JP2017134934A - Ion source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the reliability of an ion source.SOLUTION: An ion source 10 comprises: a vacuum chamber 18; an annular magnetic field generator 16 placed in the vacuum chamber 18, and generating an axial direction magnetic field B in its radially inside region; a cylindrical plasma chamber 12 placed in the vacuum chamber 18, which is disposed in the radially inside region of the magnetic field generator 16 so as to partition the radially inside region of the magnetic field generator 16 into an electrode outside area 46 and an electrode inside area, and which generates an electric field of a radial direction in the electrode outside area 46; a first conducting obstructive member 50 disposed in the electrode outside area 46, electrically connected to the magnetic field generator 16, and electrically insulated from the plasma chamber 12; and a second conducting obstructive member 52 disposed circumferentially close to the first conducting obstructive member 50 in the electrode outside area 46, electrically insulated from the magnetic field generator 16, and electrically connected to the plasma chamber 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ion source.

  One known ion source includes a plasma chamber, an insulating member provided so as to surround the outer periphery of the plasma chamber, a magnetic field generator provided outside the insulating member and generating a magnetic field in the plasma chamber, a plasma chamber, And a vacuum container for storing the insulating member and the magnetic field generator therein. The plasma chamber is connected to a power source for setting a higher potential than the magnetic field generator.

  According to this ion source, since the insulating member is provided between the plasma chamber and the magnetic field generator, the insulation between the plasma chamber and the magnetic field generator can be enhanced. Further, even when plasma is generated between the plasma chamber and the magnetic field generator, the electric field between the plasma chamber and the magnetic field generator is reduced by charging the surface of the insulating member. The discharge between the magnetic field generator can be suppressed. Thereby, it is possible to prevent an overcurrent from flowing to a power source that applies a high voltage to the plasma chamber, and to improve the reliability of the ion source.

JP2015-109150A

  One exemplary object of certain aspects of the present invention is to provide an ion source having an alternative configuration for increasing the reliability of the ion source.

  According to an aspect of the present invention, the ion source includes a vacuum vessel, an annular magnetic field generator installed in the vacuum vessel, and a magnetic field generator that generates an axial magnetic field in a radially inner region thereof; A cylindrical high-voltage electrode unit installed in the vacuum vessel, wherein the magnetic field generator is arranged in a radially inner region so as to partition a radially inner region of the magnetic field generator into an electrode outer region and an electrode inner region. A high voltage electrode unit disposed and generating a radial electric field in the electrode external region, and disposed in the electrode external region, electrically connected to the magnetic field generator and electrically insulated from the high voltage electrode unit A first conductor baffle member, a second conductor baffle disposed in the circumferential direction in the electrode external area, electrically insulated from the magnetic field generator and electrically connected to the high voltage electrode portion; A conductor baffle member.

  According to an aspect of the present invention, the ion source includes a vacuum vessel, and an annular magnetic field generator installed so as to surround the vacuum vessel, the magnetic field generator generating an axial magnetic field in the vacuum vessel; A cylindrical high-voltage electrode unit installed in the vacuum vessel, the high-voltage electrode unit generating a radial electric field in an electrode external area between the vacuum vessel and the high-voltage electrode unit, A first conductor baffle member disposed in the electrode outer section, electrically connected to the vacuum vessel and electrically insulated from the high voltage electrode portion; and in the circumferential direction of the first conductor baffle member in the electrode outer section A second conductor baffle member that is disposed in proximity, electrically insulated from the vacuum vessel, and electrically connected to the high voltage electrode portion.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to the present invention, the reliability of the ion source can be improved.

It is a figure which shows typically the structure of the ion source which concerns on embodiment. It is sectional drawing which shows typically the structure of the ion source which concerns on embodiment. It is a figure which shows typically the electric field and magnetic field which arise between a plasma chamber and a magnetic field generator in the ion source which concerns on a comparative example. It is sectional drawing which shows typically the structure of the ion source which concerns on other embodiment. It is a figure which shows typically the structure of the ion source which concerns on other embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. Moreover, the structure described below is an illustration and does not limit the scope of the present invention at all.

  1 and 2 schematically show a configuration of an ion source 10 according to the embodiment, and FIG. 2 shows a cross section taken along line AA in FIG. 1 shows a cross section taken along line BB in FIG.

