JP2025041207A - Accelerating Cavity - Google Patents

Abstract

To provide an acceleration cavity capable of switching energy of charged particles without using a complex mechanism.SOLUTION: An acceleration cavity comprises: a body that is in an electrically conductive cylindrical shape and includes a plurality of division members obtained by division using a plane along the central axis so that division surfaces along the plane are provided in a state of facing each other with a gap; a plurality of cell parts that are disposed inside the body in a state of being arranged in the axial direction of the central axis of the body and are communicated with each other using a communication part through which charged particles can pass; and a switch member that is disposed in the gap of the body, is movable in the gap along the plane, and performs movement to switch the magnitude of an electric field for accelerating the charged particles.SELECTED DRAWING: Figure 2

Description

This disclosure relates to acceleration cavities.

When high frequency waves are input into an acceleration cavity, an acceleration electric field is generated inside the cavity, accelerating charged particles such as electrons. For example, an acceleration cavity of this type is known to have a configuration in which multiple cell sections are arranged in the axial direction of the central axis, and the cell sections are connected to each other by communication sections (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 1-107499

In the above-mentioned accelerating cavities, a configuration has been proposed that allows the energy of the charged particles to be switched by changing the magnitude of the accelerating electric field. In such accelerating cavities, a configuration that allows the energy of the charged particles to be switched without using a complex mechanism is required.

The present disclosure has been made in consideration of the above, and aims to provide an acceleration cavity that can switch the energy of charged particles without using a complex mechanism.

The acceleration cavity according to the present disclosure includes a cylindrical, electrically conductive housing in which a divided member is divided into a plurality of parts on a plane along a central axis, with the divided surfaces along the plane facing each other with a gap therebetween, a plurality of cell sections arranged inside the housing in a line along the central axis of the housing and connected to each other by communication sections that allow charged particles to pass through, and a switch member arranged in the gap in the housing and movable through the gap along the plane, the movement of which switches the magnitude of the electric field that accelerates the charged particles.

The present disclosure provides an acceleration cavity that can switch the energy of charged particles without using a complex mechanism.

FIG. 1 is a plan view illustrating an example of an acceleration cavity according to an embodiment. FIG. 2 is a diagram showing the configuration along the cross section AA in FIG. FIG. 3 is a diagram showing the configuration along the cross section BB in FIG. FIG. 4 is a diagram showing an example of a configuration for moving the switch member. FIG. 5 is a diagram showing an example of a configuration for moving the switch member. FIG. 6 is a diagram showing an example of a configuration for moving the switch member. FIG. 7 is a diagram showing an example of a configuration for moving the switch member. FIG. 8 is a diagram showing an example of a configuration for moving the switch member. FIG. 9 is a diagram showing an example of a configuration for moving the switch member. FIG. 10 is a diagram showing another example of an accelerating cavity. FIG. 11 is a diagram showing an example of a usage mode of the accelerating cavity. FIG. 12 is a diagram showing an example of a usage mode of the accelerating cavity.

Below, an embodiment of an acceleration cavity according to the present disclosure will be described with reference to the drawings. Note that the present invention is not limited to this embodiment. Furthermore, the components in the following embodiments include those that are replaceable and easy for a person skilled in the art, or those that are substantially identical.

Figure 1 is a plan view showing an example of an acceleration cavity 100 according to this embodiment. Figure 2 is a diagram showing the configuration along the A-A cross section in Figure 1. Note that in Figure 2, although it is not a cross section, the dividing surface 12 is shown with hatching. Figure 3 is a diagram showing the configuration along the B-B cross section in Figure 2.

The acceleration cavity 100 shown in Figures 1 to 3 generates an acceleration electric field inside by inputting high frequency waves from the high frequency input unit WI, and accelerates charged particles M such as electrons emitted from the radiation source BS. The acceleration cavity 100 and the radiation source BS are used to form an accelerator AC. The accelerator AC is used in various fields, such as academic fields such as high energy physics experiments and synchrotron radiation facilities, medical fields such as radiation therapy or inspection, and industrial fields such as non-destructive inspection. In the following description, when describing the axial direction of the central axis AX among the directions in the acceleration cavity 100, the radiation source BS side (the side where the charged particles M are incident) is referred to as the incident side or rear, and the side opposite the incident side (the side where the charged particles are emitted) is referred to as the exit side or front. In addition, when the acceleration cavity 100 is placed in a facility, the vertical direction is referred to as the up-down direction, and the direction perpendicular to the up-down direction when looking forward from the rear of the central axis AX is referred to as the left-right direction.

