Beam adjustment mechanism

Abstract

This beam adjustment mechanism can be applied to a circulating ring that increases the valences while circulating particles. The circulating ring has: a first trajectory part that has a linear trajectory of one beam including particles having different valences, and has a stripper for increasing the valences of the particles; and a second trajectory part that has a plurality of trajectories of beams corresponding to the valences of the particles. The beam adjustment mechanism has, in the second trajectory part, a plurality of slit formation members that form slits for narrowing the beams in the plurality of trajectories. Each of the slit formation members has a substantially U-shape when viewed in the traveling direction of the corresponding beam, and changes the orientation of a recess relative to the beam by being rotated about a drive shaft, thereby changing the amount of aperture. The drive shaft and the direction in which the beam is narrowed intersect each other.

Description

Beam adjustment mechanism 【0001】 The present disclosure relates to a beam adjustment mechanism. 【0002】 Conventionally, as a technique for passing the beam of an accelerator through a slit, the one described in Patent Document 1 is known. In the accelerator described in Patent Document 1, a beam generated by accelerating particles passes through a slit, and a part of the beam is cut off by the slit to adjust the width of the beam. 【0003】 International Publication No. 2018-42539 【0004】 Here, as a device for adjusting the width of the slit of the beam adjustment mechanism for adjusting the width of the beam, the following can be mentioned. For example, a drive unit for reciprocating the member forming the slit is provided. By the drive unit adjusting the amount of movement of the member, the amount of beam aperture is adjusted. In such a mechanism, the beam aperture direction and the drive direction by the drive unit are in the same direction. Therefore, the drive unit is provided on the lateral side of the beam. In this case, there is a problem that the adjustment mechanism for the slit for another beam cannot be provided adjacent to the adjustment mechanism for the slit for one beam. In this case, each of the plurality of juxtaposed beams cannot be apertured. 【0005】 Therefore, an object of the present disclosure is to provide a beam adjustment mechanism capable of aperturing each of a plurality of juxtaposed beams. 【0006】 The beam adjustment mechanism according to one aspect of the present disclosure is a beam adjustment mechanism applicable to a circulating ring that raises the valence while circulating particles. The circulating ring has a linear orbit of a single beam containing particles with different valences, and a first orbit section having a stripper for raising the valence of the particles, and a second orbit section having orbits of a plurality of beams corresponding to the valence of the particles. The beam adjustment mechanism has a plurality of slit forming members that form slits for aperturing the beams in a plurality of orbits in the second orbit section. The slit forming member has a substantially U shape when viewed from the traveling direction of the beam, and changes the aperture amount by changing the direction of the concave portion with respect to the beam by rotating around the drive shaft. The drive shaft and the direction of aperturing the beam intersect each other. 【0007】The beam adjustment mechanism has a second trajectory section having multiple beam trajectories, and includes multiple slit-forming members that form slits to narrow the beams in each of the multiple trajectories. Here, the slit-forming members are substantially U-shaped when viewed from the direction of beam propagation, and the amount of narrowing is changed by rotating them on a drive shaft to change the orientation of the recesses relative to the beam. That is, because the slit-forming members are substantially U-shaped, the amount of narrowing can be easily adjusted by rotating them to change the orientation of the recesses relative to the beam. The drive shaft and the direction of narrowing the beam intersect each other. Therefore, it is possible to avoid placing the drive shaft and the mechanism that applies driving force to the drive shaft on the side adjacent to the direction of narrowing the beam. For this reason, a slit adjustment mechanism for one beam can be provided next to a slit adjustment mechanism for another beam. As a result, each of the multiple beams arranged in a row can be narrowed. 【0008】 In the slit-forming member, the area where the slit is formed may have a curved surface when viewed from the direction in which the drive shaft extends. In this case, by appropriately setting the shape of the curved surface, the amount of beam narrowing can be adjusted in accordance with the change in the rotation angle of the slit-forming member. 【0009】 Multiple slit-forming members may each be provided with an independent drive unit. In this case, the amount of beam throttling can be adjusted independently for each slit-forming member. 【0010】 The beam adjustment mechanism may have a flow path for a cooling medium to cool the slit-forming member. In this case, the thermal load on the beam of the slit-forming member can be reduced. 