JP2008171605A - High frequency acceleration cavity apparatus, and its operating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency acceleration cavity apparatus and its operating method capable of suppressing vacuum leak from a high frequency acceleration cavity. <P>SOLUTION: The high frequency acceleration cavity apparatus is provided with an input coupler 4, and a vertical magnetic field generating coil 11. The input coupler 4 is provided with a main body 1 having a vacuum-maintained cavity formed therein, an inner conductor 6 extending from the cavity toward the outside of the main body 1, and an outer conductor 5 extending so as to surround the inner conductor 6 coaxially with the inner conductor 6 and having a ceramic window 7 surrounding a part of the inner conductor 6 with respect to the axial direction. The vertical magnetic field generating coil 11 generates a magnetic field in an axial direction of an inner conductor 6 of the inner conductor 6. The high frequency acceleration cavity apparatus may be provided with a horizontal magnetic field generating coil 10 for generating a magnetic field perpendicular to the axial direction of the inner conductor 6. Rod antennas 23 of high order mode attenuators 3 and noses 2 formed around circle holes 21 of the main body 1 through which charged particles pass are arranged so as not to directly view the ceramic window 7. The ceramic window 7 may be subjected to coating at both ends thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high-frequency accelerating cavity device and a method for operating the same.

Generally, a high-frequency accelerating cavity has a nose for obtaining high performance, and an input coupler for supplying high power and an attenuator for attenuating higher-order modes are attached (Patent Document 1 and Patent). Reference 2).
Japanese Patent Laid-Open No. 8-190997 Japanese Patent Laid-Open No. 7-6897

  In the high-frequency accelerating cavity, electrons are generated by field emission from the nose portion of the high-frequency accelerating cavity generating a high electric field or the tip of the rod antenna of the higher-order mode attenuator when a large electric power is applied. The electrons collide with the inside of the cavity on the acceleration electric field and generate bremsstrahlung X-rays. The generated X-rays enter the metal conductor and emit secondary electrons. The secondary electrons are adsorbed and charged on the ceramic by a high-frequency electric field in the vicinity of the ceramic window, and the charging of the ceramic proceeds. For this reason, dielectric breakdown may occur, resulting in a vacuum leak.

  Accordingly, an object of the present invention is to suppress vacuum leakage in a high-frequency acceleration cavity.

  In order to achieve the above-described object, the present invention provides a high-frequency accelerating cavity device comprising: a main body having a cavity capable of maintaining a vacuum therein; an inner conductor extending from the cavity toward the outside of the main body; An input coupler including an outer conductor provided with a ceramic window extending in a direction coaxial with the conductor and surrounding the inner conductor; and a magnetic field oriented along the axial direction of the inner conductor And a first coil for generating.

  Further, the present invention provides a high-frequency accelerating cavity device in which a main body in which a cavity capable of maintaining a vacuum is formed, an inner conductor extending from the cavity toward the outside of the main body, and the inner conductor coaxially with the inner conductor An input coupler having an outer conductor provided with a ceramic window that extends around the inner conductor and encloses a part in the axial direction, and generates a magnetic field in a direction perpendicular to the axial direction of the inner conductor And a second coil to be provided.

  The present invention also provides a main body in which a cavity capable of maintaining a vacuum is formed in an internal high frequency accelerating cavity device, an inner conductor extending from the cavity toward the outside of the main body, and the inner conductor coaxially with the inner conductor. An input coupler including an outer conductor provided with a ceramic window that extends so as to surround the conductor and surrounds a part of the axial direction of the conductor, and a high-order that includes a rod antenna having a tip disposed at a position where the ceramic window is not seen And a mode attenuator.

  The present invention also relates to a high-frequency accelerating cavity apparatus, in which a main body in which a cavity that can be maintained in a vacuum is formed and a nose is formed around a circular hole through which a charged particle passes, An inner conductor extending toward the inner conductor, and a ceramic window extending so as to surround the inner conductor in the same direction as the inner conductor, surrounding a part in the axial direction, and disposed at a position where it is not removed from the nose And an input coupler including an outer conductor.

  Further, the present invention relates to a high-frequency accelerating cavity device, in which a main body in which a cavity that can be maintained in a vacuum is formed, extends from the cavity toward the outside of the main body, and is partially in the axial direction than before and after the main body. An inner conductor having a bulge portion having a large outer diameter, and an outer conductor provided with a ceramic window extending in a direction coaxial with the inner conductor so as to surround the inner conductor and surrounding a part in the axial direction And an input coupler.

