Ion source and accelerator

Abstract

To provide an ion source and an accelerator, which can be miniaturized.SOLUTION: In an ion source 11, a wiring part 33 from a power source 31 is connected to a negative electrode 13A on a lower end 12a side, and a wiring part from the power source 31 is not connected to a negative electrode 13B on an upper end 12b side. Therefore, the wiring part 33 from the power source 31 is integrated only in the negative electrode 13A on the lower end 12a side, and thus, a complication of the wiring part 33 in a fetching out can be suppressed. Accordingly, the ion source can be miniaturized. In such an ion source 11, the wiring part 33 is only distributed by only fixing it to a magnetic electrode 21 on a lower side, and not require a fixing of the negative electrode 13B on the upper side to a magnetic electrode 23 on the upper side. Therefore, since a maintenance can be performed without breaking a vacuum of a cyclotron, maintainability is deteriorated.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an ion source and an accelerator. [Background technology]

[0002] A conventional technique in this field is an ion source described in Patent Document 1. This ion source is a cold cathode Penning ion gauge (PIG) ​​shaped ion source, and includes a cylindrical anode and cathodes provided on both ends of the anode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2011-505670 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned ion source requires wiring from a power source to be connected to both cathodes, which makes the wiring layout complicated and increases the size of the device.

[0005] In view of the above problems, an object of the present invention is to provide an ion source and accelerator that can be made smaller. [Means for solving the problem]

[0006] An ion source according to one embodiment of the present invention includes a cylindrical first electrode having a first polarity and a second electrode having a second polarity and provided on both ends of the first electrode, wherein a wiring portion from a power source is connected to the second electrode on one end side of the first electrode, and a wiring portion from the power source is not connected to the second electrode on the other end side of the first electrode.

[0007] This ion source includes a cylindrical first electrode having a first polarity and second electrodes having a second polarity, each of which is provided on both ends of the first electrode. By applying a magnetic field in the axial direction of the first electrode and passing a current from a power supply through the second electrode, a discharge occurs in the space inside the cylinder of the first electrode, generating ions. Wiring from the power supply is connected to the second electrode on one end side of the first electrode, while wiring from the power supply is not connected to the second electrode on the other end side of the first electrode. Therefore, by consolidating the wiring from the power supply to only the second electrode on one end side, the complexity of the wiring arrangement can be suppressed. As a result, the ion source can be made smaller.

[0008] The ion source may further include a conductive member extending through the cylindrical space of the first electrode from the second electrode at one end toward the second electrode at the other end. In this case, the second electrode at one end and the second electrode at the other end can be connected by the conductive member. Furthermore, by arranging the conductive member connected to the second electrode in a position close to the inner circumferential surface of the first electrode in the cylindrical space, a structure can be achieved that makes it easy to generate magnetron discharge, which is a discharge that can lower the discharge voltage, in the cylindrical space.

[0009] The second electrode at the other end may be supported by an elastically deformable support. In this case, the support is elastically deformed by pressing the conductive member extending from the second electrode at one end against the second electrode at the other end. This allows the support to maintain contact between the conductive member and the second electrode at the other end while absorbing dimensional errors of each member.

[0010] The second electrode on the other end side may have a housing portion that houses the other end side end of the conductive member. In this case, housing the other end side end of the conductive member in the housing portion makes it easier to maintain contact between the second electrode on the other end side and the conductive member.

[0011] The other end of the conductive member may be in non-contact with the second electrode on the other end side. In this case, by placing the conductive member close to the second electrode on the other end side without contacting them, the two can be electrically coupled.

[0012] The accelerator of the present invention is an accelerator comprising a pair of magnetic poles for forming a magnetic field necessary for particle acceleration and an ion source provided on the magnetic poles, wherein the ion source comprises a cylindrical first electrode having a first polarity and a second electrode having a second polarity and provided on both ends of the first electrode, and a wiring portion from a power supply is connected to the second electrode on one end side of the first electrode, and a wiring portion from the power supply is not connected to the second electrode on the other end side of the first electrode.

[0013] This accelerator can provide the same functions and effects as the above-mentioned ion source. In addition, by suppressing the complexity of the wiring of the ion source, it can be easily incorporated into the accelerator, and accelerator maintenance is also simplified.