【0011】 According to this disclosure, a beam adjustment mechanism can be provided that can focus each of several beams arranged in a row. 【0012】This is a schematic plan view showing a circumferential ring to which a beam adjustment mechanism according to one embodiment of the present disclosure is applied. This is a perspective view of the beam adjustment mechanism. This is an enlarged perspective view showing the beam adjustment mechanism in the closed state. This is an enlarged perspective view showing the beam adjustment mechanism in the open state. This is an enlarged view of the slit-forming member in the open state of Figure 4. This is a diagram showing the relationship between the angle of the slit-forming member and the slit width. This is a diagram showing the drive unit. This is a cross-sectional view of the structure near the slit-forming member and the rotation axis. This is a diagram showing the relationship between the angle of the slit-forming member and the slit width. 【0013】 A beam adjustment mechanism according to one embodiment of this disclosure will be described below with reference to the attached drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted. 【0014】 Figure 1 is a schematic plan view showing a circulating ring 100 to which a beam adjustment mechanism 1 according to one embodiment of the present disclosure is applied. The circulating ring 100 is a device that increases the valence of particles while circulating them. The circulating ring 100 comprises an inlet section 101, a first orbital section 102, a second orbital section 103, and an outlet section 104. The inlet section 101 is the orbit to which particles P are injected into the circulating ring 100. The outlet section 104 is the orbit to which the accelerated beam B is emitted. For example, the circulating ring 100 is U ３５＋ By repeatedly orbiting and changing the charge of the particle, U ６４＋ Beam B may be emitted. The orbiting ring 100 raises the charge of particles that have not reached the desired valence by making them orbit the ring and repeatedly converting their charge. 【0015】The first orbital section 102 has a duct L1 that forms a linear orbit of a single beam containing particles of different valencies, and a stripper 110 that increases the valency of the particles. A resonator 120 that re-accelerates the lost energy of the particles is provided in the duct L1 at the positive side in the X-axis direction of the stripper 110. The second orbital section 103 has orbits of multiple beams B corresponding to the valencies of the particles. In the following description, the direction in which the beam B propagates in the first orbital section 102 is defined as the X-axis direction, and the downstream side of the propagating beam B is defined as the positive side. The direction perpendicular to the X-axis is defined as the Y-axis direction. One side in the Y-axis direction is defined as the positive side. When a center line CL extending in the Y-axis direction is set at the central position in the X-axis direction with respect to the circumferential ring 100, the first orbital section 102 and the second orbital section 103 have a configuration that is substantially symmetric with respect to the center line CL. 【0016】 The first orbital section 102 has a resonant cavity 111A on the positive side in the X-axis direction relative to the resonator 120, and a resonant cavity 111B on the negative side in the X-axis direction. The resonant cavity 111B suppresses vibrations of beam B. The second orbital section 103 extends from the positive end in the X-axis direction of the first orbital section 102, wrapping around to the negative end in the X-axis direction of the first orbital section 102. The second track section 103 comprises, in order from the positive end in the X-axis direction of the first track section 102, a deflection electromagnet 112A, a duct L2, a deflection electromagnet 112B, a duct L3, a deflection electromagnet 112C, a duct L4, a deflection electromagnet 112D, a duct L5, a deflection electromagnet 112E, a duct L6, a deflection electromagnet 112F, a duct L7, a deflection electromagnet 112G, a duct L8, and a deflection electromagnet 112H. Each of the deflection electromagnets 112A to 112H changes the direction of travel of the beam B that has come through the upstream duct so that it is directed toward the downstream duct. 【0017】The deflection electromagnet 112A is provided at the positive end of the first track section 102 in the X-axis direction. The duct L2 extends from the deflection electromagnet 112A in the positive direction in the Y-axis direction. The deflection electromagnet 112B is provided at the positive end of the duct L2 in the Y-axis direction. The duct L3 extends from the deflection electromagnet 112B in the negative direction in the X-axis direction. The deflection electromagnet 112C is provided at the negative end of the duct L3 in the X-axis direction. The duct L4 extends from the deflection electromagnet 112C toward the negative side in the X-axis direction and then toward the negative side in the Y-axis direction. The deflection electromagnet 112D is provided at the negative end of the duct L4 in the X-axis direction. The duct L5 extends from the deflection electromagnet 112D toward the negative side in the X-axis direction. The deflection electromagnets 112H, 112G, 112F, 112E and the ducts L8, L7, L6 have a structure that is symmetrical with respect to the center line CL, with respect to the deflection electromagnets 112A, 112B, 112C, 112D and the ducts L2, L3, L4. 