Ion generator

Abstract

To provide an ion generator capable of adequately controlling temperatures of a plasma electrode, thereby efficiently extracting ions.SOLUTION: An ion generator 1 of the present invention generates ion beams by a surface generation method. The ion generator 1 includes: a discharge vessel 2 for storing a discharge gas; a plasma electrode 3 having a plurality of ion extraction holes 30 through which an internal space of the discharge vessel 2 communicates with an external space of the discharge vessel 2; a refrigerant passage 32 disposed to pass between the plurality of ion extraction holes 30 at the inside of the plasma electrode 3; and a refrigerant supply part 7 for supplying a refrigerant gas into the refrigerant passage 32.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to, for example, an ion generating device that generates ions. [Background technology]

[0002] Conventionally, an ion generating device has been proposed that includes a discharge vessel into which a discharge gas is introduced, a plasma electrode that is placed inside the discharge vessel to draw ions from the discharge plasma generated from the discharge gas to the outside of the discharge vessel, a heat transfer section that is connected to the plasma electrode, and a temperature adjustment device that is installed in the heat transfer section and that maintains the temperature of the plasma electrode at a predetermined temperature (see Patent Document 1).

[0003] In the ion generator described in Patent Document 1, the temperature adjustment device has a cooling flow path through which a liquid refrigerant such as water, alcohol, or a mixture thereof flows, a heater, etc. The ion generator described in Patent Document 1 aims to improve ion generation efficiency by uniforming the temperature distribution of the plasma electrode and reducing the temperature gradient through temperature control that utilizes the functions of the temperature adjustment device.

[0004] However, in the ion generating device described in Patent Document 1, the temperature of the plasma electrode is controlled locally and indirectly, resulting in a slow time response and a low temperature adjustment effect, and there is room for improvement in terms of the efficiency of ion generation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-180999 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above-mentioned problems, an object of the present invention is to provide an ion generating device that allows appropriate temperature control of a plasma electrode and that can efficiently extract ions. [Means for solving the problem]

[0007] The present invention is an ion generator of a type that generates an ion beam by a surface generation method, characterized in that it comprises: a discharge vessel that contains a discharge gas; a plasma electrode having a plurality of ion extraction holes that connect the internal space of the discharge vessel with the external space of the discharge vessel; a coolant passage arranged inside the plasma electrode so as to pass between the plurality of ion extraction holes; and coolant supply means that supplies coolant gas to the coolant passage. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an ion generating device that can appropriately control the temperature of the plasma electrode and efficiently extract ions. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an ion generating device. [Figure 2] FIG. 2 is a plan view showing the configuration of a plasma electrode. [Figure 3] Cross-sectional view of the plasma electrode taken along the line AA. [Figure 4] FIG. 2 is a block diagram showing the peripheral configuration of a plasma electrode. [Figure 5] FIG. 10 is a block diagram showing the configuration of a refrigerant path in a modified example. [Figure 6] FIG. 10 is a time chart showing direction switching control in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a diagram showing the configuration of an ion generator 1. The ion generator 1 is a device that generates an ion beam that is emitted in a predetermined direction by removing electrons from atoms of the introduced gas (discharge gas) through plasma discharge caused by introducing gas into a vacuum. The ion generator 1 has several methods for generating ion beams, which differ in the method of supplying ionization energy for ionizing the atoms of the discharge gas.

[0011] The ion generator 1 of this embodiment is an ion generator of a type that generates an ion beam by a surface generation method. As shown in Fig. 1, the ion generator 1 has a discharge vessel (plasma discharge vessel) 2, a plasma electrode 3, and an extraction electrode 4.

[0012] In the surface generation method, alkali metal introduced into the discharge vessel 2 in a gaseous state is deposited on the surface of the plasma electrode (negative ion generating electrode) 3, lowering the work function of the surface of the plasma electrode 3 (making it easier to generate ions), which then donates electrons to positive ions or atoms that are incident on the plasma electrode 3, generating ions (negative ions). The work function depends on the thickness of the alkali metal film, and by appropriately controlling the film thickness, negative ions can be generated several times more efficiently than with the volume generation method.