[0014] The ion source may be arranged relative to only one of the magnetic poles, which makes it easier to incorporate into the accelerator and facilitates maintenance of the accelerator. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an ion source and an accelerator that can be made smaller in size. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is a plan view of the interior of the accelerator according to the present invention. [Figure 2] FIG. 2 is a schematic diagram of a pair of magnetic poles provided in the accelerator of FIG. 1. [Figure 3] 1 is a cross-sectional view of an ion source according to the present invention. [Figure 4] 10 is a cross-sectional view showing a manner in which a conductive member is connected to the cathode on the other end side. FIG. [Figure 5] 10 is a cross-sectional view showing a manner in which a conductive member is connected to the cathode on the other end side. FIG. [Figure 6] 10 is a cross-sectional view showing a manner in which a conductive member is connected to the cathode on the other end side. FIG. [Figure 7] FIG. 10 is a cross-sectional view of an ion source according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of an ion source and an accelerator according to the present invention will be described in detail with reference to the drawings. In this embodiment, a cyclotron is used as an accelerator. In the cyclotron 1 of this embodiment shown in FIG. 1, the spiral orbit B of the charged particles is assumed to be on a horizontal plane.

[0018] As shown in FIG. 1, the cyclotron 1 includes a vacuum vessel 3, electrodes 5A and 5B, and a magnetic channel 9. The vacuum vessel 3 is a vessel for maintaining a high vacuum state in the acceleration space of charged particles. A pair of magnetic poles 21 and 23 (see FIG. 2) are provided within the vacuum vessel 3 to generate the magnetic field necessary for particle acceleration. The magnetic poles 21 and 23 are circular in plan view and are symmetrical above and below the median plane, which is the acceleration plane. The magnetic poles 21 and 23 are arranged facing each other in the vertical direction (a direction perpendicular to the plane of FIG. 1) across the orbit B of the charged particles. Coils are arranged around each of the magnetic poles 21 and 23, and a magnetic field is generated between the magnetic poles 21 and 23.

[0019] FIG. 2 is a perspective view schematically illustrating only the magnetic poles 21 and 23. As shown in the figure, the magnetic poles 21 and 23 are cylindrical. The terms "radial direction" and "circumferential direction" used below refer to the radial direction and circumferential direction of the circle that defines the contour of the magnetic poles 21 and 23 as viewed from the direction of FIG. 1. Four spirally curved convex portions 21a and four spirally curved concave portions 21b are formed on the upper surface of the magnetic pole 21 and are alternately arranged in the circumferential direction. Similarly, four spirally curved convex portions 23a and four spirally curved concave portions 23b are formed on the lower surface of the magnetic pole 23 and are alternately arranged in the circumferential direction. The convex portions 21a and 23a, and the concave portions 21b and 23b are arranged with a gap between them so as to be plane-symmetrical with respect to the median plane. Here, the convex portions 21a, 23a of the magnetic poles 21, 23 are portions that protrude toward the median plane, and the concave portions 21b, 23b are portions that are concave away from the median plane. The median plane is the plane on which the circular orbit B along which the charged particle beam accelerates and travels is located. Strictly speaking, since the charged particle beam travels while vibrating in the direction in which the magnetic poles 21, 23 face each other (the up-and-down direction in FIG. 3), the median plane is the plane that is approximately the median of the positions of the vibrating charged particle beam in the direction in which the magnetic poles 21, 23 face each other. The shapes of the convex portions 21a, 23a and the concave portions 21b, 23b are not limited to the spirally curved shapes described above, and may be fan-shaped.

[0020] A hill region 25h with a narrow gap between the protrusions 21a and 23a and a valley region 25v with a wide gap between the recesses 21b and 23b are formed between the magnetic poles 21 and 23. A spiral orbit B of charged particles is formed on the symmetric plane between the magnetic poles 21 and 23.

[0021] The DI electrodes 5A and 5B are part of the cavity that generates an electric field for accelerating charged particles inside the vacuum vessel 3. Both DI electrodes 5A and 5B are arranged in the valley region 25v and are arranged so as to face each other radially. The DI electrodes 5A and 5B are formed in a shape that follows the shape of the valley region 25v in a plan view. An ion source 11 is arranged in the center of the magnetic pole 21. The ion source 11 supplies charged particles on the median plane. The ion source 11 is arranged only relative to the lower magnetic pole 21 and is not fixed to the upper magnetic pole 23.

[0022] 1 has the function of deflecting charged particles orbiting in circular orbit B in a magnetic field and extracting them to an extraction orbit. The magnetic channel 9 has the function of further bending the charged particles extracted by the electrostatic deflector 90 outward and the function of focusing the charged particles in the horizontal direction. The magnetic channel 9 includes magnetic channel 9A and magnetic channel 9B.

