JP2022029437A - Non-contact DC ion beam source with hollow cylindrical cathode and deformation collimator - Google Patents

Abstract

To provide a non-contact DC ion beam source that generates a high-quality ion beam having high efficiency, a long life even at a high output, and excellent stability and focusing in principle.SOLUTION: A non-contact DC ion beam source includes an ion generation device, and a neutralizing device that can accelerate ions and add electrons to electrically convert them into a neutral plasma beam. Thermions emitted from a ribbon ring-shaped thermal cathode of the ion generation device are transported to a zero magnetic field region on the central axis along the radial magnetic field of a deformed collimeter, and accelerated in the anode direction along the axial magnetic field of the first deformed collimeter. A cascade discharge near the central axis on the anode side of the orifice ionizes filling gas by using the thermion as a seed electron. The generated cations penetrate the inside of the hollow cylindrical cathode along the axial magnetic field, are accelerated to the required value by the potential applied to the ribbon ring-shaped thermal cathode in the neutralizing device, and further, the beam is neutralized by the thermions from the ribbon ring-shaped thermal cathode along the radial magnetic field of the second deformed collimator.SELECTED DRAWING: Figure 1

Description

The present invention creates plasma by discharging the filled gas, separates cations from the plasma and accelerates them, and, if necessary, adds electrons to the accelerated ion beam to create an electrically neutral plasma beam. Ions are processed non-contact with the cathode, grid and other structures throughout the entire process of obtaining a particle beam, such as conversion, and as a result, high-quality ions with minimal deterioration of the device and excellent focusing even when operating at high output. It relates to a high-efficiency non-contact type DC ion beam source that stably generates a particle beam such as plasma or plasma with a simple structure.

Various ion beam generators have been developed that can be used for pre-stage ion sources of various accelerators, ion engines for interplanetary rockets, medical applications such as particle beam therapy, and industrial applications such as ion beam processing. Among them, the classic Geissler discharge tube method has the simplest structure of applying a DC potential difference between the cathode plate and the anode plate in a vacuum vessel, and is the origin of the ionizing device for filled gas, and ions such as plasma generation and ion accelerators. It is still widely used as a source. Since then, various methods have been developed for plasma discharge of the filling gas, such as a more efficient ion source and a high-frequency plasma source having no electrode in a magnetic field. For example, Patent Document 1 describes a high-frequency electrode device having an exciting electrode provided with an exciting surface, and a high-frequency electric field applied to an ion extraction electrode to extract a plasma beam generated by an electromagnetic field to generate positive plasma ions. Techniques for accelerating and extracting plasma beams are described.

However, with the Geisler method, which has the simplest structure, and the method of generating ions by high-frequency electromagnetic waves in a magnetic field that creates plasma with high efficiency, cations are separated from the plasma in order to accelerate the ions obtained by the discharge of the filling gas. When extracting or extracting accelerated cations from the system, only a part of the ion beam leaking from the holes provided in the cathode plate is adopted, or the mesh cathode is passed through the plasma generated by a high-frequency electric field. A method such as drawing out ions is used, and energy loss and deterioration of the device are inevitable as a result of the ions colliding with a structure such as a cathode. That is, due to the collision of the accelerated beam particles with the structure, the efficiency of ion beam particle generation is impaired by that amount, the structure is deformed by heating and quenching during long-term operation, and ions with a large momentum irradiate the structure. This causes problems such as brittleness and shape change in metal structures and the like.

Furthermore, if there is collision or contact of ions with the cathode, etc., the ion beam contains impurities derived from evaporation of structural materials, sputtering, etc., so there is a concern that the quality of the ion beam may deteriorate depending on the application. The invention also provides an effective solution to this. In addition, for future nanotechnology beam processing technology, which is expected to be one of the methods of using ion beams, it is desired to generate ion beams that have excellent focusing properties and make ultra-precise processing. For example, the radial emission of beam particles due to the dispersibility of ion generation points is one of the factors that hinder the improvement of beam processing technology.