[0013] The discharge vessel 2 is a vessel with a semi-cylindrical cross section, the inside of which is kept in a vacuum state. A filament made of tungsten or the like is installed inside the discharge vessel 2, and a plasma electrode 3 is provided at the opening of the discharge vessel 2. Although not shown in the figure, the discharge vessel 2 is provided with ports for introducing a discharge gas into the interior of the discharge vessel 2 and ports for evacuating the interior of the discharge vessel 2.

[0014] The plasma electrode 3 is a flat plate-shaped member made of a conductive metal material such as molybdenum. The plasma electrode 3 is electrically connected to a voltage application unit (not shown), and a predetermined voltage (positive voltage) is applied to the plasma electrode 3. The plasma electrode 3 is formed in a substantially rectangular shape in a plan view, and a circular ion extraction hole 30 is provided in the center of the plasma electrode 3.

[0015] The extraction electrode 4 is a flat plate-shaped member made of a conductive metal material such as molybdenum. The extraction electrode 4 is electrically connected to a voltage application unit (not shown), and a predetermined voltage (positive voltage) is applied to it. A circular ion extraction hole 40 is provided in the center of the extraction electrode 4. The ion extraction hole 40 of the extraction electrode 4 is located at the same position as the ion extraction hole 30 of the plasma electrode 3 when viewed in the direction of travel of the ion beam.

[0016] A plurality of extraction electrodes 4 are provided, and in this embodiment, five extraction electrodes 4 are provided. The extraction electrodes 4 and the plasma electrode 3 are arranged parallel to each other. The distance between adjacent extraction electrodes 4 is the same. In other words, the extraction electrodes 4 are arranged at equal intervals in the direction of travel of the ion beam.

[0017] Furthermore, the voltage value of the positive voltage applied to plasma electrode 3 and extraction electrode 4 can be set appropriately depending on the size and configuration of ion generator 1, the target amount of ions to be generated, and the like.

[0018] In the ion generator 1 configured as described above, negative ions generated on the surface of the plasma electrode 3 pass through the ion extraction hole 30 and then through the ion extraction hole 40 of the extraction electrode 4, and are emitted to the outside of the ion generator 1. At this time, the negative ions are accelerated by the positive voltage applied to the plasma electrode 3 and the extraction electrode 4, and are emitted to the outside of the ion generator 1 as a beam.

[0019] <Configuration of the plasma electrode part of the present invention> The plasma electrode 3 of the present invention and its peripheral configuration will be described below. Fig. 2 is a plan view showing the configuration of the plasma electrode 3 and its peripheral configuration. Fig. 3 is a cross-sectional view of the plasma electrode 3 taken along the line AA.

[0020] As shown in FIGS. 2 and 3 , in this embodiment, the plasma electrode 3 is formed by overlapping a first metal plate 3a and a second metal plate 3b, each of which has a substantially rectangular shape in a plan view. The first metal plate 3a and the second metal plate 3b are formed with a refrigerant passage groove 3c and a refrigerant passage groove 3d, respectively. By overlapping the first metal plate 3a and the second metal plate 3b, the refrigerant passage groove 3c and the refrigerant passage groove 3d are connected to form a refrigerant passage 32. This configuration allows for the formation of minute refrigerant passages 32 of a consistent size within the plasma electrode 3. Furthermore, a plurality of ion extraction holes 30 are provided in the center of the plasma electrode 3 in a plan view. Each ion extraction hole 30 is defined by a circular opening edge 30a formed in the plasma electrode 3. The ion extraction holes 30 are the same size and are arranged in a matrix. In this embodiment, 25 ion extraction holes 30 (5 x 5) are arranged in a matrix.

[0021] The plasma electrode 3 is also provided with a first opening 31 and a second opening 33. The first opening 31 and the second opening 33 are recesses formed in one of the main surfaces (front or back) of the plasma electrode 3, and the first opening 31 and the second opening 33 form a recess space in the plasma electrode 3.

