JP2014241217A - Cyclotron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cyclotron capable of easily adjusting a position of a vacuum container that houses a coil, while enhancing the performance.SOLUTION: A cyclotron 1 has an elastic body 40 provided in clearance in the radial direction between a vacuum container 4 and a yoke 8. Consequently, the vacuum container 4 is configured so that it can be supported in the radial direction by the elastic body 40. Since adjusting a position can be carried out with the elastic force of the elastic body 40 by simply assembling the vacuum container 4 to the yoke 8, alignment of the vacuum container 4 can be facilitated. Furthermore, slide slip of the vacuum container 4 (cryostat) can be prevented, and the clearances SP1, SP2 for assembling between the yoke 8 and vacuum container 4 can be ensured.

Description

  The present invention relates to a cyclotron.

  2. Description of the Related Art Conventionally, a cyclotron including an annular coil disposed so as to surround a pole, a vacuum vessel that accommodates the coil, and a yoke provided around the vacuum vessel is known (for example, Patent Document 1). In such a cyclotron, it is necessary to adjust the position of the vacuum vessel that accommodates the coil, and as a method for adjusting the position, a method in which a bolt is brought into contact with the outer surface of the vacuum vessel may be employed.

JP 2002-431117 A

  However, when adjusting the position of the vacuum vessel using bolts, there is a problem that adjustment takes time. Further, in this method, a local load acts on the vacuum vessel at the position where the bolt is in contact. The vacuum vessel may be deformed by such a local load, and the performance of the cyclotron may be affected.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a cyclotron capable of easily adjusting the position of a vacuum vessel that accommodates a coil and improving performance.

  The cyclotron according to the present invention is provided in an annular coil, a vacuum container that houses the coil, a yoke that faces the vacuum container at least in a radial direction of the coil, and a radial gap between the vacuum container and the yoke. An elastic body.

  The cyclotron according to the present invention has an elastic body provided in a radial gap between the vacuum vessel and the yoke. Accordingly, the vacuum container can be supported in the radial direction by the elastic body. Therefore, since the position can be adjusted by the elastic force of the elastic body simply by assembling the vacuum container to the yoke, the vacuum container can be easily aligned. In addition, unlike the case where the position is adjusted using a bolt, the use of an elastic body can suppress the local application of a load to the vacuum vessel and suppress the deformation of the vacuum vessel. As described above, the position of the vacuum vessel accommodating the coil can be easily adjusted and the performance of the cyclotron can be improved.

  In the cyclotron according to the present invention, the elastic body may be formed over the entire circumference in the circumferential direction of the coil. Thereby, the elastic body can reliably support the vacuum vessel over the entire circumference in the circumferential direction.

  In the cyclotron according to the present invention, the yoke may have a groove extending in the circumferential direction of the coil, and the elastic body may be fitted into the groove. Thereby, the elastic body is supported in the axial direction of the coil by the groove. Therefore, it is possible to prevent the elastic body from shifting in the axial direction.

  In the cyclotron according to the present invention, a plurality of elastic bodies may be provided along the axial direction of the coil. Thereby, the vacuum vessel is supported by the elastic body at a plurality of positions in the axial direction. Therefore, the vacuum vessel can be reliably supported by the elastic body.

  In the cyclotron according to the present invention, the elastic body may be provided on the end side of the vacuum vessel in the axial direction. Thereby, an elastic body can support a vacuum vessel stably.

  In the cyclotron according to the present invention, the coil may be a superconducting coil. When the position of the vacuum vessel is adjusted with bolts using a superconducting coil as in the past, when the load is locally applied to the vacuum vessel and the coil deforms, the members in the vacuum vessel come into contact with each other, Is more easily transmitted. This causes a problem that the superconductivity of the coil is destroyed. However, in the cyclotron according to the present invention, it is possible to suppress the deformation of the vacuum vessel due to a load acting locally, so that the superconductivity can be prevented from being destroyed.

  According to the present invention, it is possible to easily adjust the position of the vacuum vessel that houses the coil and to improve the performance of the cyclotron.