[0023] The magnetic channel 9A is provided inside the D-electrode 5A. The magnetic channel 9A is provided at the outer end of the D-electrode 5A, at a position corresponding to the outermost periphery of the orbit B. The magnetic channel 9A has both the function of further bending outward the charged particles extracted by the electrostatic deflector 90 and the function of focusing the charged particles in a horizontal direction. The magnetic channel 9B is provided downstream from the magnetic channel 9A in the orbit B of the charged particles. The magnetic channel 9B is provided outside the magnetic poles 21 and 23 in a plan view. The magnetic channel 9B is arranged inside the wall of the vacuum vessel 3. The magnetic channel 9B has the function of focusing the charged particles in a horizontal direction.

[0024] In cyclotron 1, a magnetic field is generated between magnetic poles 21 and 23, and a high-frequency electric field is applied between electrodes 5A, 5B and earth plate 13, causing charged particles to accelerate and travel along a spiral orbit B on the median plane. Charged particles that reach the outer periphery in the radial direction are separated from the orbit by electrostatic deflector 90, and are repeatedly deflected and focused by passing through the introduction gap of magnetic channel 9A, and are further focused by passing through the introduction gap of magnetic channel 9B, before being extracted to the outside through the beam extraction duct.

[0025] The ion source 11 will be described in detail with reference to Fig. 3. Fig. 3 is a cross-sectional view of the ion source 11. As shown in Fig. 3, the ion source 11 includes an anode 12 (first electrode), a pair of cathodes 13A and 13B (second electrodes), a conductive member 14, and a wiring structure 30.

[0026] The anode 12 is a cylindrical member. The direction in which the central axis of the anode 12 extends may be referred to as the axial direction D1. In this embodiment, the axial direction D1 is parallel to the vertical direction. The anode 12 has a lower end 12a (one end), an upper end 12b (the other end), and an inner circumferential surface 12c. The anode 12 has an inner cylindrical space 17 extending in the axial direction D1 between the lower end 12a and the upper end 12b. The anode 12 is provided with an insulating member 18A on the lower end 12a side for supporting the cathode 13A. The anode 12 is provided with an insulating member 18B on the upper end 12b side for supporting the cathode 13B.

[0027] A pair of cathodes 13A, 13B are provided at both ends of the anode 12. As a result, the cathode 13A and the cathode 13B are arranged to face each other while being spaced apart from each other in the axial direction D1. The cathode 13A is provided on the lower end 12a side of the anode 12. The cathode 13A is supported on the lower end 12a side of the anode 12 via an insulating member 18A. The cathode 13A is supported by the insulating member 18A while penetrating the insulating member 18A in the axial direction D1. A lower end portion of the cathode 13A is exposed from the lower end of the insulating member 18A. An upper end portion of the cathode 13A is exposed to the in-tube space 17 from the upper end of the insulating member 18A. The cathode 13B is provided on the upper end 12b side of the anode 12. The cathode 13B is supported on the upper end 12b side of the anode 12 via the insulating member 18B. The cathode 13B is exposed to the cylindrical space 17 from the lower end of the insulating member 18B.

[0028] The conductive member 14 extends through the cylindrical space 17 of the anode 12 from the cathode 13A on the lower end 12a side toward the cathode 13B on the upper end 12b side. The conductive member 14 is a columnar member fixed to the upper end of the cathode 13A on the lower end 12a side and extending upward. A gap for discharge is formed between the conductive member 14 and the inner peripheral surface of the anode 12. The upper end of the conductive member 14 is electrically coupled to the cathode 13B on the upper end 12b side. The manner of coupling will be described later.

[0029] The wiring structure 30 includes a power supply 31, a wiring portion 32, a wiring portion 33, and a ground portion 34. The power supply 31 applies a discharge voltage between the anode 12 and the cathodes 13A and 13B. The wiring portion 32 electrically connects the power supply 31 and the anode 12. The wiring portion 32 is connected to a position on the anode 12. The wiring portion 32 is connected to the ground portion 34. This sets the anode 12 at ground potential.

[0030] The wiring portion 33 electrically connects the power source 31 to the cathodes 13A and 13B. Here, the wiring portion 33 from the power source 31 is connected to the cathode 13A on the lower end 12a side. On the other hand, the wiring portion 33 from the power source 31 is not connected to the cathode 13B on the upper end 12b side. The cathode 13B on the upper end 12b side is electrically coupled to the cathode 13A on the lower end 12a side via the conductive member 14. Therefore, the cathode 13B on the upper end 12b side is electrically connected to the power source 31 via the wiring portion 33, the cathode 13A on the lower end 12a side, and the conductive member 14.