  Further, the present invention provides a high-frequency accelerating cavity device in which a main body in which a cavity capable of maintaining a vacuum is formed, an inner conductor extending from the cavity toward the outside of the main body, and the inner conductor coaxially with the inner conductor And an input coupler including an outer conductor that extends so as to surround the inner conductor and is provided with a ceramic window that is partially coated on the outer side and is coated on the outer side.

  The present invention also includes a main body in which a cavity capable of maintaining a vacuum is formed, an inner conductor extending from the cavity toward the outside of the main body, and surrounding the inner conductor in a direction coaxial with the inner conductor. An input coupler including an outer conductor provided with a ceramic window that extends and surrounds a portion of the axial direction of the high-frequency accelerating cavity device, wherein a magnetic field oriented along the axial direction of the inner conductor is applied. It is characterized by generating.

  The present invention also includes a main body in which a cavity capable of maintaining a vacuum is formed, an inner conductor extending from the cavity toward the outside of the main body, and surrounding the inner conductor in a direction coaxial with the inner conductor. An input coupler including an outer conductor provided with a ceramic window that extends and surrounds a portion of the axial direction of the high-frequency accelerating cavity device, and is perpendicular to the direction along the axial direction of the inner conductor. A magnetic field having a direction is generated.

  According to the present invention, it is possible to suppress vacuum leakage in the high-frequency acceleration cavity.

  An embodiment of a high frequency acceleration cavity according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a longitudinal sectional view of a high frequency acceleration cavity according to a first embodiment of the present invention. 2 is a longitudinal sectional view taken along the line II-II in FIG.

  The high-frequency accelerating cavity in this embodiment includes a main body 1, an input coupler 4, a higher-order mode attenuator 3, a vertical magnetic field generating coil (first coil) 11, and a horizontal magnetic field generating coil (second coil) 10. Have. The main body 1 of the high-frequency acceleration cavity is formed in a cylindrical shape. A circular hole 21 is formed at the center of both end faces of the cylinder. A nose 2 is formed inside the main body 1 around the circular hole 21.

  The circular hole 21 of the main body 1 is connected to, for example, the circular hole 21 of the main body 1 of another high-frequency acceleration cavity directly or via a duct, and the high-frequency acceleration cavity accelerates charged particles passing through the circular hole 21. . During operation of the high frequency acceleration cavity, the interior of the main body 1 is maintained in a vacuum.

  The input coupler 4 is attached to the cylindrical surface of the main body 1. The input coupler 4 has a cylindrical outer conductor 5 and an inner conductor 6 extending coaxially with the outer conductor 5 inside the outer conductor 5. The outer conductor 5 and the inner conductor 6 are joined at both ends in the axial direction, and a gap is formed between the outer conductor 5 and the inner conductor 6 except for both ends.

  In a part of the outer conductor 5 in the axial direction, a ceramic window 7 is formed on a cylindrical surface centered on the axis. A substantially rectangular tube-shaped metal waveguide 9 is attached to the ceramic window 7. An air surface coating 8 is applied to the outer surface of the ceramic window 7, that is, the surface facing the waveguide 9. A vacuum surface coating 12 is applied to the inner surface of the ceramic window 7, that is, the surface facing the inner conductor 6. The vacuum surface coating 12 is a TiN coating having a thickness of 20 nm or more.

  On both sides of the ceramic window 7 outside the outer conductor 5, a vertical magnetic field generating coil 11 is disposed. The vertical magnetic field generating coil 11 generates a magnetic field oriented along the axial direction of the outer conductor 5 and the inner conductor 6. Further, a horizontal magnetic field generating coil 10 is disposed between the ceramic window 7 outside the outer conductor 5 and the main body 1 of the high-frequency acceleration cavity. The horizontal magnetic field generating coil 10 generates a magnetic field in a direction perpendicular to the axial direction of the outer conductor 5 and the inner conductor 6.