Japanese Unexamined Patent Publication No. 2016-35925

The present invention follows the method of generating DC plasma by cascade discharge of filled gas by electron acceleration in a Geisler discharge tube having the simplest structure of only an anode plate and a cathode plate in a vacuum vessel, and separate oscillators and the like. Plasma is generated by DC discharge that does not require AC equipment or shielding of radio waves, linear acceleration by separating cations, and if necessary, electrons are added to the cation beam to make an electrically neutral DC. Throughout the entire process leading to the conversion to a particle beam, the ions are processed without contacting the cathode and other structures, resulting in high total energy efficiency, high output, steady operation for structural simplification, and beam focusing. It provides the principle of a non-contact DC ion beam source with excellent performance in terms of stability during long-term operation.

According to the present invention, in order to solve the above problems, the following ([1] to [] utilizing the hollow cylindrical cathode and the combination set of the ribbon ring-shaped hot cathode and the deformed collimeter magnetic field for both the ion generator and the neutralizing device. A non-contact DC ion beam source having the configuration of 7]) is provided. In the combination set proposed here, the unit is composed of a combination of a ribbon ring-shaped hot cathode and a deformed collimeter magnetic field, and the magnetic field of this unit has zero axial magnetic field on the central axis of the deformed collimeter magnetic field, and this zero magnetic field. A magnetic field spreads radially from the region along the curved surface of zero magnetic flux, and is connected to the thermoelectron generation region on the inner surface of the ribbon ring-shaped thermal cathode. This thermionic generation region is a domain where the inner surface of the cathode and the curved surface of zero magnetic flux intersect, and the cathode surface is subjected to oxide treatment to emit thermions. In the ion generator A, this set generates a thermionic flow, transfers it to the zero magnetic field region on the central axis, and changes it into an axial electron flow toward the anode, which is the most important in the present invention. Share one of the functions.

The modified collimator magnetic field of this combination set can form a unit having a relatively wide zero magnetic field region at the center of the coil in the magnetic field by the reverse Helmholtz coil shown in FIG. Further, even in the cusp magnetic field, which is a typical one having a zero magnetic field region at the center of the coil shown in FIG. 5, a unit with a simpler deformed collimator magnetic field can be configured. Depending on the purpose and application of the ion beam, a unit with a deformed collimator magnetic field suitable for either can be selected.

[1] The present invention is an ion generator that ionizes the filling gas in an axially symmetric manner and extracts ions from the ion generator, and the ions obtained there are accelerated to the required energy by applying a negative potential to the cathode of the device. If necessary, a neutralizing device that adds electrons to this to electrically convert it into a neutral plasma beam is installed on the same axis in the vacuum vessel, and both are connected by magnetic lines of force, an ion beam. Is a system that provides.

[2] The inner surface of the first ribbon ring-shaped hot cathode 14 in the ion generator is equipped with a line intersecting the zero magnetic flux curved surface and a set in the vicinity thereof which has been subjected to oxide treatment to facilitate thermionic emission. ing. The thermions emitted from this region are transferred to the zero magnetic field region near the central axis by the radial magnetic field along the radial magnetic field of the deformation collimator, and from here, the electric field in the axial magnetic field direction of the deformation collimeter causes the seed electrons in the anode direction. Induces a cascade discharge in a region that is accelerated and accelerated to sufficient energy for ionization of the filling gas.

[3] Ions generated by cascade discharge due to DC electric field near the central axis between the anode of the ion generator and the hollow cylindrical cathode coaxial with the anode are deformed along the axial magnetic field of the collimeter in the direction of the cathode. Accelerated in the direction of the cathode along the axial magnetic field of the collimator, it passes through the zero magnetic field region by inertia, and at the same time, it penetrates the hollow interior of the hollow cylindrical cathode in a non-contact manner along the axial magnetic field and neutralizes from the ion generator. It is discharged to the side of the device.

[4] It is required to avoid charge exchange and other collisions between the gas pressure of the filling gas required for discharging in the cascade discharge region of the ion generator and the filling gas in the ion acceleration region and the neutralizing device. The pressure difference from the low gas pressure is maintained by the differential exhaust through the orifice 15. The place where the ions are generated has a relatively high potential, and as a result, the ions pass through the zero magnetic field region by inertia, and as a result, the backflow of the ions in the direction following the electric field to the ribbon ring-shaped hot cathode is suppressed.

[5] Ions are accelerated to a required value by the potential difference from the hollow cylindrical cathode 13 applied to the second ribbon ring-shaped hot cathode 24 in the neutralizer.

