JP4627551B2 - Foil stripper - Google Patents

Description

  The present invention relates to a foil stripper that moves a foil for taking out accelerated particles and switches a foil disposed on an orbit of accelerated particles.

The foil stripper provided in particle accelerators such as cyclotrons reverses the curvature of the orbit by converting the proton or deuteron beam from H ⁻ (D ⁻ ) to H ⁺ (D ⁺ ) by carbon foil. And pull it out of the system. When this carbon foil is consumed due to long-term use, it is forced to stop the accelerator, release the vacuum to the atmosphere, and replace it with a new carbon foil. This work has demerits such as reduced machine operating time and exposure to workers.

Thus, for example, Patent Document 1 discloses a method of automatically switching foils. In this method, a foil holder that can be loaded with four foils is provided. When a foil that has been used is damaged, the foil holder can be rotated from the outside to replace the foil.
Japanese Patent Laid-Open No. 10-256000

  On the other hand, in a particle accelerator, it is preferable if one foil stripper can handle more targets. Therefore, it is conceivable that a plurality of targets are provided in the circumferential direction on the outer periphery of the magnet, and one foil stripper is moved along the trajectory of the acceleration particles to induce the acceleration particles to each target.

  However, when a foil switching mechanism as in Patent Document 1 is further applied to the method of guiding the accelerated particles to a plurality of targets by moving the foil stripper, the driving system for moving the foil stripper and the foil are switched. For this reason, there is a problem in that a drive system is required separately and a space for installing these drive systems must be taken into consideration.

  An object of the present invention is to provide a foil stripper that solves the above-described problems and can realize the movement and switching of the foil with a single drive system.

  The foil stripper according to the present invention is a foil stripper that moves a foil for taking out accelerated particles and switches a foil disposed on the orbit of the accelerated particles, and rotates at least two foils around a rotation axis. In preparation, a rotating body configured to arrange one foil on the orbit of the accelerating particle, a moving means for moving the rotator along the orbit of the accelerating particle, and a rotation axis of the rotating body are provided. A plurality of protrusions and a lever provided on a moving track of the rotating body and capable of contacting a protrusion of the plurality of protrusions, the first contact surface being contactable with the one protrusion And the second abutment surface, the operation is restricted when the first abutment surface abuts on the one projection, and the second abutment surface abuts on the one projection, Solve the contact state between the second contact surface and one protrusion. And a, a lever movable to.

  According to this configuration, the rotating body including the foil is moved in the direction of the lever by the moving means, and further rotated in the direction of the lever from the state where one protrusion of the rotating body is in contact with the first contact surface of the lever. By moving the body, the reaction force from the lever is transmitted to the protrusion that is in contact with the first contact surface, and the rotating body is rotated to switch the foil. In addition, after the foil is switched, when the rotating body is moved in the direction opposite to the lever by the moving means, the other protrusions of the rotating body come into contact with the second contact surface of the lever. Therefore, the rotating body moves away from the lever without rotating in the original direction. Since the moving means is also a drive system for moving the foil stripper, the movement and switching of the foil can be realized by one drive system. Also, by combining the drive system into one, it leads to cost reduction and space saving.

  In the foil stripper according to the present invention, the lever is supported so as to be rotatable around the support point, and the rotation restricting member is configured so that the rotation in one direction around the support point does not rotate from the reference rotation position. And is elastically urged by the urging member so as to return to the reference rotation position when rotated in the other direction around the support point, and the lever is When contacting with one protrusion, the rotation in one direction is restricted at the reference rotation position, and when contacting with one protrusion at the second contact surface, the second It is preferable that it can be rotated in the other direction against the urging force of the urging member so as to eliminate the abutting state between the abutting surface and the one protrusion.

  With this configuration, after the foil is switched, when the rotating body moves in the direction opposite to the lever by the moving means and one protrusion of the rotating body comes into contact with the second contact surface of the lever, the lever moves from the protrusion. Since it rotates along the direction of the transmitted force, the contact state between the second contact surface and the one projection can be smoothly eliminated. Further, after the contact state between the second contact surface and the one protrusion is eliminated, the lever can be automatically returned to the reference rotation position by the biasing force of the biasing member.

