Ion generator, particle beam accelerator, and particle beam therapy system

Abstract

To increase the pulse width of an ion beam generated by an ion generation device.SOLUTION: An ion generation device 20 comprises laser devices 2a and 2b. The ion generation device 20 also comprises laser optical paths 3a and 3b provided corresponding to the laser devices 2a and 2b, a wave plate 5 and a beam splitter 4. The laser optical paths 3a and 3b have optical path lengths different from each other. The laser optical paths 3a and 3b guide laser beams generated by the laser devices 2a and 2b to the beam splitter 4, respectively. The beam splitter 4 integrates the light guided to the laser optical paths 3a and 3b and irradiates a target 14 with the integrated light. The target 14 generates ions according to the light irradiated from the beam splitter 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an ion generating device, a particle beam accelerator, and a particle beam therapy system, and more particularly to a device using a target that generates ions in response to irradiation with light. [Background technology]

[0002] Particle beam therapy, which irradiates a particle beam to an affected area, is widely used. Generally, particle beam therapy uses a particle beam therapy system equipped with an accelerator. Ions such as carbon ions, helium ions, and protons are injected into the accelerator, and the ions are accelerated until they have the energy required for treatment. A beam of ions accelerated by the accelerator is irradiated toward the affected area. In the particle beam therapy system, the energy and spatial spread of the ion beam are adjusted according to the position and shape of the affected area.

[0003] Accelerators include synchrotrons and cyclotrons. In synchrotrons, the magnetic field that bends the ion's orbit and the frequency of the high-frequency electric field are changed over time, accelerating the ions while keeping their orbit radius constant, and the ion's energy increases as it accelerates. In synchrotrons, a circular path is constructed through which the ions pass. Before the ion's energy reaches the designed maximum energy, the ions are extracted from an extraction port provided in the ion's passage, making it possible to control the energy of the ion beam. However, synchrotrons have the problem that the facilities are larger than cyclotrons.

[0004] In a cyclotron, ions injected into a magnetic field are accelerated by a radio-frequency electric field and move around inside the chamber. As the ions accelerate, their orbital radius increases. The ion's energy increases as the orbital radius increases, and the ions are extracted when they reach their maximum energy. In a cyclotron, it is difficult to control the energy of the charged particle beam, since the ions are extracted when they reach their maximum energy.

[0005] Accelerators include synchrocyclotrons as described in the following Patent Document 1. Unlike cyclotrons in which ions are accelerated by a radio frequency electric field of a constant frequency, synchrocyclotrons modulate the frequency of the radio frequency electric field in response to changes in the period of motion caused by changes in the mass of the ions. This frequency modulation accelerates ions when they pass through a region where the radio frequency electric field is generated. For the same reasons as with cyclotrons, it is difficult to control the energy of the extracted charged particle beam in synchrocyclotrons.

[0006] The following Patent Document 1 describes an eccentric orbit accelerator in which the energy of extracted ions can be controlled. In a typical cyclotron, an ion injection port is provided at the center of the top surface of a vessel in which ions are caused to make an orbital motion, and an ion extraction port is provided on the side surface of the vessel.

[0007] In contrast, in an eccentric orbit accelerator, the ion injection port is located at a position shifted toward the beam extraction port from the center of the top surface of the vessel. This makes multiple beam orbits around which ions of different energies orbit, denser on the beam extraction port side. This makes it easier to remove ions of different energies from the beam orbits near the beam extraction port, and charged particle beams of different energies can be obtained efficiently. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2019-96404 A [Non-patent literature]

[0009] [Non-Patent Document 1] W. Kleeven, “The IBA Superconducting Synchrocyclotron Project S2C2”, Proceedings of Cyclotrons 2013 [Non-Patent Document 2] B. Sharkov, “LaSer Ion SourceS”, IEEE TranSactionS on PlaSma Science 33, 6 (2005) Summary of the Invention [Problem to be solved by the invention]

[0010] When accelerating an ion beam in a cyclotron, a synchrotron, or an eccentric orbit accelerator, it is possible to use either an internal ion source or an external ion source as the ion source. An example of an internal ion source is a PIG ion source, and an example of an external ion source is an ECR ion source or a laser ion source as described in Non-Patent Document 2. In general, carbon ions C 6+ In the case of accelerating heavy particles such as the ion source, an external ion source is used.