[0022] The first opening 31 is provided along one of the ends (either end in the front, rear, left or right direction) of the plasma electrode 3 in a plan view, and the second opening 33 is provided along an end of the plasma electrode 3 that faces the end where the first opening 31 is provided. The first opening 31 and the second opening 33 are provided at opposite ends of the plasma electrode 3 so as to sandwich the multiple ion extraction holes 30 therebetween.

[0023] In this embodiment, the first opening 31 and the second opening 33 are formed in a rectangular shape extending in a direction perpendicular to the opposing direction (the width direction of the first opening 31 and the second opening 33) in a plan view. The first opening 31 and the second opening 33 are also arranged so that their longitudinal directions are parallel to each other.

[0024] Furthermore, the widthwise ends of the first opening 31 and the second opening 33 are located outside the outermost positions of the multiple ion extraction holes 30. That is, the widthwise dimensions of the first opening 31 and the second opening 33 are greater than the outermost widths of the multiple ion extraction holes 30. Therefore, all the ion extraction holes 30 are located inside (within the widths of) the first opening 31 and the second opening 33 in the widthwise direction.

[0025] Furthermore, the plasma electrode 3 is provided with a coolant passage 32 that connects the first opening 31 and the second opening 33 inside the plasma electrode 3. Specifically, the coolant passage 32 connects the opposing inner walls of the first opening 31 and the second opening 33.

[0026] In this embodiment, the coolant passage 32 is provided so as to pass between the plurality of ion extraction holes 30. Specifically, the coolant passage 32 is arranged so as to pass between the plurality of ion extraction holes 30 in the width direction of the first opening 31 and the second opening 33.

[0027] In addition, the refrigerant passages 32 in this embodiment extend linearly in the opposing direction and are provided so as to connect the first opening 31 and the second opening 33 over the shortest distance. Furthermore, a plurality of refrigerant passages 32 are provided so as to branch off from each of the first opening 31 and the second opening 33, and the plurality of refrigerant passages 32 are arranged so as to extend parallel to one another.

[0028] In this embodiment, if five ion extraction holes 30 arranged in the opposing direction of the first opening 31 and the second opening 33 are defined as one row of ion extraction holes, the coolant passages 32 are arranged so as to pass between each row of ion extraction holes. In addition, the coolant passages 32 are also arranged outside the outermost ion extraction hole row. That is, in this embodiment, the ion extraction holes 30 are sandwiched between the coolant passages 32 from one side or the other in the width direction. That is, the coolant passages 32 in this embodiment are arranged so as to sandwich the ion extraction holes 30 from two directions.

[0029] The ion extraction hole 30 and the coolant passage 32 are disposed close to each other. That is, the coolant passage 32 is provided so as to pass near the ion extraction hole 30. Specifically, the distance between the ion extraction hole 30 and the coolant passage 32 (the distance between the closest ion extraction hole 30 and the shortest part of the coolant passage 32) can be set to within 1 / 5 of the diameter of the ion extraction hole 30, preferably within 1 / 8 of the diameter of the ion extraction hole 30, and more preferably within 1 / 10 of the diameter of the ion extraction hole 30.

[0030] 2, a first manifold 5 is connected to the first opening 31, and a second manifold 6 is connected to the second opening 33. The first manifold 5 is attached to the plasma electrode 3 so as to cover the entire first opening 31. The second manifold 6 is attached to the plasma electrode 3 so as to cover the entire second opening 33.

[0031] The first manifold 5 is attached without any gaps to the main surface of the plasma electrode 3 around the first opening 31. Therefore, the internal space 51 of the first manifold 5 is in communication with the first opening 31, and the internal space 51 of the first manifold 5 and the recessed space formed by the first opening 31 form an integrated space.