It is sectional drawing which shows schematic structure of the cyclotron which concerns on embodiment of this invention. It is an expanded sectional view of the cyclotron shown in FIG. It is the schematic which looked at the elastic body from the axial direction of the coil. It is the schematic which shows the structure at the time of using a spring as an elastic body. It is the schematic which shows the structure at the time of using a contact band as an elastic body. It is the schematic which shows the structure at the time of using an O-ring as an elastic body.

  Hereinafter, embodiments of a cyclotron according to the present invention will be described in detail with reference to the drawings.

  A cyclotron 1 according to this embodiment shown in FIG. 1 is a circular accelerator that accelerates charged particles supplied from an ion source (not shown) and outputs a charged particle beam (charged particle beam). Examples of the charged particles include protons, heavy particles (heavy ions), and electrons.

  The cyclotron 1 is arranged in an annular coil 2, 3 arranged around the central axis C, an annular vacuum vessel 4 for accommodating the coils 2, 3, and an air core part of the first coil 2. An upper pole (upper magnetic pole) 5, a lower pole (lower magnetic pole) 6 disposed at an air core portion of the second coil 3, a refrigerator (cooling means) 7 for cooling the coils 2 and 3, And a yoke 8. The yoke 8 is a hollow disk-shaped block, and the vacuum vessel 4, the upper pole 5 and the lower pole 6 are disposed therein. The vacuum vessel 4 and the cooler constitute a cryostat 9 that can cool the accommodated coils 2 and 3 until they become superconductive.

  In the cyclotron 1, the inside of the vacuum vessel 4 is evacuated, and then a strong magnetic field is formed by passing a current through the coils 2 and 3 that are brought into a superconducting state by the refrigerator 7. The charged particles supplied from the ion source are accelerated by the influence of the magnetic field in the space G between the upper pole 5 and the lower pole 6 and output as a charged particle beam.

  The first coil 2 and the second coil 3 are integrally held in the vacuum vessel 4 by a coil holding member (not shown). The refrigerator 7 is provided so as to be in contact with the coil holding member or in contact with the coils 2 and 3, and the coils 2 and 3 are directly cooled by the refrigerator 7 in a vacuum state. As the refrigerator 7, for example, a small GM refrigerator can be adopted.

  Next, a detailed configuration around the vacuum vessel 4 of the cyclotron 1 according to the present embodiment will be described with reference to FIG. In FIG. 2, only the peripheral structure of the second coil 3 is shown, but the peripheral structure of the first coil 2 also has the same concept.

  As shown in FIG. 2, the annular coil 3 has a rectangular cross section viewed from the circumferential direction, and has an outer circumferential surface 3 a and an inner circumferential surface 3 b, and end surfaces 3 c and 3 d that are opposed in the axial direction. Have. In the present embodiment, the coil 3 is held and reinforced by the holding member 10. The holding member 10 includes flange portions 11 and 12 provided for the end surfaces 3c and 3d of the coil 3, and an outer peripheral portion 13 provided on the outer peripheral side of the outer peripheral surface 3a of the coil 3 and connecting the flange portions 11 and 12 to each other. Have. The upper flange portion 12 is provided with a connection portion 14 for connection to a flange portion provided for the first coil 2 (not shown).

  An annular heat shield 16 is provided around the coil 3 so as to cover the coil 3. The heat shield 16 has a rectangular frame shape as viewed from the circumferential direction. The heat shield 16 is arranged so that its central axis substantially coincides with the central axis C of the coil 3. The heat shield 16 has an outer peripheral wall portion 17 that is radially opposed to the outer peripheral portion 13 on the outer peripheral side, an inner peripheral wall portion 18 that is radially opposed to the inner peripheral surface 3b of the coil 3 on the inner peripheral side, And a lower wall portion 19 opposed to the flange portion 11 at the lower side. In addition, the outer peripheral wall part 17 and the inner peripheral wall part 18 are extended upwards rather than the upper 1st coil 2, and the upper end is sealed by the upper wall part. Each wall portion is disposed away from the coil 3 and the holding member 10. Each wall portion of the heat shield 16 is constituted by a plate-like member.