  The ion source 10 inputs a microwave power C to a plasma chamber 12 to which a magnetic field satisfying an electron cyclotron resonance (ECR) condition or a magnetic field higher than that is applied, and generates a high-density plasma to extract ions. It is. The ion source 10 may be an ECR ion source. The ion source 10 is configured to generate a plasma of a source gas by the interaction between a magnetic field and a microwave, and to extract ions from the plasma to the outside of the plasma chamber 12.

  The ion source 10 is used as an ion source for an ion implantation apparatus or a particle beam therapy apparatus, for example. The ion source 10 is used as, for example, a monovalent ion source or a multivalent ion source. The ion source 10 can also be used as an ion source for a proton accelerator or an X-ray source.

  As is well known, the strength of the magnetic field that satisfies the ECR condition is uniquely determined with respect to the microwave frequency used, and a magnetic field of 87.5 mT (875 gauss) is required when the microwave frequency is 2.45 GHz. It is. Hereinafter, for convenience of explanation, a magnetic field that satisfies the ECR condition may be referred to as a resonance magnetic field.

  The ion source 10 includes a plasma chamber 12, a magnetic field generator 16, and a vacuum vessel 18. The plasma chamber 12 and the magnetic field generator 16 are accommodated in the vacuum vessel 18.

  The plasma chamber 12 is a vacuum chamber configured to generate and maintain plasma in its internal space. Hereinafter, the internal space of the plasma chamber 12 may be referred to as a plasma generation space 14.

  The plasma chamber 12 has a cylindrical shape having both ends. Hereinafter, the direction from one end to the other end of the plasma chamber 12 may be referred to as an axial direction for convenience. In addition, a direction orthogonal to the axial direction may be referred to as a radial direction, and a direction surrounding the axial direction may be referred to as a circumferential direction. However, these do not necessarily mean that the plasma chamber 12 has a rotationally symmetric shape. The axial length of the plasma chamber 12 may be longer or shorter than the radial length of the end portion of the plasma chamber 12.

  The plasma chamber 12 includes an ion extraction unit 22 and a microwave introduction unit 26. The ion extraction unit 22 and the microwave introduction unit 26 are opposed to each other with the plasma generation space 14 interposed therebetween.

  The plasma chamber 12 includes a side wall portion 20 that connects the ion extraction portion 22 and the microwave introduction portion 26 and surrounds the plasma generation space 14. The side wall 20 is fixed to the outer periphery of each of the ion extraction unit 22 and the microwave introduction unit 26. The side wall 20 is made of a nonmagnetic metal material such as stainless steel or aluminum.

  Note that the side wall 20 may include a cooling unit for cooling the side wall 20. This cooling part may be built in the side wall part 20 or may be attached outside the side wall part 20. Moreover, in order to protect the side wall part 20 of the plasma chamber 12 from a plasma, the liner (for example, boron nitride) which coat | covers the inner surface of the side wall part 20 may be provided.

  A plasma generation space 14 is defined in the plasma chamber 12 by the microwave introduction part 26, the ion extraction part 22, and the side wall part 20. The plasma chamber 12 is configured such that the microwave introduction part 26, the ion extraction part 22, and the side wall part 20 integrally surround the plasma generation space 14, so that the side wall part 20 connected to the ion extraction part 22 is provided. The end can also be regarded as a part of the ion extraction part 22. Similarly, the end of the side wall part 20 connected to the microwave introduction part 26 can also be regarded as a part of the microwave introduction part 26.

  The plasma chamber 12 has, for example, a cylindrical shape. In this case, the microwave introduction part 26 and the ion extraction part 22 are substantially disk-shaped, and the side wall part 20 is substantially cylindrical. The plasma chamber 12 may have any shape as long as plasma can be appropriately accommodated.

  The microwave introduction unit 26 includes a vacuum window 32. The vacuum window 32 seals the inside of the plasma chamber 12 to a vacuum. One side of the vacuum window 32 faces the plasma generation space 14, and the other side of the vacuum window 32 is directed to the microwave supply system or the waveguide 30. The propagation direction C of the microwave is perpendicular to the vacuum window 32. In the present embodiment, the vacuum window 32 occupies the entire microwave introduction part 26, but the vacuum window 32 may be formed in a part (for example, the central part) of the microwave introduction part 26.

  The microwave incident power to the plasma chamber 12 is greater than about 100 W, for example. Alternatively, the microwave incident power to the plasma chamber 12 may be about 500 W or more, or about 1 kW or more. The waveguide 30 and the vacuum window 32 are suitable for supplying such a high-power microwave compared to other supply means such as a coaxial line.

