage electrodes 120 of the individual electrode arrangements 110 from one another along the longitudinal direction 101.

5 shows a section through the electrode structure 100 in one of the transverse planes 110. In the transverse direction 102, the DC voltage electrodes 120 each have an electrode width 140 of 1.4 mm. The insulating gap 129, which surrounds the DC voltage electrodes 120, has a gap width 142 of 0.1 mm. The longitudinal path 20, along which the charged particles 11 are trapped transversely, lies in a central plane 108 between the first and second conductor layers 212, 222 and each has a path distance 106 of Ro = 0.5 mm from the conductor layers 212, 222. As shown in FIGS. 3 to 5, the first and second conductor layers 212, 222 are designed mirror-symmetrically with respect to the center plane 108.

The first conductor layer 212 is arranged on a first surface 211 of a first carrier structure 210 and the second conductor layer 222 is arranged on a second surface 221 of a second carrier structure 220. On the sides opposite the surfaces 211, 221, the carrier structures 210, 220 each have further conductor layers 214, 224, in each of which a first lead 215 and a second lead 216 are formed. The leads 215, 216 run in the conductor layers 214, 224 along the longitudinal path 20, respectively.

The first lead 215 has the first electrode voltage 51 applied to it, and the second lead 216 has the second electrode voltage 52 applied to it. The first DC voltage electrodes 121 and the second counter-electrodes 124 are connected to the respective first supply lines 215 of the conductor layers 214, 224 via vias 218, which each run through the carrier structures 210, 220 and the second DC voltage electrodes 122 and the second counter electrodes 124 are connected via analog vias 218 to the respective second leads 216 of the conductor layers 214, 224.

The individual electrode arrangements 110 each form quadrupole lenses centered around the path 20 with longitudinally alternating polarity. In the rest system of the charged particles 11 propagating along the path 20, the electrode arrangements 110 generate an oscillating quadrupole field with an effective frequency W | _{m ze} jt | j _C h _en means experience the charged particles

L _p Lp

11 shows a transverse restoring force in the direction of the path 20, which is described by the ponderomotive potential.

In Fig. 6 the ponderomotive potential Y - shown which the Electrode structure 100 shown in Figures 4 and 5 in the transversa len planes 30 for electrons with a kinetic energy of 1 keV (UA = 1 kV) and electrode voltages 51, 52 of U _DC = +100 V generated. The mean value (E ² ) of the square magnitude of the electric field was formed over a period length 112, the square magnitude of the field being formed from all three spatial field components E _x , E _y , E _z along the direction 101, 102, 103. As a first approximation, the ponderomotive potential Y forms a harmonic potential which generates a linear restoring force in the direction of the path 20 in all directions 102, 103 perpendicular to the longitudinal path 20.

FIG. 7 shows a second embodiment of the electrode structure 100, in which the charged particles 11 are guided along an S-shaped path 20. In this case, a plan view of the first conductor layer 212 of the electrode structure 100 is shown in FIG. 7. Insofar as there are no differences from the figures and the description, the second embodiment shown in FIG. 7 is the Electrode structure 100 is formed, as disclosed in connection with the first embodiment shown in FIGS. 3 to 5, and vice versa.

The electrode structure 100 has a first contact surface 217 on a longitudinal side, which via a through-hole contact 218 with the first supply line

215 on the other conductor layer 214 opposite to the first conductor layer 212 is electrically conductively connected, and a contact surface 219 which is electrically conductively connected via a further through-hole contact 218 to the second lead 215 on the further conductor layer 214.

8 shows a plan view of the further conductor layer 214 of the second embodiment of the electrode structure 100. The viewing direction is oriented counter to the height direction 103, so that a side of the further conductor layer 214 facing the first carrier structure 210 can be seen. The leads 215,

216 run side by side along the longitudinal path 20, the first feed line 215 branching out into two sub-lines arranged on both sides of the second feed line 216. The partial lines of the first feed line 215 and the second feed line 216 each run in a meandering manner alongside one another along the path 20.

9 shows a detailed view of the leads 215, 216 on the input side 150 of the electrode structure 100 and FIG. 10 shows a detailed view of the leads 215, 216 on the output side 152 of the electrode structure 100 DC voltage electrodes 120 formed first conductor layer 212 are shown in dashed lines. The second DC voltage electrodes 122 are successively connected in an electrically conductive manner via the plated-through holes 218 to the second feed line 216 running between the two sub-lines of the first feed line 215. The partial lines of the first supply line 215 are each alternating with the first DC voltage electrodes 121 along the longitudinal direction 101 via vias 218 of the individual electrode arrangements 110 are electrically conductively connected. The contacting of the DC voltage electrodes 121, 122 shown in FIGS. 8 to 10 can also take place analogously in the first embodiment of the electrode structure 100.