[6] If required, activate a set of combinations of a second ribbon ring-shaped hot cathode 24 and a deformation collimeter in the neutralizer for accelerating the ion flow to deform thermions emitted from it. Transferred to the zero magnetic field region on the central axis along the radial magnetic field line of the collimeter, absorbed by the cation beam near the center axis of the deformed collimeter, and electrically neutralized to make the ion beam an electrically neutral particle beam. To convert to.

[7] In order to prevent backflow of electrons to the ion generator side during ion neutralization in the neutralizer, a suppressor electrode 23 having a negative potential of about 40 to 50 volts is attached to the second ribbon ring-shaped hot cathode. Coaxially installed on the upstream side (anode side) of the deformation collimeter magnetic field zero point.

In the non-contact type DC ion beam source of the present invention, the operation of the particle beam is a steady operation throughout the entire process from ion generation to linear acceleration and neutralization to emission from the neutralizer as a plasma beam. Throughout the entire process, the particles do not partially connect to or contact the structure, so in principle they are highly efficient, have high output, operate stably over a long period of time, and are of high quality and long with excellent focusing properties. Provides a lifetime DC particle beam. The fields of application are specifically: (1) A system that combines a wide thermionic emission region and a reverse Helmholtz coil, which will be described later, has a large beam radius and is suitable for generating high-power ion beams, making it suitable for interplanetary rockets. When a neutralized ion beam is applied, a high-performance ion engine capable of stable operation for an ultra-long time even with high efficiency and high output can be obtained.
(2) The inner surface of the first ribbon ring-shaped hot cathode in the ion generator is partially subjected to oxide treatment to facilitate thermionic emission. The thermions emitted from this region are transferred to the radial zero region along the radial magnetic field of the deformation collimator. It can be applied to the first-stage ion sources of various ion accelerators and, in the future, to supply low-noise, high-power thermal neutrons by fusion reactions with opposed beams of deuterium plasma for boron neutron capture therapy (BNCT).
(3) In a system in which a thin thermionic emission region and a cusp coil are combined, seed electrons are supplied on the central axis, and therefore the ion generation location is on the central axis. The resulting ions are velocity components only in the direction of the magnetic field lines, and the beam particles do not diffuse out of the ion beam column, resulting in a strong focusing property. It provides one of the foundations of various particle beam technologies. The device is axially symmetric, so the canonical momentum of charged particles is conserved under sufficient high vacuum, and the cylinder of the particle beam of plasma, ions, etc. accelerated by the axial electrostatic field is centered on the symmetric. The diameter of the beam column is inversely proportional to the magnetic flux density at the location where the particles are present, regardless of where the ion axis is generated. In other words, the beam radius around the central axis is very clearly determined by the magnetic flux density, and there are no beam particles dissipating to the outside.
It brings about the fundamental technological development of each field in various fields such as.

It is a figure which shows the schematic structure of the non-contact type DC ion beam source of one Embodiment of this invention. It is a figure which shows the arrangement and operation of a coil and an electrode in a non-contact type DC ion beam source. It is a figure which shows the relationship between the electrode system of a non-contact type DC ion beam source, an ion beam, and a plasma beam. It is a figure which shows the example of the magnetic force line of the deformation collimator magnetic field formed by using the antiparallel Helmholm coil. It is a figure which shows the example of the magnetic force lines of the deformation collimator magnetic field formed by using the pair coil which forms the cusp magnetic field. It is a figure which shows the potential distribution (the line of electric potential) by a conical anode and a hollow cylindrical cathode. It is a figure which shows the power source for applying a voltage (potential) to each electrode. It is a figure which shows the relationship between the electrode of the ion generator and the ion flow in embodiment of this invention. It is a figure which shows the relationship between an electrode, a coil, an ion beam and a neutral particle in a non-contact type DC ion beam source. It is a figure which shows the relationship between an electrode and an ion flow in an ion generator.

Hereinafter, the non-contact type DC ion beam source according to the present invention will be described based on the embodiment.