The vacuum window 32 is made of a dielectric such as alumina (Al ₂ O ₃ ) or boron nitride (BN). The vacuum window 32 may have a two-layer structure including an alumina layer and a boron nitride layer. For example, a boron nitride layer is provided on the surface of the vacuum window 32 made of alumina in contact with the plasma generation space 14. Thereby, the boron nitride layer covering the vacuum window 32 protects the vacuum window 32 from electrons flowing back from the outside of the plasma chamber 12 to the plasma chamber 12 through the extraction opening 24.

  On the other hand, at least one extraction opening 24 is formed in the ion extraction portion 22. The drawer opening 24 is, for example, a slit that is elongated in a direction perpendicular to the paper surface. The extraction opening 24 is formed in the central portion of the ion extraction portion 22. The extraction opening 24 is formed at a position facing the vacuum window 32 across the plasma generation space 14. The vacuum window 32, the plasma generation space 14, and the extraction opening 24 are arranged along the central axis of the plasma chamber 12.

  The plasma chamber 12 is connected to a power source 62 for applying a positive high voltage. When a high voltage is applied to the plasma chamber 12, the same high voltage is also applied to the ion extraction part 22, which is a part of the plasma chamber 12. Therefore, the ion extraction part 22 may be called a plasma electrode. The side wall portion 20 of the plasma chamber 12 functions as a cylindrical high voltage electrode portion installed in the vacuum vessel 18.

  An extraction electrode system having at least one extraction electrode 40 for extracting ions to the outside of the plasma chamber 12 is provided outside the extraction opening 24 in the axial direction. The extraction electrode 40 is opposed to the ion extraction portion 22 with an extraction gap 42 in the axial direction. The extraction electrode 40 is formed, for example, in an annular shape, and has an opening 44 for allowing ions extracted from the plasma chamber 12 to pass through at the center thereof. In addition, the extraction electrode system includes an extraction power source (not shown) for applying a potential to the extraction electrode 40.

  The magnetic field generator 16 is disposed so as to surround the side wall portion 20 of the plasma chamber 12 in order to generate a magnetic field directed in the axial direction on the central axis of the plasma chamber 12. The direction of the line of magnetic force is indicated by an arrow B in FIG. The magnetic field line direction B by the magnetic field generator 16 is the same direction as the microwave propagation direction C. Further, the magnetic field B has a resonance magnetic field or higher intensity at least at a part on the central axis of the plasma chamber 12. The magnetic field generator 16 can also generate a magnetic field lower than the resonance magnetic field in at least a part of the axis of the plasma chamber 12.

  The magnetic field generator 16 has an annular coil, and a conducting wire is wound around the plasma chamber 12 in the circumferential direction. The magnetic field generator 16 has a coil power supply (not shown) for flowing a current through the coil. A plurality of the magnetic field generators 16 may be arranged along the axial direction of the plasma chamber 12 and may include a permanent magnet instead of or together with the coil.

  The magnetic field generator 16 is directly attached to the inner wall of the vacuum vessel 18 and grounded, for example. The vacuum vessel 18 is grounded. Therefore, different potentials are applied to the grounded magnetic field generator 16 and the plasma chamber 12 connected to the power source 62. A power source (not shown) different from the power source 62 for applying a potential different from that of the plasma chamber 12 may be connected to the magnetic field generator 16. In this case, a potential different from the ground potential may be applied to the magnetic field generator 16.

  Thus, the magnetic field generator 16 is formed in an annular shape, and is configured to generate an axial magnetic field B in its radially inner region. The side wall 20 of the plasma chamber 12 is disposed in the radially inner region of the magnetic field generator 16 so as to partition the radially inner region of the magnetic field generator 16 into an electrode outer region 46 and an electrode inner region (that is, the plasma generation space 14). ing. Since different potentials are applied to the side wall portion 20 and the magnetic field generator 16, a radial electric field E is generated in the electrode outer region 46.

  The ion source 10 further comprises a plasma suppression structure in the electrode outer area 46. The plasma suppression structure includes a first conductor baffle member 50 and a second conductor baffle member 52 disposed in the electrode outer area 46. The second conductor baffle member 52 is disposed adjacent to the first conductor baffle member 50 in the circumferential direction in the electrode outer area 46. However, the second conductor baffle member 52 is disposed in non-contact with the first conductor baffle member 50. Each of the first conductor baffle member 50 and the second conductor baffle member 52 is, for example, a metal rectangular plate. The circumferential position of the plasma suppression structure is arbitrary. For ease of understanding, the first conductor baffle member 50 is shown by a broken line in FIG.