As shown in Figures 1 to 3, the acceleration cavity 100 according to this embodiment includes a housing 10, a cell section 20, a coupling cavity 30, a vacuum manifold 40, and a switch member 50.

The housing 10 has a cylindrical shape having electrical conductivity. The housing 10 is formed by joining a plurality of divided members 11. The divided members 11 have planar dividing surfaces 12 along the central axis AX. The divided members 11 are joined with the dividing surfaces 12 facing each other. The divided members 11 are provided with a gap 13 between the divided surfaces 12 facing each other. In this embodiment, an example is described in which the housing 10 is divided in the left-right direction of the central axis AX along a plane perpendicular to the horizontal plane and passing through the central axis AX. The number of divisions of the housing 10 is not limited to two, and may be three or more. The divided members 11 have a shape in which the parts facing each other are generally rounded. This suppresses localized application of voltage.

The cell units 20 are formed inside the housing 10. The cell units 20 are arranged side by side in the axial direction of the central axis AX of the housing 10. The cell units 20 are connected to each other by communication units 22 that allow charged particles to pass through. The communication units 22 are formed along the central axis AX. The cell units 20 accelerate the charged particles by high frequency waves.

The coupling cavity 30 connects adjacent cell parts 20. The coupling cavity 30 propagates high frequency waves between adjacent cell parts 20. The coupling cavity 30 is arranged in a location that does not contribute to the acceleration of charged particles. The coupling cavity 30 is arranged on the outside of the same direction perpendicular to the central axis AX with respect to the cell part 20. In this embodiment, all the coupling cavities 30 are arranged above the cell part 20 with respect to the central axis AX as a reference. The coupling cavity 30 has a first space part 31 connected to the cell part 20, a second space part 32 arranged at a position radially outwardly away from the central axis AX with respect to the first space part 31, and a connection part 33 that connects the first space part 31 and the second space part 32 in the radial direction. The first space part 31, the second space part 32, and the connection part 33 are cylindrical with the center being an axis extending along the vertical direction, for example. The first space 31, the second space 32, and the connection portion 33 may be in the shape of a rectangular prism, etc. The connection portion 33 has a smaller diameter centered in the vertical direction than the first space 31 and the second space 32.

The vacuum manifold 40 is a part that forms a negative pressure when evacuating the multiple cell parts 20. The vacuum manifold 40 is connected to a vacuum forming part 42 such as a vacuum pump via a pipe 43. In this embodiment, the vacuum manifold 40 is provided, for example, inside the housing 10. The vacuum manifold 40 is formed as one space and is arranged above each coupling cavity 30. The vacuum manifold 40 is connected to the multiple cell parts 20 via the gaps 13 between the dividing members 11. Each cell part 20 is connected to one vacuum manifold 40. In this embodiment, the vacuum manifold 40 is connected to the coupling cavity 30 via the communication part 45. Therefore, the vacuum manifold 40 is connected to the second space part 32 of each coupling cavity 30, and is connected to the multiple cell parts 20 from the second space part 32 via the coupling cavity 30. This configuration ensures a connection between the vacuum manifold 40 and the multiple cell parts 20.

As shown in FIG. 2, in the housing 10, the dividing surface 12 of each divided member 11 is formed with a unit cell portion 21 and a unit communication portion 23 which constitute a part of the cell portion 20 and the communication portion 22, a unit combined cavity 35 which constitutes a part of the combined cavity 30, and a unit manifold 41 which constitutes a part of the vacuum manifold 40.

The cell section 20 is formed by combining unit cell sections 21 provided in each divided member 11. The communication section 22 is formed by combining unit communication sections 24 provided in each divided member 11. The coupling cavity 30 is formed by combining unit coupling cavities 35 provided in each divided member 11. The vacuum manifold 40 is formed by combining unit manifolds 41 formed in each divided member 11.