  An annular vacuum vessel 4 is provided around the heat shield 16 (that is, around the coil 3) so as to cover the heat shield 16. The vacuum container 4 has a rectangular frame shape as viewed from the circumferential direction. The vacuum vessel 4 is arranged so that its central axis substantially coincides with the central axis C of the coil 3. The vacuum vessel 4 is radially opposed to the outer peripheral wall portion 21 of the heat shield 16 in the radial direction on the outer peripheral side and radially opposed to the inner peripheral wall portion 18 of the heat shield 16 on the inner peripheral side. An inner peripheral wall portion 22 and a lower wall portion 23 facing the lower wall portion 19 of the heat shield 16 at the lower side are provided. In addition, the outer peripheral wall part 21 and the inner peripheral wall part 22 are extended to the upper direction rather than the upper wall part of the upper coil 1 and the heat shield 16, and the upper end is sealed by the upper wall part. Each wall portion of the vacuum vessel 4 is disposed away from each wall portion of the heat shield 16. Each wall part of the vacuum vessel 4 is comprised by the plate-shaped member.

  A yoke 8 is provided around the vacuum vessel 4 (that is, around the coil 3) so as to cover the vacuum vessel 4. The yoke 8 includes an outer peripheral wall portion 26 that is radially opposed to the outer peripheral wall portion 21 of the vacuum vessel 4 on the outer peripheral side, and an inner surface that is radially opposite to the inner peripheral side of the inner peripheral wall portion 22 of the vacuum vessel 4. The peripheral wall part 27 and the lower wall part 28 which opposes the lower wall part 23 of the vacuum vessel 4 below are provided. For ease of assembly when assembling the cryostat 9 to the yoke 8, a gap is formed at least in the radial direction between the yoke 8 and the vacuum vessel 4 of the cryostat 9. A gap SP <b> 1 is formed between the inner peripheral surface 26 a of the outer peripheral wall portion 26 of the yoke 8 and the outer peripheral surface 21 a of the outer peripheral wall portion 21 of the vacuum vessel 4. A gap SP <b> 2 is formed between the outer peripheral surface 27 a of the inner peripheral wall portion 27 of the yoke 8 and the inner peripheral surface 22 a of the inner peripheral wall portion 22 of the vacuum vessel 4. These gaps SP1 and SP2 are ensured for assembly, and it is preferable to secure a minimum of about 3 mm from the viewpoint of ease of assembly. A stepped portion 31 that rises upward is formed at the inner peripheral end of the yoke 8. On the other hand, the lower wall portion 19 of the vacuum vessel 4 is formed with a fixing portion 25 extending to the inner peripheral side with respect to the inner peripheral wall portion 22. The lower surface of the fixing portion 25 is in contact with the upper surface of the step portion 31, and a sealing member 32 such as an O-ring is disposed at the portion to ensure airtightness.

  An elastic body 40 is provided in the radial gap SP1 between the vacuum vessel 4 and the yoke 8. The elastic body 40 is a member that can be positioned in the radial direction of the cryostat 9 by contacting the vacuum vessel 4 and supporting it while applying an elastic force. A plurality of elastic bodies 40 are provided along the axial direction. The elastic body 40 is provided on the end side of the vacuum vessel 4 in the axial direction of the central axis C. In the present embodiment, as shown in FIG. 1, two sets of elastic bodies 40 are provided in the axial direction, a set of elastic bodies 40 is provided on the upper end 4a side of the vacuum vessel 4, and the lower end 4b side. A pair of elastic bodies 40 is provided.

  The “end side of the vacuum vessel 4 in the axial direction” is a region at least on the end side of the central position of the vacuum vessel 4 in the axial direction. It is not limited. However, in order to improve the stability of the vacuum vessel 4, it is preferable to arrange the elastic body 40 as close to the end as possible. For example, the elastic body 40 is preferably disposed at least on the end side in the axial direction with respect to the flange portion 11. In the present embodiment, as shown in FIG. 2, the elastic body 40 is vacuumed more than the lower end surface 3 d of the coil 3, the lower flange portion 11 of the holding member 10, and the lower wall portion 19 of the heat shield 16. The container 4 is disposed on the lower end 4 b side.