[0031] Next, with reference to FIGS. 4 to 6 , an example of a coupling mode between the conductive member 14 and the cathode 13B on the upper end 12b side will be described. As shown in FIG. 4 , the cathode 13B on the upper end 12b side may be supported by an elastically deformable support portion 41. The support portion 41 is configured by a leaf spring or the like. A housing portion 42 is formed on the upper end 12b side of the anode 12 to house an insulating member 18B that supports the cathode 13B. The housing portion 42 supports the insulating member 18B so that it can move in the axial direction D1. A flange portion 43 is formed on the upper end of the housing portion 42. The support portion 41 is disposed between the insulating member 18B and the flange portion 43. Thus, during assembly, when the conductive member 14 fixed to the cathode 13A is inserted from below upward into the cylindrical space 17 via the insulating member 18A on the lower end 12a side, the upper end of the conductive member 14 abuts against the cathode 13B on the upper end 12b side. When conductive member 14 is pressed further upward, cathode 13B and insulating member 18B are pressed upward, elastically deforming support portion 41. This allows support portion 41 to maintain the state in which conductive member 14 and cathode 13B are in contact with and pressed against each other.

[0032] Next, the functions and effects of the ion source 11 and the cyclotron 1 according to this embodiment will be described.

[0033] The ion source 11 according to this embodiment includes a cylindrical anode 12 having a positive polarity (first polarity) and cathodes 13A and 13B having a negative polarity (second polarity) and provided at both ends of the anode 12. When a current is applied from a power source 31 to the cathodes 13A and 13B while a magnetic field is applied in the axial direction D1 of the anode 12, a discharge occurs in the cylindrical space 17 of the anode 12, and ions are generated. The ion source 11 includes a conductive member 14 extending in the axial direction D1. Therefore, a concentric electric field is formed in the cylindrical space 17 in a direction perpendicular to the magnetic field. This generates plasma circulating around the conductive member 14, generating ions. This method of generating a discharge by forming an electric field perpendicular to the magnetic field is called magnetron discharge. Magnetron discharge has high discharge efficiency, allowing for a lower discharge voltage than PIG discharge and the like.

[0034] Here, with reference to FIG. 7 , an ion source 100 according to a comparative example will be described. As shown in FIG. 7 , the ion source 100 according to the comparative example is a cold-cathode Penning ion gauge (PIG) ​​ion source. The ion source 100 does not have the conductive member 14 described above. Therefore, the cathodes 13A and 13B are not connected to each other via the conductive member 14. Therefore, wiring sections 33A and 33B from the power supply 31 are connected to both the cathodes 13A and 13B. This causes a problem in that the ion source 100 becomes large due to the complicated routing of the wiring sections 33A and 33B. For example, in a radial cyclotron, the ion source can be inserted from the radial direction. However, in the spiral cyclotron 1 according to the present embodiment, the ion source 11 cannot be inserted from the radial direction and must be inserted from above and below. Here, the wiring sections 33A and 33B cannot cross the median plane and therefore must be routed appropriately around the magnetic poles 21 and 23. Therefore, the cathode 13A on the lower end 12a side is fixed to the lower magnetic pole 21 and has wiring 33A routed therearound, and the cathode 13B on the upper end 12b side is fixed to the upper magnetic pole 23 and has wiring 33B routed therearound. With this structure, maintenance cannot be performed without breaking the vacuum in the cyclotron 1, which reduces maintainability.

[0035] In contrast, in the ion source 11 according to this embodiment, the wiring 33 from the power supply 31 is connected to the cathode 13A on the lower end 12a side, and the wiring from the power supply 31 is not connected to the cathode 13B on the upper end 12b side. Therefore, by consolidating the wiring 33 from the power supply 31 only to the cathode 13A on the lower end 12a side, it is possible to prevent the wiring 33 from becoming complicated. As a result, the ion source can be made smaller. In this ion source 11, it is only necessary to fix the wiring 33 to the lower magnetic pole 21 and route it around, and there is no need to fix the upper cathode 13B to the upper magnetic pole 23. Therefore, maintenance can be performed without breaking the vacuum in the cyclotron 1, which reduces maintainability.

[0036] The ion source 11 may further include a conductive member 14 extending through the intra-cylinder space 17 of the anode 12 from the cathode 13A on the lower end 12a side toward the cathode 13B on the upper end 12b side. In this case, the cathode 13A on the lower end 12a side and the cathode 13B on the upper end 12b side can be connected by the conductive member 14. Furthermore, by arranging the conductive member 14 connected to the cathodes 13A and 13B in a position close to the inner circumferential surface 12c of the intra-cylinder space 17 of the anode 12, a structure can be achieved that makes it easy to generate a magnetron discharge, which is a discharge that can lower the discharge voltage, in the intra-cylinder space 17.