[0011] A laser ion source uses a target that generates ions in response to irradiation with light. The laser ion source generates ions by interacting a pulsed laser with the target. The time structure of the generated ion beam correlates with the pulse width of the pulsed laser. In other words, the larger the pulse width of the pulsed laser, the larger the pulse width of the generated ion beam tends to be. Therefore, when the pulse width of the pulsed laser is small, the pulse width of the ion beam may be small relative to the injection time of the ion beam required by the accelerator, and the time-averaged current of the beam may decrease.

[0012] An object of the present invention is to increase the pulse width of an ion beam generated by an ion generating device. [Means for solving the problem]

[0013] The present invention relates to a plurality of Pulse a laser source; and Pulse Two optical paths provided corresponding to the laser source, PulseThe present invention is provided with two optical paths each of which guides a laser beam generated by a laser source, and an optical combiner which combines the beams guided to the two optical paths and irradiates the beams on a target, Pulse The optical integrator has a laser source and two optical paths, and the optical integrator is provided with a wave plate provided in one of the two optical paths, which changes the polarization direction of the light guided by the two optical paths, and a beam splitter that reflects one of the two light beams guided to the two optical paths and transmits the other in the direction of the reflected light, and the target generates ions in response to the light irradiated from the optical integrator, and the two optical paths have different optical path lengths. Effect of the Invention

[0014] According to the present invention, the pulse width of the ion beam generated by the ion generating device can be increased. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing a configuration of an ion generating device according to a first embodiment. [Diagram 2] 1 is a cross-sectional view of an ion generating unit. [Diagram 3] FIG. 2 is a conceptual diagram of a time structure of laser light irradiated onto a target. [Figure 4] FIG. 2 is a conceptual diagram of the time structure of the charge amount of an ion beam. [Diagram 5] 5 is a diagram showing a configuration of an ion generating device according to a second embodiment. FIG. [Figure 6] FIG. 1 is a diagram showing a configuration of a delay optical system using a mirror. [Figure 7] FIG. 1 is a diagram showing a configuration of a delay optical system using a concave mirror. [Figure 8] FIG. 1 is a diagram showing a configuration of a particle beam accelerator. [Figure 9] FIG. 1 is a diagram showing a configuration of a particle beam therapy system; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The same components shown in multiple drawings are designated by the same reference numerals and the description thereof will be omitted.

[0017] 1 shows the configuration of an ion generating device 20 according to a first embodiment. The ion generating device 20 includes an ion generating unit 1, laser devices 2a and 2b, and a laser optical system 8. The laser optical system 8 includes a beam splitter 4, a wave plate 5, and a mirror 6. For example, a carbon dioxide laser, a helium-neon laser, a YAG laser, a titanium sapphire laser, or the like may be used for the laser devices 2a and 2b.

[0018] The beam splitter 4 transmits and reflects light depending on the direction of the linear polarization of the incident light. Linear polarization is classified as P polarization and S polarization. The wave plate 5 rotates the direction of linear polarization in a plane perpendicular to the propagation direction by imparting a phase change of a specific angle to the one-directional polarization component contained in the incident light. When the wave plate 5 is configured to impart a phase change of 180° to the one-directional polarization component contained in the incident light, the wave plate 5 rotates the direction of linear polarization by 90° in a plane perpendicular to the propagation direction.

[0019] In this embodiment, laser light is incident on the ion generation unit 1 from the laser devices 2a and 2b through a laser optical system 8. One laser light is incident on the beam splitter 4 from the laser device 2a, and another laser light is incident on the mirror 6 from the laser device 2b. The laser light reflected by the mirror 6 is incident on the beam splitter 4 via a wave plate 5, and the two laser light beams are combined by the beam splitter 4.

[0020] The beam splitter 4 is configured to transmit P polarized light and reflect S polarized light. When the laser light emitted from the laser device 2a and passing through the laser optical path 3a is P polarized light, the laser light passes through the beam splitter 4.