FIGS. 11a and 11b show experimental detector signals for the detection of electrons with a kinetic energy of 2.5 keV, which emerge on the output side 152 from the ponderomotive potential of the S-shaped electrode structure 100 according to the second embodiment. When the detector signal shown in Fig. 11a was recorded, the DC voltage electrodes 120 were connected to ground potential (UDC = 0 V), while electrode voltages of UDC = 410 V were applied to the DC voltage electrodes 120 when the detector signal shown in Fig. 11b was recorded. If the DC voltage electrodes 120 are at ground potential, the electrons emerge from the electrode structure 100 as an unguided beam 15. At electrode voltages of UDC = 410 V, on the other hand, all electrons are guided as a transversely enclosed beam 10 along the path 20, so that they emerge from the electrode structure 100 laterally offset from the position of the unguided beam 10 in the transverse direction 102.

FIGS. 12a and 12b show analog detector signals for helium ions for the same acceleration voltage 62 of 2.5 kV. As can be seen from FIGS. 11a / b and 12a / b, the transverse inclusion of the charged particles in the transverse ponde romotor potential generated by the electrode structure 100 is independent of the mass of the charged particles 11 with the same acceleration voltage 62.

Fig. 13 shows the intensity 80 of the detector signal of the guided beam 10 of electrons as a function of the acceleration voltage 62 and the Electrode voltages 51, 52 and Fig. 14 shows the corresponding intensity 80 of the detector Led steel 10 gate signal of helium ions. As can be seen from FIGS. 13 and 14, both types of charged particles 11 are stably guided along the longitudinal path when the stability parameter qoc given by the ratio of electrode voltage UDC and acceleration voltage UA is between 0.4 and 0.9. In Figures 13 and 14, the effective frequencies ü = ²ⁿ ^ ^{2 QUA} f ^M _ are given, which for the respective

L _p gene particle results from the acceleration voltage UA, which determines the kinetic energy of the particles. Further experimental investigations have shown that the stated limits of the stability parameter qoc are also valid for ions of greater mass, for example for neon, argon, krypton or xenon ions.

As can be seen from FIG. 13, effective frequencies of more than 5 GHz, in particular of more than 6.5 GHz, can be generated for electrons. Alternative embodiments of the electrode structure 100 with shorter period lengths 112 can also be designed to generate frequencies of more than 10 GHz, for example of more than 50 GHz, 100 GHz, 500 GHz or 1 THz, effective for electrons. For example, with a period length 112 of 56 pm for electrons with a kinetic energy of 1 keV, an effective frequency of 330 GHz can be generated.

15 shows a plan view of the first conductor layer 212 of a third embodiment of the electrode structure 100. Unless there are differences from the figures and the description, the third embodiment of the electrode structure 100 is designed as disclosed for the first embodiment and vice versa. In the third embodiment of the electrode structure 100, the DC voltage electrodes 120, unlike in the first embodiment, are arranged directly adjoining one another along the longitudinal path 20. In particular, the third embodiment of the electrode structure 100 has none in the longitudinal direction 101 between the individual electrode arrangements 110 arranged sections of the ground plane 125. Instead, the individual DC voltage electrodes 120 are spaced apart in the longitudinal direction 101 by a longitudinal spacing 111 which corresponds to the gap width 142 between the DC voltage electrodes 120 and the ground plane 125. In principle, all other described embodiments of the electrode structure 100 can also have DC voltage electrodes 120 which, as shown in FIG. 15, are arranged directly adjacent to one another.

The third embodiment of the electrode structure 100 shown in FIG. 15 is also designed to generate multipole fields designed as quadrupole fields in the transverse planes 30, which alternate along the path 20 by a multipole field which is different from zero and is also designed as a quadrupole field. This is achieved in that electrode arrangements 110 lying next to one another along the longitudinal direction 101 each generate multipole fields with opposite polarity and different field magnitudes.

