JP2005347184A - Resonant frequency adjustment method of rotary joint for high frequency transmission and rotary joint for high frequency transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resonant frequency adjustment method of a rotary joint for high frequency transmission adjusting to a desired resonant frequency with high practical usefulness, low cost and simplicity and a rotary joint for the high frequency transmission. <P>SOLUTION: The resonant frequency adjustment method of the rotary joint for high frequency transmission is constituted by having a pair of wave guides 12 and 14 provided with hollow waveguides 12b and 14b for high frequency transmission inside connected relatively rotatably to each other with an axial center Z-Z which is coaxial as a center. At least 3 blocks are constituted with a cylinder part 16 of one of the wave guides of the pair of wave guides 12 and 14 serially installed in the axial direction, the block positioned in a middle part in the axial direction is a disk for frequency adjustment and adjustment to the desired resonance frequency is carried out by adjusting the thickness in the axial direction of the disk for frequency adjustment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for adjusting a resonance frequency of a high-frequency transmission rotary joint used in a radiotherapy apparatus and the like, and a high-frequency transmission rotary joint.

  As a radiotherapy apparatus using a microwave generated by a magnetron or a klystron, for example, the following Patent Document 1 is disclosed.

  As shown in FIG. 4, the radiotherapy apparatus of Patent Document 1 includes an irradiation head 51 having an electron gun, a linear accelerator, and a target, and a support moving mechanism 52 that supports and moves the irradiation head on a predetermined spherical coordinate. A microwave oscillator 53 installed on the floor, a waveguide section 54 having one end electromagnetically connected to the microwave oscillator and the other end electromagnetically connected to the linear accelerator, and a position in the irradiation head And an RF window provided in the waveguide section.

Further, in such a radiotherapy apparatus, each waveguide section 54 is a metal hollow tube, so that a rotary joint is used to connect a plurality of waveguide sections rotatably and electromagnetically. It is done.
In this rotary joint (rotary RF coupler in Patent Document 1), as shown in FIG. 5, the waveguide of the waveguide 54 communicates with the rotary spaces 57a and 57b surrounded by the rotary member of the rotary joint 56. The microwave is guided in the in-pipe mode 2a (2b).
In this figure, 58 indicates a bearing and 59 indicates a λ / 4 wavelength choke. By such a combination of the rotary joint 56 and the waveguide section 54, acceleration microwaves can be smoothly supplied to an irradiation head moving from an acceleration microwave source such as a klystron fixed to a floor or the like.

  By the way, recent technological trends in high-frequency devices are toward high power and small size, and devices capable of transmitting high-power high-frequency devices are desired. In a general high-frequency mechanism, since the frequency band of the transmitted microwave is wide, it is not necessary to adjust the resonance frequency at a level of several tens of MHz. However, in a high-frequency mechanism that transmits high-power high-frequency, in order to prevent discharge in the waveguide, it is necessary to adopt a shape and dimensions that reduce the surface electric field strength, and thereby the frequency band to be transmitted is There is a case where it becomes narrow to about 20 MHz. Further, in the case of a rotary joint, the fluctuation of the resonance frequency due to the rotation mechanism is about 30 MHz. For this reason, it is necessary to make the resonance frequency of the rotary joint as close as possible to the operating frequency.

  Here, the following Patent Document 2 discloses a technique related to adjustment of the resonance frequency of a high-frequency accelerator tube used in a synchrotron radiation generator or the like. As shown in FIG. 6, the “resonance frequency adjusting device for a high-frequency acceleration cavity” of Patent Document 2 includes a high-frequency acceleration cavity 61 by inserting a resonance frequency-adjusting cylinder 62 into a high-frequency acceleration cavity 61 in a variable amount of insertion. The resonance frequency is adjusted.

JP 2003-175117 A JP-A-5-47495

  Thus, conventionally, in an acceleration tube that needs to adjust the resonance frequency, a mechanism for adjusting the resonance frequency as in Patent Document 2 is provided. However, separately providing such a resonance frequency adjusting mechanism in the high-frequency transmission rotary joint not only lacks practicality but also increases costs.