  The yoke 8 has a groove portion 50 extending in the circumferential direction, and the elastic body 40 is fitted in the groove portion 50. Specifically, the groove part 50 is formed in the inner peripheral surface 26a of the outer peripheral wall part 26 of the yoke 8 along the circumferential direction at a position where the elastic body 40 is provided. In the example of FIG. 2, the shape of the groove portion 50 is rectangular when viewed from the circumferential direction, but the shape is not particularly limited, and may be triangular or arcuate. The depth (the size in the radial direction) of the groove 50 is such that when the elastic body 40 is fitted into the groove 50 and the vacuum container 4 is assembled to the yoke 8, the elastic body 40 abuts on the outer peripheral surface 21 a of the vacuum container 4. The size is set such that an elastic force can be applied. Further, the width (size in the axial direction) of the groove portion 50 is such that the elastic body 40 fitted in the groove portion 50 does not fall out and the elastic body 40 supports the vacuum vessel 4 and the position of the elastic body 40 is shifted. The size is set such that the elastic body 40 can be supported in the axial direction so that no sticking occurs.

  Moreover, as shown to Fig.3 (a), the elastic body 40 may be formed over the perimeter in the circumferential direction. In FIG. 3, the colored part corresponds to the elastic body 40. As described above, when the elastic body 40 is provided over the entire circumference, an elastic force can be applied to the vacuum container 4 over the entire circumference, so that the vacuum container 4 can be reliably supported, and the vacuum can be accurately obtained. The container 4 can be aligned. Or as shown in FIG.3 (b), the elastic body 40 is divided | segmented into plurality in the circumferential direction, and may be formed in a part of circumferential direction. In the example shown in FIG. 3B, the elastic bodies 40 divided into three are arranged at equal pitch intervals in the circumferential direction. However, the division | segmentation number of the elastic body 40 should just be two or more, and the magnitude | size of a pitch is not specifically limited. In both cases where the elastic body 40 is provided over the entire circumference and when the elastic body 40 is divided in the circumferential direction, a load is not locally applied in the circumferential direction as in the conventional position adjustment mechanism using a bolt. The elastic body 40 can apply an elastic force to the vacuum container 4 with respect to a predetermined range in the circumferential direction.

  The elastic body 40 may have any configuration as long as it can apply a radial elastic force to the vacuum vessel 4. For example, as shown in FIG. 4, a spring 60 may be used as the elastic body 40. An elastic body 40 is configured by connecting one end and the other end of the long spring 60 to form an annular shape and disposing it between the vacuum vessel 4 and the yoke 8. When the elastic body 40 is partially arranged as shown in FIG. 3B, the long spring 60 is arranged so as to draw an arc along the groove portion 50 of the yoke 8. Accordingly, the spring 60 is arranged so as to draw a spiral around an axis extending in the radial direction of the vacuum vessel 4 (coil 3). When the vacuum vessel 4 is assembled to the yoke 8, one side of the spring 60 is in contact with the outer peripheral surface 21 a of the vacuum vessel 4, and the other side is in contact with the bottom surface 50 a of the groove 50 of the yoke 8. A radial elastic force is applied to the container 4. FIG. 4 schematically shows the state of the spring 60 viewed from the axial direction in order to facilitate understanding of the structure, and the relationship between the curvature of the vacuum vessel 4 and the pitch of the spring 60 is schematic. It is.