The switch member 50 is disposed in the gap 13 of the housing 10. The switch member 50 is movable in the gap 13 along a plane passing through the central axis AX. In this embodiment, the switch member 50 is movable in the gap 13 along a plane passing through the central axis AX and perpendicular to the left-right direction. The switch member 50 switches the magnitude of the electric field that accelerates the charged particles as it moves. By switching the magnitude of the electric field with the switch member 50, the magnitude of the energy of the charged particles can be switched.

The switch member 50 is formed using a conductor such as metal. The switch member 50 is, for example, a plate-like member with a thickness thinner than the dimension of the gap 13. The switch member 50 is arranged so as to appear and disappear into the coupling cavity 30. When the switch member 50 is arranged in a state in which it is inserted inside the coupling cavity 30, it is possible to block the electromagnetic field of the coupling cavity 30. The switch member 50 is movable between a retracted position P1 in which it is retracted from the coupling cavity 30, and a blocking position P2 in which it is inserted inside the coupling cavity 30. In this embodiment, the blocking position P2 can be set to a position in which it is inserted into the connection portion 33 of the coupling cavity 30.

The switch member 50 is connected to a transmission mechanism 51. The transmission mechanism 51 is connected to the outside of the housing 10. The transmission mechanism 51 transmits a driving force generated outside the housing 10 to the switch member 50. The driving force to be transmitted to the switch member 50 may be generated, for example, manually by an operator, or may be generated by a driving source such as a motor.

Figures 4 to 9 are diagrams showing examples of configurations for moving the switch member 50. Figures 4, 6 and 8 are plan views. Figures 5, 7 and 9 are diagrams showing configurations along the A-A cross section of Figure 1.

4 and 5, the switch member 50 is rotated around a rotation axis BX perpendicular to the central axis AX. The rotation axis BX is set in the left-right direction. In this example, the transmission mechanism 51A is formed in a rod shape and extends from the switch member 50 along the rotation axis BX through the housing 10 to the outside of the housing 10. In this way, the transmission mechanism 51A extends in a direction perpendicular to the plane along the central axis AX. In addition, a bearing having a sealing mechanism may be provided at the portion where the transmission mechanism 51A penetrates the housing 10 so as to maintain a vacuum state inside the housing 10. In addition, the switch member 50 may be rotated from the outside of the housing 10 in a non-contact manner by a magnetic coupling or the like. A rotating unit 52A that rotates the transmission mechanism 51A is provided outside the housing 10. The rotating unit 52A is, for example, a motor device. In addition, the rotating unit 52A may be configured so that an operator manually rotates the transmission mechanism 51A.

By rotating the transmission mechanism 51A with the rotating part 52A, the switch member 50 rotates around the rotation axis BX. The switch member 50 rotates along a plane including the central axis AX between a retracted position P1A where it is retracted from the coupling cavity 30 and a blocking position P2B where it is inserted into the coupling cavity 30. The rotation range of the switch member 50 may be adjusted by providing an encoder or the like to adjust the amount of rotation by the rotating part 52A, or may be adjusted by a physical mechanism such as a stopper.

6 and 7, the switch member 50 is configured to slide along the central axis AX. In this example, the transmission mechanism 51B has a rotating member 53B, a rod-shaped member 54B, and a support member 55B. The rotating member 53B is formed in an L-shape extending from the base end in two directions (here, for example, the left-right direction and the front-back direction). The rotating member 53B rotates around a rotation axis CX that passes through the base end and runs in the up-down direction. The tip of the rotating member 53B that extends in the left-right direction is connected to the switch member 50. The tip of the rotating member 53B that extends in the front-back direction is connected to the rod-shaped member 54B. The rod-shaped member 54B extends outside the housing 10 along the left-right direction. In this way, the transmission mechanism 51B extends in a direction perpendicular to a plane along the central axis AX.

A drive unit 52B is provided on the outside of the housing 10 to move the rod-shaped member 54B in the left-right direction. The drive unit 52B is, for example, a bellows mechanism. The rod-shaped member 54B can be moved in the left-right direction by expanding and contracting the bellows. Note that, instead of the bellows mechanism, other drive mechanisms such as a ball screw mechanism or an air cylinder mechanism may be used as the drive unit 52B.