  The present invention has been made to solve such problems. In other words, an object of the present invention is to provide a high-frequency transmission rotary joint and a high-frequency transmission rotary joint that are highly practical, low-cost, and can be easily adjusted to a desired resonance frequency. There is.

  In order to achieve the above object, the resonance frequency adjusting method for a high-frequency transmission rotary joint according to the present invention is a method in which a pair of waveguides having a hollow waveguide for high-frequency transmission therein are relatively opposite to each other about a coaxial axis. A resonance frequency adjustment method for a rotary joint for high-frequency transmission, which is connected rotatably, wherein cylindrical portions of one of the pair of waveguides are arranged in series in the axial direction. A block located in the middle portion in the axial direction is a frequency adjusting disk, and the axial thickness of the frequency adjusting disk is adjusted to a desired resonance frequency. (Claim 1).

  In the present invention, preferably, a waveguide is temporarily assembled by the blocks including the frequency adjusting disk, a rotary joint is configured using the waveguide, and a resonance frequency of the rotary joint is measured. Then, the thickness in the axial direction of the frequency adjusting disk is finely adjusted based on the measurement result (claim 2).

  The high-frequency transmission rotary joint according to the present invention is a high-frequency transmission comprising a pair of waveguides having hollow waveguides for high-frequency transmission therein, which are rotatably connected to each other around a coaxial axis. A transmission rotary joint, wherein a cylindrical portion of one of the pair of waveguides is composed of at least three blocks arranged in series in an axial direction, The block located in the middle of the direction is a frequency adjusting disk, and is adjusted to a desired resonance frequency by adjusting the axial thickness of the frequency adjusting disk (claim 3). .

  The resonance frequency of the rotary joint can be adjusted by the volume such as the inner diameter and length of the waveguide. In the present invention, any one of the pair of waveguides is composed of at least three blocks arranged in the axial direction, and a block located in the middle in the axial direction is used as a frequency adjusting disk, and this frequency adjustment is performed. Since the axial thickness of the disk is adjusted to the desired resonance frequency, the resonance frequency can be finely adjusted, and adjustment after the rotary joint is completed is not necessary. Further, since the frequency adjusting mechanism is incorporated in one component part of the waveguide, it is not necessary to separately provide a frequency adjusting mechanism in the rotary joint, and therefore the resonance frequency can be adjusted at a low cost. Further, since the thickness of the frequency adjusting disk can be estimated to some extent from the analysis, the adjustment by the correction process of the disk can be performed by a small number of times, and the resonance frequency can be adjusted very easily.

  That is, according to the present invention, it is possible to obtain an excellent effect that it is highly practical, can be easily adjusted to a desired resonance frequency at low cost.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a cross-sectional view of a rotary joint according to an embodiment of the present invention. The rotary joint 10 is used to transmit a high frequency of about 11 GHz with high power (for example, 10 MW) generated by a magnetron or a klystron.

  As shown in the figure, the rotary joint 10 includes a pair of waveguides 12 and 14, a rotation support portion 20, and a quarter wavelength choke 30. The pair of waveguides 12 and 14 are connected in series so that the end faces thereof are in series with a certain gap 15 therebetween, and can be rotated relative to each other about the concentric axis ZZ by the rotation support portion 20. ing.

  The waveguides 12 and 14 have hollow waveguides 12b and 14b for transmitting a high frequency generated by a magnetron or a klystron inside, and a hollow cylindrical cylindrical portion forming a waveguide having a circular cross section inside. 16, an end plate 17 that closes the end of the cylindrical portion 16, and a waveguide having a rectangular cross section formed in the inside thereof, which is connected to the cylindrical portion 16 and the end plate 17 and whose axial direction is perpendicular to the axial direction of the cylindrical portion 16 And a rectangular portion 18 to be formed.

