Vacuum pipeline and accelerator

Abstract

The invention provides a vacuum pipeline and an accelerator, which can enable charged particles to pass through in a mutually intersecting direction without three-dimensionally intersecting a plurality of pipelines with different vacuum degrees. A vacuum duct (10) is provided with: a first duct (21) that forms a first beam trajectory (11) for charged particles; a vacuum container (15) provided so as to cut off the midway of the linear portion of the first duct (21); and a second duct (22) that forms a second beam trajectory (12) that intersects the first beam trajectory (11) inside the vacuum container (15).

Description

Technical Field

[0001] Embodiments of the present invention relate to vacuum pipes and accelerators through which charged particles pass. Background Technology

[0002] Research into high-energy charged particle beams, produced by feeding and accelerating charged particles (ions) into accelerators, is progressing in a wide range of fields, including engineering and medicine. Currently, widely used accelerator systems generally consist of an ion source, a linear accelerator, and a circular accelerator, accelerating charged particles in stages according to this sequence. Then, when the charged particles orbiting in the circular accelerator reach a predetermined energy, the ejection control device activates, extracting the charged particle beam, whose direction of travel has been changed, and delivering it to the beam delivery system.

[0003] If gas molecules are present in the region through which charged particles pass in a circular accelerator, the accelerated charged particles will disappear due to scattering and charge changes caused by their interactions. Therefore, the region through which charged particles pass in a circular accelerator is formed inside a vacuum pipe designed for ultra-high vacuum.

[0004] On the other hand, beam delivery systems connecting ion sources to circular accelerators do not require high vacuum levels compared to circular accelerators. This is because charged particles pass through repeatedly in a circular accelerator, while in a beam delivery system, charged particles pass through only once at a low speed.

[0005] Prior art literature Patent documents Patent Document 1: Japanese Patent Application Publication No. 2021-012776 Summary of the Invention

[0006] The problem that the invention aims to solve In recent years, the miniaturization of circular accelerators has necessitated the relocation of ion sources and linear accelerators, previously located inside the circular accelerator, to its outer side. Therefore, for ease of equipment configuration, it is sometimes necessary to arrange the circular accelerator and the beam delivery system in a three-dimensional intersection. Consequently, to bend the beam trajectory of charged particles passing through the beam delivery system, additional deflecting electromagnets need to be installed in the vacuum pipe.

[0007] The embodiments of the present invention were made with this situation in mind, and the purpose is to provide a vacuum pipe and accelerator that allows charged particles to pass through in intersecting directions without having to make multiple pipes with different vacuum levels intersect three-dimensionally. Attached Figure Description

[0008] Figure 1 This is a top view of an accelerator system equipped with a vacuum tube according to an embodiment of the present invention.

[0009] Figure 2 (A) is a horizontal cross-sectional view of the vacuum pipe according to the first embodiment. Figure 2 (B) is a longitudinal sectional view of the vacuum pipe according to the first embodiment.

[0010] Figure 3 This is a horizontal cross-sectional view of a vacuum pipe in each embodiment that is equipped with a converging lens element containing a charged particle beam.

[0011] Figure 4 This is a horizontal cross-sectional view of a vacuum pipe equipped with an on / off valve carrying a particle beam in each embodiment.

[0012] Figure 5 This is a horizontal cross-sectional view of the vacuum pipe involved in the second embodiment.

[0013] Figure 6 This is a horizontal cross-sectional view of the vacuum pipe involved in the third embodiment. Detailed Implementation

[0014] (First Implementation) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a top view of an accelerator 30 equipped with a vacuum conduit 10 according to an embodiment of the present invention. The accelerator 30 is a system consisting of an ion source 35, a linear accelerator 36 (as a linear accelerator), and a synchrotron 20 (as a circular accelerator), which sequentially accelerates the charged particle beams 24 (24a, 24b). Then, when the charged particles orbiting in the synchrotron 20 reach a predetermined energy, the ejection device 29 is activated while maintaining that energy, and the charged particle beam 24c, having changed its direction of travel from its orbital path, is extracted into the beam delivery system 28.

