JP2017004599A - Charged particle accelerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle accelerator which is easily designed and capable of obtaining a high-energy ion beam even without using a DC high-voltage power source.SOLUTION: A charged particle accelerator 300 comprises: a charged particle generator 330 that generates a charged particle; a plurality of conductive electrode plates P1-P24 to which a predetermined voltage is applied, thereby accelerating charged particles; a pulse power source 310 that applies a voltage to each of the electrode plates P1-P24; and a control unit 320 for controlling the voltage that the pulse power source 310 applies to each of the electrode plates P1-P24. The electrode plates P1-P24 are disposed at equal intervals. The control unit 320 controls the pulse power source 310 to apply the voltage to each of the electrode plates P1-P24 in such a manner that charged particles generated by the charged particle generator 330 are pulled in between the electrode plates P1 and P2 and accelerated in one direction by an electric field formed between neighboring electrode plates.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a charged particle accelerator that accelerates charged particles to obtain a high energy charged particle beam (ion beam).

  Charged particle accelerators that accelerate charged particles are known. For example, Patent Document 1 below discloses a charged particle accelerator configured as shown in FIG. The charged particle accelerator 1 includes a charged particle generation source 2 that generates charged particles, acceleration power sources 3A and 3B for applying an acceleration voltage for accelerating charged particles, and switches 4A and 4B to the acceleration power sources 3A and 3B. And an acceleration gradient by a voltage dividing circuit is formed between the pair of acceleration voltage application electrode plates 5A and 5B and the pair of acceleration voltage application electrode plates 5A and 5B. The voltage dividing electrode plates 6A and 6B arranged and connected to each other and the acceleration voltage application electrode plates 5A and 5B and the voltage dividing electrode plates 6A and 6B are sequentially passed and accelerated at a predetermined timing. And a control unit 7 that performs on / off control of the switches 4A and 4B. Further, two pairs of acceleration voltage applying electrode plates 5C, 5D, and 5E, 5F are arranged on the charged particle traveling path through gaps G2, G3, and each through a common power bus B1, B2. Are connected to the acceleration power supplies 3A and 3B via the switches 4C, 4D and 4E, 4F.

  The charged particle accelerator 1 has a voltage applied to the electrode plates 5A, 6A, 6B and 5B so that the ions are accelerated in this direction in order to extract and accelerate ions generated by the charged particle generation source 2 by the control unit 7. (If positive ions are applied, the potential is applied in order to decrease). Similarly, voltages are applied to the electrode plates 5C, 6C, 6D and 5D, and 5E, 6E, 6F and 5F. Thereby, the ion group is accelerated between the electrode 5A and the electrode 5B. After that, at the timing when the head of the ion group reached the electrode 5B, the voltage was applied to the electrode plates 5A, 6A, 6B and 5B while maintaining the potential gradient of the electrode plates 5A, 6A, 6B and 5B. Apply a voltage opposite to the voltage. Thereby, further ions are prevented from being drawn into the electrode plate 5A, and a cluster or bunch of ion beams having a predetermined spread, that is, having a rear end is formed and accelerated. A voltage for focusing ions is applied to the electrode plates 5A, 6A, 6B, and 5B by the voltage dividing resistors 9A to 9C, and the bunch is accelerated while being focused in the radial direction.

  When the bunch passes through the electrode plate 5C after passing through the electrode plate 5B and inputs to the electrode plate 5C, the electrode plates 5C, 6C, 6D are accelerated in the same manner as accelerated by the electrode plates 5A, 6A, 6B and 5B. And 5D. Similarly, a voltage that focuses ions is applied to the electrode plates 5C, 6C, 6D, and 5D by the voltage dividing resistors 9D to 9F, and the bunch is accelerated while being focused in the radial direction.

  At the timing when the end of the bunch reaches the electrode plate 5C, the voltage gradient opposite to that applied to the electrode plates 5C, 6C, 6D and 5D is maintained while maintaining the potential gradient of the electrode plates 5C, 6C, 6D and 5D. Apply voltage. A voltage that focuses ions is applied to the electrode plates 5C, 6C, 6D, and 5D by the voltage dividing resistors 9D to 9F, and the bunch is accelerated while being focused in the radial direction.

  Similarly, at the timing when the end of the bunch reaches the electrode plate 5E, the potential gradient of the electrode plates 5E, 6E, 6F, and 5F is maintained and applied to the electrode plates 5E, 6E, 6F, and 5F. Apply a voltage opposite to the voltage. A voltage that focuses ions is applied to the electrode plates 5E, 6E, 6F, and 5F by the voltage dividing resistors 9G to 9I, and the bunch is accelerated while being focused in the radial direction.

  When a reverse voltage is applied to the electrode plates 5E, 6E, 6F and 5F at the timing when the terminal end of the bunch reaches the electrode plate 5E, it is first applied to the electrode plates 5A, 6A, 6B and 5B. By applying the same voltage as the above, the next ion group generated by the ion source is drawn and accelerated in the same manner as described above.

  In this way, the charged particle accelerator 1 sequentially passes through the pair of acceleration voltage applying electrode plates and the voltage dividing electrode plates between them by providing the voltage dividing electrode plates forming the voltage dividing circuit. In the meantime, the ion beam is always accelerated by the acceleration gradient, and a focusing electric field for maintaining the ion beam is formed, thereby suppressing the divergence of the ion beam. Even when an ion beam having a large current exceeding 1000 mA is extracted from the ion source, the ion beam can be accelerated without colliding with the inner wall of the acceleration tube.