[0021] Furthermore, when the laser light emitted from the laser device 2b is also P-polarized, the direction of linear polarization of the laser light incident on the wave plate 5 in the laser optical path 3b is changed by the wave plate 5. In this embodiment, the rotation angle of the wave plate 5 is determined so as to rotate the polarization direction by 90°, so that the laser light passing through the laser optical path 3b becomes S-polarized. Therefore, the laser light passing through the laser optical path 3b is reflected after entering the beam splitter 4, and the light passing through the laser optical path 3a and the light passing through the laser optical path 3b pass through the same laser optical path 3 and enter the ion generation unit 1.

[0022] In this way, the laser beams emitted from the laser device 2a and the laser device 2b are irradiated onto the target 14 via different laser optical paths 3a and 3b. In this embodiment, the laser optical paths 3a and 3b have different optical path lengths. Therefore, there is a difference in the time at which the laser beams emitted simultaneously from the laser device 2a and the laser device 2b are irradiated onto the target 14. As a result, the target 14 is irradiated with two laser beams with different irradiation timings, and the pulse width of the laser beam irradiated onto the target 14 becomes large. Furthermore, the pulse width of the ion beam generated by the ion generating device 20 becomes large due to a principle described later.

[0023] 2 shows a cross-sectional view of the ion generation unit 1. The ion generation unit 1 includes an optical window 11, a chamber 12, an off-axis parabolic mirror 13, a target 14, and an extraction electrode 16. The chamber 12 houses the off-axis parabolic mirror 13, the target 14, and the extraction electrode 16. The optical window 11 is formed of a material that transmits laser light.

[0024] The laser light entering the chamber 12 through the optical window 11 is focused on the target 14 by the off-axis parabolic mirror 13, which is a focusing system. A parabolic mirror or an optical lens may be used instead of the off-axis parabolic mirror 13. Also, optical devices such as mirrors may be appropriately installed to handle the laser light. When the intensity of the focused laser light is sufficient to ionize the atoms that make up the target 14, plasma 15 is generated. A typical focused intensity is 10 8W / cm 2 From 10 14 W / cm 2 It can be changed depending on the charge and valence of the required ions.

[0025] The target 14 may be changed according to the type of ions to be generated, and may be any of solid, liquid, and gas. When the target 14 is liquid or gas, the charge amount of the ion beam 17 can be changed by changing the supply amount of the liquid or gas. In addition, a plurality of targets 14 may be provided, and the type and valence of the ions to be generated can be switched by controlling the target to be irradiated with the laser light and the irradiation timing.

[0026] A high-frequency voltage is applied to an extraction electrode 16 located downstream of the target 14. When the plasma 15 passes through the extraction electrode 16, the electrons and ions that make up the plasma 15 are separated, and the separated ions are made into an ion beam 17 and injected into the accelerator located downstream.

[0027] 3 shows a conceptual diagram of the time structure of the laser light irradiated to the target 14. The horizontal axis indicates time, and the vertical axis indicates the number of photons. When the laser devices 2a and 2b are pulsed laser devices and output laser light having a pulsed time waveform, a laser pulse 31 having a certain laser pulse width 32 is irradiated to the target 14. Since the optical path lengths of the laser optical paths 3a and 3b corresponding to the laser devices 2a and 2b are different, two laser pulses 31 having a time difference of a laser delay time 33 are irradiated to the target 14. The laser delay time 33 is determined according to the difference in the optical path lengths of the laser optical paths 3a and 3b.

[0028] When a laser repetition period 34 , which is a period during which the target 14 is irradiated with laser light, is sufficiently longer than the laser pulse width 32 and the laser delay time 33 , two laser pulses 31 are irradiated to the target 14 for each laser repetition period 34 .

[0029] FIG. 4 shows a conceptual diagram of the time structure of the charge amount of an ion beam. The horizontal axis indicates time and the vertical axis indicates the charge amount. When a laser pulse 31 is irradiated onto a target 14, a plasma 15 generated at the target 4 passes through an extraction electrode 16, and an ion beam pulse 41 is generated. Ion beam pulse 41 is an ion beam having a pulsed time waveform. Plasma 15 is generated at a time corresponding to the irradiation time of laser pulse 31 onto target 14. Ion beam pulse 41 is generated after a certain time delay from the irradiation time of laser pulse 31.