  The foil stripper according to the present invention is a disc that is provided so as to be orthogonal to the rotation axis of the rotating body and is rotatable in conjunction with the rotating body, and includes at least one recess provided on the peripheral surface thereof. It is preferable to further include a disk and a roller that is elastically biased in the centripetal direction of the disk, is in contact with the circumferential surface of the disk, and can be fitted into the recess.

  With this configuration, when the foil is switched, the roller rotates along the circumferential surface of the disk and is fitted into the recess on the circumferential surface when the new foil rotates to a desired position. Thereby, after a foil is switched, it can suppress that a rotary body and foil rotate.

  With the foil stripper according to the present invention, the movement and switching of the foil can be realized by one drive system.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a front view illustrating a configuration of a main body 12 of a cyclotron 10 as a particle accelerator including a foil stripper according to the present embodiment. As shown in FIG. 1, the cyclotron 10 includes a pair of magnetic poles 16, a pair of coils (not shown), a vacuum box 20, a pair of acceleration electrodes 22, a foil stripper 46, and targets 48 a to 48 c. Yes.

  Each of the pair of magnetic poles 16 has a disk-like outer shape as shown in FIGS. On the opposing surfaces of these magnetic poles 16, valley regions 16a and mountain regions 16b are alternately and continuously provided. More specifically, the opposing surfaces of these magnetic poles 16 are divided into eight sector sectors in which four valley regions 16a and four mountain regions 16b appear alternately. With such a configuration, the convergence effect of the orbits of the accelerated particles is enhanced by using sector focusing.

  As shown in FIG. 1, the vacuum box 20 has a box body 21 and a box lid (not shown). An opening 21b having substantially the same diameter as the outer shape of the magnetic pole 16 is provided in the bottom wall portion 21a of the box body 21, and a surface including a valley region 16a and a mountain region 16b of one magnetic pole 16 from the opening 21b. Is protruded into the vacuum box 20. Further, the box body 21 is provided with an exhaust port (not shown) for vacuum exhaust, and a vacuum pump (not shown) is connected to the exhaust port. The box lid closes the upper opening of the box body 21 so that the vacuum box 20 can be evacuated by a vacuum pump. Similarly to the box body 21, the box lid is provided with an opening having substantially the same diameter as the outer shape of the magnetic pole 16 so that the surface including the valley region 16 a and the mountain region 16 b of the other magnetic pole 16 protrudes from the vacuum box 20. It has been.

  A pair of coils (not shown) are provided around the side surfaces of the pair of magnetic poles 16 to constitute an electromagnet.

  As shown in FIG. 1, each of the pair of acceleration electrodes 22 has a triangular shape in front view. Each acceleration electrode 22 is made of an electrical conductor such as copper, and is formed by connecting two upper and lower triangular plates at the bottom. A tube 32 for passing a cooling refrigerant is provided on the plate surface of the acceleration electrode 22.

  The pair of acceleration electrodes 22 is located in the valley region 16 a of the pair of magnetic poles 16. And as shown in FIG. 1, the front-end | tip parts of the acceleration electrode 22 are mechanically and electrically connected by the connection member 34 which has an external shape like a butterfly wing.

  A foil stripper 46 for taking out accelerated particles is provided on one side of the acceleration electrode 22. The foil stripper 46 is provided with four cassette roll exchangeable foils 47 (see FIG. 3), one of which is arranged on the orbit of the accelerated particles. The foil is moved by the foil stripper 46 so as to be positioned at the first predetermined position 101a, the second predetermined position 101b, the third predetermined position 101c, and the fourth predetermined position 101d on the orbit of the accelerated particles. The

  When the foil stripper 46 moves the foil 47 to the fourth predetermined position 101d, the foil stripper 46 can switch the foil on the trajectory of the accelerated particles to another one. Details thereof will be described later with reference to FIGS. 5 and 7 to 10.