  The first conductor baffle member 50 is electrically connected to the magnetic field generator 16 and is electrically insulated from the side wall portion 20 of the plasma chamber 12. Therefore, the same potential as that of the magnetic field generator 16 is applied to the first conductor baffle member 50. That is, the first conductor baffle member 50 is grounded. The second conductor baffle member 52 is electrically insulated from the magnetic field generator 16 and is electrically connected to the side wall 20 of the plasma chamber 12. Therefore, the same potential as that of the plasma chamber 12 is applied to the second conductor baffle member 52 by the power source 62. The first conductor baffle member 50 and the second conductor baffle member 52 are disposed so as to be electrically insulated from each other. That is, the first conductor baffle member 50 is separated from the second conductor baffle member 52 so as to ensure an insulation distance.

  FIG. 3 is a diagram schematically showing a radial electric field E and an axial magnetic field B generated between the side wall 20 of the plasma chamber 12 and the magnetic field generator 16 in the ion source according to the comparative example. The comparative example differs from the present embodiment in that it does not have the above-described plasma suppression structure. As illustrated, an electric field E is generated in the radial direction between the side wall portion 20 of the plasma chamber 12 and the magnetic field generator 16 having different potentials, and the magnetic field B generated by the magnetic field generator 16 intersects the electric field E in the axial direction. Has occurred. Since the magnetic field generator 16 hits the cathode and the plasma chamber 12 hits the anode, electrons can be emitted from the magnetic field generator 16. The electrons are accelerated under an axial magnetic field B and a radial electric field E, and perform a cycloidal motion in the circumferential direction. The electrons can move clockwise or counterclockwise in the vacuum region between the side wall 20 of the plasma chamber 12 and the magnetic field generator 16 and can stay in the vacuum region until it collides with the side wall 20 of the plasma chamber 12.

  In the vacuum region between the side wall 20 of the plasma chamber 12 and the magnetic field generator 16, a trace amount of residual gas may exist. Residual gas is ionized by collision of electrons accelerated by drift, and plasma P can be generated in a region between the side wall 20 of the plasma chamber 12 and the magnetic field generator 16. Current may flow between the 12 side wall portions 20 and the magnetic field generator 16, and insulation may not be ensured. Such a discharge may affect the power supply 62 that applies a high voltage to the plasma chamber 12.

  As shown in FIGS. 1 and 2, the first conductor baffle member 50 and the second conductor baffle member 52 are separated from each other by a gap G in the circumferential direction. The circumferential interval G is set so that electrons that perform a cycloidal motion so as to bypass the tip 50 a of the first conductor baffle member 50 under the axial magnetic field B and the radial electric field E are received on the surface of the second conductor baffle member 52. , Based on the axial magnetic field B and the radial electric field E. For example, the circumferential interval G is a rotational movement performed by the electron having the maximum kinetic energy estimated from the radial electric field E by the axial magnetic field B in the vicinity of the first conductor baffle member 50 and / or the second conductor baffle member 52. It is desirable to be smaller than the diameter (twice the so-called Larmor radius).

  In this way, electrons that perform a cycloidal motion in the electrode outer area 46 can be efficiently captured on the surface of the second conductor baffle member 52. Therefore, the generation of plasma in the electrode external area 46 can be suppressed, and the discharge between the magnetic field generator 16 and the side wall portion 20 in the area can be suppressed.

  As shown in FIG. 1, the first conductor baffle member 50 extends in the axial direction over at least part of the axial length of the side wall portion 20 of the plasma chamber 12. Here, the first conductor baffle member 50 extends in the axial direction over substantially the entire axial length of the side wall portion 20 of the plasma chamber 12. The second conductor baffle member 52 extends in the axial direction so as to face the first conductor baffle member 50 in the circumferential direction. Therefore, the second conductor baffle member 52 also extends in the axial direction over substantially the entire axial length of the side wall portion 20 of the plasma chamber 12. Thereby, it is possible to suppress the generation of plasma over almost the entire length in the axial direction in the electrode outer area 46, and to suppress the discharge between the magnetic field generator 16 and the side wall portion 20 in the area.