Japanese Patent No. 5686453

  However, the charged particle accelerator of Patent Document 1 is not easy to design because it appropriately adjusts the interval between the plurality of electrode plates and generates the ion beam focused potential by the voltage dividing resistors 9A to 9I. Further, the number of parts increases due to the voltage dividing resistors 9A to 9I. Further, a DC high voltage power supply is required as the acceleration power supplies 3A and 3B. For example, a cockcroft type power supply is used, but the cockcroft type power supply becomes very expensive when the output voltage becomes high.

  The present invention has been made in view of such circumstances, is easy to design, and is capable of obtaining a high-energy ion beam without using a DC high-voltage power supply exceeding 100 kV. An object is to provide a particle accelerator.

  The charged particle accelerator according to the present invention includes a charged particle generating source that generates charged particles, and a predetermined voltage that is applied to accelerate the charged particles in one direction along a predetermined axis. A conductive electrode plate; a pulse power source that applies a voltage to each of the plurality of electrode plates; and a control unit that controls a voltage applied by the pulse power source to the plurality of electrode plates. The plurality of electrode plates are arranged at equal intervals along a predetermined axis, and the control unit is configured to draw charged particles generated by the charged particle generation source between the electrode plates and to generate an electric field formed between the adjacent electrode plates. The pulse power supply is controlled so as to apply a voltage to each of the plurality of electrode plates so as to be accelerated in one direction.

  Preferably, the plurality of electrode plates sequentially form a first acceleration section, a second acceleration section, and a third acceleration section along a predetermined axis, and the charged particles generated by the charged particle generation source are: Charged particles that are drawn into the first acceleration section and accelerated in one direction by the electric field formed between the electrode plates arranged in the first acceleration section and passed through the first acceleration section are second acceleration section The charged particles that have been focused by the electric field formed between the electrode plates disposed in the first and second passes through the second acceleration section are accelerated in one direction by the electric field formed between the electrode plates disposed in the third acceleration section. A voltage is applied from the pulse power source to the electrode plate disposed in the first acceleration section so that a uniform potential gradient is generated along one direction, and the electrode plate disposed in the second acceleration section is applied to the electrode plate disposed in the second acceleration section. Produces an electric field whose potential gradient alternates along one direction. In so that, a voltage is applied from the pulse power supply, the third electrode plate arranged on the acceleration section, to produce a uniform potential gradient along the one direction, a voltage is applied from the pulse power supply.

  Preferably, the control unit applies each of the plurality of electrode plates at a timing at which the head of the ion beam bunch formed by the charged particles reaches the boundary between the second acceleration section and the third acceleration section. The pulse power supply is controlled so that the positive and negative voltages are reversed.

  Preferably, the pulse power supply includes a plurality of power cells having a first terminal and a second terminal that receive a control signal from the control unit and output voltages having different positive and negative values, and the plurality of power cells are one power source. The first terminal of the cell and the second terminal of the power cell adjacent to one power cell are connected in series, and the power cell is connected to the first terminal by inverting the level of the control signal. And the polarity of the voltage at the second terminal is inverted.

  Preferably, each first terminal of the plurality of power cells outputs the same voltage at the same time, each second terminal of each of the plurality of power cells outputs the same voltage at the same time, and the pulse power source includes the first terminal and the terminal From these interconnection nodes, a voltage that is an integral multiple of the voltage between the first terminal and the second terminal of one power cell can be applied to the electrode plate.

  Preferably, the charged particle accelerator includes a plurality of charged particle generating sources and a plurality of acceleration tubes composed of a plurality of electrode plates, and the arrangement of the electrode plates constituting the acceleration tube is the same among the plurality of acceleration tubes. In the plurality of accelerator tubes, corresponding electrode plates are electrically connected to each other.

  Preferably, the charged particle accelerator further includes a timing control unit that independently controls the timing of generating charged particles by each of the plurality of charged particle generation sources.

  According to the present invention, an ion beam can be generated without using a cockcroft type DC high-voltage power supply as in the prior art and without adjusting the voltage applied to the electrode plate by a voltage dividing resistor. Accordingly, it is possible to realize a charged particle accelerator that is smaller and less expensive than the conventional one.

  Moreover, since the intervals between the plurality of electrode plates constituting the acceleration tube are equal, the design is easier than in the prior art.

  Since the pulse power supply has a structure in which a plurality of pulse power supply modules in which a plurality of pulse power supply cells are connected in series are connected in series, and the voltage of a connection node between adjacent pulse power supply modules can be output from each output terminal. Depending on the design, a voltage can be supplied to each electrode plate from an appropriate output terminal.