  On the orbit of the accelerated particles after passing through the foil 47 when the foil 47 of the foil stripper 46 is positioned at the first predetermined position 101a, the second predetermined position 101b, and the third predetermined position 101c, A first target 48a, a second target 48b, and a third target 48c for generation are provided. Each target is provided with collimators 49a, 49b, and 49c for limiting the beam width of the accelerated particles introduced into the target at the inlet for introducing the accelerated particles.

  Next, the details of the foil stripper 46 will be described with reference to FIGS. FIG. 3 is a diagram showing a detailed configuration of the foil stripper 46. 4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 5 is a diagram showing components related to foil switching. 6 is a cross-sectional view taken along the line VI-VI in FIG.

  As shown in FIG. 3, the foil stripper 46 includes a guide 51, a moving body 52, a drive mechanism 56, a foil changer 63, and a control device (not shown).

  The guide 51 is a plate member that is disposed on the outer peripheral side of the pair of magnetic poles 16 and has side surfaces 51a and 51b on the outer side and the inner side along the arc shape. The arc formed by the guide 51 is designed to have the same center point as the arc passing through the three points 101a, 101b, and 101c on the beam trajectory of the accelerated particles near the guide 51. The center of curvature of the arc formed by the guide 51 is a point P different from the center O of the magnetic pole 16, and the radius of curvature is smaller than the radius of the magnetic pole 16.

  A movable body 52 is engaged with the guide 51 so as to be movable along the guide 51. The moving body 52 includes a foil cassette unit 50 having four foils 47. The foil cassette unit 50 is provided in the moving body 52 so that one of the four foils 47 is positioned on the inner side of the arc formed by the guide 51 and arranged on the orbit of the accelerated particles. The single foil is used to pass the acceleration particles to bend the trajectory in the centrifugal direction of the magnetic pole 16, and the remaining three foils are provided in the foil cassette unit 50 as spare foils for replacement.

  As shown in FIGS. 4 and 5, the foil cassette unit 50 includes a cassette roll (rotating body) 71 that stores four foils 47. The cassette roll 71 is installed so as to be rotatable around a rotation axis 72 parallel to the opposing direction of the pair of magnetic poles 16, and the first holder 73a, the second holder 73b, A third holder 73c and a fourth holder 73d are provided. One foil 47 is attached to each of the first to fourth holders 73a to 73d. 4 to 6, the foil 47 attached to the third holder 73c among the first to fourth holders 73a to 73d is arranged on the orbit of the accelerated particles.

  As shown in FIGS. 5 and 6, on the surface of the cassette roll 71 on the guide 51 side, the first index spin 74a, the second index spin 74b, and the third index are spaced about 90 degrees around the rotation axis 72. A pin 74c and a fourth index pin 74d are provided. Each of the first to fourth index pins (projections) 74a to 74d is provided below the cassette roll 71 in the vicinity where the first to fourth holders 73a to 73d are disposed.

  An index wheel (disc) 75 centering on the rotation shaft 72 is connected to the surface of the cassette roll 71 opposite to the guide 51. The index wheel 75 is provided so as to be orthogonal to the rotation shaft 72 and rotates in conjunction with the cassette roll 71. On the peripheral surface of the index wheel 75, a first recess 76a, a second recess 76b, a third recess 76c, and a fourth recess 76d are provided around the rotation shaft 72 at intervals of approximately 90 degrees.

  Further, a suppression roller (roller) 77 is in contact with the peripheral surface of the index wheel 75. As shown in FIG. 4, the suppression roller 77 is connected to the coil spring 78 and is elastically biased in the centripetal direction of the index wheel 75. In addition, the suppression roller 77 is regulated in the circumferential direction of the index wheel 75 by a jig (not shown) or the like. Therefore, when the index wheel 75 rotates, the suppression roller 77 can rotate along the circumferential surface with its position fixed.