[0032] Furthermore, the second manifold 6 is attached without any gaps to the main surface of the plasma electrode 3 around the second opening 33. Therefore, the internal space 61 of the second manifold 6 is in communication with the second opening 33, and the internal space 61 of the second manifold 6 and the recessed space formed by the second opening 33 form an integrated space.

[0033] Therefore, the internal space 51 of the first manifold 5, the first opening 31, the plurality of refrigerant passages 32, the second opening 33, and the internal space 61 of the second manifold 6 are connected to each other to form an integrated passage. Refrigerant gas, which will be described later, is supplied to this passage from the first manifold 5. At this time, the internal space 51 and the first opening 31 of the first manifold 5 form an integrated space, and the refrigerant gas is distributed from this integrated space to the plurality of refrigerant passages 32, so that the refrigerant gas can be supplied to the plurality of refrigerant passages 32 in a balanced manner.

[0034] 3, the inner surface of opening edge 30a forming ion extraction hole 30 is a tapered inclined surface. Specifically, the inner surface of opening edge 30a is formed by front-side tapered surface 30b formed on the inner space side of discharge vessel 2 (front surface side of plasma electrode 3: upper side in FIG. 3) and back-side tapered surface 30c formed on the outer space side of discharge vessel 2 (back surface side of plasma electrode 3: lower side in FIG. 3).

[0035] The front-side tapered surface 30b is an inclined surface whose diameter decreases from the front side of the plasma electrode 3 toward the back side of the plasma electrode 3, and the back-side tapered surface 30c is an inclined surface whose diameter decreases from the back side of the plasma electrode 3 toward the front side of the plasma electrode 3. The front-side tapered surface 30b and the back-side tapered surface 30c intersect midway in the thickness direction (hereinafter simply referred to as the "thickness direction") of the plasma electrode 3. The position where the front-side tapered surface 30b and the back-side tapered surface 30c intersect is slightly toward the back side from the center in the thickness direction.

[0036] The inner diameters of the opening edges 30a on the front and back surfaces of the plasma electrode 3 are the same. Therefore, the front surface tapered surface 30b has a larger surface area than the back surface tapered surface 30c. As described above, when negative ions are generated on the surface of the plasma electrode 3, the front surface tapered surface 30b also functions as a reaction surface. Therefore, the large surface area of ​​the front surface tapered surface 30b can improve the ion generation efficiency.

[0037] Furthermore, the width dimension (thickness in the width direction) of the portion (partition wall portion) 34 between the ion extraction holes 30 in the plasma electrode 3 becomes maximum at a position slightly toward the back surface side from the center in the thickness direction where the front surface tapered surface 30b and the back surface tapered surface 30c intersect. Here, the plasma electrode 3 can be configured as an integral unit (as a single block), or can be configured as separate parts made up of multiple members.

[0038] For example, the plasma electrode 3 can be configured with two members stacked in the thickness direction. In this case, it is preferable to divide the plasma electrode 3 into a front-side member and a back-side member at the position where the front-side tapered surface 30b and the back-side tapered surface 30c intersect (the position where the front-side tapered surface 30b and the back-side tapered surface 30c intersect is defined as the joining surface), and join them by an appropriate joining means such as brazing.

[0039] The cross-sectional shape of the refrigerant passage 32 is not particularly limited. For example, it may be circular or polygonal. However, from the perspective of the temperature adjustment effect of the refrigerant gas, it is preferable that the surface area of ​​the refrigerant passage 32 is large.

[0040] In this embodiment, the coolant passage 32 is formed so as to overlap the maximum width portion of the partition wall 34 (the intersection of the front-side tapered surface 30b and the back-side tapered surface 30c) in the thickness direction of the plasma electrode 3. This ensures the thickness of the partition wall 34 and allows the cross section of the coolant passage 32 to be set large. That is, the surface area of ​​the coolant passage 32 can be increased, and the temperature adjustment effect of the refrigerant gas can be enhanced.