It is a schematic block diagram which shows the charged particle accelerator which concerns on the 1st Embodiment of this invention. It is a perspective view which shows arrangement | positioning of the electrode plate shown in FIG. It is a schematic block diagram which shows the front | former stage part of the charged particle accelerator shown in FIG. It is a schematic block diagram which shows the middle stage part of the charged particle accelerator shown in FIG. It is a schematic block diagram which shows the back | latter stage part of the charged particle accelerator shown in FIG. It is a block diagram which shows the internal structure of a 1st pulse power supply. It is a block diagram which shows the internal structure of the pulse power supply module of FIG. It is a circuit diagram which shows the internal structure of the pulse power supply cell of FIG. It is a timing chart which shows the control signal of the 1st-3rd pulse power supply. It is a schematic block diagram which shows the charged particle accelerator which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the internal structure of the pulse power supply which comprises the charged particle accelerator which concerns on the 2nd Embodiment of this invention. It is a timing chart which shows the control signal and output signal of a pulse power supply in the charged particle accelerator which concerns on the 2nd Embodiment of this invention. It is a schematic block diagram which shows the modification of a charged particle accelerator. It is a block diagram which shows the modification of a pulse power supply cell. It is a schematic block diagram which shows the conventional charged particle accelerator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

(First embodiment)
Referring to FIG. 1, a charged particle accelerator 100 according to the first embodiment of the present invention includes a first pulse power supply 111, a second pulse power supply 112, a third pulse power supply 113, an ion source 110, a control unit 120, A container 130 and a plurality of electrode plates P are provided. The container 130 and the plurality of electrode plates P constitute an acceleration tube. Under the control of the control unit 120, the ion source 110 opens the beam shutter at a predetermined timing and outputs ions. The first pulse power supply 111, the second pulse power supply 112, and the third pulse power supply 113 apply appropriate voltages to each of the plurality of electrode plates P at a predetermined timing under the control of the control unit 120. Thereby, the ions emitted in the vicinity of the ion source 110 are accelerated by the electric field generated between the electrode plates P, and are output as an ion beam IB from the acceleration tube.

  Referring to FIG. 2, the plurality of electrode plates P constituting the accelerating tube have the same shape (doughnut-shaped (concentric outer diameter D1 and inner diameter D2) and a thickness t), and their centers are on the same straight line. It is located and arranged so that it may become equal interval W. Depending on the value of the ion beam extraction current, for example, D1 = 90 to 300 (mm), D2 = 50 to 260 (mm), W = 30 to 200 (mm), and t = 0.5 to 3 (mm). The electrode plate P should just be electroconductive, for example, can be formed with stainless steel. However, the present invention is not limited to this.

  The container 130 is formed in a cylindrical shape that accommodates a plurality of electrode plates P, and forms a vacuum inside. The container 130 is made of polyethylene, for example. The material is not limited to this.

  The acceleration tube is composed of three parts. Referring to FIG. 3, the front portion includes electrode plates P1 to P15. These are supplied with a predetermined voltage from the first pulse power supply 111. As will be described later, the first pulse power supply 111 includes 36 terminals T1 to T36, and outputs different voltages simultaneously from the respective terminals. The output voltage at each terminal is proportional to the terminal number. The electrode plates P1 to P4 are connected to a terminal Tn (n = 9, 18, 27 and 36) and a terminal having an integer multiple of 9, respectively. Thereby, as will be described later, a linear voltage is applied to the electrode plates P1 to P4, and an electric field having a constant potential gradient is formed in the section G1. The electrode plates P5 to P12 are alternately connected to the terminals T33 and T36. The odd-numbered electrode plate P is connected to the terminal T33, and the even-numbered electrode plate P is connected to the terminal T36. Thereby, between the electrode plates P4 to P12 (section S1), an electric field in which the direction of the potential gradient is alternately reversed is generated. The electrode plates P13, P14, and P15 are connected to the terminal T24, the terminal T12, and the terminal T0 (ground), respectively. As a result, an electric field having a constant potential gradient is also formed in the section G2A.

  Referring to FIG. 4, the middle portion includes electrode plates P15 to P33. These are supplied with a predetermined voltage from the second pulse power source 112. In the above description, the electrode plate P15 is described as constituting the previous stage portion. However, for convenience, the electrode plate P15 is described as also constituting the middle stage portion (there are not two electrode plates P15).

  As will be described later, the second pulse power source 112 is configured in the same manner as the first pulse power source 111, and includes 36 terminals T1 to T36. The output voltage of each terminal is proportional to the terminal number. The electrode plates P15 to P18 are connected to a terminal T0 (ground), a terminal T12, a terminal T24, a terminal T36, and a terminal having an integer multiple of 12. Thereby, an electric field with a constant potential gradient is formed in the section G2B. The electrode plates P19 to P30 are alternately connected to the terminal T33 and the terminal T36. The odd-numbered electrode plate P is connected to the terminal T33, and the even-numbered electrode plate P is connected to the terminal T36. Thereby, between the electrode plates P18 to P30 (section S2), an electric field in which the direction of the potential gradient is alternately reversed is generated. The electrode plates P31, P32, and P33 are connected to the terminal T24, the terminal T12, and the terminal T0 (ground), respectively. As a result, an electric field having a constant potential gradient is also formed between them (section G3A).

  Referring to FIG. 5, the rear portion includes electrode plates P33 to P53. These are supplied with a predetermined voltage from the third pulse power source 113. In the above description, the electrode plate P33 is described as constituting the middle portion. However, for convenience, the electrode plate P33 is also described as constituting the latter portion (there are not two electrode plates P33).