  Further, the suppression roller 77 can be fitted to any one of the first to fourth recesses 76 a to 76 d provided on the peripheral surface of the index wheel 75. In this case, the foil 47 of any one of the first to fourth holders 73a to 73d is positioned on the trajectory of the accelerated particles. In the example of FIG. 5, when the suppression roller 77 is engaged with the first recess 76a, the foil of the third holder 73c is positioned on the track of the acceleration particles.

  As shown in FIGS. 3 and 4, the moving body 52 has two pairs of flanged rollers 53 a, 53 b, 54 a, and 54 b on the back surface of the surface on which the foil cassette unit 50 is mounted. It is provided so as to be freely rotatable with a rotation shaft orthogonal to it. Among these, the rollers 53a and 54a are arranged to engage with the outer side surface 51a of the guide, and the rollers 53b and 54b are arranged to engage with the inner side surface 51b of the guide. That is, as shown in FIG. 4, the moving body 52 is engaged with the guide from the outer side surface 51a and the inner side surface 51b of the guide 51 by a pair of flanged rollers 53a and 53b. The movable body 52 is engaged with the guide from the outer side surface 51a and the inner side surface 51b of the guide 51 by the pair of flanged rollers 54a and 54b. As a result, the moving body 52 can move along the guide 51.

  The moving body 52 has an outer peripheral surface along the arc-shaped track of the guide 51, and a sector gear 55 is provided on the outer peripheral surface.

  A driving mechanism 56 that applies a driving force for moving the moving body 52 is connected to the moving body 52 via the sector gear 55 of the moving body 52. As shown in FIG. 4, the drive mechanism 56 includes a stepping motor 57 and a gear mechanism that decelerates rotation and converts it into rotation in an orthogonal direction. The gear mechanism is engaged with a first shaft 58 which is a rotation shaft of the stepping motor 57, a first bevel gear 59 attached to the first shaft 58, and a first bevel gear 59. An orthogonal second bevel gear 60, a second shaft 61 that is the rotation center of the second bevel gear 60, and a pinion gear 62 attached to the second shaft 61 are provided. As shown in FIG. 3, the pinion gear 62 is meshed with the sector gear 55 of the moving body 52.

  The foil stripper 46 has a control device (not shown), and feedback control of the position of the foil 47 is performed by this control device. Specifically, the current value is detected by a pair of collimators 49a to 49c provided at the inlets of the targets 48a to 48c. Since these current values take a larger value as the area hit by the beam increases, the relative deviation between the center of the beam diameter and the center of the target entrance can be detected by comparing these current values. That is, when one of the current values is large, it indicates that the beam is biased in the direction of the detection point of the current value. It then shows that the beam has been correctly introduced to the desired target.

  A control device (not shown) of the foil stripper 46 controls a control command to the stepping motor 57 according to a difference between current values measured by a pair of collimators provided at an entrance of a target to which a beam is to be introduced among the targets 48a to 48c. Feedback control. As a result, the position of the foil 47 on the beam trajectory is adjusted so that the center of the beam diameter coincides with the center of the target entrance.

  The foil stripper 46 is provided with a foil changer 63. The foil stripper 46 can be replaced with a new foil by using the foil changer 63 when the foil 47 arranged on the orbit of the accelerated particles is worn out due to long-term use or the like and deteriorates or breaks. . The foil changer 63 contacts the foil cassette unit 50 when the foil 47 is moved from the third predetermined position 101c to the fourth predetermined position 101d. Configured to replace.

  As shown in FIGS. 5 and 6, the foil changer 63 includes a pedestal 81 fixed to the guide 51. The pedestal 81 is provided with a support shaft 82 in a direction parallel to the rotation shaft 72 of the cassette roll 71 of the foil cassette unit 50, and a lever supported to be rotatable about the support shaft (support point) 82. 83 is connected.

  As shown in FIG. 6, the lever 83 includes a base 84 that is rotatably attached to the base 81 via a support shaft 82, and one of index pins 74 a to 74 d of the cassette roll 71 of the foil cassette unit 50. And a connecting portion 85 that connects the base portion 84 and the operating portion 86.