For this purpose, first DC voltage electrodes 131 with a first electrode voltage U ₀ + U _DC and second DC voltage electrodes 132 with a second electrode voltage U _{0 -} U _DC are alternately arranged in the first row 251, the first and second electrode voltages having _{a first mean value U 0} . In the second row 252 alternately third DC voltage electric are the 133 with a third electrode voltage -U ₀ - and fourth U _DC DC clamping voltage electrodes 134 with a fourth electrode voltage -U ₀ + U _DC angeord net, wherein the third and fourth electrode voltage a second mean -U _{Have 0} . The first and second mean values are symmetrical around the ground potential of 0 V. Alternatively, the first and second mean values can also be symmetrical around a potential other than zero, which causes an electrical potential at the location of path 20 that is different from zero. In the transverse direction 102 side by side DC voltage electrodes 120 are each either as first DC voltage electrodes 131 with the first electrode voltage U ₀ + U _DC and as third DC voltage electrodes 133 with the third electrode voltage -U _{Q -} U _DC or as second DC voltage electrodes with the second electrode voltage U _{0 -} U _DC and fourth DC voltage electrode 134 with the fourth electrode voltage -U ₀ + U _DC formed. As with the first and second embodiment of the electrode structure 100, the third embodiment of the electrode structure 100 also comprises counter-electrodes which are opposite the DC voltage electrodes 120 in the height direction 103, with electrodes lying opposite one another in the height direction 103 as well as in the transverse direction Direction 102 next to each other arranged electrodes each have different electrode voltages.

Making them the first DC voltage electrodes 131 in the height direction 103 opposite counter electrode with the third electrode voltage -U _{0 -} loaded U _DC and the third DC voltage electrodes 133 opposite in the height direction 103 counter electrodes with the first electric denspannung U ₀ + U _DC. Analogously, the second DC voltage electrodes applied to the 132 in the height direction 103 opposite the counter electrodes with the four th electrode voltage -U ₀ + U _DC and the fourth DC clamping voltage electrode 134 in the height direction 103 opposite Gegenelekt roden with the second electrode voltage U _{0 -} U _DC.

FIG. 16 is a schematic diagram showing the contacting of the disposed in the first conductor layer 212 DC voltage electrodes 120 by the first electrode voltage U ₀ + U _DC leading first lead 135, a second electrode voltage U _{0 -} U _DC leading second supply line 136, a third Electrode voltage -U _{Q -} U _DC leading third lead 137 and a fourth electrode voltage -U _Q + U _DC leading fourth lead 138. The leads 135, 136, 137, 138 each run parallel to one another in the further conductor layer 214 on the side of the carrier structure 210 opposite the first conductor layer 212 and are electrically conductively connected to the DC voltage electrodes 120 of the first conductor layer 212 by means of individual vias 218.

The first and second mean values ± U _{0 of} the electrode voltages generate a quadrupole field centered around path 20 and homogeneous along path 20, which as an overlay field generates a non-zero stability parameter a _DC = ^h * ^u °. As a result, only charged particles are left

11, the kinetic energies of which lie in an energy range limited on both sides, stably guided along the longitudinal path 20.

This is illustrated by FIG. 17, which shows a stability diagram 400 of the electrode structure according to the third embodiment, the stability diagram corresponding to the stability diagram of a linear quadrupole trap. A stability range 405 comprises all value pairs from the first stability parameter 401 (q _DC ) and the second stability parameter 402 (a _DC ), for which the charged particles 11 propagate on stable trajectories along the path 20. The stability range 405 is limited for large values of the first stability parameter 401 by a first stability limit 407 and for small values of the first stability parameter 401 by a parabolic second stability limit 408 running through the origin. The stability limits 407, 408 intersect at a vertex 409 which defines a maximum value 422 of the second _{stability parameter 402 of a DC max} = 0.237 and an assigned value 423 of the first stability parameter 401 of q _DC = 0.706.

With a given ratio U ₀ / U _DC , the operating parameters for all acceleration voltages U _{A are} on a working line 410, which is a straight line through the origin with a gradient of 2U ₀ / U _DC . Individual acceleration voltages U _A or partial Chene energies then define operating points 411, 412 on the working line 410, the operating points 411, 412 moving away _{from the origin with decreasing acceleration voltage U A} or particle energy. A first operating point 411 shown in FIG. 17 thus corresponds to a first acceleration voltage and the second operating point 412 also shown corresponds to a higher, second acceleration voltage.

A passage area 415, which is defined by the intersection of the stability area 405 with the working line 410, then determines the particle energies at which the charged particles 11 execute stable trajectories in the ponderomotive potential of the electrode structure 100. The larger the ratio U ₀ / U _DC is selected, the narrower the pass band 415. Without the static superimposed field, a _DC = 0 and the electrode structure 100 acts as a high-pass filter, with a maximum value 421 of the first stability parameter 401 being qoc ax = 0 _* 92 is defined.