By stretching the bellows in the drive unit 52B, the rod-shaped member 54B moves to the right. When the rod-shaped member 54B moves to the right, the rotating member 53B rotates clockwise around the rotation axis CX when viewed from above. In this case, the tip of the part that extends left and right from the base end moves forward. As a result, the switch member 50 moves forward.

By contracting the bellows in the drive unit 52B, the rod-shaped member 54B moves to the left. When the rod-shaped member 54B moves to the left, the rotating member 53B rotates counterclockwise around the rotation axis CX when viewed from above. In this case, the tip of the part that extends left and right from the base end moves rearward. As a result, the switch member 50 moves rearward.

In this way, the switch member 50 can be slid forward and backward by the transmission mechanism 51B and the drive unit 52B. In the example shown in Figures 6 and 7, the position to which the switch member 50 has moved forward is the retracted position P1B, and the position to which the switch member 50 has moved rearward is the blocking position P2B. Note that the position to which the switch member 50 has moved forward may be the blocking position P2B, and the position to which the switch member 50 has moved rearward may be the retracted position P1B.

8 and 9, the switch member 50 is configured to slide along the central axis AX. In this example, the transmission mechanism 51C has a linear member 53C and a guide member 54C. One end (switch side end) of the linear member 53C is connected to the switch member 50. The linear member 53C may be a member that has rigidity in the longitudinal direction and is deformable in a direction perpendicular to the longitudinal direction, such as a wire. The linear member 53C is, for example, drawn forward from the switch member 50, curved to the left by the guide member 54C, and disposed with its tip extending outside the housing 10. The guide member 54C may be a tubular member such as a tube. The linear member 53C is provided in a state of being passed through the inside of the guide member 54C. In this way, the transmission mechanism 51C extends in a direction perpendicular to a plane along the central axis AX.

A drive unit 52C for moving the linear member 53C in the left-right direction is provided outside the housing 10. The drive unit 52C is connected to the other end (the drive side end) of the linear member 53C. The drive unit 52C is, for example, a bellows mechanism, similar to the drive unit 52B described above. The linear member 53C can be moved in the left-right direction by expanding and contracting the bellows. Note that instead of the bellows mechanism, other drive mechanisms such as a ball screw mechanism or an air cylinder mechanism may be used as the drive unit 52C.

By stretching the bellows in the drive section 52C, the drive side end of the linear member 53C is pulled to the right. The linear member 53C is curved by the guide member 54C so that the switch side end is arranged along the front-to-rear direction. Therefore, when the drive side end of the linear member 53C is pulled to the right, the switch side end moves forward. This causes the switch member 50 to move forward.

By compressing the bellows in the drive section 52C, the drive side end of the linear member 53C is pushed to the left. The linear member 53C is curved by the guide member 54C so that the switch side end is arranged along the front-to-rear direction. Therefore, when the drive side end of the linear member 53C is pushed to the left, the switch side end moves rearward. This causes the switch member 50 to move rearward.

In this way, the switch member 50 can be slid forward and backward by the transmission mechanism 51C and the drive unit 52C. In the example shown in Figures 8 and 9, similar to the example shown in Figures 6 and 7, the position to which the switch member 50 has moved forward is the retracted position P1C, and the position to which the switch member 50 has moved rearward is the blocking position P2C. Note that the position to which the switch member 50 has moved forward may be the blocking position P2C, and the position to which the switch member 50 has moved rearward may be the retracted position P1C.

Figure 10 is a diagram showing another example of an acceleration cavity 100. As shown in Figure 10, a movement gap 14 may be provided in at least a part of the movable range of the switch member 50 in the portion of the gap 13 where the switch member 50 is disposed. The movement gap 14 is a portion where the distance between the dividing surfaces 12 is greater than the gap 13. By providing the movement gap 14, it is possible to prevent the switch member 50 from interfering with the dividing surface 12 of the housing 10.

Figures 11 and 12 are diagrams showing an example of how the acceleration cavity 100 is used. As shown in Figure 11, when the switch member 50 is placed in the retracted position P1, the high frequency input from the high frequency input unit WI is propagated to all the cell units 20. Therefore, the charged particles M emitted from the radiation source BS and entering the inside of the acceleration cavity 100 are accelerated and emitted by all the cell units 20 that they pass through.