  As shown in FIG. 5, the operating portion 86 of the lever 83 has a first contact surface 87 facing the cassette roll 71 and an acute angle on the opposite side of the cassette roll 71 with respect to the first contact surface 87. The second abutment surface 88 that is opposed to the first abutment surface 88 can abut against one of the index pins 74a to 74d.

  When the lever 83 is rotated around the support shaft 82, a reaction force is applied by a torsion coil spring (biasing member) 89 provided around the support shaft 82, and the lever 83 rotates in the direction opposite to the rotation direction. To return to a predetermined position. Here, the predetermined position (reference rotation position) of the lever 83 is, for example, a position where both the first contact surface 87 and the second contact surface 88 are arranged on the moving track of the cassette roll 71. That is.

  When the lever 83 is in a predetermined position, a stopper (rotation restricting member) 90 provided on the pedestal 81 is in contact with the side portion of the base portion 84. The stopper 90 restricts the lever from rotating from a predetermined position in one direction around the support shaft 82. That is, in this embodiment, as shown in FIG. 5, when a force is applied to the first contact surface 87, the stopper 90 causes the lever 83 to rotate clockwise from a predetermined position around the support shaft 82. Is restricted from rotating.

  On the other hand, when a force is applied to the second contact surface 88, the lever 83 is elastically biased to return to the reference position by the torsion coil spring 89, and from a predetermined position around the support shaft 82. It rotates counterclockwise. When no force is applied to the second contact surface 88, the second contact surface 88 is returned to a predetermined position by the reaction force of the coil spring 89.

  Next, the operation of the cyclotron 10 and the foil stripper 46 configured as described above will be described.

  Accelerated particles such as protons or deuterons are extracted from the beam extraction portion O provided at the center of the magnetic pole 16 to a space where a uniform magnetic field is applied by the magnetic pole 16 and multiplexed by the electric field generated by the RF cavity. Accelerated. Accelerating particles have an orbital radius that increases with acceleration.

  In the foil stripper 46, the stepping motor 57 of the drive mechanism 56 is driven, and the pinion gear 62 rotates through the gear mechanism in the drive mechanism 56. The sector gear 55 of the moving body 52 meshed with the pinion gear 62 is interlocked, and the moving body 52 moves along the guide 51. The foil 47 of the foil cassette unit 50 mounted on the moving body 52 is positioned at the first predetermined position 101a, the second predetermined position 101b, or the third predetermined position 101c.

  Next, the foil switching operation by the foil stripper 46 will be described with reference to FIGS. 5 and 7 to 10.

  FIG. 5 shows the positional relationship between the cassette roll 71 and the foil changer 63 when the foil cassette unit 50 is at the third predetermined position 101c. As shown in FIG. 5, when the foil cassette unit 50 is at the third predetermined position 101 c, the lever 83 of the foil changer 63 is not in contact with any of the index pins 74 a to 74 d of the cassette roll 71.

  When the foil cassette unit 50 mounted on the moving body 52 is driven toward the fourth predetermined position 101d by the drive mechanism 56, the lever 83 of the foil changer 63 is moved to the first contact position as shown in FIG. The contact surface 87 contacts the first index pin 74a. At this time, since the foil cassette unit 50 is moved in the direction approaching the foil changer 63 by the drive mechanism 56, a force is applied to the first contact surface 87 from the first index pin 74a. Further, since the lever 83 is restricted from rotating by the stopper 90, a reaction force is applied from the first contact surface 87 to the first index pin 74a. Then, the suppression roller 77 is removed from the first recess 76a, and the cassette roll 71 begins to rotate clockwise. At this time, the suppression roller 77 rotates along the circumferential surface of the index wheel 75.

  When the foil cassette unit 50 reaches the fourth predetermined position 101d, as shown in FIG. 8, the cassette roll 71 is rotated approximately 90 degrees to complete the foil switching, and the fourth holder 73d is placed on the trajectory of the accelerated particles. Be placed. At this time, the suppression roller 77 is fitted in the second recess 76b.