  The third pulse power supply 113 is also configured in the same manner as the first pulse power supply 111 and includes 36 terminals T1 to T36, and the output voltage of each terminal is proportional to the terminal number. The electrode plates P33 to P35 are connected to a terminal T0 (ground), a terminal T18, a terminal T36, and a terminal whose number is an integral multiple of 18. Thereby, an electric field with a constant potential gradient is formed in the section G3B. The electrode plates P36 to P50 are alternately connected to the terminal T33 and the terminal T36. The even-numbered electrode plate P is connected to the terminal T33, and the odd-numbered electrode plate P is connected to the terminal T36. Thereby, between the electrode plates P35 to P50 (section S3), an electric field in which the direction of the potential gradient is alternately reversed is generated. The electrode plates P51, P52, and P53 are connected to the terminal T24, the terminal T12, and the terminal T0 (ground), respectively. As a result, an electric field having a constant potential gradient is also formed between them (section G4).

  Referring to FIG. 6, the first pulse power supply 111 includes 36 pulse power supply modules 200, a timing control circuit 210, and an optical fiber 213. The timing control circuit 210 includes a pulse generator 211 and EO converters 212 that are twice (72) the number (36) of the pulse power supply modules 200. The output NOUT or POUT of the pulse generator 211 is input to each EO converter 212. The EO converter 212 converts an input electric signal into an optical signal and outputs the optical signal. In each pulse power supply module 200, the output of one EO converter 212 to which NOUT is input and the output of one EO converter 212 to which POUT is input are input to the N $ ON terminal and the P $ ON terminal, respectively. Is done. Each pulse power supply module 200 has two output terminals MA and MB, and 36 pulse power supply modules 200 are connected in series by connecting adjacent terminals MA and MB. The terminal MB of the pulse power supply module 200 (the lowermost pulse power supply module 200 in FIG. 6) located at one end of the 36 pulse power supply modules 200 is connected to the terminal T0, and the terminal T0 is grounded. The terminal MA of the pulse power supply module 200 (the uppermost pulse power supply module 200 in FIG. 6) located at the other end of the 36 pulse power supply modules 200 is connected to the terminal T36. Connection nodes of the terminals MA and MB are connected to the terminals T1 to T35.

  The second pulse power source 112 and the third pulse power source 113 are also configured similarly to the first pulse power source 111 shown in FIG.

  With reference to FIG. 7, the pulse power supply module 200 includes four pulse power supply cells 230, OE converters 240 and 241, a DC / DC converter 250, and a lithium battery 251. The N $ ON terminal is connected to the OE converter 240 via the optical cable 242, and the output end of the OE converter 240 is connected to N $ OUT of each pulse power supply cell 230. The P $ ON terminal is connected to the OE converter 241 via the optical cable 243, and the output terminal of the OE converter 241 is connected to P $ OUT of each pulse power supply cell 230. The OE converters 240 and 241 convert input optical signals into electrical signals and output the electrical signals.

  The lithium battery 251 has, for example, a capacity of 60 Wh and outputs DC 3.7V. The DC / DC converter 250 converts the DC voltage supplied from the lithium battery 251 into a predetermined voltage and supplies it to the OE converter 240, the optical cable 242, and the PW $ GATE terminal of each pulse power supply cell 230. The dotted rectangle surrounding the OE converters 240 and 241 indicates the power supply to them. The four pulse power cells 230 are connected in series by connecting adjacent CA terminals and CB terminals. The CB terminal of the pulse power cell 230 (the lowermost pulse power cell 230 in FIG. 7) located at one end of the four pulse power cells 230 is connected to the MB terminal. The CA terminal of the pulse power cell 230 (the uppermost pulse power cell 230 in FIG. 7) located at the other end of the four pulse power cells 230 is connected to the MA terminal.

  Referring to FIG. 8, the pulse power source cell 230 includes FETs 271 to 274, gate drivers 281 to 284, DC / DC converters 290 and 291, and lithium batteries 292 and 293. The FETs 271 to 274 are, for example, N-channel MOSFETs (Metal-Oxide-Semiconductor Field-Effect-Transistors). The FETs 271 to 274 may be SiC-MISFETs (Silicon Carbide Metal-Insulator-Semiconductor Field-Effect-Transistor). The gate drivers 281 to 284 are, for example, insulated gate drivers having a withstand voltage of DC 7 kV.

  The N $ OUT terminal is connected to the input terminals of the gate driver 282 and the gate driver 283. Output terminals of the gate driver 282 and the gate driver 283 are connected to the gates G of the FET 272 and the FET 273. The P $ OUT terminal is connected to the input terminals of the gate driver 281 and the gate driver 284. Output terminals of the gate driver 281 and the gate driver 284 are connected to the gates G of the FET 271 and the FET 274.

  The lithium batteries 292 and 293 have, for example, a battery capacity of 60 Wh and output DC 3.7V. The DC / DC converter 290 generates a positive high voltage (for example, DC + 550V) from the DC voltage (for example, DC + 3.7V) supplied from the lithium battery 292, and supplies the positive voltage to the drains D of the FET 271 and the FET 273. The DC / DC converter 291 generates a negative high voltage (for example, DC−550V) from the DC voltage (for example, DC + 3.7V) supplied from the lithium battery 293 and supplies the negative high voltage (for example, DC−550V) to the sources S of the FET 272 and the FET 274. Both the source S of the FET 271 and the drain D of the FET 272 are connected to the terminal CA. The source S of the FET 273 and the drain D of the FET 274 are both connected to the terminal CB.

  The PW $ GATE terminal is connected to the power supply line of the gate drivers 281 to 284. Dotted rectangles surrounding the gate drivers 281 to 284 indicate their connection to the power supply lines.

  6-8, the output values of the MA terminal and MB terminal of the pulse power supply module 200 are determined by the output values of the CA terminal and CB terminal of the pulse power supply cell 230, and the pulse power supply module 200 The output values of the terminals T1 to T36 are determined.