[0015] Besides high-frequency (including microwave) irradiation types such as ECR (Electron Cyclotron Resonance) ion sources and PIG (Penning Ionization Gauge) ion sources, other ion sources include laser irradiation types, but are not limited to these.

[0016] The linear accelerator 36 arranges multiple accelerating electric fields with adjacent electric field components facing opposite directions into a straight line, causing the electric field direction to repeatedly reverse at a high frequency, so that the charged particle beam 24a passing through the accelerating electric field is always accelerated in only one direction. Furthermore, the linear accelerator 36 accelerates the ions incident from the ion source 35 to a predetermined energy and then ejects them into the synchrotron 20.

[0017] The synchrotron 20 comprises a high-frequency acceleration cavity 25 that accelerates charged particles incident from the linear accelerator 36 by high-frequency electricity, multiple deflecting electromagnets 26 that generate a magnetic field that imparts a centripetal force to the surrounding charged particles, multiple quadrupole electromagnets 27 that generate a magnetic field that causes the surrounding charged particles to diverge / converge and remain in the orbit, and an ejection device 29 that ejects the charged particle beam 24b surrounding the synchrotron 20 toward the delivery system 28.

[0018] The synchrotron 20 configured in this way accelerates charged particles incident from the linear accelerator 36 at low energy levels to 70-80% of the upper limit of the speed of light while orbiting, allowing the charged particle beam 24c to pass through the beam delivery system 28.

[0019] In addition, the beam delivery system 28 is also equipped with: a four-pole electromagnet 27, which is used to keep the straight-moving charged particle beam 24c in the track; and a deflection electromagnet 26, which is used to apply a centripetal force to the charged particle beam 24c to bend the track. Moreover, a device for irradiating the charged particle beam 24c is connected to the front end of the beam delivery system 28 (illustration omitted).

[0020] Figure 2 (A) is a horizontal cross-sectional view of the vacuum pipe 10A (10) according to the first embodiment. Figure 2 (B) is a longitudinal sectional view of the vacuum pipe 10A (10). Thus, the vacuum pipe 10A includes: a first pipe 21 forming a first beam trajectory 11 for charged particles; a vacuum container 15, which is provided by cutting off the middle of the straight section of the first pipe 21; and a second pipe 22 forming a second beam trajectory 12 that intersects the first beam trajectory 11 inside the vacuum container 15.

[0021] Here, the first conduit 21 forms part of a beam delivery system extending from the linear accelerator side (ion source 35 and linear accelerator 36). Moreover, the second conduit 22 forms part of a circular accelerator (synchrotron 20).

[0022] In vacuum pipe 10A, the second pipe 22 is provided with openings 16 (16a, 16b) that penetrate the vacuum container 15 and allow the first beam trajectory 11 to pass through. Here, the vacuum container 15 has a sufficiently large longitudinal cross-section compared to both the first pipe 21 and the second pipe 22. Furthermore, the openings 16 (16a, 16b) are configured to be sufficiently small compared to the longitudinal cross-section of the second pipe 22. This allows for differential exhaust, suppressing the inflow of gas molecules from the vacuum container 15, which is connected to the first pipe 21, into the second pipe 22.

[0023] Here, differential exhaust refers to a vacuum container 15, with a volume sufficiently large than these pipes, being used to connect a first pipe 21 (relatively low vacuum) to a second pipe 22 (higher vacuum). This container is connected to a vacuum pump 17 with a large diameter and short distance. This allows the conductance of the first pipe 21 and the second pipe 22 to be smaller than the conductance of the vacuum pump 17, suppressing the inflow of gas molecules into the second pipe 22 (higher vacuum) and stably maintaining the vacuum difference between the two pipes. Furthermore, when the first pipe 21 and the second pipe 22 intersect, a three-dimensional structure is achieved without the need for electromagnets or similar devices.