  Subsequently, when the drive mechanism 56 is driven again toward the third predetermined position 101c to separate the foil cassette unit 50 from the foil changer 63, the lever 83 of the foil changer 63 is moved to the first position 101c as shown in FIG. The second contact surface 88 contacts the second index pin 74b. At this time, since the foil stripper 46 is moved in the direction away from the foil changer 63 by the driving mechanism 56, a force is applied to the second contact surface 88 from the second index pin 74b. As a result, the lever 83 receives a reaction force from the torsion coil spring 89 and counterclockwise around the support shaft 82 in order to eliminate the contact state between the second contact surface 88 and the second index pin 74b. It is turned around. While the lever 83 is rotated counterclockwise, the second index pin 74b moves on the second contact surface 88 to the end. At this time, the cassette roll 71 is not rotating, and the suppression roller 77 remains fitted in the second recess 76b.

  When the second index pin 74b exceeds the end of the second contact surface 88 and the second contact surface 88 moves away from the second index pin 74b, the index pin 74b is placed on the second contact surface 88. As shown in FIG. 10, the lever 83 is returned to the predetermined position even when the lever 83 is rotated clockwise around the support shaft 82 by the reaction force of the torsion coil spring 89.

  As described above, the foil stripper 46 according to the present embodiment moves the cassette roll 71 including the foil 47 in the direction of the lever 83 of the foil changer 63 by the driving mechanism 56, and the index pins 74 a to 74 d of the cassette roll 71. The index roll is in contact with the first contact surface 87 by moving the cassette roll 71 further in the direction of the lever 83 from the state in which one of them is in contact with the first contact surface 87 of the lever 83. The reaction force from the lever 83 is transmitted to the cassette roll 71 and the foil 47 is switched. Since the drive mechanism 56 is also a drive system that moves the foil 47, the movement and switching of the foil 47 can be realized by a single drive system. Also, by combining the drive system into one, it leads to cost reduction and space saving.

  Further, after the foil is switched, when the cassette roll 71 is moved in the direction opposite to the lever 83 by the drive mechanism 56, another index pin of the cassette roll 71 comes into contact with the second contact surface 88 of the lever 83. In this case, since the lever 83 rotates along the direction of the force transmitted from the index pin, the contact state between the second contact surface 88 and the index pin can be smoothly eliminated. Further, after the contact state between the second contact surface 88 and the index pin is eliminated, the lever 83 can be automatically returned to a predetermined position by the biasing force of the torsion coil spring 89.

  Further, the foil stripper 46 according to the present embodiment is configured such that when the foil 47 is switched, the suppression roller 77 rotates along the circumferential surface of the index wheel 75 and the new foil rotates to a desired position. Is fitted into any of the recesses 76a to 76d on the peripheral surface. Thereby, after the foil 47 is switched, it can suppress that the cassette roll 71 and the foil 47 rotate.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the number of foils 47 provided in the foil stripper 46 is not limited to four, and may be any other number as long as it is a plurality. In the above-described embodiment, the plurality of foils 47 are arranged at equal intervals of about 90 degrees around the rotation shaft 72, but may be arranged around the rotation shaft 72 at arbitrary intervals.

  Further, the index pins 76a to 76d for rotating the cassette roll 71 may be in contact with the lever 83 of the foil changer 63, and may be a protruding member other than the pin. Further, in the above embodiment, the index pins 76 a to 76 d are arranged such that the number of the foils 47 provided in the foil stripper 46 or the same number is the same as the foil 47 around the rotation shaft 72 at an equal interval of about 90 degrees. The number may be different from the number of foils, or may be arranged around the rotation axis 72 at an arbitrary interval.

  Furthermore, the lever 83 of the foil changer 63 rotates around the support shaft 82 to avoid the index spin as in the above-described embodiment when the second contact surface 88 is pushed by the index spin. Instead, for example, using the component force in the centrifugal direction of the moving track of the cassette roll 71 out of the force received by the second contact surface 88, it moves horizontally along the rail linearly provided in the centrifugal direction. For example, the index spin may be avoided by other operations.

  The drive mechanism 56 of the foil stripper 46 may be a friction mechanism other than a gear mechanism, or may be a cylinder mechanism using a crank.