18 shows a representation, not true to scale, of a first conductor layer 212 of a fourth embodiment of the electrode structure 100. Unless there are differences from the figures and the description, the fourth embodiment of the electrode structure 100 shown in FIG the first embodiment shown in Figures 3 to 5 is disclosed and vice versa.

The fourth embodiment of the electrode structure 100 is designed as a fork 300 to guide the charged particles along a path 20 which splits into a first partial path 21 and a second partial path 22. In the first conductor layer 212, the individual electrode arrangements 110 each include three DC voltage electrodes 120 arranged next to one another in the transverse direction 102, the DC voltage electrodes 120 along the longitudinal direction 101 in an inner row of electrodes 320 and in two outer electrode rows 330, 340 running in the transverse direction 102 on both sides of the inner electrode row 320 are arranged. The individual DC voltage electrodes 120 have a length of 550 μm in the longitudinal direction 101 and a spacing of 750 μm from one another. The electrode structure 100 has a length 105 of 113 mm along the longitudinal direction 101.

The fork 300 forms a beam splitter which splits the charged particles 11 simultaneously into a first part propagating along the first partial path 21 and into a second part propagating along the second partial path 22. Denspannung to the DC electrodes 120 of the individual electrode rows 320, 330, 340 are in the longitudinal direction 101 alternately a first electric + f / _DC, and an oppositely polarized second electrode clamping voltage -U _DC applied. _{In addition, the first and second electrode voltages + U DC} , -U _DC , are alternately applied to the DC voltage electrodes 120 of the individual electrode arrangements 110, which are arranged next to one another in the transverse direction 102, so that in the transverse direction 102 adjacent DC voltage electrodes 120 are each different Have electrode voltage.

19 shows a transverse section perpendicular to the longitudinal direction 101 through one of the electrode arrangements 110 of the fork 300. The fork 300 comprises a flat second conductor layer 222, which is arranged parallel to the first conductor layer 212 at a distance 201 of 1 mm. The electrode structure of the second conductor layer 222 corresponds to the electrode structure of the first conductor layer 212 mirrored at the center plane 108.

In the first conductor layer 212, the direct voltage electrodes 120 of the first outer electrode row 330 each form first outer electrodes 331 and the direct voltage electrodes 120 of the second outer electrode row 340 Second outer electrodes 341 in each case. Inner electrodes 321 of the inner electrode row 320 are arranged between the outer electrodes 331, 341. In the second conductor layer 222, first outer counter-electrodes 332 are arranged, which are opposite the first outer electrodes 331 of the first conductor layer 212, second outer counter-electrodes 342, which are opposite the second outer electrodes 341 of the first conductor layer 212, and inner counter-electrodes 322, which are the inner electrodes 321 of the first conductor layer 212 are opposite.

At the fork 300, the DC electrodes 321, 331, 341 of the first conductor layer 212 and the counter electrodes 322, 332, 342 opposite the individual DC electrodes 321, 331, 341 have different electrode voltages. For example, if the two outer electrodes 331, 341 of the first conductor layer 212 have the first electrode voltage + U _DC and the inner electrode 321 has the second electrode voltage -U _DC , then the two outer counter-electrodes 332, 342 are at the second electrode voltage -U _DC and the inner counter electrodes 322 at the first electrode voltage + U _DC . In the case of electrode arrangements 110 arranged longitudinally adjacent to such an electrode arrangement 110, the two outer electrodes 331, 341 and the inner counter-electrodes 322 then have the second electrode voltage -U _DC and the inner electrode 321 and the two outer counter-electrodes 332, 342 have the first electrode voltage + f / _DC on.

On the sides of the carrier structures 210, 220 facing away from the conductor layers 212, 222, the fork 300 has two first leads 215 _{carrying the first electrode voltage + f / DC and two second leads 216 carrying the second electrode voltage -U DC} , the first and second Supply lines 215,

216 each run along the longitudinal direction 101 and are arranged alternately next to one another in the transverse direction 102. Analogous to the leads 215, 216 of the electrode structure 100 according to the second embodiment shape, the feed lines 215, 216 of the fork 300 run meander-shaped along the longitudinal direction 101. The feed lines 215, 216 arranged on the inside of the first carrier structure 210 each contact either one of the outer electrodes 331, 341 or the inner electrode 321, 322 alternately , while the two externally arranged supply lines 215, 216 are alternately connected in the longitudinal direction 101 to every second first or second outer electrode 331, 341. The counterelectrodes 322, 332, 342 are contacted on the second carrier structure 220 in an analogous manner.