【0018】 Because the beam B orbiting the circular ring 100 contains particles with different valencies, the amount of deflection at each bending electromagnet 112A to 112H differs according to the valency. By being bent by the bending electromagnets 112A, 112B, 112C, and 112D, beam B is divided into multiple beams B such that the difference between them increases according to the valency. By being bent by the bending electromagnets 112E, 112F, 112G, and 112H, the multiple beams B are bent to converge and become a single beam B in the first orbital section 102. In the second orbital section 103, the lengths of the paths of the divided beams B are set to be equal to each other. 【0019】 Ducts L4, L5, and L6 are divided into multiple (eight in this case) individual ducts LX for beams B. One portion of the divided beam B passes through each individual duct LX. Each individual duct LX is equipped with an electromagnet (not shown) for constricting beam B. Electromagnets (not shown) are also provided in each of the ducts L1, L2, L3, L7, and L8. 【0020】The beam adjustment mechanism 1 according to this embodiment is provided in the circular ring 100 as described above to narrow the beam B and adjust the amount of narrowing. In the example shown in Figure 1, it is provided in the duct L4 extending from the deflection electromagnet 112C. The beam adjustment mechanism 1 is provided at an intermediate position in the plurality of individual ducts LX (or between the outlet of the deflection electromagnet 112C and each individual duct LX). The beam adjustment mechanism 1 narrows the divided plurality of beams B individually. 【0021】 Figure 2 is a perspective view of the beam adjustment mechanism 1. In the drawings from Figure 2 onward, the beam adjustment mechanism 1 will be described using an xyz coordinate system (a different coordinate system from the XY coordinate system in Figure 1). The y-axis direction is horizontal to the direction of travel of each beam B. The downstream side of the direction of travel of beam B is the positive side. The x-axis direction is the direction in which the multiple beams B are aligned. One side in the x-axis direction is the positive side. The z-axis direction is perpendicular to the x-axis and y-axis directions. The z-axis direction corresponds to the vertical direction, with the upper side being the positive side. The beam adjustment mechanism 1 narrows the beam B with the x-axis direction as the narrowing direction. 【0022】 The beam adjustment mechanism 1 has a plurality of slit-forming members 2 in the second track section 103 (see Figure 1) that form slits to narrow the beam B in each of the plurality of track sections (individual ducts LX). One pair of slit-forming members 2A, 2B is provided for each beam B. The slit-forming member 2A is positioned on the negative side in the x-axis direction relative to the beam B. The slit-forming member 2B is positioned on the positive side in the x-axis direction relative to the beam B. In this embodiment, the second track section 103 (see Figure 1) is divided into eight beams B, so the beam adjustment mechanism 1 has eight pairs of slit-forming members 2A, 2B. Since the beams B are divided so that they are aligned in the x-axis direction, each pair of slit-forming members 2A, 2B is provided so that they are aligned in the x-axis direction. 【0023】 Independent drive units 3A and 3B are provided for the slit-forming members 2A and 2B, respectively. Furthermore, independent drive units 3A and 3B are provided for different sets of slit-forming members 2A and 2B. Each drive unit 3A and 3B is provided so as to extend above the slit-forming members 2A and 2B. The detailed configuration of the drive units 3A and 3B will be described later. 【0024】 The beam adjustment mechanism 1 has a housing 4 that rotatably accommodates multiple sets of slit-forming members 2A and 2B. The housing 4 has a wall portion 4a positioned on the negative side in the y-axis direction relative to the slit-forming members 2A and 2B. Through holes 6 are formed in the wall portion 4a for each beam B to pass through. A frame 7 supporting each set of drive units 3A and 3B is provided on the upper side of the housing 4. 【0025】 The configurations of the slit-forming members 2A and 2B will be described in detail with reference to Figures 3 and 4. Note that, as shown in Figure 3, the state in which the aperture is smallest is sometimes referred to as the "closed state," and the state in which the aperture is largest (no aperture) is sometimes referred to as the "open state." 