As the outline of the non-contact DC ion beam source according to the embodiment of the present invention is shown in FIG. 1, the ion generator A and the neutralizing device B are coaxially connected by a magnetic field. Further, FIG. 2 shows the arrangement and operation of the coil and the electrode of this non-contact type DC ion beam source. Further, FIG. 3 shows the relationship between the electrode system of this non-contact type DC ion beam source, the ion beam, and the plasma beam. The radial magnetic field on the zero magnetic flux plane of the deformation collimeter in the ion generator A is, for example, the line intersecting the curved surface of the zero magnetic flux on the inner surface of the coaxial and hollow ribbon ring-shaped hot cathode and its vicinity to emit thermions. Oxide treatment such as LAD scan date is applied. Thermions emitted from this region are transferred along the radial magnetic field to the zero magnetic field region near the central axis. Electrons are accelerated toward the anode by an electric field in the direction of the deformation collimator axial magnetic field near the axis, and contribute to the discharge of the filling gas as seed electrons for cascade ionization of the filling gas.

The ion generator A has a conical anode 12 on the axis target axis in a cylindrical vacuum vessel 01 filled with a predetermined gas, and a hollow cylindrical cathode 13 provided on the central axis on the downstream side away from the anode. Further, an orifice 15 is provided on the downstream side (cathode side) of the anode side cascade discharge region of the first ribbon ring-shaped hot cathode 14 provided in the vicinity of the hollow cylindrical cathode between the anode and the hollow cylindrical cathode. The orifice 15 on the central axis is coaxially installed from the vicinity of the hollow cylindrical cathode to the anode side at a position where the potential is slightly higher than the first ionization potential of the filling gas. A certain amount of filling gas in the cascade discharge region is required for ionization of the filling gas on a realistic scale, and an ultra-high vacuum such as to avoid charge exchange is required elsewhere, and this orifice operates. This is to maintain this pressure difference constantly by exhaust gas.

As described above, in the ion generator A, a pair of coils 17 forming a first deformation collimator magnetic field is provided, and the pair of coils functions as an electron flow redirector (direction converter). That is, the radial magnetic force lines on the zero magnetic flux plane near the central axis are connected to the axial magnetic force lines in the region near the zero magnetic field, and the thermionic flow from the first ribbon ring-shaped hot cathode is the radial magnetic field of the deformation collimeter. It reaches a region of zero magnetic field along and is accelerated in the anode direction along the axial magnetic field lines by an axial electric field in this region.

In the present embodiment, as shown in FIG. 1, a Helmholtz coil (hereinafter referred to as an antiparallel Helmholtz coil) installed as a first magnetic field generating coil 17 in a direction of canceling it at the center in a uniform magnetic field is used as a basis. However, depending on the application, it can also be formed on the basis of a cusp magnetic field coil. FIG. 4 shows an example of the magnetic force lines of the deformed collimator magnetic field formed when the antiparallel Helmholm coil is used, and FIG. 5 shows an example of the magnetic force lines formed when the coil forming the cusp magnetic field is used. .. In either case, the magnetic force lines are in the region where the magnetic field is zero near the center of the magnetic field pair coil whose central axis is the axis of symmetry, and the magnetic force lines extend radially on the curved surface of the zero magnetic flux from here.

The former deformed collimator magnetic field is suitable for large capacity ion beam sources, and the latter is suitable for highly focused ion beam sources for more precise ion beam processing. In the ion generator A, a region of zero magnetic field is formed in the vicinity of the anode side of the hollow cylindrical cathode 13, and inside the first ribbon ring-shaped hot cathode near the intersection with the zero magnetic flux surface (due to thermionic emission). The region treated with surface oxide and the region of this zero magnetic field are connected to the axial magnetic field by radial magnetic field lines, which makes it possible to inject thermions into this region.

In the examples so far, the antiparallel Helmholtz coil is adopted as the pair coil 17 for generating the deformation collimator magnetic field, and a region of zero magnetic field is formed on the central axis, and the axial magnetic field becomes the radial magnetic field in this region. Connected to convert the electron flow along the magnetic field into an axial flow. The strength of the magnetic field in the antiparallel Helmholtz coil type deformation collimator of FIG. 4 is proportional to the fourth power of the distance from the point of the zero magnetic field, and in the case of the cusp magnetic field type of FIG. 5, it is proportional to the distance. Therefore, the selection of this deformed collimator magnetic field coil is related to the size of the zero magnetic field region, and the selection of the beam diameter and the beam flow rate, coupled with the selection of the size of the thermionic radiation region.