  Specifically, under the control of the control unit 120, when the pulse generator 211 sets NOUT to a high level (hereinafter referred to as H) and POUT to a low level (hereinafter referred to as L), the N of each pulse power supply module 200 is set. $ ON becomes H and P $ ON becomes L. As a result, in each pulse power supply module 200, N $ OUT of each pulse power supply cell 230 becomes H and P $ OUT becomes L (see FIG. 7). Thereby, the FET 272 and the FET 273 of each pulse power source cell 230 are turned on, the FET 271 and the FET 274 are turned off, the output voltage (−550 V) of the DC / DC converter 291 is output from the terminal CA, and the terminal CB The output voltage (+ 550V) of the DC / DC converter 290 is output (see FIG. 8). Here, among the 36 pulse power supply modules 200, the terminal MB of one end of the pulse power supply module 200 (the lowermost pulse power supply module 200 in FIG. 6) is grounded, so that the pulse power supply module 200 is configured. Of the four pulse power cells 230, the terminal CB of the pulse power cell 230 at one end (the lowermost pulse power cell 230 in FIG. 7) is grounded. Therefore, in this pulse power cell 230, the terminal CB is 0V and the terminal CA is -1100V. Therefore, the terminal CA of the next-stage pulse power cell 230 (second from the bottom in FIG. 7) connected to the pulse power cell 230 becomes −2200 V, which is 1100 V lower than the terminal CB (−1100 V). Similarly, the terminal CA of the third pulse power cell 230 from the bottom in FIG. 7 is −3300V, and the terminal CA of the uppermost pulse power cell 230 in FIG. 7 is −4400V. That is, the terminal MA (terminal T1) of the lowermost pulse power supply module 200 in FIG. Similarly, the terminal MA of each pulse power supply module 200 is 4400 V lower than the terminal MB. Therefore, when NOUT is set to H and POUT is set to L, the voltage at the terminal Tn (n = 1 to 36) is −4400 × n (V).

  Under the control of the control unit 120, when the pulse generator 211 sets NOUT to H and POUT to L, the FET 271 and FET 274 of each pulse power supply cell 230 are turned on, and the FET 272 and FET 273 are turned off (see FIG. 8). As a result, the output voltage (+ 550V) of the DC / DC converter 290 is output from the terminal CA of each pulse power supply cell 230, and the output voltage (−550V) of the DC / DC converter 291 is output from the terminal CB. Is done. Therefore, the MA terminal (terminal T1) of the lowermost pulse power supply module 200 in FIG. 6 is + 4400V. Due to the pulse power supply modules 200 connected in series, the voltage at the terminal Tn (n = 1 to 36) becomes + 4400 × n (V).

  In this way, by setting NOUT and POUT to the mutually inverted levels, from the terminal Tn (n = 1 to 36) of the first pulse power supply 111, −4400 × n (V) or + 4400 × n (V ) Is output. The same applies to the second pulse power supply 112 and the third pulse power supply 113.

  FIG. 9 shows control timings of the first pulse power supply 111, the second pulse power supply 112, and the third pulse power supply 113 for accelerating ions to generate the ion beam IB in the charged particle accelerator 100 configured as described above. Show.

  At time t0, the control unit 120 starts emitting ions from the ion source 110. Here, it is assumed that positive ions are released. At the same time, the control unit 120 controls the pulse generators 211 of the first pulse power supply 111, the second pulse power supply 112, and the third pulse power supply 113 to set NOUT to H and POUT to L. Thereby, the voltage of the terminal Tn (n = 1 to 36) becomes −4400 × n (V), and the ion group is drawn into the section G1 and accelerated. Thereafter, the ion group is focused by repeating acceleration and deceleration in the section S1. This focusing is due to the known Einzel lens effect.

  At the timing (time t1) when the head of the ion group reaches the electrode plate P4, the control unit 120 controls the pulse generator 211 of the first pulse power supply 111 to set NOUT to L and POUT to H. As a result, the voltage at the terminal Tn (n = 1 to 36) of the first pulse power supply 111 becomes + 4400 × n (V), and the ion group is accelerated in the sections G2A and G2B. Note that ions generated in the ion source 110 are not drawn into the section G1. Thus, the ion group forms a cluster or bunch of ion beams having a rear end.

  At the timing (time t2) when the rear end of the bunch reaches the electrode plate P18, the control unit 120 controls the pulse generator 211 of the second pulse power source 112 to set NOUT to L and POUT to H. As a result, the voltage at the terminal Tn (n = 1 to 36) of the second pulse power source 112 becomes + 4400 × n (V), and the bunch is repeatedly focused and accelerated in the section S2. Further, the bunch is accelerated in the sections G3A and G3B.

  At the timing (time t3) when the rear end of the bunch reaches the electrode plate P35, the control unit 120 controls the pulse generator 211 of the third pulse power supply 113 to set NOUT to L and POUT to H. As a result, the voltage at the terminal Tn (n = 1 to 36) of the third pulse power supply 113 becomes + 4400 × n (V), and the bunch is repeatedly focused and accelerated in the section S3. Further, the bunch is accelerated in the section G4 and then emitted to the outside as an ion beam IB.

  Thus, the charged particle accelerator 100 can accelerate the ion beam to about 950 keV by using three pulse power supplies with the maximum output voltage ± 158.4 kV (= 4 × 36 × 1.1 kV).