  The vertical and horizontal designations of the vertical magnetic field generating coil 11 and the horizontal magnetic field generating coil 10 indicate the direction of the magnetic field when the input coupler 4 is attached to the upper part of the main body 1. Even when the mounting position of the input coupler 4 is changed, the vertical magnetic field generating coil 11 and the horizontal magnetic field generating coil 10 are respectively magnetic fields oriented along the axial direction of the outer conductor 5 and the inner conductor 6, and Any coil that generates a magnetic field in a direction perpendicular to the axial direction may be used.

  Between the position of the inner conductor 6 facing the ceramic window 7 and the end portion close to the main body 1 of the high-frequency acceleration cavity, a bulge portion 22 having an outer diameter larger than that in the axial direction is formed.

  A pair of high-order mode attenuators 3 are disposed on the cylindrical surface of the main body 1 of the high-frequency acceleration cavity with the input coupler 4 interposed therebetween. The high-order mode attenuator 3 has a rod antenna 23 protruding inside the main body 1. The high-order mode attenuator 3 is disposed at a position where the tip of the rod antenna 23 does not look through the ceramic window 7.

  Not looking through the ceramic window 7 means that another object exists between the straight line connecting the tip of the rod antenna 23 and the ceramic window 7. In the present embodiment, for example, the outer conductor 5, the inner conductor 6, or the bulge portion 22 exists between the tip of the rod antenna 23 and the ceramic window 7.

  The high frequency (microwave) transmitted from the waveguide 9 is input into the cavity through the ceramic window 7 of the input coupler 4. When a large electric power is input to the high-frequency accelerating cavity in this way, electrons may be generated by field emission from the nose 2 where a high electric field is generated or the tip of the rod antenna 23. The generated electrons may collide with the inside of the high-frequency acceleration cavity and generate bremsstrahlung X-rays. When the X-rays generated in this way enter the metal conductor, secondary electrons may be emitted.

  However, in the high-frequency accelerating cavity of the present embodiment, a magnetic field oriented along the axial direction of the outer conductor 5 and the inner conductor 6 is formed by the vertical magnetic field generating coil 11, and is directed from the inner conductor 6 to the ceramic window 7. The number of electrons can be suppressed. Thereby, charging to the ceramic window 7 is suppressed.

  Further, the horizontal magnetic field generating coil 10 forms a magnetic field in a direction perpendicular to the axial direction of the outer conductor 5 and the inner conductor 6, and the number of electrons from the main body 1 toward the ceramic window 7 can be suppressed. Thereby, charging to the ceramic window 7 is suppressed. Further, since the tip of the rod antenna 23 of the high-order mode attenuator 3 is disposed at a position not looking through the ceramic window 7, the metal near the ceramic window 7 for X-rays or electrons generated from the tip of the rod antenna 23. Collisions are suppressed. Thereby, charging to the ceramic window 7 is suppressed.

  Since the nose 2 of the main body 1 is also arranged at a position where the ceramic window 7 is not seen, the collision of X-rays and electrons generated from the nose 2 with the metal near the ceramic window 7 is suppressed. Thereby, charging to the ceramic window 7 is suppressed. Since the bulging portion 22 is provided in the axial direction of the input coupler 4, the incidence of X-rays on the metal in the vicinity of the ceramic window 7 is suppressed, and charging to the ceramic window 7 is suppressed.

  Further, when the vacuum surface coating 12 is not applied, multi-pactoring may occur on the vacuum surface side of the ceramic window 7.

  Multipactoring is a phenomenon in which, when a specific condition is satisfied in a state where a high frequency is applied, electrons ejected from the electrodes come and go between the electrodes like a catch ball and discharge occurs. When electrons hit the ceramic, secondary electrons are emitted. If the secondary electron emission coefficient is large, when multi-pactoring occurs, the discharge increases, the degree of vacuum may deteriorate, and the ceramic window 7 may be damaged.

  Therefore, in the present embodiment, TiN coating is applied to the vacuum surface side of the ceramic window 7 to reduce the secondary electron emission coefficient. Thereby, secondary electron emission and charging of the ceramic window 7 can be reduced.

  Since the air surface coating 8 is applied to the air surface side of the ceramic window 7, the coating serves as a boundary surface with the air, not the ceramic window 7 itself.

  As described above, the high-frequency accelerating cavity according to the present embodiment suppresses charging of the ceramic window 7 and also forms a boundary layer on the atmosphere side of the ceramic window 7, thereby suppressing vacuum leakage of the ceramic window 7. be able to. For this reason, it becomes possible to input a large current under an ultra-high vacuum, and a high-efficiency high-frequency accelerating cavity capable of stably operating a long beam lifetime accelerator that generates a high-intensity voltage can be obtained.