In contrast, as shown in FIG. 12, when the switch member 50 is placed in the cut-off position P2, the high frequency input from the high frequency input section WI is cut off at the cut-off position P2. In the acceleration cavity 100, the high frequency is not propagated to the cell section 20 beyond the cut-off position P2. Therefore, the charged particle M emitted from the radiation source BS and entering the inside of the acceleration cavity 100 is accelerated in the cell section 20 through which the high frequency is propagated among the cell sections 20 through which it passes, and is emitted without being accelerated from the cell section 20 through which the high frequency is not propagated. In this case, the energy of the charged particle M is smaller than when the switch member 50 is placed in the retract position P1. In this way, by switching the energy of the charged particle M, the acceleration cavity 100 can be widely used for examination devices, treatment devices, etc.

As described above, according to the first aspect of the present disclosure, an acceleration cavity is provided that includes a cylindrical conductive housing 10 in which a dividing member 11 is divided into a plurality of parts on a plane along the central axis AX, with the dividing surfaces 12 along the plane facing each other with a gap 13 therebetween, a plurality of cell sections 20 arranged inside the housing 10 in a lined-up state along the axial direction of the central axis AX of the housing 10 and connected to each other by communication sections 22 that allow charged particles to pass through, and a switch member 50 arranged in the gap 13 of the housing 10 and movable through the gap 13 along a plane passing through the central axis AX, and which switches the magnitude of the electric field that accelerates the charged particles as it moves.

With this configuration, in a configuration in which the divided surfaces 12 of the divided members 11, which are divided into multiple parts, face each other with a gap 13 between them, the housing 10 is provided, and by using the gap 13 to move the switch member 50, it is possible to easily switch the energy of the charged particles M without using a complex mechanism.

In the acceleration cavity according to the second aspect of the present disclosure, in the first aspect, a coupling cavity 30 is provided inside the housing 10 and connects adjacent cell units 20, and the switch member 50 is arranged to appear and disappear in the coupling cavity 30.

With this configuration, the switch member 50 is positioned so that it appears and disappears from the coupling cavity, allowing efficient switching between transmitting and blocking high frequency waves.

In the acceleration cavity according to the third aspect of the present disclosure, in the second aspect, all of the coupling cavities 30 are arranged on the same side of the cell section 20 in a direction perpendicular to the central axis AX.

With this configuration, by moving the coupling cavity 30 to the same side of the cell section 20 in the direction perpendicular to the central axis AX, the center of the electric field distribution in the direction perpendicular to the central axis AX can be aligned with the central axis AX. This makes it possible to suppress bias in the charged particle beam.

In the acceleration cavity according to the fourth aspect of the present disclosure, in the second aspect, the coupling cavity 30 has a first space portion 31 connected to the cell portion 20, a second space portion 32 arranged at a position radially outwardly spaced from the first space portion 31 with respect to the central axis AX, and a connection portion 33 that radially connects the first space portion 31 and the second space portion 32, and the switch member 50 is arranged so as to appear and disappear from the connection portion 33.

With this configuration, the switch member 50 is positioned so that it appears and disappears from the connection portion 33 of the coupling cavity 30, allowing efficient switching between transmitting and blocking high frequency waves.

In the acceleration cavity according to the fifth aspect of the present disclosure, in the first aspect, the coupling cavity 30 has the second space portion 32 connected to the vacuum manifold 40.

With this configuration, the vacuum manifold 40 is connected to the cell portion 20 via the coupling cavity 30, so that the vacuum manifold 40 can more reliably evacuate the cell portion 20 to a vacuum.

In the acceleration cavity according to the sixth aspect of the present disclosure, in any of the first to fifth aspects, the housing 10 has a movement gap 14 in at least a portion of the movable range of the switch member 50, in which the distance between the dividing surfaces 12 is greater than the gap 13.

With this configuration, the provision of the movement gap 14 can prevent the switch member 50 from interfering with the dividing surface 12 of the housing 10.

In the acceleration cavity according to the seventh aspect of the present disclosure, in any of the first to sixth aspects, a transmission mechanism 51 is further provided that transmits a driving force generated outside the housing 10 to the switch member 50.

With this configuration, the transmission mechanism 51 is provided, so that the switch member 50 can be moved from outside the housing 10.