By applying a magnetic field (axial magnetic field of the deformation collimator) in the axial direction showing the potential distribution (isopotential line) by the conical anode 12 and the hollow cylindrical cathode 13 in FIG. 6, the movement of electrons is caused by the magnetic field line near the central axis. As a result of being restricted only in the direction, the DC discharge from the tip of the cylindrical electrode where electrons cross the magnetic field is suppressed. According to the present invention, the thermions from the ribbon ring-shaped hot cathode by the first magnetic field generating coil 17 move along the radial magnetic field lines, are transferred to the vicinity of the central axis, and are axial electrons by the electric field in the region of zero magnetic field. It is converted into a flow and accelerated toward the anode as a seed electron.

A piezoelectric potential is applied between the conical anode 12 and the hollow cylindrical cathode 13 to appropriately accelerate the electrons. Seed electrons accelerated from the zero magnetic field region of the deformed collimator magnetic field toward the anode are accelerated to an energy equal to or higher than the first ionization voltage of the filling gas, and ionize the gas in cascade in the region on the anode side where the filling gas pressure is higher. do. The ions generated by this cascade ionization are accelerated toward the hollow cylindrical cathode along the axial magnetic field of the deformed collimator and penetrate the region of the zero magnetic field of the deformed collimator with an inertia corresponding to the energy above the first ionization voltage. .. Due to this inertia, the ions do not flow back in the direction of the electric field to the first ribbon-shaped hot cathode, but are emitted toward the neutralizing device B through the hollow cylinder of the hollow cylindrical cathode along the central axis. FIG. 8 shows the relationship between the electrode of the ion generator A and the particle flow in the non-contact type DC ion beam source of the present embodiment.

The neutralizing device B is arranged in the vacuum vessel 01, is arranged on the downstream side of the ion generator A, its central axis is common to the central axis of the ion generator A, and the devices A and B are single as a whole. Build an axis-symmetrical system. The neutralizing device B has a second ribbon ring-shaped hot cathode 24 provided around the central axis and a suppressor electrode 23 on the upstream side (ion generator side) of the second ribbon ring-shaped hot cathode 24. FIG. 9 shows the relationship between the electrodes, coils, and ion beams of the neutralizing device B provided with the pair coil 27 for generating the second magnetic field forming the magnetic field and the neutral particle beam such as ions and plasma. ing.

In the neutralizing device B, the region subjected to the oxide treatment is heated in the vicinity of the intersection line between the inner surface and the curved surface of the zero magnetic flux in order to facilitate thermionic emission, and thermionic electrons are generated. Thermions, which regard the ion beam as an anode, move along the radial magnetic field of the deformed collimator, electrically neutralize the ion flow, and are emitted from the system as a plasma beam. The above is the basic configuration, but in reality, acceleration and neutralization can be performed over coaxial series and multiple stages.

An acceleration voltage (acceleration voltage) required to accelerate the ion flow from the ion generator A by the second ribbon ring-shaped hot cathode 24 between the first ribbon ring-shaped hot cathode 14 and the second ribbon ring-shaped hot cathode 24. For example, a negative voltage of about -30 kilovolts is applied to the hollow cylindrical cathode 13, and a negative voltage of about -50 volts is applied to the second ribbon ring-shaped hot cathode of the suppressor electrode 23, which is upstream (ion generator). It suppresses the backflow of electrons to the side.

The output from the neutralizer B is connected to a beam reaction vessel and a target vessel for beam work for use in beam technology, and is released into vacuum planetary space as an ion engine for an interplanetary rocket.

Next, the operation of the non-contact DC ion beam source of the present embodiment will be described in more detail. Along the central axis direction of the ion generator A and the neutralizer B, a pair of coils 17 for generating a first deformed collimator magnetic field and a pair of coils 27 for generating a second deformed collimator magnetic field are used in the radial direction. A deformed collimator magnetic field for thermionic transfer is formed (see FIGS. 4 and 5). The central region of each pair coil is the region of the zero magnetic field on the central axis, where the radial magnetic field is connected to the axial magnetic field, which functions as a redirector for electrons. In the case of the ion generator A, the thermions from the ribbon ring-shaped hot cathode are redirected and then accelerated along the axis in the anode direction to contribute to the ionization of the filling gas by the cascade discharge. In the case of the neutralizing device B, the beam ions near the central axis are neutralized without contact.