  After time t3, at a predetermined timing, the outputs (NOUT and POUT) of the pulse generator 211 of the first pulse power supply 111, the second pulse power supply 112, and the third pulse power supply 113 are returned to the same state as the time t0, and thereafter If controlled in the same manner as described above, the next ion beam IB can be output.

  As described above, the charged particle accelerator 100 can generate the ion beam IB in the same manner as the conventional charged particle accelerator (see FIG. 15). In the charged particle accelerator 100, since the intervals between the electrode plates P are equal, the design is easier than in the prior art. Further, it is not necessary to use a cockcroft type DC high voltage power supply as in the prior art nor to adjust the voltage applied to the electrode plate by a voltage dividing resistor.

  Each of the first pulse power supply 111, the second pulse power supply 112, and the third pulse power supply 113 includes a plurality (36 in the above) series of pulse power supply modules 200 in which a plurality (four in the above) of pulse power supply cells 230 are connected in series. Since it is connected and the voltage of the connection node between the pulse power supply modules 200 can be output from the terminal Tn, the voltage according to the design of the acceleration tube (number of electrode plates P, D1, D2, t, W) Can be supplied to each electrode plate P from an appropriate terminal Tn. Further, by changing the number of pulse power supply cells 230 constituting the pulse power supply module 200 and changing the number of pulse power supply modules 200 constituting the first pulse power supply 111 to the third pulse power supply 113, the acceleration tube The design can be more flexibly handled. For example, the pulse power supply module may be composed of one pulse power supply cell.

  Although the case where the lithium batteries 251, 292, and 293 (see FIGS. 7 and 8) are used has been described above, the present invention is not limited to this, and any type of primary battery can be used. A secondary battery such as a nickel metal hydride battery may be used.

  In the above description, the output (NOUT and POUT) of the pulse generator 211 is inverted only for the third pulse power supply 113 at time t3. However, it is not limited to this. At time t3, the control unit 120 may control the first pulse power supply 111 and the second pulse power supply 112 to invert the output of the pulse generator 211 (set NOUT to L and POUT to H). By doing so, the next ion group is drawn into the section G1, and the ion beam IB can be continuously output. In this case, the output (NOUT and POUT) of the pulse generator 211 of the third pulse power supply 113 may be returned to the same state as that at time t0, for example, at a timing corresponding to time t1.

(Second Embodiment)
Referring to FIG. 10, a charged particle accelerator 300 according to the second embodiment of the present invention includes a pulse power supply 310, a control unit 320, an ion source 330, a container 340, and a plurality of electrode plates P. The container 340 and the plurality of electrode plates P constitute an acceleration tube. Under the control of the control unit 320, the ion source 330 opens the beam shutter at a predetermined timing and outputs ions. Under the control of the control unit 320, the pulse power source 310 applies an appropriate voltage to each of the plurality of electrode plates P at a predetermined timing. As a result, the ions emitted in the vicinity of the ion source 330 are accelerated by the electric field generated between the electrode plates P and output as an ion beam IB.

  In the present embodiment, the accelerating tube is configured in the same manner as in the first embodiment. However, unlike the first embodiment, 24 electrode plates P are provided. Further, in the present embodiment, there is one pulse power supply, and it has an output terminal of terminal T0 and terminals T1 to T300 as will be described later. The output voltage of the terminals T1 to T300 is proportional to the terminal number.

  The electrode plates P1 to P24 are connected to predetermined terminals among the terminals T1 to T300 of the pulse power supply 310. That is, the electrode plates P1 to P5 are respectively connected to the terminal Tn (n = 33, 66, 99, 132 and 165) and a terminal having an integer multiple of 33. As a result, a linear voltage is applied to the electrode plates P1 to P5. The electrode plates P6 to P9 are connected to a terminal Tn (n = 197, 230, 263, and 300) and a terminal having a number close to an integral multiple of 33, respectively. Thereby, a substantially linear voltage is also applied to the electrode plates P5 to P9. Thereby, an electric field having a substantially constant potential gradient is formed in the section G1. The reason why the electrode plates P6 to P9 are not exactly an integral multiple of 33 is that the velocity of the ion beam is slow near the ion source (electrode plates P1 to P5), which is easily affected by the focusing electric field and is strictly electric. Although it is necessary to create (potential gradient), the velocity of the ion beam is considerably high near the electrode plate P8, and the envelope is not easily affected even if the value of the electric field (potential gradient) is slightly changed.

  The electrode plates P10 to P18 are alternately connected to the terminal T295 and the terminal T300. The odd-numbered electrode plate P is connected to the terminal T300, and the even-numbered electrode plate P is connected to the terminal T295. Thereby, between the electrode plates P9 to P182 (section S1), an electric field in which the direction of the potential gradient is alternately reversed is generated.

  The electrode plates P19 to P24 are connected to a terminal Tn (n = 250, 200, 150, 100, 50 and 0) and a terminal having an integer multiple of 50, respectively. As a result, an electric field having a substantially constant potential gradient is formed in the section G2. In the section G2, since the speed of the ion beam is considerably high, as described above, the envelope is not easily affected even if the value of the electric field (potential gradient) is slightly changed, so that the accuracy of the electric field (potential gradient) is constant. Does not have to be so expensive.