In the acceleration cavity according to the eighth aspect of the present disclosure, in the seventh aspect, the transmission mechanism 51 extends in a direction perpendicular to the plane.

With this configuration, the transmission mechanism 51 extends in a direction perpendicular to the plane, so that the driving force can be appropriately transmitted whether the switch member 50 is rotated or slid.

In the acceleration cavity according to the ninth aspect of the present disclosure, in any of the first to seventh aspects, the transmission mechanism 51 transmits a driving force so that the switch member 50 rotates about a rotation axis BX that is aligned in a direction perpendicular to the central axis AX.

With this configuration, the transmission mechanism 51 can move the switch member 50 so that it rotates around the rotation axis BX that is aligned in a direction perpendicular to the central axis AX.

In the acceleration cavity according to the tenth aspect of the present disclosure, in any of the first to seventh aspects, the transmission mechanism 51 transmits the driving force so that the switch member 50 slides in a direction along the central axis AX.

With this configuration, the transmission mechanism 51 can move the switch member 50 so that it slides in a direction perpendicular to the central axis AX.

In the above embodiment, a configuration in which one switch member 50 is provided has been described as an example, but this configuration is not limited to this. A plurality of switch members 50 may be provided. In this case, the plurality of switch members 50 can be individually movable and can be provided so as to appear and disappear into different coupling cavities 30.

10 Housing 11 Dividing member 12 Dividing surface 13 Gap 14 Movement gap 20 Cell portion 21 Unit cell portion 22, 45 Communication portion 23, 24 Unit communication portion 30 Coupling cavity 31 First space portion 32 Second space portion 33 Connection portion 35 Unit coupling cavity 40 Vacuum manifold 41 Unit manifold 42 Vacuum forming portion 43 Pipe 50 Switch member 51, 51A, 51B, 51C Transmission mechanism 52A Rotating portion 52B, 52C Driving portion 53B Rotating member 53C Linear member 54B Rod-shaped member 54C Guide member 55B Support member 100 Acceleration cavity AC Accelerator AX Central axis BS Radiation source BX, CX Rotation axis M Charged particle P1, P1A, P1B, P1C Retraction position P2, P2A, P2B, P2C Shut-off position WI High Frequency Input Section

Claims (10)

a housing having a conductive cylindrical shape, the housing including a divided member divided into a plurality of parts along a plane along a central axis, the divided surfaces along the plane being opposed to each other with a gap therebetween;
a plurality of cell units arranged inside the housing in an axial direction of a central axis of the housing and connected to each other by communication units through which charged particles can pass;
a switch member that is disposed in the gap of the housing, movable in the gap along the plane, and switches the magnitude of an electric field that accelerates the charged particles as the switch member moves. a coupling cavity provided inside the housing and communicating with adjacent cells at a position offset from the central axis;
The accelerating cavity according to claim 1 , wherein the switch member is arranged to appear and disappear from the coupling cavity. The acceleration cavity according to claim 2 , wherein all of the coupling cavities are disposed on the same side of the cell portion in a direction perpendicular to the central axis. the coupling cavity has a first space portion connected to the cell portion, a second space portion disposed at a position radially outwardly spaced from the first space portion with respect to the central axis, and a connection portion connecting the first space portion and the second space portion in the radial direction,
The acceleration cavity according to claim 2 , wherein the switch member is disposed so as to appear and disappear from the connection portion. a vacuum manifold connected to the plurality of cells via the gap;
The acceleration cavity according to claim 4 , wherein the second space of the coupling cavity is connected to the vacuum manifold. The acceleration cavity according to claim 1 , wherein the housing has a movement gap in which the distance between the divided surfaces is larger than the gap, in at least a part of a movable range of the switch member. The acceleration cavity according to claim 1 , further comprising a transmission mechanism that transmits a driving force generated outside the housing to the switch member. The acceleration cavity according to claim 7 , wherein the transmission mechanism extends in a direction perpendicular to the plane. The acceleration cavity according to claim 7 , wherein the transmission mechanism transmits the driving force such that the switch member rotates about a rotation axis extending in a direction perpendicular to the central axis. The acceleration cavity according to claim 7 , wherein the transmission mechanism transmits the driving force so that the switch member slides in a direction along the central axis.

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