【0026】 First, the shapes of the slit-forming members 2A and 2B will be described using the open state shown in Figure 4 as a reference. As shown in Figure 4, the slit-forming members 2A and 2B are roughly U-shaped when viewed from the direction of travel of the beam B (i.e., the y-axis direction). The slit-forming members 2A and 2B have a main body portion 10 that extends in the vertical direction, a protruding portion 11A that protrudes laterally from the upper end of the main body portion 10, and a protruding portion 11B that protrudes laterally from the lower end of the main body portion 10. The main body portion 10 has a roughly rectangular prism shape. The protruding portions 11A and 11B protrude toward the beam B side (towards the center of the through hole 6). That is, the protruding portions 11A and 11B of the slit-forming member 2A protrude toward the positive side in the x-axis direction. The protruding portions 11A and 11B of the slit-forming member 2B protrude toward the negative side in the x-axis direction. The protruding portion 11A is positioned above the through hole 6, and the protruding portion 11B is positioned below the through hole 6. The slit-forming members 2A and 2B have a recess 12 formed by the side surface 10a of the main body portion 10, the lower surface of the protruding portion 11A, and the upper surface of the protruding portion 11B. 【0027】Next, the axial support structure of the slit-forming member 2A will be described with reference to Figure 5. Figure 5 is an enlarged view of the slit-forming member 2A in the open state shown in Figure 4. In Figure 5, each component will also be described based on the open state. Figure 5(a) is a view of the slit-forming member 2A from the y-axis direction. Figure 5(b) is a view of the slit-forming member 2A from the x-axis direction. The slit-forming member 2B also has an axial support structure of the same nature. The upper surface of the protrusion 11A is fixed to the rotating shaft 13 that extends upward. The lower surface of the protrusion 11B is fixed to the support shaft 14 that extends downward. The rotating shaft 13 is connected to the drive unit 3A (see Figure 2) at its upper end. The support shaft 14 is rotatably supported by the bearing part 15 at its lower end. The bearing part 15 is provided in the housing 4 (see Figure 4). The rotating shaft 13 and the support shaft 14 are provided coaxially. The center line CL1 of the rotation axis 13 and the support axis 14 extends parallel to each other in the vertical direction. As shown in Figure 5(a), the center line CL1 is set to a position eccentric to the positive side in the x-axis direction, on the side of the recess 12, rather than the center position in the x-axis direction of the main body 10. In this embodiment, the center line CL1 is set at the boundary position between the main body 10 and the recess 12, i.e., at the position of the side surface 10a. As a result, the entire main body 10 operates to pivot around the center line CL1. As shown in Figure 5(b), the center line CL1 is set to a position eccentric to the positive side in the y-axis direction, rather than the center position in the y-axis direction of the main body 10. As a result, the negative side surface 10b of the main body 10 in the y-axis direction operates to pivot significantly around the center line CL1. 【0028】The slit-forming members 2A and 2B change the amount of throttling by changing the orientation of the recesses 12 relative to the beam B by rotating on the rotation axis 13. As shown in Figure 4, in the open state, the recesses 12 of the slit-forming member 2A and the recesses 12 of the slit-forming member 2B are arranged to open toward the beam B. Therefore, the slit-forming members 2A and 2B are arranged so that the sides 10a of each main body portion 10 are spaced apart in the x-axis direction and face each other. As a result, when viewed from the beam propagation direction (y-axis direction), the recesses 12 of the slit-forming members 2A and 2B form slits SL that avoid the through hole 6. In this embodiment, in the open state, when viewed from the positive side to the negative side in the y-axis direction, the entire area of ​​the through hole 6 is exposed without being covered by the slit-forming members 2A and 2B. Therefore, in the open state, there is no throttling of the beam B. However, the beam B may be throttled by a predetermined amount even in the open state. 【0029】 As shown in Figure 3, in the closed state, the recess 12 of the slit-forming member 2A and the recess 12 of the slit-forming member 2B are arranged to open toward the downstream side in the beam propagation direction, i.e., toward the positive side in the y-axis direction. Therefore, the slit-forming members 2A and 2B are arranged so that the sides 10b of each main body portion 10 are spaced apart in the x-axis direction and face each other. As a result, when viewed from the beam propagation direction (y-axis direction), the main body portions 10 of the slit-forming members 2A and 2B form a slit SL that narrows the area through which the beam B can pass. In this embodiment, in the closed state, when viewed from the positive side to the negative side in the y-axis direction, the area extending vertically, including the vicinity of the center of the through-hole 6, is exposed without being covered by the slit-forming members 2A and 2B, while the areas on both sides of the through-hole 6 in the x-axis direction are covered by the slit-forming members 2A and 2B. 