[0041] In this embodiment, the coolant passage 32 has a protrusion 32a that protrudes toward the front surface of the plasma electrode 3. The protrusion 32a is formed with a U-shaped cross section that opens toward the back surface of the plasma electrode 3. The tip of the protrusion 32a (the end on the front surface side of the plasma electrode 3) is located closer to the front surface than the center of the plasma electrode 3 in the thickness direction.

[0042] Two protrusions 32a are formed, and the two protrusions 32a are provided to extend parallel to each other. Furthermore, the coolant passage 32 has a connecting portion 32b that connects the base ends of the protrusions 32a (the back surface side ends of the plasma electrode 3). In this way, by providing multiple grooves that serve as multiple protrusions on one of the first metal plate 3a and the second metal plate 3b and providing a single wide groove (with a width equal to or greater than the total width of the multiple grooves) that serves as a connecting portion on the other, it is possible to form a coolant passage 32 that has a large surface area and is less likely to clog even if brazing material leaks when the first metal plate 3a and the second metal plate 3b are overlapped.

[0043] The connecting portion 32b is formed to have a rectangular cross section (rod-like) extending in the width direction, and is formed so as to protrude outward in the width direction beyond the two protruding portions 32a.

[0044] Furthermore, the lower edge of the connecting portion 32b (the end on the back surface side of the plasma electrode 3) is located closer to the back surface side than the center in the thickness direction of the plasma electrode 3. Therefore, the refrigerant passage 32 is provided from the back surface side to the front surface side so as to straddle the center in the thickness direction of the plasma electrode 3 (the maximum width part of the partition wall portion 34). Therefore, the temperature adjustment effect by the refrigerant gas can be obtained on both the front surface side and the back surface side of the plasma electrode 3.

[0045] Furthermore, in this embodiment, the upper edge of the connecting portion 32b is formed at the same position in the thickness direction as the intersection of the front-side tapered surface 30b and the back-side tapered surface 30c. With this configuration of the connecting portion 32b, the plasma electrode 3 can be divided into a front-side member and a back-side member at the intersection of the front-side tapered surface 30b and the back-side tapered surface 30c. In this case, if the front-side member and the back-side member are brazed together, and the brazing material overflows from the joining surface, the brazing material can be guided toward the connecting portion 32b, thereby suppressing or preventing it from entering and accumulating at the tip end of the protruding portion 32a. Therefore, the tip end of the protruding portion 32a can be prevented from being blocked by the brazing material, which would reduce the temperature adjustment effect of the refrigerant gas.

[0046] Fig. 4 is a block diagram showing the peripheral configuration of the plasma electrode 3. As shown in Fig. 4, in addition to the components described above, the ion generating device 1 has, in relation to the plasma electrode 3, a coolant supply unit 7, a coolant discharge unit 8, a temperature sensor 9, and a control unit 10.

[0047] The refrigerant supply unit 7 is connected to the first manifold 5 and supplies refrigerant gas to the refrigerant passage 32 via the first manifold 5. The refrigerant supply unit 7 has a refrigerant supply passage for supplying the refrigerant gas, and an air compressor, an air tank (reserve tank), a pressure gauge, a mass flow controller, and the like, which are provided at appropriate positions in the refrigerant supply passage. The refrigerant supply unit 7 also has solenoid valves and manual valves provided at appropriate positions, and supplies refrigerant gas at a desired pressure to the refrigerant passage 32 via the first manifold 5. Examples of refrigerant gases that can be used in the present invention include compressed air, argon gas, and nitrogen gas.

[0048] The refrigerant discharge unit 8 is connected to the second manifold 6 and discharges the refrigerant gas discharged from the refrigerant passage 32 to the outside space via the second manifold 6. The refrigerant discharge unit 8 has a refrigerant discharge passage for discharging the refrigerant gas, and a flow meter, a pressure gauge, and the like provided in the refrigerant discharge passage. The refrigerant discharge unit 8 also has solenoid valves and manual valves provided at appropriate positions to adjust the flow rate and pressure appropriately and discharge the refrigerant gas discharged from the refrigerant passage 32 to the outside space.