As shown in FIG. 18, the DC voltage electrodes 120 of the inner electrode row 320 widen continuously along the longitudinal direction 101. On the input side 150, the inner electrodes 321, 322 have a transverse width 325 of 300 μm and on the output side 152 a transverse width 325 of 2.2 mm. The outer electrodes 331, 332, 341, 342 each have a constant transverse width 335 of 1.4 mm along the longitudinal direction 101.

The fork 303 is designed to generate a multipole field with a dominant quadrupole component in the transverse planes 310 located on the input side 150. The corresponding ponderomotive potential 44 is shown in a transverse section in FIG. 20 a and has a single minimum at the location of the longitudinal path 20. In the center of the fork 300, the electrode arrangements 110 generate a multipole field with a dominant flexapole portion due to the widening of the central electrodes 321, 32 in a transverse plane 311. The associated ponderomotive potential 44 is shown in FIG. 20b and has two minima spaced apart along the transverse direction 102 at the location of the two partial paths 21, 22. At the output side 152, the fork 300 generates a multipole field in a transverse plane 312, the dominant components of which are two quadrupole fields with two centers spaced apart along the transverse direction 102 at the location of the partial paths 21, 22. The associated The ponderomotive potential 44 is shown in FIG. 20c and has two minima at the location of the two partial paths 21, 22, which have a significantly greater transverse distance from one another than the two minima of the potential shown in FIG. 20b.

The ponderomotive potentials 44 shown in FIGS. 20a, 20b, 20c were each _{calculated for an electron beam with a longitudinal energy of 800 eV and for a voltage amplitude of U DC} = 210V. 21 a shows a corresponding detector signal with an electron beam split into a first part 12 and a second part 14. For comparison, Fig. 21a shows an experimental detector signal with grounded DC voltage electrodes 120, which only detects a single unguided beam 15 of electrons.

With the voltage loading described above, the fork 300 splits the entering beam 10 of charged particles simultaneously into the first and second parts 12, 14. According to an alternative embodiment, the fork treatment 300 can also be designed to selectively split the incoming beam 10 of charged particles either into the first part 12 propagating along the first partial path 21 or into the second part 14 propagating along the second partial path 22, so that the fork acts as a switch.

A selective splitting is possible, for example, if the fork 300 is designed to supply either the electrode voltage of the transversely adjacent first outer electrodes 331, 332 or the electrode voltage of the transversely adjacent second outer electrodes to the individual inner electrodes 321 and the corresponding counter-electrodes 322 Electrodes 341, 342 to apply. If the electrode voltage of the transversely adjacent first outer electrodes 331, 332 is applied to the inner electrodes 321, 322, the charged particles follow the path along the second outer electrodes 341, 342. If, on the other hand, the electrode voltage of the transversely adjacent second outer electrodes 341, 342 is applied to the inner electrodes 321, 322, the charged particles follow the first partial path 21 running along the first outer electrodes 331, 332.

22 shows a contacting of the direct voltage electrodes 120 of the first conductor layer 212 of the fork 300, with which the described selective splitting of the beam 10 along the first or second partial path 21, 22 is possible. The fork 300 includes a first lead 351 and a second lead 352 for each of the electrode rows 320, 330, 340, the leads 351, 352 being arranged in the further conductor layer 214 and alternating in the longitudinal direction 101 via vias 218 with the direct voltage electrodes 120 of the individual rows 320, 330, 340 are connected.

The first leads 351 of the outer rows of electrodes 330, 340 each carry the first electrode voltage and the second leads 352 of the outer rows of electrodes 330, 340 each carry the second electrode voltage. In the inner row of electrodes 320, either the first lead 351 can be supplied with the first electrode voltage and the second lead 352 with the second electrode voltage or the first lead 351 with the second electrode voltage and the second lead 352 with the first electrode voltage. In the first-mentioned case, the inner electrodes 321 and the first outer electrodes 331 are at the same electrode voltage and the charged particles follow the second partial path 22 along the second row of outer electrodes 340. In the second-mentioned case, the inner electrodes 321 and the second outer electrodes 341 are located on the same electrode voltage and the charged particles follow the first partial path 21 along the first outer row of electrodes 330. The counter electrodes are contacted in an analogous manner such that electrodes opposite one another in the height direction 103 have different and opposite electrode voltages. 23 shows a further alternative embodiment of the fork 300, with which a beam of charged particles entering along the path 20 can be guided selectively along the first or second partial path 21, 22. Insofar as there are no differences from the figures or the description, the further alternative embodiment of the fork 300 shown in FIG. 23 is designed like the alternative embodiment shown in FIGS. 18, 19 and 22 and vice versa.