[0024] Furthermore, in Figure 2 In (B), the vacuum pump 17 is located on the bottom surface of the vacuum container 15 within the vacuum pipe 10A. However, this is not a limitation; the vacuum pump 17 can also be located on the upper surface or side surface of the vacuum container 15, or multiple pumps can be combined. In the external surface view of the vacuum container 15, the first pipe 21 and the second pipe 22 are connected from the side, thus increasing the freedom in the position and number of the vacuum pumps 17. Therefore, it is possible to achieve an improved vacuum level while avoiding interference with surrounding equipment.

[0025] Alternatively, it is possible that the vacuum pump 17 is not installed in the vacuum container 15. Or, sometimes a substance with a gas-adsorbing effect (a suction pump) that adsorbs gas molecules is used to coat or install the inner surface of the vacuum container 15. With such a suction pump, gas molecules can be adsorbed without affecting the charged particle beam 24, achieving exhaust with high flow conductance and maintaining a high vacuum level inside the vacuum container 15.

[0026] Additionally, in the accelerator 30 assembled in the embodiment ( Figure 1 In the vacuum pipe 10, a vacuum container 15 is provided in the first pipe 21, which has a lower vacuum than the second pipe 22. As a result, the decrease in vacuum caused by leakage from the vacuum container 15 or gas discharged from its inner surface into the pipe (second pipe 22) on the high vacuum side can be suppressed, and the loss of the beam accelerated through the pipe can be reduced.

[0027] However, it is not necessary to be particularly limited to this method; the first pipe 21, where the vacuum container 15 is provided, can also be set to a higher vacuum than the second pipe 22. Furthermore, while the vacuum levels of the first pipe 21 and the second pipe 22 are illustrated, they can also be the same.

[0028] Figure 3This is a horizontal cross-sectional view of the vacuum pipe 10, which is equipped with a converging lens element for the charged particle beam 24. Thus, in the first pipe 21, a pair of quadrupole electromagnets 27 (27a, 27b) are provided on both sides of the vacuum container 15 as lens elements to converge the charged particle beam 24.

[0029] In this way, by setting up quadrupole electromagnets 27 (27a, 27b) and focusing the charged particle beam 24, the diameter of the openings 16 (16a, 16b) in the second pipe 22 can be reduced. As a result, the decrease in vacuum level in the pipe (second pipe 22) on the high vacuum side can be suppressed, and the loss of the accelerated beam passing through the pipe can be further reduced.

[0030] Figure 4 This is a horizontal cross-sectional view of the vacuum pipe 10 equipped with an on / off valve 37 for charged particle beams. The on / off valves 37 (37a, 37b) are positioned on both sides of the first pipe 21, separated by the vacuum container 15. Thus, by providing the on / off valves 37 (37a, 37b) in the first pipe 21, where the vacuum level is relatively low, the valves 37 can be set to open only when the beam passes through, and otherwise to close. This suppresses the decrease in vacuum level in the pipe on the high vacuum side (second pipe 22), further reducing the loss of the accelerated beam passing through that pipe.

[0031] (Second Implementation) Next, refer to Figure 5 The second embodiment of the present invention will be described. Figure 5 This is a horizontal cross-sectional view of the vacuum pipe 10B (10) according to the second embodiment. Compared with the structure of the first embodiment described above, the vacuum pipe 10B of the second embodiment adopts a structure in which the straight section is cut off in the middle and joined to the outer peripheral surface of the vacuum container 15. In addition, in Figure 5 In, it has the same Figure 1 Parts with common structure or function are indicated by the same label, omitting repeated descriptions.

[0032] The second embodiment is a preferred structure where there is no significant difference in vacuum levels between the first pipe 21 and the second pipe 22, and there is no problem with the inflow of gas molecules from one direction to the other. Furthermore, by employing... Figure 4 The on / off valve 37 of the charged particle beam shown can suppress the decrease in vacuum level of the pipe (second pipe 22) on the high vacuum side and reduce the loss of the beam accelerated through the pipe.