[0049] With the above-described configuration, the refrigerant gas supplied from the refrigerant supply unit 7 is introduced into the plurality of refrigerant passages 32 through the internal space 51 of the first manifold 5 and the first opening 31, passes through each refrigerant passage 32, passes through the second opening 33 and the internal space 61 of the second manifold 6, reaches the refrigerant discharge unit 8, and is discharged to the outside of the device.

[0050] Temperature sensor 9 is a sensor for detecting the temperature of plasma electrode 3, and transmits a detection signal corresponding to the temperature of plasma electrode 3 to control unit 10. For example, temperature sensor 9 is a thermocouple or the like, and any known temperature sensor capable of detecting temperatures in the range of 100°C to 400°C can be used as temperature sensor 9. Temperature sensor 9 is attached directly to the outer surface of plasma electrode 3, or attached to a heat transfer member attached to the outer surface of plasma electrode 3. If temperature sensor 9 is a non-contact type, it may be located at a position separated from plasma electrode 3.

[0051] The control unit 10 controls at least the refrigerant supply unit 7 and the refrigerant discharge unit 8. In this embodiment, the control unit 10 is configured to control not only the refrigerant supply unit 7 and the refrigerant discharge unit 8, but also each component (structural element) included in the ion generating device 1.

[0052] Control unit 10 includes a calculation unit, a storage unit, etc., and executes various calculations and control operations in the components to be controlled. The calculation unit is an arithmetic processing unit including a CPU or an MPU, etc. The storage unit includes a RAM (DRAM), a ROM, etc., and stores various programs for executing various calculations and control operations in various operations of ion generating device 1, as well as default values ​​for various information. A series of operations in ion generating device 1 is realized by control of each component of ion generating device 1 by control unit 10.

[0053] For example, the control unit 10 controls the refrigerant supply unit 7 (controlling the operation of the air compressor, the operation of the mass flow controller, the operation of the solenoid valve, etc.) and the refrigerant discharge unit 8 (controlling the operation of the solenoid valve, etc.) by operating in accordance with an appropriate program stored in the memory unit.

[0054] A demonstration experiment was conducted on the ion generator of the present invention configured as described above. In an MeV-class ion source test facility (MTF), the plasma electrode of an arc discharge-type hydrogen negative ion source with a maximum output of 40 kW and a maximum DC current of 1 MV was used as the plasma electrode 3 of the present invention, and the peripheral configuration of the plasma electrode 3 of the present invention was added. Compressed air was supplied to the coolant passage 32 at a maximum flow rate of 250 SLM as a coolant gas. Because there is a correlation between the alkali metal film thickness and the temperature of the plasma electrode 3, the supply of compressed air was controlled using the temperature of the plasma electrode 3 as a parameter for long-term operation. To achieve the desired alkali metal film thickness, it is preferable to control the temperature of the plasma electrode 3 within the range of 190°C to 300°C, which allows for efficient ion generation. Of the 25 ion extraction holes 30, nine ion extraction holes 30 (18 cm x 18 cm), consisting of three x three holes in the center, were used as the ion generation region.

[0055] If compressed air is not supplied, the temperature will rise by 1°C per second. However, in the configuration of the present invention, feedback control is performed based on the temperature of the plasma electrode 3 obtained from the detection signal of the temperature sensor 9, and compressed air is supplied as a refrigerant gas. This makes it possible to control the temperature within the range of 195°C to 220°C relative to the target value of 200°C for 300 seconds, and a 62 mA negative ion beam can be stably generated from the ion generation region.

[0056] As described above, according to the present invention, the refrigerant gas can be supplied directly to the refrigerant passage 32 arranged close to the ion extraction hole 30, resulting in a fast response time and a high temperature adjustment effect. This allows the temperature of the plasma electrode 3 to be appropriately controlled, and ions can be extracted efficiently.