[0030] 3, the ion beam pulse 41 has a certain ion beam pulse width 42. Since two laser pulses 31 are irradiated to the target 14, two ion beam pulses 41 are generated at a timing with a time difference of an ion beam pulse delay time 43. The time width during which the two ion beam pulses 41 are generated may be regarded as an effective ion beam pulse width 44.

[0031] A period 46 in which the generation of the ion beam pulse 41 is repeated (ion beam pulse repetition period 46) is determined by the laser repetition period 34. The maximum value (maximum value of the charge amount) of the ion beam pulse 41 and the ion beam pulse width 42 are adjusted by the focusing intensity of the irradiating laser and the laser pulse width 32, whereby the charge amount of the ions entering the accelerator can be adjusted.

[0032] The effective ion beam pulse width 44 can be adjusted by changing the laser delay time 33 in addition to the laser focusing intensity and the laser pulse width 32. The laser delay time 33 can be adjusted by changing the generation time of the laser pulses 31 from the laser devices 2a and 2b.

[0033] In this embodiment, a configuration including two laser devices has been shown, but by providing a number of laser optical systems 8 corresponding to the number of laser devices, it is possible to extend the effective ion beam pulse width 44. In the above, an example has been shown in which the components of the laser optical system 8 are on the same plane, but the components may be arranged three-dimensionally, and a smaller ion generating device 20 can be provided.

[0034] A generalized configuration of the ion generating device 20 according to this embodiment will be described below. The ion generating device 20 includes two laser sources, namely, laser devices 2a and 2b. The ion generating device 20 also includes laser optical paths 3a and 3b as two optical paths provided corresponding to the laser devices 2a and 2b, and further includes a wave plate 5, a beam splitter 4, and an off-axis parabolic mirror 13 as an optical integrator. The laser optical paths 3a and 3b have different optical path lengths.

[0035] The wave plate 5 constituting the light integrator may be provided on one of the two laser optical paths 3a and 3b, and changes the polarization direction of the light guided by the laser optical paths 3a and 3b. The beam splitter 4 reflects one of the two lights guided to the laser optical paths 3a and 3b, and transmits the other light in the direction of the reflected light.

[0036] Laser optical paths 3a and 3b guide the laser light generated by the corresponding laser devices 2a and 2b to a beam splitter 4. The beam splitter 4 integrates the light guided to the laser optical paths 3a and 3b and causes the light to enter the ion generation unit 1. A target 14 in the ion generation unit 1 generates ions in response to the light incident on the laser optical system 8.

[0037] In addition, by adding a laser device, a beam splitter, and a laser optical path, the laser light generated by three or more laser devices may be guided to three or more laser optical paths having different optical path lengths and integrated. At least one of the multiple optical path lengths may be provided with an optical path length adjustment mechanism described later.

[0038] 5 shows the configuration of an ion generating device 22 according to the second embodiment. The ion generating device 22 includes an ion generating unit 1, a laser device 2, and a laser optical system 9. The laser optical system 9 includes a wave plate 5, beam splitters 4a and 4b, mirrors 6a, 6b, and 6c, and a mirror moving mechanism 7.

[0039] Laser optical paths 3a and 3b are formed in the ion generating device 22. The laser optical path 3a runs from the laser device 2 to the beam splitter 4b via the wave plate 5 and the beam splitter 4a. The laser optical path 3b runs from the laser device 2 to the beam splitter 4b via the wave plate 5, the beam splitter 4a, and mirrors 6a and 6b.

[0040] That is, the positions and attitudes of the laser device 2, the wave plate 5, the beam splitters 4a and 4b, and the mirrors 6a and 6b are determined so that the laser optical paths 3a and 3b are formed. The mirror 6c and the ion generation unit 1 are arranged so that the laser light passing through the laser optical paths 3a and 3b is integrated at the beam splitter 4b, reflected by the mirror 6a, and reaches the ion generation unit 1.