The fork 300 illustrated in FIG. 23 has a first group 115 of electrode arrangements 110 which are arranged along the first path 21 and a second group 116 of electrode arrangements 110 which are arranged along the second partial path 22. In this case, only the DC voltage electrodes of the electrode arrangements 110 arranged in the first conductor layer 212 are shown in FIG. 23. The electrode arrangements 110 of the first group 115 and the electrode arrangements 110 of the second group 116 are each arranged alternately along the longitudinal direction 101. The fork 300 is designed to selectively apply either the direct voltage electrodes of the first group 115 of electrode arrangements 110 with the first and second direct voltage in order to guide the charged particles along the first partial path 21, or the direct voltage electrodes 120 of the second group 116 to apply the first and second direct voltage of electrode arrangements 110 in order to guide the charged particles along the second partial path 22.

Compared to the alternative embodiment, described in connection with FIG. 22, of the fork formed as a switch and contacted, the further alternative embodiment shown in FIG. 23 does not require supply lines to one and the same DC voltage electrode 120 to be optionally applied with the first or second DC voltage. Instead, the in Fig. 23 further alternative embodiment shown, all DC voltage electrodes to be connected only to a single voltage source, whose output can be optionally connected to a single electrode voltage or to ground.

24 shows a use of the fork 300 described in connection with FIGS. 18 to 21 and designed as a beam splitter in an electron microscope 500. The electron microscope 500 comprises an acceleration device 60 which generates an electron beam 10 and accelerates it with the acceleration voltage UA. After exiting the acceleration device 60, the electron beam 10 is imaged on the output side 152 of the fork 300 on the output of the first partial path 21 by means of beam optics 510, which comprise several electron lenses 512, so that the electrons are enclosed transversely along the first partial path 21 to the Propagate entrance side 150 of fork 300.

On the input side 150 of the fork 300, an electron game 513 is arranged, which reflects the electrons propagating along the path 20 back into the gift 300. Within the fork 300, the electron beam 10 is then split into a first component propagating along the first partial path 21 and a second partial beam propagating along the second partial path 22. The first part is imaged by the beam optics 510 back in the direction of the acceleration device 60, the second part onto a microscope object 520.

With such an arrangement, the fork 300 can coherently split the quantum mechanical wave functions of the electrons after reflection at the electron mirror 513 into transverse quantum states of the first and second partial paths 21, 22. These coherent quantum states can then be used to only use the microscope object 520 in the manner of the quantum Zeno effect image minimal interaction between the electron beam 10 and the Mikrosko pieobjekt 520. The measurement method is based on the fact that the presence of the microscope object 520 prevents the electrons from spreading in the second partial path 22. Due to the coherence of the wave functions, this can then be detected in that a higher proportion of the electron beam 10 is reflected back from the electron mirror 513 into the first partial path 21 than would be the case in the absence of the microscope object 520.

Reference list

1 system

10 beam

11 charged particle

12 first part

14 part two

15 unguided beam

16 longitudinal speed

20 longitudinal path

21 first partial path

22 second partial path

30 transverse plane

44 ponderomotive potential

51 first electrode voltage

52 second electrode voltage

60 Accelerator

62 Accelerating Voltage

70 control device

73 Accelerating voltage source

75 DC voltage source

80 intensity

100 electrode structure

101 longitudinal direction

102 transverse direction

103 Altitude Direction

105 length

106 Path spacing

108 middle level

110 electrode arrangements 111 longitudinal distance

112 period length L _p 115 first group

117 second group

120 DC voltage electrodes

121 first DC voltage electrode

122 second DC voltage electrode

123 first counter electrode

124 second counter electrode

125 ground plane 129 insulating gap

131 first DC voltage electrode

132 second DC voltage electrode

133 third DC voltage electrode

134 fourth DC voltage electrode

135 first lead

136 second supply line

137 third supply line

138 fourth feed line

140 electrode width

141 electrode length

142 gap width

150 Entry side 152 Exit side 201 Distance

210 first support structure

211 first surface

212 first conductor layer

214 additional conductor layer

215 first leads 216 second supply lines

217 first contact surface

218 via

219 second contact surface

220 second support structure

221 second surface

222 second conductor layer

224 further conductor layer

251 first row

252 second row

300 fork

310 transverse plane

311 transverse plane

312 transverse plane

320 inner row of electrodes

321 inner electrode

322 inner counter electrode

325 transverse width

330 first outer row of electrodes

331 first outer electrode

332 first outer counter electrode

335 transverse width

340 second outer row of electrodes

341 second outer electrode

342 second outer counter electrode

351 first feed line

352 second supply line

400 stability diagram

401 first stability parameter

402 second stability parameter 405 stability area

407 first stability limit

408 second stability limit

409 vertex 410 working line

411 first working point

412 second working point 415 pass band

421 Maximum value of the first stability parameter 422 Maximum value of the second stability parameter

423 the value of the first stability parameter 500 associated with the maximum value of the second stability parameter. Electron microscope 505 beam source 510 beam optics