【0030】Referring to Figure 6, the amount of throttling of the slit SL formed by the slit-forming members 2A and 2B will be explained in more detail. In Figure 6, the main body portion 10 of the slit-forming members 2A and 2B in the closed state is shown by a solid line. The state in which the slit-forming members 2A and 2B are opened at a constant angle around the center line CL1 is shown by dashed lines as "state ST1," "state ST2," and "state ST3." The slit-forming members 2A and 2B in the open state are also shown by dashed lines. The portion of the slit-forming members 2A and 2B that forms the slit SL has a curved surface 16 when viewed from the direction in which the rotation axis 13 extends (up and down direction). In this embodiment, the sides 10b that face each other in the closed state are configured as the curved surface 16. In the closed state, the curved surface 16 curves such that the distance between the slit-forming members 2A and 2B is narrowest at the negative end in the y-axis direction, and the distance gradually widens as it moves toward the positive side in the y-axis direction. In the closed state, the slit width of slit SL is "W1". As a result, the beam B emitted from the through hole 6 passes through slit SL and becomes a beam B with a width of "W1". In state ST1, the slit width is wider than "W1" and becomes "W2". In state ST2, the slit width is wider than "W2" and becomes "W3". In state ST3, the slit width is wider than "W3" and becomes "W4". The slit widths W1, W2, W3, and W4 increase by a constant amount in proportion to a certain increase in angle. 【0031】Next, with reference to Figure 7, the details of the drive unit 3A for the slit-forming member 2A and the drive unit 3B for the slit-forming member 2B will be described. Figure 7 is a view of the drive units 3A and 3B from the y-axis direction. Note that in Figure 7, the couplings 20, 21, and 24 of the drive unit 3B are omitted in order to show the configuration of each component. As mentioned above, a rotating shaft 13 extends upward from the slit-forming members 2A and 2B. A motor 17 is provided on the upper side of the rotating shaft 13 to provide rotational driving force to the rotating shaft 13. The motor 17 has a drive shaft 17a that extends downward and a drive shaft 17b that extends upward. The upper end of the rotating shaft 13 and the drive shaft 17a of the motor 17 are connected via a coupling 20. The motor 17 can control the rotation angle of the drive shaft 17a (i.e., the rotation angle of the slit-forming members 2A and 2B). A limit sensor 18 is provided on the upper side of the drive shaft 17b of the motor 17. The drive shaft 17b of the motor 17 is connected to the lower end of the rotating shaft 19 via a coupling 21. A limit sensor 18 is provided around the rotating shaft 19 and limits the rotation angle of the slit-forming members 2A and 2B via the rotating shaft 19. The upper end of the rotating shaft 19 is connected to a support member 23 fixed to the frame 7 (see Figure 2) via a coupling 24. Each rotating shaft 13, drive shafts 17a and 17b, rotating shaft 19, and support member 23 are arranged coaxially. With this configuration, the direction in which the drive shaft 17a of the motor 17 and the direction in which the slit-forming members 2A and 2B narrow the slit SL (i.e., the x-axis direction) intersect with each other. Here, the direction in which the drive shaft 17a and the direction in which the slit SL narrow are orthogonal to each other. 【0032】 Next, the cooling structure for the slit-forming members 2A and 2B will be described with reference to Figure 8. Figure 8 is a cross-sectional view of the structure near the slit-forming members 2A and 2B and the rotating shaft 13. As shown in Figure 8, the rotating shaft 13 extends upward from the slit-forming members 2A and 2B, penetrates the upper wall portion 30 of the housing 4, and extends upward. The rotating shaft 13 is provided with a bracket 31 for the inflow and outflow of the cooling medium in the region between the upper wall portion 30 and the joint 20. The bracket 31 has a joint 31a for inflow of the cooling medium and a joint 31b for outflow of the cooling medium. 【0033】Two vertically extending channels 34a and 34b are formed inside the rotating shaft 13. The lower ends of the channels 34a and 34b merge in a cavity 36 formed at the lower end of the rotating shaft 13. The cavity 36 is located inside the protruding portion 11A of the slit-forming members 2A and 2B. Channel 34a is connected to the joint 31a at its upper end, and channel 34b is connected to the joint 31b at its upper end. As a result, the cooling medium flowing in from the joint 31a passes through channel 34a downwards, through the cavity 36 and channel 34b upwards, and is discharged from the joint 31b. Therefore, the slit-forming members 2A and 2B are cooled by the cooling medium. 【0034】 Next, the operation and effects of the beam adjustment mechanism 1 according to this embodiment will be described. 