[0041] The laser device 2 generates P-polarized or S-polarized laser light. The wave plate 5 rotates the polarization direction of linearly polarized light by 45°. As a result, the laser light that passes through the wave plate 5 has P-polarized light and S-polarized light overlapping in a 1:1 ratio.

[0042] The P-polarized light component that enters the beam splitter 4a passes through the beam splitter 4a and proceeds to the laser optical path 3b. On the other hand, the S-polarized light component that enters the beam splitter 4a is reflected by the beam splitter 4a and proceeds to the laser optical path 3a. Therefore, the laser light that enters the beam splitter 4a is split into the laser optical paths 3a and 3b at a 1:1 ratio.

[0043] The laser light reflected by beam splitter 4a and traveling to laser optical path 3a enters beam splitter 4b. Since this laser light is S-polarized, it is reflected by beam splitter 4b and enters mirror 6c. Meanwhile, the laser light that passes through beam splitter 4a and travels to laser optical path 3b is reflected by mirrors 6a and 6b and enters beam splitter 4b. Since this laser light is P-polarized, it passes through beam splitter 4b and enters mirror 6c.

[0044] The mirrors 6a and 6b on the laser optical path 3b are placed on a mirror movement mechanism 7. The mirror movement mechanism 7 is an optical path length adjustment mechanism that adjusts the optical path length of the laser optical path 3b. The laser delay time 33 is adjusted by controlling the position of the mirror movement mechanism 7 in the linear movement direction. Here, the linear movement direction is the direction in which the laser light is incident on the mirror 6a and the direction in which the laser light is reflected by the mirror 6b.

[0045] A generalized configuration of the ion generating device 22 according to this embodiment will be described below. The ion generating device 22 includes a laser device 2 as a laser source. The ion generating device 22 also includes a wave plate 5 and a beam splitter 4a as a light separator that separates the laser light generated by the laser device 2, and two laser optical paths 3a and 3b that guide the two laser lights obtained by the beam splitter 4a. The laser optical paths 3a and 3b have different optical path lengths.

[0046] The wave plate 5 constituting the optical separator changes the polarization direction of the incident light. The beam splitter 4a reflects one of two lights having different polarization directions and transmits the other light in a direction different from that of the reflected light.

[0047] Ion generator 22 further includes a beam splitter 4b, a mirror 6c, and an off-axis parabolic mirror 13 as a light combiner that combines the light guided to the two laser optical paths 3a and 3b and irradiates the light onto target 14. Target 14 generates ions in response to the light irradiated from beam splitter 4b.

[0048] In addition, a configuration may be used in which a beam splitter and a laser optical path are added to guide the laser light separated into three or more laser optical paths having different optical path lengths and integrate them. At least one of the optical path lengths may be provided with the optical path length adjustment mechanism described above. For example, a delay optical system may be additionally disposed in the laser optical path 3b. This results in a larger laser delay time 33.

[0049] 6 shows the configuration of a delay optical system 60 using mirrors. The delay optical system 60 using mirrors includes multiple N mirrors 6-1 to 6-N, and the laser optical path 3 is formed so that the laser optical path 3 is folded. That is, the multiple mirrors 6-1 to 6-N are cascaded so that the laser light is incident on a mirror 6-j in the previous stage and reflected by the mirror 6-j in the previous stage is incident on a mirror in the next stage 6-(j+1). Here, j is an integer between 1 and N-1.

[0050] As a result, the laser light incident on the delay optical system 60 is emitted from the delay optical system 60 with a delay after being incident on the first-stage mirror 6-1. By providing the delay optical system 60 on the laser optical path 3b, the laser delay time 33 per a certain arrangement space of the ion generator 22 becomes large.

[0051] FIG. 7 shows the configuration of a delay optical system 70 using a concave mirror. The delay optical system 70 using a concave mirror includes a pair of concave mirrors 71a and 71b. An entrance through hole 72a is provided above the concave mirror 71a, and an exit through hole 72b is provided below the concave mirror 71b. The concave mirrors 71a and 71b are arranged so that their concave sides face each other. The laser light incident between the concave mirrors 71a and 71b through the entrance through hole 72a travels back and forth between the concave mirrors 71a and 71b multiple times, and then exits outside the area between the concave mirrors 71a and 71b through the exit through hole 72b.