[0057] Furthermore, according to the present invention, the coolant passages 32 are arranged so as to pass between the multiple ion extraction holes 30, which makes it possible to make the temperature distribution of the plasma electrode 3 (particularly around the ion extraction hole 30) as uniform as possible, thereby enabling spatially uniform generation of negative ions, which was previously difficult to achieve. Similarly, according to the present invention, the coolant passages 32 are arranged so as to sandwich the ion extraction hole 30 from two directions, which makes it possible to adjust the temperature of the area around the ion extraction hole 30 from two directions, thereby enabling spatially uniform generation of negative ions.

[0058] Furthermore, according to the present invention, since the coolant passage 32 has the protrusion 32a that protrudes toward the surface of the plasma electrode 3, it is possible to maximize the surface area of ​​the coolant passage 32, particularly the surface area on the surface side of the plasma electrode 3, thereby enhancing the temperature adjustment effect of the coolant gas. This in turn improves the time response speed of the temperature adjustment of the plasma electrode 3.

[0059] Furthermore, the present invention can be used regardless of the ambient temperature because it uses compressed air as a refrigerant gas that is chemically stable even at high temperatures. Furthermore, compressed air can be supplied via insulating piping to devices that apply high voltage, such as ion sources for particle accelerators, enabling appropriate temperature control of the plasma electrode 3 and efficient extraction of ions.

[0060] Furthermore, the present invention can be applied to ion generators using the surface generation method in a wide range of fields, and can contribute to stabilizing negative ion beam generation over long periods of time under high-voltage environments, including medical negative ion sources, and reducing semiconductor manufacturing costs through the development of uniform, large-area plasma sources.

[0061] The ion generating device of the present invention corresponds to ion generating device 1 of the above embodiment, and similarly, the discharge vessel corresponds to discharge vessel 2, the plasma electrode corresponds to plasma electrode 3, the ion extraction hole corresponds to ion extraction hole 30, the coolant passage corresponds to coolant passage 32, the coolant supply means corresponds to coolant supply unit 7, the first manifold corresponds to first manifold 5, the second manifold corresponds to second manifold 6, and the protrusion corresponds to protrusion 32a, but the present invention is not limited to this embodiment and can be embodied in various other ways. Furthermore, the specific configurations and the like given in the above embodiment are merely examples and can be changed as appropriate depending on the actual product.

[0062] For example, instead of or in addition to performing feedback control based on the temperature of the plasma electrode 3 obtained from the detection signal of the temperature sensor 9, a detection means for detecting the current value of the negative ion beam may be provided, and the flow rate of the refrigerant gas may be controlled in real time using the state variable of the current value of the negative ion beam as an index, thereby enabling appropriate temperature control of the plasma electrode 3 and realizing stable generation of negative ions over a long period of time. Furthermore, in the present invention, a state variable correlated with the temperature of the plasma electrode 3 may be detected, not limited to the temperature or the current value of the negative ion beam, and the flow rate of the refrigerant gas may be controlled in real time using this state variable as an index.

[0063] The refrigerant paths between the refrigerant supply unit 7 and the refrigerant discharge unit 8 and the first opening 31 and the second opening 33 may also be modified. For example, as shown in FIG. 5 , a first path 20, a second path 21, a third path 22, and a fourth path 23 may be provided (Modification 1). In Modification 1, the first path 20 connects the refrigerant supply unit 7 and the first opening 31. The second path 21 connects the second opening 33 and the refrigerant discharge unit 8. The third path 22 branches off from a branch point P1 midway along the first path 20 and joins the second path 21 at a branch point P2 midway along the second path 21. The fourth path 23 branches off from a branch point P3 located midway along the first path 20 between the branch point P1 and the first opening 31, and merges with the second path 21 at a branch point P4 located midway along the second path 21 between the branch point P2 and the refrigerant discharge section 8.