  Further, the number of targets for introducing accelerated particles from one foil stripper 46 may be other than three.

  Further, in the above embodiment, the acceleration particles are taken out from one place using one foil stripper 46. However, a plurality of foil strippers are arranged at equal intervals on the orbit of the acceleration particles, and accelerated from a plurality of places at the same time. You may comprise so that particle | grains may be taken out.

It is a front view which shows the structure of a cyclotron as a particle accelerator which concerns on this embodiment. It is a perspective view which shows the structure of a pair of magnetic pole. It is a figure which shows the detailed structure of a foil stripper. It is IV-IV sectional drawing of FIG. It is a figure which shows the component regarding foil switching, and is a figure which shows the positional relationship of a cassette roll and foil changer when a foil cassette unit exists in the 3rd predetermined position. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. It is a figure which shows the state which the foil changer is rotating the cassette roll. It is a figure which shows the positional relationship of a cassette roll and foil changer in case a foil cassette unit exists in the 4th predetermined position, and is immediately after foil switching. When a foil cassette unit leaves | separates from a foil changer, it is a figure which shows the state which the 2nd contact surface of the lever of a foil changer is contact | abutting with the index pin of a cassette roll. When a foil cassette unit leaves | separates from a foil changer, it is a figure which shows the state which the 2nd contact surface of the lever of the foil changer left | separated from the index roll of the cassette roll.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Cyclotron, 16 ... Magnetic pole, 22 ... Acceleration electrode, 46 ... Foil stripper, 47 ... Foil, 48a, 48b, 48c ... Target, 50 ... Foil cassette unit, 51 ... Guide, 51a ... Outer side, 51b ... Inner side, 52 ... moving body, 53a, 53b, 54a, 54b ... roller with collar, 55 ... sector gear, 56 ... driving mechanism (moving means), 63 ... foil changer, 71 ... cassette roll (rotating body), 72 ... rotating shaft, 74a to 74d ... index pin (projection), 75 ... index wheel (disc), 76a to 76d ... recess, 77 ... index roller (roller), 82 ... support shaft, 83 ... lever, 87 ... first contact Surface, 88 ... second contact surface, 89 ... torsion coil spring (biasing member), 90 ... stopper (rotation restricting member).

Claims (3)

A foil stripper that moves a foil for taking out accelerated particles and switches a foil disposed on the orbit of the accelerated particles,
A rotating body comprising at least two foils rotatably about an axis of rotation, the rotating body configured to place one foil on the trajectory of the accelerating particles;
Moving means for moving the rotating body along the orbit of the accelerated particles;
A plurality of protrusions provided around the rotation axis of the rotating body;
A lever provided on the moving track of the rotating body and capable of abutting against one projection of the plurality of projections, wherein the first abutment surface and the second abutment are capable of abutting against the one projection. When the first contact surface is in contact with the one protrusion, the operation is restricted, and when the second contact surface is in contact with the one protrusion, A lever that is movable so as to cancel the contact state between the second contact surface and the one protrusion;
Foil stripper with The lever is supported so as to be rotatable about a support point, and the rotation in one direction around the support point is restricted by a rotation restricting member so as not to rotate more than a reference rotation position, and the lever When it is rotated in the other direction around the support point, it is elastically urged by the urging member so as to return to the reference rotation position,
When the lever is in contact with the one protrusion on the first contact surface, the lever is positioned at the reference rotation position and is restricted from rotating in the one direction.
When the second abutment surface abuts on the one protrusion, the urging force of the urging member so as to cancel the abutment state between the second abutment surface and the one protrusion. The foil stripper of claim 1, wherein the foil stripper is pivotable in the other direction against. A disc provided so as to be orthogonal to the rotation axis of the rotating body and rotatable in conjunction with the rotating body, the disc including at least one recess provided on a peripheral surface thereof;
A roller that is elastically biased in the centripetal direction of the disk, is in contact with the circumferential surface of the disk, and can be fitted into the recess;
The foil stripper according to claim 1 or 2, further comprising:

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