[0052] The delay optical system 60 using a mirror and the concave mirror 70 may configure the laser optical path 3 three-dimensionally. In addition, in the present embodiment, a configuration including one laser device 2 has been shown, but a number of laser optical systems 9 corresponding to the number of laser devices 2 may be provided. In this case, the laser optical system 8 according to the first embodiment may integrate the laser beams emitted from the plurality of laser optical systems 9.

[0053] For example, a laser beam emitted from one of the plurality of laser optical systems 9 is integrated with a laser beam emitted from another laser optical system 9, and the integrated laser beam is further integrated with a laser beam emitted from another laser optical system 9. This allows the laser beams emitted from the plurality of laser optical systems 9 to be integrated into one, making it possible to extend the effective ion beam pulse width 44. In the above, an example has been shown in which the components of the laser optical system 9 are on the same plane, but the components may be arranged three-dimensionally, and a smaller ion generating device 22 can be provided.

[0054] Here, an example has been shown in which the delay optical system 60 or 70 is provided in the laser optical path 3b, but the delay optical systems 60 or 70 having different delay times may be provided in both the laser optical paths 3a and 3b.

[0055] 8 shows the configuration of a particle beam accelerator 78 including an ion generator 24 and an accelerator 80. The ion generator 20 according to the first embodiment or the ion generator 22 according to the second embodiment is used as the ion generator 24. The accelerator 80 is a synchrocyclotron. The outer shell of the accelerator 80 is formed by a main electromagnet 81 that can be separated in the vertical direction, and the beam acceleration region inside the main electromagnet 81 is kept in vacuum.

[0056] An ion generator 24 is installed above the main electromagnet 81. The ion beam injected from the ion generator 24 is injected into the accelerator 80 through a low-energy beam transport line 83 and a deflection electrode 84 such as a spiral inflector. The accelerator 80 accelerates the ion beam. The ion beam extracted from the accelerator 80 is transported to the subsequent stage through a high-energy beam transport line 86 serving as an ion beam transport device.

[0057] A time width 45 (FIG. 4) during which an ion beam can be injected into the accelerator 80 is determined by the design of the accelerator 80. By bringing an effective ion beam pulse width 44 close to or coinciding with the time width 45 during which an ion beam can be injected into the accelerator 80, an ion beam with a necessary and sufficient amount of charge is injected into the accelerator 80. An ion beam pulse repetition period 46 is determined by a laser repetition period 34, and by coinciding with the beam acceleration operation period of the accelerator 80, for example, injection is performed every laser repetition period 34.

[0058] The accelerator 80 may be a synchrotron, a cyclotron, an eccentric orbit accelerator as described in Patent Document 1, or the like. By making the effective ion beam pulse width 44 close to or equal to the time width 45 that can be injected into the accelerator 80, an ion beam with a sufficient amount of charge is injected into the accelerator 80.

[0059] 9 shows the configuration of a particle beam therapy system 26 equipped with a particle beam accelerator 78. The particle beam therapy system 26 is equipped with the particle beam accelerator 78, a rotating gantry 90, an irradiation device 91, a treatment table 101, a treatment control device 102, and an accelerator control device 103. The ion beam emitted from the particle beam accelerator 78 is transported to the irradiation device 91 by the rotating gantry 90. The ion beam is irradiated from the irradiation device 91 to an affected area of ​​a patient 100 lying on the treatment table 101. When the ion beam is irradiated to the patient 100, the energy and shape of the ion beam are adjusted according to the position of the affected area.