[0037] Cathode 13B on the upper end 12b side may be supported by an elastically deformable support 41. In this case, conductive member 14 extending from cathode 13A on the lower end 12a side is pressed against cathode 13B on the upper end 12b side, thereby elastically deforming support 41. This allows support 41 to maintain contact between conductive member 14 and cathode 13B on the upper end 12b side while absorbing dimensional errors of each member.

[0038] The cyclotron 1 according to this embodiment includes a pair of magnetic poles 21, 23 for forming a magnetic field necessary for particle acceleration, and an ion source 11 provided on the magnetic pole 21. The ion source 11 includes a cylindrical anode 12 having a positive polarity (first polarity) and cathodes 13A, 13B having a negative polarity (second polarity) and provided on both ends of the anode 12. A wiring section 33 from a power supply 31 is connected to the cathode 13A on the lower end 12a side, and a wiring section from the power supply 31 is not connected to the cathode 13B on the upper end 12b side.

[0039] This cyclotron 1 can provide the same functions and effects as the above-described ion source 11. Furthermore, by preventing the wiring section 33 of the ion source 11 from becoming complicated, the cyclotron 1 can be easily incorporated into the cyclotron 1, and maintenance of the cyclotron 1 is also easy.

[0040] The ion source 11 may be disposed relative to only one of the magnetic poles 21. In this case, the ion source 11 can be easily incorporated into the cyclotron 1, and the maintenance of the cyclotron 1 also becomes easier.

[0041] The present invention is not limited to the above-described embodiments.

[0042] There is no particular limitation on how to connect conductive member 14 to cathode 13B on the upper end 12b side. For example, as shown in FIG. 5, cathode 13B on the upper end 12b side may have a housing portion 44 that houses the upper end portion of conductive member 14. In this case, by housing the upper end portion of conductive member 14 in housing portion 44, the outer circumferential surface of conductive member 14 and the inner circumferential surface of housing portion 44 can be brought into contact with each other due to eccentricity or tilt due to errors between the members. This makes it easier to maintain contact between cathode 13B on the upper end side and conductive member 14.

[0043] 6, the upper end of conductive member 14 may be out of contact with cathode 13B on upper end 12b. In this case, conductive member 14 is placed close to cathode 13B on upper end 12b without contacting it, and cathode 13B is left floating. When a high discharge voltage is applied to both in this state, they can be electrically coupled.

[0044] In the above-described embodiment, the axial direction D1 is the up-down direction, but the attitude of the ion source 11 in use is not particularly limited and may be changed as appropriate in accordance with the orientation of the accelerator, etc. Furthermore, although the wiring portion 33 is connected to the cathode 13A on the lower end 12a side, the wiring portion 33 may also be connected to the cathode 13B on the upper end 12b side.

[0045] The accelerator is not limited to a spiral type, but may be a radial type. The type of accelerator is not limited to a cyclotron, but may be a microtron, betatron, or the like. [Explanation of symbols]

[0046] 1...cyclotron (accelerator), 11...ion source, 12...anode (first electrode), 13A, 13B...cathode (second electrode), 14...conductive member, 21, 23...magnetic pole, 31...power supply, 33...wiring section, 41...support section, 44...accommodation section.

Claims

1. a cylindrical first electrode having a first polarity; second electrodes having a second polarity and provided on both ends of the first electrode; a wiring portion from a power source is connected to the second electrode on one end side of the first electrode; the wiring portion from the power source is not connected to the second electrode on the other end side of the first electrode, the conductive member extends through a cylindrical space of the first electrode from the second electrode on the one end side toward the second electrode on the other end side, and has an end on the other end side electrically coupled to the second electrode on the other end side.

2. The ion source according to claim 1 , wherein the second electrode on the other end side is supported by an elastically deformable support portion.

3. The ion source according to claim 1 , wherein the second electrode on the other end side has a housing portion that houses the end portion on the other end side of the conductive member.

4. The ion source according to claim 1 , wherein the other end of the conductive member is not in contact with the second electrode on the other end.

5. a pair of magnetic poles for forming a magnetic field necessary for particle acceleration; an ion source provided in the magnetic pole, The ion source comprises: a cylindrical first electrode having a first polarity; second electrodes having a second polarity and provided on both ends of the first electrode; a wiring portion from a power source is connected to the second electrode on one end side of the first electrode; the wiring portion from the power source is not connected to the second electrode on the other end side of the first electrode, the accelerator further comprising a conductive member extending through a cylindrical space of the first electrode from the second electrode on the one end side toward the second electrode on the other end side, the conductive member having an end on the other end side electrically coupled to the second electrode on the other end side.

6. The accelerator of claim 5 , wherein the ion source is positioned relative to only one of the magnetic poles.

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