The ion flow that has passed through the hollow cylindrical cathode 13 is accelerated along the magnetic field lines by the second ribbon ring-shaped hot cathode 24 of the neutralizing device B having a negative potential with respect to the hollow cylindrical cathode downstream thereof, and becomes an ion beam of the required energy. .. When the total current of the ion beam is large and the beam is long and the radius is small, so-called kink mode instability is excited and the beam particles are scattered in the radial direction. In order to avoid this, the neutralizer for ion acceleration is a coaxial multi-stage ribbon-shaped hot cathode & deformed collimator magnetic field set as multi-stage ion acceleration to shorten the unit length of the ion beam or strengthen the axial magnetic field. Therefore, it may be necessary to take measures such as suppressing this instability.

The second ribbon ring-shaped hot cathode 24 of the neutralizer B is not irradiated with ions as in the case of the first ribbon ring-shaped hot cathode 14 of the ion generator A, and therefore both are on the inner surface thereof. For example, a LAD scandate can be adopted as the oxide film, and when it is heated to 800 to 950 ° C. as needed, the thermions emitted from the hot electron are emitted with high efficiency. Thermions from the second magnetic field generating coil are sucked into an ion stream that can be regarded as an "anodic" along the radial lines of magnetic force, where the charge of the ion beam is neutralized and the ion beam is electrically medium. Convert to a sex plasma beam. Unlike the beam flow of neutral atoms, this ion beam does not necessarily mean that electrons are bonded to ions to form neutral atoms, and ions and electrons coexist to form an electrically neutral plasma on average. It is a beam in a state. It is also possible to achieve more complete neutralization of accelerated ions by forming a multi-stage configuration of equipotential ribbon ring-shaped hot cathodes that utilize the advantages of the non-contact type.

This beam neutralization generally involves only positively charged ions, without electrons, except in the special case where the ion beam particle beam processing target is an electric field that can be used in combination with the cathode. When emitted outside the system, the target of the insulator is positively charged, and the resulting electric field causes unintentional disturbance to the ion beam, or the entire system is negatively charged and the device loses its function. It is for avoiding such things.

When a negative potential is set for the hollow cylindrical hot cathode 13 in the ribbon ring-shaped hot cathode 14 of the ion generator A as described above, as shown in FIG. 10, the region of the zero magnetic field becomes the virtual anode for the ribbon ring-shaped hot cathode. Become. By the way, in the neutralizing device B, in a single unit, the ion beam itself near the central axis is a virtual anode for the ribbon ring-shaped hot cathode 24, and the thermion is a potential barrier formed near the surface of the ribbon ring-shaped hot cathode. A radial electric field is formed to overcome the problem and move in the central axis direction, and the value of this electric field controls the number of seed electrons supplied near the central axis together with the area of the thermionic generation region and the heating temperature. do.

When the first magnetic field generation pair coil 16 of the ion generator A is a cusp magnetic field type deformation collimeter coil, the thermion generation region is set as a curved surface of zero magnetic flux, and the spread is minimized as much as possible. Is localized almost on the central axis, so the canonical momentum of the cations ionized on the central axis is infinitely close to zero. This is accelerated in the direction of the electric field while maintaining the canonical angular momentum, and penetrates the orifice 15 and the hollow cylindrical cathode 13 to form an ion flow (ion beam). During this period, there are no structures such as electrodes that obstruct the movement of the beam, and the cations are emitted from the ion generator A without contact, and are accelerated by the axial DC magnetic field near the central axis of the vacuum space of the target. The cathode is irradiated. If necessary, the accelerated ions are electrically neutralized and then released into the vacuum space.

The ions having zero canonical momentum generated here can be introduced into a magnetic field formed by an antiparallel Helmholtz type collimator, a cusp magnetic field, a magnetic island, or the like. Utilizing this property, cations with non-zero canonical momentum are excluded from the beam by passing the accelerated ion beam through a cusp magnetic field, magnetic islands, etc., and only cations with zero canonical momentum are called. It is also possible to obtain an ion or plasma beam that is close to the ideal.