[0060] The irradiation device 91 includes a dose monitor and monitors the irradiated dose for each irradiation spot on the patient 100 to obtain dose data. Based on this dose data, the treatment control device 102 calculates the required dose for each irradiation spot and obtains input data for the accelerator control device 103. The accelerator control device 103 controls the conditions of the ion beam in the particle beam accelerator 78, such as the injection, acceleration, and extraction. The irradiation device 91 may include a scanning magnet to perform scanning scanning. By using the particle beam accelerator 78, an ion beam having an appropriate energy and pulse width in the scanning irradiation method is injected into the scanning magnet. [Explanation of symbols]

[0061] 1 ion generation unit, 2, 2a, 2b laser device, 3, 3a, 3b laser optical path, 4, 4a, 4b beam splitter, 5 wave plate, 6, 6a, 6b, 6c mirror, 7 mirror movement mechanism, 8, 9 laser optical system, 11 optical window, 12 chamber, 13 off-axis parabolic mirror, 14 target, 15 plasma, 16 extraction electrode, 17 ion beam, 20, 22, 24 ion generator, 26 particle beam therapy system, 31 laser pulse, 32 laser pulse width, 33 laser delay time, 34 laser repetition period, 41 ion beam pulse, 42 ion beam pulse width, 43 ion beam pulse delay time, 44 effective ion beam pulse width, 45 time width that can be injected into accelerator, 46 ion beam pulse repetition period, 60 delay optical system using mirror, 70 Delay optical system using a concave mirror, 71a, 71b concave mirrors, 72a entrance hole, 72b exit hole, 78 particle beam accelerator, 80 accelerator, 81 main electromagnet, 83 low energy beam transport system, 84 deflection electrode, 86 high energy beam transport system, 90 rotating gantry, 91 irradiation device, 100 patient, 101 treatment table, 102 treatment control device, 103 accelerator control device.

Claims

1. A plurality of pulsed laser sources; Two optical paths provided corresponding to the plurality of pulsed laser sources, each of which guides a laser beam generated by the corresponding pulsed laser source; a light integrator that integrates the light guided to the two optical paths and irradiates the light onto a target; Two of the pulsed laser sources and two of the optical paths are provided, The optical integrator includes: A wave plate provided in one of the two optical paths, the wave plate changing the polarization direction of light guided by the two optical paths; a beam splitter that reflects one of the two light beams guided to the two optical paths and transmits the other in the direction of the reflected light, the target generates ions in response to light irradiated from the light integrator; The ion generating device according to the present invention is characterized in that the two optical paths have different optical path lengths.

2. A pulsed laser source; an optical separator for separating the laser light generated by the pulsed laser source; a plurality of optical paths through which the plurality of laser beams obtained by the optical separator are guided; a light integrator that integrates the light guided to the plurality of optical paths and irradiates the light onto a target; The optical separator includes: A wave plate that changes the polarization direction of incident light; a beam splitter that reflects one of the two light beams having different polarization directions and transmits the other in a direction different from the direction of the reflected light; the target generates ions in response to light irradiated from the light integrator; The ion generating device, wherein the plurality of optical paths have different optical path lengths.

3. The ion generating device according to claim 1 or 2, An ion generating device comprising: an optical path length adjustment mechanism provided in at least one of the optical paths.

4. The ion generating device according to claim 3, The optical path length adjustment mechanism includes: Miller and A mirror moving mechanism for moving the mirror is provided, forming an optical path by the incidence of light on the mirror and the reflection of light at the mirror; The ion generating device is characterized in that the optical path length is adjusted by adjusting the position of the mirror.

5. The ion generating device according to claim 1 or 2, a delay optical system provided in at least one of the optical paths and including a plurality of mirrors; The plurality of mirrors include 1. An ion generating device, comprising mirrors arranged in cascade such that light is incident on a mirror in a previous stage and reflected by the mirror in the previous stage is incident on a mirror in the next stage.

6. The ion generating device according to claim 1 or 2, An ion generating device comprising: a delay optical system provided in at least one of the plurality of optical paths, for making light go back and forth a plurality of times between mirrors disposed opposite to each other.

7. The ion generating device according to claim 1 or 2, an accelerator that accelerates the ions generated by the ion generating device, A particle beam acceleration device, characterized in that the pulse laser source repeatedly outputs laser light with the same period as that at which ions are extracted from the accelerator.

8. A particle beam accelerator according to claim 7; an ion beam transport device for transporting ions extracted from the particle beam accelerator; an irradiation device that irradiates a patient with the ions transported by the ion beam transport device; A particle beam therapy system comprising:

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