  Referring to FIG. 11, pulse power supply 310 is configured in the same manner as first pulse power supply 111 in FIG. The pulse power supply 310 in FIG. 11 is different from the first pulse power supply 111 in FIG. 6 in that 300 pulse power supply modules 200 are connected in series, and 200 sets of EO converters 212 and terminals T0 to T300 are connected. It is only a point to prepare. Each pulse power supply module 200 of FIG. 11 is configured as shown in FIG. 7, and the pulse power supply cell 230 is configured as shown in FIG. Therefore, by setting NOUT and POUT to a mutually inverted level, a voltage of −4400 × n (V) or + 4400 × n (V) is generated from the terminal Tn (n = 1 to 300) of the pulse power supply 310. Is output.

  FIG. 12 shows the control timing of the pulse power source 310 for accelerating ions and generating the ion beam IB in the charged particle accelerator 300 configured as described above. In FIG. 12, the positions of POUT and NOUT are opposite to those in FIG.

  The control unit 320 controls the pulse generator 211 of the pulse power supply 310 so that POUT is set to H and NOUT is set to L (the voltage at the terminal Tn (n = 1 to 300) is + 4400 × n (V)). Release of ions from the ion source 330 is started. Here, it is assumed that positive ions are released. The control unit 320 sets POUT to L at time t1, and sets NOUT to H at time t2 immediately thereafter. As a result, the voltage at the terminal Tn (n = 1 to 300) becomes −4400 × n (V), and the ion group generated by the ion source 330 is drawn into the section G1 and accelerated. Thereafter, the ion group is repeatedly accelerated and decelerated in the section S1 to be focused.

  Thereafter, at a predetermined time t3 (in FIG. 12, 100 ns has elapsed from time t2), the control unit 320 controls the pulse generator 211 of the pulse power supply 310 to set NOUT to L, and at time t4 immediately thereafter, POUT To H. Time t3 is the timing when the head of the ion group reaches the vicinity of the electrode plate P18. As a result, the voltage at the terminal Tn (n = 1 to 300) of the pulse power source 310 becomes + 4400 × n (V), and the ion group is accelerated in the section G2 and output from the accelerator tube as the ion beam IB. Note that ions generated in the ion source 330 are not drawn into the section G1. Thus, the ion group forms a cluster or bunch of ion beams having a rear end.

  Thereafter, after a predetermined time (1 μs in FIG. 12) has elapsed, control unit 320 controls the levels of POUT and NOUT in the same manner as times t1 to t4. Thereby, the ion discharge | released by the ion source 330 is drawn in to the area G1, is accelerated, and is output as the ion beam IB.

  As described above, the charged particle accelerator 300 is emitted from the ion source 330 by repeating NOUT to be H and POUT to be L at a predetermined period (for example, 1 μs) for a predetermined period (for example, 100 ns). Ions can be continuously output as an ion beam IB.

  In the charged particle accelerator 300, as in the first embodiment, since the intervals between the electrode plates P are equal, the design is easier than in the prior art. Further, it is not necessary to use a cockcroft type DC high voltage power supply as in the prior art nor to adjust the voltage applied to the electrode plate by a voltage dividing resistor.

  Note that the period of 1 μs, the period of 100 ns in which NOUT is set to H, and POUT is set to L, and the connection relationship between each electrode plate P and the terminal Tn shown in FIG. 10 are merely examples, and the present invention is not limited thereto. Depending on the design of the accelerating tube (number of electrode plates P, D1, D2, t, W), it can be appropriately changed.

  Further, the pulse power supply 310 changes the number of the pulse power supply cells 230 constituting the pulse power supply module 200 and the pulses constituting the pulse power supply 310 in the same manner as the first pulse power supply 111 of the first embodiment. By changing the number of power supply modules 200, the design of the acceleration tube can be dealt with more flexibly. For example, the pulse power supply module may be composed of one pulse power supply cell.

(First modification)
Referring to FIG. 13, a charged particle accelerator can be configured by including three accelerator tubes. The charged particle accelerator 400 includes a pulse power source 310, a controller 322, ion sources 330 to 332, containers 340 to 342, and an ion source controller 410. The control unit 322 controls the pulse power supply 310 and the ion source control device 410. The ion source control device 410 individually controls the beam shutters of the ion sources 330 to 332 to output ions.

  The acceleration tube including the ion source 330, the container 340, and the plurality of electrode plates P is configured in the same manner as in the second embodiment, and each electrode plate P is configured in the second embodiment (see FIG. 10). Similarly to the above, the pulse power supply 310 is connected to a predetermined terminal of the terminal Tn (n = 1 to 300). The acceleration tube composed of the ion source 331, the container 341, and the plurality of electrode plates P, and the acceleration tube composed of the ion source 332, the container 342, and the plurality of electrode plates P are also the same as those in the second embodiment. It is constituted similarly. In the three acceleration tubes, corresponding electrode plates P are connected to each other.

  With this configuration, the control unit 322 controls the pulse power supply 310 in the same manner as in the second embodiment (see FIG. 12), so that the charged particle accelerator 400 can generate ion beams IB1 to IB1 from three accelerator tubes. IB3 can be output.

  In the charged particle accelerator 400, the ion source control device 410 can individually control the beam shutters of the ion sources 330 to 332, so that the acceleration current value (intensity of the ion beam IB) of each accelerator tube is set. It can be adjusted independently.

