SU1550589A1 - Electrostatic energy analyzer - Google Patents

Abstract

The invention relates to analytical instrumentation, in particular, to the technique of separation and energy analysis of beams of charged particles. The aim of the invention is to simultaneously increase the dispersion and resolution. The electrostatic energy analyzer contains a source of charged particles 1, their receiver 2, two parallel split plates 3, 4, separated by gaps in the form of parts of rings into symmetrical sections, and a screen. In the vicinity of the annular gaps, the particles are reflected and further focused and separated by energy. The potentials in pairwise symmetric regions are the same. Dispersions of the first three stages are reduced by increasing the last stage and therefore can reach very large values with high quality spatial focus. 4 il.

Description

Si

cn

about ate

00

The invention relates to analytical instrumentation, and more specifically to the technique of separation and analysis of the energy of beams of charged particles, and can also be used in mass spectrometry to achieve energy focusing.

The aim of the invention is to simultaneously increase the dispersion and resolution.

FIG. Figure 1 shows the multiscale garden energy analyzer with gaps

the form of parts of the rings, the projection on the red plane; in fig. 2 - the same distance to the plane perpendicular to the middle one; in fig. 3 — multi-stage energy analyzer with rings in the form of rings and parts of rings; distance to the middle plane: to shlg. 4 - the same, the projection onto a plane perpendicular to the average Electrostatic Energy Sector ™ 1ator (Fig. 1 and 2) consists of a source of 1 charged particles, their reception 2, two parallel split plates 3 and 4 , divided by the grooves i in the form of parts of rings with medium ranges R - R on electrodes 5–9, and ec) ana 10, which excludes ingress of charged particles directly from the source to the receiver. Each of Electrodes 5-9 consists of two sections with the same shape and size of the upper 3 and lower 4 plates. These segments are located symmetrically with respect to the median plane and Electrically interconnected. The potentials on the electrodes must be selected so as to provide the required power. the deflection of the beam, the passage of the yoke in all cascades and the focusing of particles in the right places. The slits form four groups, in each of which the centers of the slits lie on a common axis Perpendicular to the surfaces of plates 3 and 4 "The centers of the slits of the first Group lie on the axis 0, the second - Q, i the Third - Oj, the fourth - 0, Each group slots corresponds to one cascade of the analyzer. The cascades are separated by floor-free spaces. The course of the axial trajectory 11 of the beam being analyzed is shown in FIG. 1. The electrostatic energy analysis shown in FIGS. 1 and 2 works as follows.

A beam of charged particles leaving a source 1 with a certain

the energy to which the analyzer is tuned, falling into the field of the first cascade beam, is deflected by it and focused between the first and second cascades, forming an intermediate image 12. This image is aligned with the front main focus of the second cascade, which therefore forms

parallel beam in the interval between the second and third cascades. The third cascade collects the beam in the rear main focus 13, and the fourth cascade focuses it in the plane of the gap

receiver 2. Particles of other energies are deflected differently and do not fall into the receiver slit. By changing the energy settings of the analyzer, you can remove the energy spectrum. In order for the energy of the percy to accumulate from cascade to cascade, the following rule must be fulfilled: in the case where the beam between two adjacent cascades is parallel, they must

5 to deflect it in the same direction, if the beam is collected in an intermediate focus, into different ones. The linear dispersion of the energy of the analyzer shown in FIG. 1 and 2, is determined by the equality D (D + 2D.j) pc + D, where D and Ots. - linear dispersion of the energy of the first and fourth cascades; 2D is the total dispersion of identical second and third cascades; m 4 is the linear increase in the eventhance of the correct cascade. The linear increases of the first TP (and the fourth t of cascades are related by the equality m, 1 / m4, therefore the linear increase of the entire instrument is 1 ". The values of D (, D, D4, m

0 can be calculated using the formulas for aberration coefficients. Calculations performed on the BESM-6 showed that in the system under consideration with R4 5sOOd; R 6.36d; %

5 10.00d; R4 11.29 d when deflecting the whole beam path in each of the cascades by 90 ° and reaching the second focus on the angle of divergence of the beam D, 18.4 d; 2D3

0 37.6 d; D4 41.1 d; m4 2.23. Therefore, D 166.0 d; d is the distance between the electrode plates. While in the prototype the dispersions of individual cascades are simply

d is added up; in the proposed device, the dispersions of the first three cascades still increase the increase in the last cascade, and therefore the dispersion of the analyzer D reaches a very large i

their values. This circumstance, as well as the fact that the second order spherical aberration is compensated, makes it possible to create an instrument with a very high resolution.

Multistage electrostatic energy analyzer, of images in FIG. 3 and 4 also consists of a source 1, a receiver 2 and two electrode plates 3 and 4 separated by annular gaps with radii R ,, and R2 and gaps in the form of parts of rings with radii R on electrodes 5-8. The centers of the cracks lie on the axes. The axial trajectory of the beam of charged particles is indicated in FIG. 3 position 11.

The energy analyzer shown in FIG. 3 and 4, works like this. The beam of charged particles released from the source enters the field of electrodes 5–7 four times, is reflected and exits from it (four cascades), and three times is reflected in the fields of electrodes 5 and 8 (three more cascades), after which it enters the receiver. The dispersion of all seven cascades is summed by D 4 D, + 3 Vg, where D ,, is the linear dispersion of the cascades associated with the field of electrodes 5-7, and D4 - cascades with electrodes 5 and 8. For Rj 5.00 d; R4 6.34 d; R3 19.96 d and the deviation of the axial trajectory in the field of electrodes 5-7 at an angle of 90.0 the field of electrodes 5 and 8 164.4 ° D 2299 d; D 26,8 d; D - 172 d. The advantage of multi-stage anafft

505896

The lysator (Fig. 3 and 4) is its exceptional compactness.

The proposed implementation of multi-stage energy analyzers allows increasing their energy dispersion and, therefore, resolution. In the energy analyzer shown in FIG. 1 and 2, with dimensions of 560 x 230 x 10 mm D 1660 mm, in the analyzer shown in FIG. 3 and 4, D 1720 mm is achieved with overall dimensions of 300 x 280 x 10 mm. Since in the proposed device the source is placed outside the electrode system for a sufficient distance, no restrictions are imposed on its size and design.

ten

15

20

formula of invention

An electrostatic energy analyzer containing a source, a receiver of charged particles and an electrode system of two plane-symmetrical parallel to each other split plates with gaps, wherein the symmetric portions in each of the split plates are electrically connected in pairs and isolated from other portions, simultaneously increasing the variance and resolution in each of the two split

The slit plates are made in the form of rings or parts of rings, and at least part of the slits are made concentric.

Oz

fiv.1

Compiled by K.Menshikov Editor T.Parfenova Tehred M.Hodanich v Proofreader S.Shekmar

Order 277

Circulation 395

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5

Production and Publishing Combine Patent, Uzhgorod, st. Gagarin, 101

Subscription

Claims (1)

Claim An electrostatic energy analyzer containing a source, a charged particle receiver and an electrode system of two plane-symmetric parallel to one another split plates with slots, moreover, the symmetrical sections in each of the split plates are pairwise electrically connected and isolated from other sections, characterized in that, in order to simultaneously increase dispersion and resolution, in each of the two split plates, the slots are made in the form of rings or parts, at least partly centric. rings, moreover, on the edge