【0035】 The beam adjustment mechanism 1 has a second trajectory section 103 having trajectories for multiple beams B, and includes multiple slit-forming members 2A and 2B that form slits SL that narrow the beams B in each of the trajectories. Here, the slit-forming members 2A and 2B are substantially U-shaped when viewed from the direction of travel of the beams B, and the amount of narrowing is changed by rotating them on the drive shaft 17a to change the orientation of the recesses 12 relative to the beams B. That is, because the slit-forming members 2A and 2B are substantially U-shaped, the amount of narrowing can be easily adjusted by rotating them to change the orientation of the recesses 12 relative to the beams B. The drive shaft 17a and the direction of narrowing the beams B intersect each other. Therefore, it is possible to avoid arranging the drive shaft 17a and the mechanism that applies driving force to the drive shaft 17a on the side adjacent to the direction of narrowing the beams B. For this reason, an adjustment mechanism for the slits SL for one beam B can be provided next to an adjustment mechanism for the slits SL for another beam B. As a result, each of the multiple beams arranged in a row can be narrowed. 【0036】The areas in the slit-forming members 2A and 2B where the slit SL is formed may have a curved surface 16 when viewed from the direction in which the drive shaft 17a extends. For example, as shown in Figure 9, the side surfaces 10b of the slit-forming members 2A and 2B may be flat surfaces instead of curved surfaces. In the example of Figure 9, even when the slit-forming members 2A and 2B are rotated at a constant angle, the slit width does not increase at a constant angle. Specifically, the difference between the slit width W1 in the closed state and the slit width W2 in state ST1 is small. On the other hand, the difference between the slit width W2 in state ST1 and the slit width W3 in state ST2 is large. Furthermore, the difference between the slit width W3 in state ST2 and the slit width W4 in state ST3 is even larger. On the other hand, in the example shown in Figure 6, if the rotation angle of the slit-forming members 2A and 2B is increased, the slit width can be increased by the same amount. That is, by appropriately setting the shape of the curved surface 16, the amount of throttling of the beam B can be adjusted in accordance with the change in the rotation angle of the slit-forming members 2A and 2B. 【0037】 Multiple slit-forming members 2A and 2B may each be provided with independent drive units 3A and 3B. In this case, the amount of throttling of the beam B can be adjusted independently in each of the slit-forming members 2A and 2B. 【0038】 The beam adjustment mechanism 1 may have flow paths 34a and 34b for a cooling medium that cools the slit forming members 2A and 2B. In this case, the thermal load on beam B of the slit forming members 2A and 2B can be reduced. 【0039】 This disclosure is not limited to the embodiments described above. 【0040】 For example, the configuration of the circular ring shown in Figure 1 is merely one example and can be modified as appropriate. Similarly, the configuration of the beam adjustment mechanism shown in Figure 2 may also be modified as appropriate, without departing from the spirit of this disclosure. 【0041】For example, the number of beams that the beam adjustment mechanism can adjust is not particularly limited. Also, the positions of the multiple motors in the beam adjustment mechanism are not limited to the configuration shown in Figure 2. For example, some of the motors may be placed below the slit-forming members. Furthermore, the shapes of all slit-forming members and the configuration of the drive unit in the beam adjustment mechanism do not need to be the same; some may be different. 【0042】 1...Beam adjustment mechanism, 2A, 2B...Slit forming members, 3A, 3B...Drive unit, 17a...Drive shaft, 34a, 34b...Flow path, 100...Circular ring, 110...Stripper, 102...First track section, 103...Second track section.

Claims

1. A beam adjustment mechanism applicable to a circulating ring that increases the valence of particles while they circulate, wherein the circulating ring has a first trajectory section having a linear trajectory of a single beam containing particles of different valences and a stripper that increases the valence of the particles, and a second trajectory section having multiple beam trajectories corresponding to the valence of the particles, the beam adjustment mechanism having a plurality of slit-forming members in the second trajectory section that each form a slit that narrows the beam in the plurality of trajectories, the slit-forming members are substantially U-shaped when viewed from the direction of the beam's propagation, and the amount of narrowing is changed by changing the orientation of the recess relative to the beam by rotating on a drive shaft, and the drive shaft and the direction of narrowing the beam intersect each other.

2. The beam adjustment mechanism according to claim 1, wherein the portion of the slit forming member has a curved surface when viewed from the direction in which the drive shaft extends.

3. The beam adjustment mechanism according to claim 1, wherein each of the multiple slit-forming members is provided with an independent drive unit.

4. The beam adjustment mechanism according to claim 1, further comprising a flow path for a cooling medium to cool the slit forming member.

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