Through the ion generator A and the neutralizer B, the ions move along an axial magnetic field and are treated non-contact with the cathode and other structures. In that sense, the neutralizing device B exerts the function of ion neutralization in combination with the ion generator A, and the neutralizing device B is unconditionally combined with another ion generator to neutralize the ion beam. It is not always attractive to try.

The ion (plasma) beam emitted from the neutralizer irradiates the reaction target along the lines of magnetic force, and when used as an ion engine, the magnetic cloud (expansion) is similar to the case of emission from the solar surface of the solar wind. It is emitted into the interplanetary space in the form of a magnetic cloud).

As described above, the principle of the non-contact type DC ion beam source of the present invention is the ion rocket of the interplanetary rocket capable of high output and safe operation for an ultra-long time, and the BNCT by fusion of a large current opposed heavy hydrogen plasma beam. It is considered to be utilized in technologies such as low-noise thermal neutron source for boron neutron capture therapy and ion beam generation for sub-nanometer-class ultra-precision ion beam processes, and will greatly contribute to technological progress in these fields. ..

A Ion generator B Neutralizer 01 Vacuum vessel 12 Conical anode 13 Hollow cylindrical cathode 14 First ribbon ring-shaped hot cathode 15 orifice 16 First solenoid magnetic field generation coil 17 First deformation collimator magnetic field generation pair coil 23 Suppressor electrode 24 Second ribbon ring-shaped hot cathode 26 Second solenoid magnetic field generation coil 27 Second deformation collimator magnetic field generation pair coil

Claims (5)

An axisymmetric ion generator that separates ions from the plasma created by the discharge of the filling gas and takes them out, accelerates the ions obtained there to a predetermined energy, and adds electrons to it as needed. A non-contact type DC ion beam source characterized in that an axisymmetric structure neutralizer that electrically converts the plasma beam into a neutral plasma beam is connected symmetrically to a common axis in one vacuum vessel. A unit that combines a deformed collimator magnetic field and a ribbon ring-shaped thermion cathode is adopted for the ion generator and the neutralizing device. Oxide treatment is applied to facilitate thermionic emission, and the axial magnetic field is connected to the radial magnetic field in the zero magnetic field region near the central axis, which is connected to the thermionic generation region, resulting in a ribbon ring-shaped thermal cathode. Thermions from this oxide treatment are transferred from this oxide-treated region to the region of zero magnetic field along the lines of magnetic force, and in the region of zero magnetic field of the ion generator, thermions are accelerated by the electric field in the direction of the cathode along the lines of magnetic force. In the neutralizing device, thermions in the region of zero magnetic field are added to the accelerated beam of cations and electrically neutralized, and these actions occur. The non-contact type DC ion beam source according to claim 1, wherein the modified collimeter magnetic field and the ribbon ring-shaped thermion cathode are combined. A negative potential is applied to the ribbon ring-shaped hot cathode of the neutralizer to the hollow cylindrical cathode of the ion generator in order to accelerate the beam ions from the ion generator to a predetermined energy, and if necessary, the neutralization is performed. From the ribbon ring-shaped hot cathode of the device, the heat-emitting electrons are transferred toward the center through the radial magnetic field of the deformation collimeter, and the ion beam accelerated there is electrically neutralized and converted into a plasma beam. The non-contact type DC ion beam source according to claim 1 or 2, wherein the neutralizing device is a combination of these electrodes and a magnetic field coil. The pressure difference between the filling gas pressure required for the cascade discharge of the ion generator and the low gas pressure required to avoid charge exchange in the acceleration region and the neutralizing device is zero. The potential for the magnetic field region is the filling gas. The non-contact type DC ion beam source according to any one of claims 1 to 3, wherein the gas is held by a differential exhaust through an orifice installed at a position equal to or higher than the first ionization voltage of the above. .. In order to prevent backflow of electrons toward the ion generator in the neutralizing device, a suppressor having a negative potential with respect to the ribbon ring-shaped hot cathode is installed upstream of the set of the deformation collimeter of the neutralizing device and the ribbon ring-shaped hot cathode unit. The non-contact type DC ion beam source according to any one of claims 1 to 4, wherein the non-contact type DC ion beam source is characterized by the installation of electrodes.

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