512 electron lens

513 electron mirror 520 microscope object

Claims

Expectations

1. Electrode structure (100) for guiding a beam (10) of charged particles

(11), for example an electron beam, along a longitudinal path (20), wherein the electrode structure (100) along the longitudinal path (20) has mutually spaced multipole electrode arrangements (110) with direct voltage electrodes (120), which are set up vertically to the longitudinal path (20) oriented transverse planes (30) around the path (20) to generate centered static multipole fields, the field strengths of the static multipole fields in the transverse planes (30) each having a local minimum at the location of the path (20) have and increase with increasing distance from the location of the path (20), field directions of the static multipole fields along the path (20) vary periodically with a period length (112), so that the particles (11) propagating along the path (20) due to their Self-movement are exposed to an inhomogeneous alternating electric field and a transverse restoring force on average over time t in the direction of the longitudinal path (20).

2. Electrode structure (100) according to claim 1, wherein the electrode structure (100) as a fork (300) comprises Electrode arrangements (110), wherein the electrode arrangements (110) of the fork (300) vary along the path (20) in such a way that the path (20) into a first partial path (21) and can be split into a second partial path (22), so that a first part (12) of the charged particles (11) along the first partial path (21) and a second part (14) of the charged particles (11) along the second partial path (22) can be performed.

3. Electrode structure (100) according to claim 2, wherein on an input side (150) of the path (20) and / or on respective output sides (152) of the partial paths (21, 22) in the transverse planes (30) a dominant multipole component of the static Multipole fields of the electrode arrangements (100) is formed by a quadrupole component.

4. Electrode structure (100) according to one of claims 2 to 3, wherein the electrode arrangements (110) of the fork (300) each have three DC voltage electrodes (120) arranged next to one another in a transverse direction (102) with an inner electrode (321, 322) and two outer electrodes (331, 332, 341, 342) arranged on both sides of the inner electrode (321, 322), the inner and outer electrodes (321, 322, 331, 332, 341, 342) of the individual electrode arrangements (110 ) form three rows of electrodes (320, 330, 340) running along the longitudinal path (20, 21, 22), a transverse width (325) of the inner electrodes (321, 322) increasing along the longitudinal path (20).

5. The electrode structure (100) according to any one of claims 2 to 4, wherein the fork (300) is configured to split the incoming charged particles (11) simultaneously into the first and second parts (12, 14) of charged particles (11) and simultaneously to guide the first part (12) of charged particles (11) along the first partial path (21) and the second part (14) of charged particles (11) along the second partial path (22).

6. Electrode structure (100) according to claim 5, wherein a dominant multipole component of the static multipole fields of the Electrode arrangements (110) of the fork (300) in at least one transversal plane (30) is formed by a hexapole component.

7. The electrode structure (100) according to any one of claims 2 to 4, wherein the fork (300) is set up to selectively accept the incoming charged particles (11) either as the first part (12) along the first partial path (21) or as the to lead the second part (14) along the second Teilpfa of (22).

8. The electrode structure (100) according to any one of the preceding claims, wherein the static multipole fields generated by the electrode arrangements (110) vary along the path (20) such that only first charged particles (11) and not second charged particles (11) have a stable one Experience inclusion along the path (20), the first charged particles (11) having a first longitudinal velocity and the second charged particles (11) having a second velocity different from the first longitudinal velocity.

9. The electrode structure (100) according to claim 8, wherein the multipole fields along the path (20) alternate by a mean multipole field different from zero, so that the particles (11) guided along the path (20) in addition to the inhomogeneous alternating electrical field are exposed to inhomogeneous static superimposition field defined by the central multipole field and only the first charged particles (11) and not the second charged particles (11) perform stable transverse oscillation along the path (20).

10. The electrode structure (100) according to claim 9, wherein a first stability parameter (401) derived from the alternating field and a second stability parameter (402) derived from the superimposed field for the first charged particles (11) have an operating point within the stability range (405) linear multipole trap and define an operating point for the second charged particles (11) outside the stability range (405) of the linear multipole trap.

11. Electrode structure (100) according to one of the preceding claims, wherein the period length (112) of the longitudinal variation of the field directions of the static multipole fields is less than 60 mm, for example less than 10 mm, 6 mm, 1 mm or 0.1 mm.