  Further, a contact band 70 as shown in FIG. 5 may be used as the elastic body 40. 5A is a view of the contact band 70 viewed from the radial direction, FIG. 5B is a view of the contact band 70 viewed from the axial direction, and FIG. 5C is a view of the contact band 70 viewed from the circumferential direction. FIG. FIG. 5 schematically shows the contact band 70 for easy understanding of the structure, and the relationship between the curvature of the vacuum vessel 4 and each dimension of the contact band 70 is schematically shown. As shown in FIG. 5, the contact band 70 includes a plurality of elastic portions 71 formed at a predetermined pitch in the circumferential direction, and a base portion 72 extending in a band shape along the circumferential direction. Although the aspect of the elastic part 71 is not particularly limited, in the example shown in FIG. 5, the elastic part 71 is formed by a member that protrudes from the base part 72 so as to be curved toward the inner peripheral side. The contact band 70 is fitted into the groove portion 50 so that the base portion 72 is supported by the bottom surface 50 a of the groove portion 50 of the yoke 8. Thereby, when the vacuum vessel 4 is assembled to the yoke 8, the elastic portion 71 is brought into contact with the outer peripheral surface 21 a of the vacuum vessel 4, thereby applying a radial elastic force to the vacuum vessel 4. The configuration of the contact band 70 is not limited to that shown in FIG. 5, and any configuration may be employed as long as it has an elastic portion 71 that can apply an elastic force in the radial direction. . For example, you may employ | adopt the contact band 70 of the type which the elastic part 71 is a hollow hemisphere.

  When the spring 60 and the contact band 70 are employed as the elastic body 40, it is preferable to use a non-magnetic material having no conductivity so as not to interfere electrically and magnetically with each component of the cyclotron 1. For example, stainless steel may be used as the material of the spring 60 and the contact band 70. In the case of using the elastic body 40 obtained by processing a material having high rigidity such as the spring 60 or the contact band 70 into a shape capable of generating an elastic force, there is an advantage that the displacement of the cryostat 9 after installation is less likely to occur.

  Further, as the elastic body 40, as shown in FIG. 6, an O-ring made of an elastic material such as rubber or silicon (or a string body in the case of the structure shown in FIG. 3B) 80 may be used. Good. As shown in FIG. 6 (a), the O-ring 80 may have a circular cross section viewed from the circumferential direction, and the cross section viewed from the circumferential direction is X-shaped as shown in FIG. 6 (b). Any other shape may be employed as long as an elastic force can be applied.

  Next, the operation and effect of the cyclotron 1 according to the present embodiment will be described.

  In the cyclotron, it is necessary to adjust the position of the vacuum vessel that accommodates the coil. At this time, the gap in the radial direction is minimized as much as possible while ensuring the gaps for assembly (for example, the gaps SP1 and SP2 shown in FIG. 2). It is required to suppress. Conventionally, as such a position adjustment method, there has been a case where a method of directly or indirectly abutting a bolt on the outer surface of a vacuum vessel has been adopted. That is, a method of adjusting the position of the vacuum vessel in the radial direction by arranging bolts at a plurality of locations in the circumferential direction with respect to the vacuum vessel and adjusting the tightening of the bolts at each location has been adopted. However, when adjusting the position of the vacuum vessel using bolts, it is necessary to repeatedly adjust the tightening of the bolts at each location while observing the overall balance. Further, in this method, a local load acts on the vacuum vessel at the position where the bolt is in contact. The vacuum vessel may be deformed by such a local load, and the performance of the cyclotron may be affected. In particular, when the position of the vacuum vessel is adjusted with a bolt using a superconducting coil as the coil of the cyclotron, when a load is applied to the vacuum vessel and the coil is deformed, the members in the vacuum vessel come into contact with each other. , Heat is more easily transferred. This causes a problem that the superconductivity of the coil is destroyed. In addition to the method using a bolt, a method of providing a guide structure or the like on the inner peripheral side of the vacuum vessel to enable position adjustment is also conceivable. However, not only the inside of the vacuum vessel but also the inner peripheral region of the yoke ( For example, since the region E) shown in FIG. 2 is also required to be in a vacuum state, there is a problem that a guide structure or the like cannot be provided, or even if it is provided, a structure for securing a vacuum is complicated. There's a problem.

  On the other hand, the cyclotron 1 according to the present embodiment has an elastic body 40 provided in a gap SP1 in the radial direction between the vacuum vessel 4 and the yoke 8. Thus, the vacuum container 4 can be supported by the elastic body 40 in the radial direction. Therefore, since the position can be adjusted by the elastic force of the elastic body 40 simply by assembling the vacuum vessel 4 to the yoke 8, the vacuum vessel 4 can be easily aligned. Further, it is possible to prevent a side slip of the vacuum vessel 4 (cryostat 9) and to secure clearances SP1 and SP2 for assembly between the yoke 8 and the vacuum vessel 4. In addition, unlike the case of adjusting the position using bolts, the use of the elastic body 40 can suppress the local application of a load to the vacuum vessel 4 and can suppress the deformation of the vacuum vessel 4 and the like. . This can prevent the superconductivity of the coil 3 from being broken. As described above, the position of the vacuum vessel 4 that houses the coil 3 can be easily adjusted, and the performance of the cyclotron 1 can be improved.