[0064] Furthermore, ion generator 1 of modification 1 has first solenoid valve 11 arranged between branch point P1 and branch point P3 of first path 20, second solenoid valve 12 arranged midway through fourth path 23, third solenoid valve 13 arranged between branch point P2 and branch point P4 of second path 21, and fourth solenoid valve 14 arranged midway through third path 22. In ion generator 1 configured in this manner, as shown in Fig. 6, refrigerant gas can flow in a first direction from first path 20 through first manifold 5 and from second manifold 6 to second path 21 by setting first solenoid valve 11 to an open state, second solenoid valve 12 to a closed state, third solenoid valve 13 to an open state, and fourth solenoid valve 14 to a closed state. Furthermore, by closing first solenoid valve 11, opening second solenoid valve 12, closing third solenoid valve 13, and opening fourth solenoid valve 14, refrigerant gas can flow in the second direction from refrigerant supply unit 7 through branch point P1 of first path 20 to third path 22, through branch point P2 to second path 21 to second manifold 6, from first manifold 5 to first path 20, through branch point P3 to fourth path 23, and from branch point P4 to second path 21 to refrigerant discharge unit 8. Here, the temperature of the refrigerant gas changes between the upstream and downstream sides of refrigerant passage 32 due to heat received from plasma electrode 3, creating a temperature gradient between the upstream and downstream sides of refrigerant passage 32, which ultimately results in different temperatures depending on the location on plasma electrode 3. However, according to the configuration of Modification 1, the direction of refrigerant gas flowing through refrigerant passage 32 is reversed between the first and second directions, and therefore, by reversing the upstream / downstream sides of first manifold 5 and second manifold 6, it is possible to uniformly adjust the temperature of plasma electrode 3 and generate spatially uniform negative ions. Furthermore, when switching the direction of refrigerant gas from the first direction to the second direction, first solenoid valve 11, second solenoid valve 12, third solenoid valve 13, and fourth solenoid valve 14 are opened / closed in this order, and when switching from the second direction to the first direction, fourth solenoid valve 14, third solenoid valve 13, second solenoid valve 12, and first solenoid valve 11 are opened / closed in this order, thereby preventing backflow of refrigerant gas. [Industrial Applicability]

[0065] The present invention can be applied to industries related to ion generating devices that generate ions. [Explanation of symbols]

[0066] 1...Ion generator 2...Discharge vessel 3...Plasma electrode 30...Ion extraction hole 31...First opening 32...Refrigerant passage 32a...Protruding part 33...Second opening 4...Extraction electrode 40...Ion extraction hole 5...First manifold 6...Second manifold 7...Refrigerant supply section 8...Refrigerant discharge part 9...Temperature sensor 10...Control unit

Claims

1. An ion generator of a type that generates an ion beam by a surface generation method, a discharge vessel containing a discharge gas; a plasma electrode having a plurality of ion extraction holes communicating with the internal space of the discharge vessel and the external space of the discharge vessel; a coolant passage disposed inside the plasma electrode so as to pass between the plurality of ion extraction holes; a refrigerant supply means for supplying a refrigerant gas to the refrigerant passage; Ion generator.

2. The coolant passage has a protruding portion that protrudes toward the internal space of the discharge vessel. The ion generating device according to claim 1.

3. a plurality of the coolant passages are provided so as to sandwich the ion extraction hole from two directions; The plurality of refrigerant passages are provided to extend in parallel. The ion generating device according to claim 2.

4. a first manifold connected to one opening of the plurality of refrigerant passages and to a refrigerant supply means; a second manifold connected to the other opening of the plurality of refrigerant passages and to a refrigerant supply means; The plurality of refrigerant passages are provided linearly so as to connect the one opening and the other opening.

4. The ion generating device according to claim 1, 2 or 3.

5. The refrigerant gas is compressed air.

5. The ion generating device according to claim 4.

6. a discharge vessel into which a discharge gas is introduced; a plasma electrode having an ion extraction hole that communicates the internal space of the discharge vessel with the external space of the discharge vessel; a plurality of coolant passages arranged inside the plasma electrode so as to sandwich the ion extraction hole from two directions; a refrigerant supply means for supplying a refrigerant to the refrigerant passage; Ion generator.

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