12. Electrode structure (100) according to one of the preceding claims, wherein a longitudinal distance (111) between the individual electrode arrangements (110) is less than 10 mm, for example less than 1 mm, 0.5 mm, 0.1 mm, 0, 05 mm or 0.01 mm.

13. The electrode structure (100) according to any one of the preceding claims, wherein the electrode arrangements (110) are arranged directly adjacent to one another along the longitudinal path (20).

14. Electrode structure (100) according to one of the preceding claims, wherein the electrode arrangements (110) along the longitudinal path (20) have the same distances (111) from one another.

15. Electrode structure (100) according to one of the preceding claims, wherein a longitudinal length (105) of the electrode structure (100) along the path (20) is between 1 mm and 1000 mm, for example between 10 mm and 500 mm.

16. Electrode structure (100) according to one of the preceding claims, wherein the DC voltage electrodes (120) are formed in at least one parallel to the path (20) oriented and structured along the path (20) Lei terschicht (221, 222).

17. Electrode structure (100) according to one of the preceding claims, wherein the DC voltage electrodes (120) are formed in two spaced voneinan the conductor layers (212, 222), the conductor layers (212, 222) being aligned, for example, parallel to one another.

18. Electrode structure (100) according to claim 17, wherein the DC voltage electrodes (120) in the two conductor layers (212, 222) are mirror-symmetrical to each other, wherein each other in the two conductor layers (212, 222) opposite de DC voltage electrodes (120), for example opposite Po show larities.

19. The electrode structure (100) according to one of claims 16 to 18, wherein the structured conductor layer (221, 222) is arranged on a continuous surface (211, 221) running parallel to the longitudinal path (20), the surface (211, 221) is, for example, a flat surface or a surface curved around the longitudinal path (20).

20. Electrode structure (100) according to one of claims 16 to 19, wherein the structured conductor layer (212, 222) is arranged on a carrier structure (210, 220), for example on a carrier plate or carrier. gerfolien.

21. The electrode structure (100) according to claim 20, wherein a lead (215, 216, 135, 136, 137, 138), which contacts individual DC voltage electrodes (120) of the electrode arrangements (110), in a parallel to the conductor layer (212, 222) extending further conductor layer (214, 224) of the carrier structure (210, 220) and is connected to the DC voltage electrodes (120) via vias (218) extending through the carrier structure (210, 220).

22. The electrode structure (100) according to claim 21, wherein a plurality of leads ((215, 216, 135, 136, 137, 138) in the further conductor layer (214, 224) run parallel to one another along the longitudinal path (20) and, for example, alternately with the DC voltage electrodes (120) of the individual electrode assemblies (110) are connected.

23. Electrode structure (100) according to one of the preceding claims, wherein the direct voltage electrodes (120) of the individual electrode structures (110) can each be acted upon with two oppositely polarized direct voltages (50, 52).

24. System (1) with an electrode structure (100) according to one of the preceding claims and an acceleration device (60), wherein the acceleration device (60) is set up to supply the charged particles (11) with a predetermined acceleration voltage (62) accelerate and then feed along the longitudinal path (20) into the electrode structure (100), the acceleration voltage (62) and electrode voltages (50, 52) applied to the multi-pole electrode arrangements (110) in such a way are coordinated so that the accelerated charged particles (11), on average over time, execute stable transverse oscillation around the location of the longitudinal path (20).

25. System (1) according to claim 24, wherein the acceleration device (60) is configured to accelerate several types of charged particles (11), for example simultaneously, to the acceleration voltage (62) and along the longitudinal path (20) in feed the electrode structure (100).

26. System (1) according to one of claims 24 to 25, wherein the system (1) is designed as an electron microscope (500) and the charged particle beam (11) is an electron microscope beam for irradiating a microscope object (520).

27. A method for guiding a beam (10) of charged particles (11) along a longitudinal path (20) comprising the following steps:

Providing an electrode structure (100) according to one of claims 1 to 23;

Applying the DC voltage electrodes (120) of the electrode arrangements (110) with electrode voltages (50, 52) which vary periodically along the longitudinal path (20), so that charged particles (11) propagating along the path (20) cause an oscillating one due to their own movement inhomogeneous alternating electric field are set and, on average over time, experience a transverse restoring force in the direction of the longitudinal path (20);

Feeding the charged particles (11) along the longitudinal path (20) into the electrode structure (100); and

Guiding the charged particles (11) along the longitudinal path des (20) by means of the transverse restoring force.