[0033] (Third implementation method) Next, refer to Figure 6 The third embodiment of the present invention will be described. Figure 6This is a horizontal cross-sectional view of the vacuum conduit 10C (10) according to the third embodiment. The vacuum conduit 10C of the third embodiment adopts a structure where the number of conduits N is 3 or more (N=3 in the illustration). Furthermore, in Figure 6 In, it has the same Figure 1 Parts with the same structure or function are represented by the same label, omitting repeated descriptions.

[0034] The vacuum tube 10C includes: a first tube 21 forming a first beam trajectory 11 for charged particles; a first vacuum container 151, which is provided by cutting off the middle of the straight section of the first tube 21; and a second tube 22 forming a second beam trajectory 12 that intersects the first beam trajectory 11 inside the first vacuum container 151. It also includes: a second vacuum container 152, which is provided by cutting off the middle of the straight section of the second tube 22; and a third tube 23 forming a third beam trajectory 13 that intersects the second beam trajectory 12 inside the second vacuum container 152.

[0035] Furthermore, the vacuum pipe 10C of the third embodiment can be extended to include a number of pipes N (N≥3). In this case, the vacuum pipe 10C includes, for any natural number n in the range of 3 to N: an (n-1)th vacuum container, which is provided by cutting off the middle of the straight section of the (n-1)th pipe; and an nth pipe, which forms an nth beam trajectory that intersects with the (n-1)th beam trajectory inside the (n-1)th vacuum container.

[0036] Therefore, multiple pipes with different vacuum levels, where the number N is 3 or more, can intersect while suppressing changes in vacuum level. In this case, the vacuum pipe 10C can be configured as the first pipe 21 with the lowest vacuum level, the second pipe 22 with the second lowest vacuum level, and the Nth pipe with the highest vacuum level.

[0037] According to at least one of the above-described embodiments of the vacuum pipe, by connecting the first pipe and the second pipe to the vacuum container in such a way that the first beam track of the first pipe and the second beam track of the second pipe intersect inside the vacuum container, it is possible to provide a vacuum pipe and accelerator that allows charged particles to pass through in mutually intersecting directions without having multiple pipes with different vacuum levels intersecting three-dimensionally.

[0038] Several embodiments of the present invention have been described above, but these embodiments are merely illustrative and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments or variations thereof are included in the scope or spirit of the invention, and are included within the scope of the invention described in the patent claims and their equivalents.

Claims

1. A vacuum pipe, characterized in that, have: The first channel forms the first beam trajectory of charged particles; A vacuum container is provided by cutting off the middle of the straight section of the first pipe; and The second conduit forms a second beam trajectory that intersects with the first beam trajectory inside the vacuum container.

2. The vacuum pipe according to claim 1, wherein, The second pipe has an opening that penetrates the vacuum container and allows the first beam trajectory to pass through.

3. The vacuum pipe according to claim 2, wherein, In the first pipe, lens elements are provided on both sides of the vacuum container to converge the beam of charged particles.

4. The vacuum pipe according to claim 1, wherein, The second conduit is abruptly cut off midway through the straight section and then joins the outer circumferential surface of the vacuum container.

5. The vacuum pipe according to any one of claims 1 to 4, wherein, A vacuum pump is installed in the vacuum container.

6. The vacuum pipe according to any one of claims 1 to 4, wherein, The first pipe and the second pipe have different vacuum levels.

7. The vacuum pipe according to any one of claims 1 to 4, wherein, On the first pipe, on both sides of the vacuum container, there are opening and closing valves.

8. The vacuum pipe according to any one of claims 1 to 4, wherein, Let the number of pipes be N, and N≥3. For all natural numbers n in the range 3 to N, the following holds true: The (n-1)th vacuum container is constructed by truncating the straight section of the (n-1)th pipe midway; and The nth conduit forms the nth beam orbit that intersects with the (n-1)th beam orbit inside the (n-1)th vacuum container.

9. An accelerator, characterized in that, A vacuum conduit comprising any one of claims 1 to 4.

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