  In the cyclotron 1 according to the present embodiment, the yoke 8 has a groove portion 50 extending in the circumferential direction of the coil 3, and the elastic body 40 is fitted in the groove portion 50. Thereby, the elastic body 40 is supported by the groove part 50 in the axial direction of the coil 3. Therefore, it is possible to prevent the elastic body 40 from shifting in the axial direction.

  In the cyclotron 1 according to the present embodiment, a plurality of elastic bodies 40 are provided along the axial direction of the coil 3. Thereby, the vacuum vessel 4 is supported by the elastic body 40 at a plurality of positions in the axial direction. Therefore, the vacuum vessel 4 can be reliably supported by the elastic body 40.

  In the cyclotron 1 according to the present embodiment, the elastic body 40 is provided on the end side of the vacuum vessel 4 in the axial direction. Thereby, the elastic body 40 can support the vacuum vessel 4 stably.

  The present invention is not limited to the embodiment described above.

  For example, in the above-described embodiment, the number of the elastic bodies 40 arranged in the axial direction is two, but may be one, or may be three or more. In addition, when the elastic body 40 is divided | segmented into the circumferential direction as shown in FIG.3 (b), the position in the circumferential direction of the elastic body 40 in one location of an axial direction is an elastic body in the other location of an axial direction. It does not have to coincide with the position in the circumferential direction of 40, and may be shifted from each other when viewed from the axial direction. In the above-described embodiment, the elastic body 40 is provided on the outer peripheral side of the vacuum container 4 (the gap SP1 between the outer peripheral surface 21a of the vacuum container 4 and the outer peripheral wall portion 26 of the yoke 8). 4 may be provided on the inner peripheral side (gap SP2 between the inner peripheral surface 22a of the vacuum vessel 4 and the inner peripheral wall portion 27 of the yoke 8), and provided on both the inner peripheral side and the outer peripheral side of the vacuum vessel 4. May be.

  Moreover, although it is good also as a position adjustment mechanism using only the above elastic bodies 40, in addition to that, you may provide the position adjustment mechanism by the conventional volt | bolt. At this time, the vacuum container 4 is generally aligned by the elastic body 40, and the bolt may be adjusted as a fine adjustment, so the local load on the vacuum container 4 is reduced.

  The structure according to the present invention is not limited to the above-described type of cyclotron, but can be applied to any type of cyclotron having a coil, a vacuum vessel, and a yoke. For example, the present invention is not limited to the type of cyclotron using a superconducting coil as described above, and may be applied to a type of cyclotron using a normal conducting coil.

  DESCRIPTION OF SYMBOLS 1 ... Cyclotron, 2, 3 ... Coil, 4 ... Vacuum container, 8 ... Yoke, 40 ... Elastic body, 50 ... Groove part, 60 ... Spring (elastic body), 70 ... Contact band (elastic body), 80 ... O-ring ( Elastic body).

Claims (6)

An annular coil;
A vacuum vessel containing the coil;
A yoke facing the vacuum vessel at least in the radial direction of the coil;
A cyclotron comprising: an elastic body provided in a gap in the radial direction between the vacuum vessel and the yoke.   The cyclotron according to claim 1, wherein the elastic body is formed over the entire circumference in the circumferential direction of the coil. The yoke has a groove extending in the circumferential direction of the coil,
The cyclotron according to claim 1, wherein the elastic body is fitted in the groove.   The cyclotron according to claim 1, wherein a plurality of the elastic bodies are provided along an axial direction of the coil.   The cyclotron according to claim 4, wherein the elastic body is provided on an end side of the vacuum vessel in the axial direction.   The cyclotron according to any one of claims 1 to 5, wherein the coil is a superconducting coil.

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