  The first conductor baffle member 50 extends from the magnetic field generator 16 toward the side wall 20 of the plasma chamber 12 by a first length L1. The second conductor baffle member 52 extends from the side wall portion 20 of the plasma chamber 12 toward the magnetic field generator 16 by a second length L2. The first conductor baffle member 50 and the second conductor baffle member 52 extend in parallel to each other substantially along the radial direction. The first length L1 is equal to the second length L2. Alternatively, the first length L1 may be different from the second length L2.

  The first length L1 and the second length L2 are each smaller than the radial distance D between the magnetic field generator 16 and the side wall portion 20 of the plasma chamber 12. The sum of the first length L1 and the second length L2 is larger than the radial distance D. In this manner, the first conductor baffle member 50 and the second conductor baffle member 52 form a maze structure in the electrode outer area 46. It is easy to receive and absorb electrons that bypass the tip 50a of the first conductor baffle member 50 on the surface of the second conductor baffle member 52.

  As described above, according to the present embodiment, the first conductor baffle member 50 having the same potential as the magnetic field generator 16 that can serve as an electron emission source guides electrons toward the second conductor baffle member 52, so-called baffle plates. Acts as Such electrons are received and absorbed by the surface of the second conductor baffle member 52 having a high potential. In this way, the first conductor baffle member 50 and the second conductor baffle member 52 can block the trajectory of electrons that can stay in the electrode outer area 46 and perform a cycloid motion. As a result, the frequency with which the electrons collide with the residual gas can be lowered, so that the generation of plasma in the electrode outer area 46 is suppressed. Therefore, the discharge between the plasma chamber 12 and the magnetic field generator 16 is also suppressed, and the reliability of the ion source 10 is improved.

  The ion source mentioned at the beginning of this document has a cylindrical insulating member surrounding the plasma chamber between the plasma chamber and the magnetic field generator. In this existing technology, the surface of the cylindrical insulating member is contaminated with conductive pollutants along with the operation of the ion source, and when such contamination progresses excessively, the insulation performance can be reduced by creeping discharge. On the other hand, since this embodiment does not have such a cylindrical insulating member, the deterioration of the insulating performance mentioned here does not occur.

  Another advantage is that, for example, the first conductor baffle member 50 and the second conductor baffle member 52 are easily available at low cost. Generally, metal materials are cheaper than insulating materials such as alumina. Moreover, since the plasma suppression structure of this Embodiment should just be provided locally in the circumferential direction, there also exists an advantage that it is reduced in weight compared with the existing technique provided in a perimeter. The local installation can reduce the influence on the vacuum conductance.

  In the above, this invention was demonstrated based on the Example. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiment, and various design changes are possible, various modifications are possible, and such modifications are within the scope of the present invention. By the way.

  FIG. 4 is a cross-sectional view schematically showing the configuration of the ion source 10 according to another embodiment. In the embodiment described above, the first conductor baffle member 50 is separated from the second conductor baffle member 52, whereas in the embodiment shown in FIG. 4, the ion source 10 moves the first conductor baffle member 50 to the second conductor baffle member 50. An insulating member 54 is provided that is structurally connected to the conductor baffle member 52. The insulating member 54 extends in the axial direction together with the first conductor baffle member 50 and the second conductor baffle member 52 (for example, over substantially the entire axial length of the side wall portion 20 of the plasma chamber 12).

  Even if it does in this way, the discharge between the plasma chamber 12 and the magnetic field generator 16 can be suppressed similarly to the above-mentioned embodiment. Further, since the space between the first conductor baffle member 50 and the second conductor baffle member 52 is filled with the insulating member 54, the passage of electrons between the first conductor baffle member 50 and the second conductor baffle member 52 is prevented. It can be surely prevented.

  FIG. 5 is a diagram schematically showing a configuration of an ion source 10 according to another embodiment. In the above-described embodiment, the magnetic field generator 16 is disposed in the vacuum container 18. However, in the embodiment illustrated in FIG. 5, the magnetic field generator 16 is disposed outside the vacuum container 18. The magnetic field generator 16 is installed in an annular shape so as to surround the vacuum vessel 18. Therefore, a radial electric field E is generated in the electrode external area 46 between the vacuum vessel 18 and the side wall 20 of the plasma chamber 12. The first conductor baffle member 50 is disposed in the electrode outer area 46, is electrically connected to the vacuum vessel 18, and is electrically insulated from the side wall portion 20 of the plasma chamber 12. The second conductor baffle member 52 is disposed adjacent to the first conductor baffle member 50 in the circumferential direction in the electrode outer area 46, is electrically insulated from the vacuum vessel 18, and is electrically connected to the side wall portion 20 of the plasma chamber 12. .