  The above-described embodiment is merely an example, and the present invention is not limited to this.

It is a longitudinal cross-sectional view in 1st Embodiment of the high frequency acceleration cavity which concerns on this invention. It is a II-II arrow longitudinal cross-sectional view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body, 2 ... Nose, 3 ... High-order mode attenuator, 4 ... Input coupler, 5 ... Outer conductor, 6 ... Inner conductor, 7 ... Ceramic window, 8 ... Atmospheric surface coating, 9 ... Waveguide, 10 ... Horizontal magnetic field generating coil (second coil), 11 ... Vertical magnetic field generating coil (first coil), 12 ... Vacuum surface coating, 21 ... Circular hole, 22 ... Swelling part, 23 ... Rod antenna

Claims (9)

A body with a cavity inside which can be maintained in a vacuum;
An inner conductor extending from the cavity toward the outside of the main body, and an outer conductor provided with a ceramic window extending to surround the inner conductor in a direction coaxial with the inner conductor and surrounding a part in the axial direction. An input coupler with
A first coil that generates a magnetic field oriented along the axial direction of the inner conductor;
A high-frequency accelerating cavity device comprising: A body with a cavity inside which can be maintained in a vacuum;
An inner conductor extending from the cavity toward the outside of the main body, and an outer conductor provided with a ceramic window extending to surround the inner conductor in a direction coaxial with the inner conductor and surrounding a part in the axial direction. An input coupler with
A second coil for generating a magnetic field in a direction perpendicular to the direction along the axial direction of the inner conductor;
A high-frequency accelerating cavity device comprising: A body with a cavity inside which can be maintained in a vacuum;
An inner conductor extending from the cavity toward the outside of the main body, and an outer conductor provided with a ceramic window extending to surround the inner conductor in a direction coaxial with the inner conductor and surrounding a part in the axial direction. An input coupler with
A high-order mode attenuator comprising a rod antenna having a tip arranged at a position not looking through the ceramic window;
A high-frequency accelerating cavity device comprising: A body in which a cavity capable of maintaining a vacuum is formed, and a nose is formed around a circular hole through which a charged particle passes;
An inner conductor extending from the cavity toward the outside of the main body, extending so as to surround the inner conductor in the same direction as the inner conductor, surrounding a part in the axial direction, and not being removed from the nose. An input coupler comprising an outer conductor provided with a ceramic window disposed;
A high-frequency accelerating cavity device comprising: A body with a cavity inside which can be maintained in a vacuum;
An inner conductor extending from the cavity toward the outside of the main body and having a bulge portion having a larger outer diameter than the front and rear in a part in the axial direction, and surrounding the inner conductor in the same direction as the inner conductor An input coupler comprising: an outer conductor provided with a ceramic window extending to and surrounding a part of the axial direction thereof;
A high-frequency accelerating cavity device comprising: A body with a cavity inside which can be maintained in a vacuum;
An inner conductor extending from the cavity toward the outside of the main body, and a ceramic window extending to surround the inner conductor in the same direction as the inner conductor and having a coating on the outside surrounding a part in the axial direction. An input coupler comprising an outer conductor provided;
A high-frequency accelerating cavity device comprising:   7. The high-frequency accelerating cavity device according to claim 1, wherein a TiN coating is applied to an inner surface of the ceramic window. A main body in which a cavity capable of maintaining a vacuum is formed, an inner conductor extending from the cavity toward the outside of the main body, an axial direction extending so as to surround the inner conductor in the same direction as the inner conductor An input coupler including an outer conductor provided with a ceramic window surrounding a part of the high-frequency accelerating cavity device,
A method for operating a high-frequency accelerating cavity device, comprising generating a magnetic field oriented along the axial direction of the inner conductor. A main body in which a cavity capable of maintaining a vacuum is formed, an inner conductor extending from the cavity toward the outside of the main body, an axial direction extending so as to surround the inner conductor in the same direction as the inner conductor An input coupler including an outer conductor provided with a ceramic window surrounding a part of the high-frequency accelerating cavity device,
A method for operating a high-frequency accelerating cavity device, comprising: generating a magnetic field in a direction perpendicular to an axial direction of the inner conductor.

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