  The number of acceleration tubes is not limited to 3 shown in FIG. Two accelerator tubes or four or more accelerator tubes are provided, corresponding electrode plates P are connected to each other, and each electrode plate P is connected to a predetermined terminal of terminal Tn (n = 1 to 300) of pulse power supply 310 May be.

(Second modification)
The pulse power cell may be configured as shown in FIG. The pulse power cell 500 is different from the pulse power cell 230 in FIG. 8 only in that wireless power supply devices 510 and 511 are provided instead of the lithium batteries 292 and 293. The wireless power supply devices 510 and 511 supply power wirelessly by known non-contact power transmission such as an electromagnetic induction method or a radio wave method (including light). The wireless power supply apparatuses 510 and 511 supply, for example, input DC 12 V to the DC / DC converters 290 and 291. Thereby, the charged particle accelerator 400 functions similarly to the pulse power cell 230 of FIG.

  The pulse power cell 230 in FIG. 8 cannot operate when the lithium batteries 292 and 293 are discharged, and thus the time that can be continuously used is limited. On the other hand, since the pulse power supply cell 500 includes the wireless power supply devices 510 and 511, power can be continuously supplied from the outside, and there is no time limit.

  The present invention has been described above by describing the embodiment. However, the above-described embodiment is an exemplification, and the present invention is not limited to the above-described embodiment, and is implemented with various modifications. be able to.

100 charged particle accelerator 110 ion source 111 first pulse power source 112 second pulse power source 113 third pulse power source 120 control unit 130 container 200 pulse power source module 210 timing control circuit 211 pulse generator 212 EO converter 213 optical fiber 230 pulse power source cell 240 241 OE converter 242, 243 Optical cable 250 DC / DC converter 251 Lithium batteries 271, 272, 273, 274 FET
281, 282, 283, 284 Gate drivers 290, 291 DC / DC converters 292, 293 Lithium battery 300 Charged particle accelerator 310 Pulse power source 320 Control unit 330 Ion source 340 Container 400 Charged particle accelerator 322 Control units 331, 332 Ion source 341 342 Container 410 Ion source control device 500 Pulse power cell 510, 511 Wireless power supply device

Claims (7)

A charged particle source that generates charged particles;
When a predetermined voltage is applied, the charged particles are accelerated in one direction along a predetermined axis, and a voltage is applied to each of the three or more conductive electrode plates and the plurality of electrode plates. Pulse power supply,
A controller that controls the voltage applied by the pulse power supply to the plurality of electrode plates;
The plurality of electrode plates are arranged at equal intervals along the predetermined axis,
The control unit includes a plurality of the electrodes such that charged particles generated by the charged particle generation source are drawn between the electrode plates and accelerated in the one direction by an electric field formed between the adjacent electrode plates. A charged particle acceleration device for controlling the pulse power supply so as to apply a voltage to each of the plates. The plurality of electrode plates form a first acceleration section, a second acceleration section, and a third acceleration section in order along the predetermined axis,
The charged particles generated by the charged particle generation source are drawn into the first acceleration section and accelerated in the one direction by an electric field formed between the electrode plates disposed in the first acceleration section,
The charged particles that have passed through the first acceleration section are focused by an electric field formed between the electrode plates disposed in the second acceleration section,
The charged particles that have passed through the second acceleration section are accelerated in the one direction by an electric field formed between the electrode plates disposed in the third acceleration section,
A voltage is applied from the pulse power source to the electrode plate disposed in the first acceleration section so as to generate a uniform potential gradient along the one direction,
A voltage is applied to the electrode plate disposed in the second acceleration section from the pulse power source so as to generate an electric field whose potential gradient is alternately reversed along the one direction,
2. The charged particle acceleration according to claim 1, wherein a voltage is applied from the pulse power source to the electrode plate disposed in the third acceleration section so as to generate a uniform potential gradient along the one direction. apparatus.   The control unit is configured so that each of the plurality of electrode plates has a timing at which a leading portion of an ion beam bunch formed by the charged particles reaches a boundary between the second acceleration section and the third acceleration section. The charged particle acceleration device according to claim 2, wherein the pulse power supply is controlled so that the positive / negative of the voltage applied to is reversed. The pulse power supply includes a plurality of power cells having a first terminal and a second terminal that receive a control signal from the control unit and output voltages having different positive and negative values,
The plurality of power cells are connected in series by connecting the first terminal of the one power cell and the second terminal of the power cell adjacent to the one power cell,
4. The power supply cell according to claim 1, wherein the level of the control signal is inverted, so that the voltage of the first terminal is inverted and the voltage of the second terminal is inverted. A charged particle accelerator according to claim 1. Each of the first terminals of the plurality of power cells outputs the same voltage at the same time,
Each of the second terminals of the plurality of power cells outputs the same voltage at the same time,
The pulse power supply may apply a voltage that is an integral multiple of the voltage between the first terminal and the second terminal of one power supply cell to the electrode plate from an interconnection node of the first terminal and the terminal. The charged particle acceleration device according to claim 4. A plurality of acceleration particles composed of the charged particle generation source and a plurality of the electrode plates,
The arrangement of the electrode plates constituting the acceleration tube is the same among the plurality of acceleration tubes,
The charged particle accelerator according to claim 1, wherein in the plurality of accelerator tubes, the corresponding electrode plates are electrically connected to each other.   The charged particle accelerator according to claim 6, further comprising a timing control unit that independently controls timing of generating charged particles by each of the plurality of charged particle generation sources.

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