  In an embodiment, the extraction electrode 40 may be formed as a cylindrical high voltage electrode portion instead of the side wall portion 20 of the plasma chamber 12. In this case, the first conductor baffle member 50 is disposed in the electrode outer area 46, is electrically connected to the vacuum vessel 18, and is electrically insulated from the extraction electrode 40. The second conductor baffle member 52 is disposed adjacent to the first conductor baffle member 50 in the circumferential direction in the electrode outer area 46, is electrically insulated from the vacuum vessel 18, and is electrically connected to the extraction electrode 40.

  Even if it does in this way, the discharge between the plasma chamber 12 and the magnetic field generator 16 can be suppressed similarly to the above-mentioned embodiment.

  In the above-described embodiment, the plasma suppressing structure is provided at one place in the circumferential direction, but the present invention is not limited to this. A plurality of plasma suppression structures (that is, a plurality of sets of the first conductor baffle members 50 and the second conductor baffle members 52) may be provided in the electrode outer area 46, and may be arranged at different positions in the circumferential direction.

  DESCRIPTION OF SYMBOLS 10 Ion source, 12 Plasma chamber, 16 Magnetic field generator, 18 Vacuum container, 20 Side wall part, 46 Electrode outer area, 50 1st conductor baffle member, 52 2nd conductor baffle member, B axial direction magnetic field, E radial electric field

Claims (8)

A vacuum vessel;
An annular magnetic field generator installed in the vacuum vessel, the magnetic field generator generating an axial magnetic field in a radially inner region thereof;
A cylindrical high-voltage electrode unit installed in the vacuum vessel, wherein the magnetic field generator is arranged in a radially inner region so as to partition a radially inner region of the magnetic field generator into an electrode outer region and an electrode inner region. A high voltage electrode portion disposed and generating a radial electric field in the electrode external area;
A first conductor baffle member disposed in the electrode external area, electrically connected to the magnetic field generator and electrically insulated from the high voltage electrode portion;
A second conductor baffle member disposed in the circumferential direction adjacent to the first conductor baffle member in the electrode external area, and electrically insulated from the magnetic field generator and electrically connected to the high voltage electrode portion. An ion source characterized by that.   The first conductor baffle member extends a first length from the magnetic field generator toward the high voltage electrode part, and the second conductor baffle member extends from the high voltage electrode part toward the magnetic field generator. The first length and the second length are each smaller than a radial distance between the magnetic field generator and the high voltage electrode portion, and the first length and the second length are The ion source according to claim 1, wherein the sum is larger than the radial distance.   The first conductor baffle member extends in the axial direction over at least a part of the axial length of the high voltage electrode portion, and the second conductor baffle member faces the first conductor baffle member in the circumferential direction. The ion source according to claim 1, wherein the ion source extends in an axial direction.   The circumferential distance from the first conductor baffle member to the second conductor baffle member is an electron that performs a cycloidal motion so as to bypass the tip of the first conductor baffle member under the axial magnetic field and the radial electric field. 4. The ion source according to claim 1, wherein the ion source is set based on the axial magnetic field and the radial electric field so as to be received on a surface of the second conductor baffle member. 5.   5. The ion source according to claim 1, wherein the first conductor baffle member and the second conductor baffle member are disposed so as to be electrically insulated from each other.   The ion source according to claim 1, further comprising an insulating member that structurally connects the first conductor baffle member to the second conductor baffle member.   The ion source according to claim 1, wherein the high voltage electrode unit includes a side wall portion of a plasma chamber in which ions are generated. A vacuum vessel;
An annular magnetic field generator installed so as to surround the vacuum vessel, and a magnetic field generator for generating an axial magnetic field in the vacuum vessel;
A cylindrical high-voltage electrode unit installed in the vacuum vessel, and a high-voltage electrode unit that generates a radial electric field in an electrode external area between the vacuum vessel and the high-voltage electrode unit;
A first conductor baffle member disposed in the electrode external area, electrically connected to the vacuum vessel and electrically insulated from the high voltage electrode portion;
A second conductor baffle member disposed in the circumferential direction adjacent to the first conductor baffle member in the electrode external area, and electrically insulated from the vacuum vessel and electrically connected to the high voltage electrode portion. An ion source characterized by.

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