  The rotation support unit 20 includes a cylindrical reinforcing piece 21 fitted to one of the waveguides 12, a bearing 22 fitted to the outer peripheral portion of the reinforcing piece 21, and a bearing housing 23 covering them. Thus, the relative rotation of the pair of waveguides 12 and 14 is supported. A gas seal 24 is interposed between the reinforcing piece 21 and the bearing housing 23, thereby preventing the gas sealed in the waveguide from leaking from the gap 15.

  The quarter-wave choke 30 is formed by extending a space having a U-shaped cross section in the circumferential direction, and this choke structure reduces high-frequency leakage to the rotation support portion 20 side.

  FIG. 2 is a cross-sectional view of one of the pair of waveguides (left side in FIG. 1). As shown in this figure, the cylindrical portion 16 of the waveguide 12 is composed of three blocks 16a, 16b, and 16c arranged in the axial direction. Of these three blocks 16a, 16b, and 16c, the block 16b located in the middle in the axial direction (the center in the figure) is a frequency adjusting disk, and the axial thickness of the frequency adjusting disk 16b is adjusted. Thus, the resonance frequency is adjusted to a desired resonance frequency. The resonance frequency of the rotary joint can be adjusted by the volume such as the inner diameter and length of the waveguide. In the present invention, by adjusting the thickness of the frequency adjusting disk 16b, the length of the waveguide (reference numeral L in FIG. 1) is adjusted to adjust the resonance frequency.

  Specifically, the resonance frequency of the rotary joint is adjusted by the following method. First, three blocks 16a, 16b, and 16c constituting the cylindrical portion 16 of one of the pair of waveguides are manufactured, and the block 16b in the axially intermediate portion is used as a frequency adjustment disk. . At this time, the blocks 16a, 16b, and 16c are manufactured so that the inner diameters of the blocks 16a, 16b, and 16c have the same size so that no step is generated in the inner peripheral portions of the blocks 16a, 16b, and 16c. When such a level difference occurs, discharge at the level difference part may occur and cause deterioration of the material, and it may be difficult to adjust to a desired resonance frequency by affecting the resonance frequency.

  Next, the frequency adjusting disk 16b is sandwiched between the other two blocks 16a and 16c, and the rotary joint 10 as shown in FIG. Next, the resonance frequency of the rotary joint 10 is measured. For this measurement, for example, a measuring device that oscillates a low power high frequency can be used. Based on the measurement result, the axial thickness of the frequency adjusting disk 16b is finely adjusted by cutting or the like so as to have a desired resonance frequency.

  Here, FIG. 3 shows an example of the relationship (measured value) between the thickness of the frequency adjusting disk 16b and the resonance frequency, with the horizontal axis representing the disk thickness and the vertical axis representing the resonance frequency. The operating conditions of this example are: operating temperature: 20 ° C., insulating gas: SF 6, pressure: 0.3 MPa, relative dielectric constant ε: 1.00612 (estimated). It can be seen from FIG. 3 that the thickness of the frequency adjusting disk and the resonance frequency have a certain relationship. Therefore, the thickness for the frequency adjusting disk can be estimated to some extent from the analysis. Thereby, the adjustment by the correction process of the disk can be completed with a small number of times. In this example, the amount of change in frequency was 40 MHz / mm.

  If the thickness of the frequency adjusting disk 16b is adjusted in this way and adjusted to a desired resonance frequency, brazing of the final process is performed, and the frequency adjusting disk 16b and the other blocks 16a, 16b, and other The parts are joined to complete the rotary joint 10.

  As described above, according to the present invention, the cylindrical portion of any one of the pair of waveguides is configured to include at least three blocks arranged in the axial direction, and an axial intermediate portion thereof is included. The block located at is used as a frequency adjustment disk, and the axial thickness of this frequency adjustment disk is adjusted to the desired resonance frequency, so that the resonance frequency can be finely adjusted. No adjustment is necessary. Further, since one component part of the waveguide is a frequency adjustment mechanism, it is not necessary to separately provide a frequency adjustment mechanism in the rotary joint, and therefore the resonance frequency can be adjusted at a low cost. Further, since the thickness of the frequency adjusting disk can be estimated to some extent from the analysis, the adjustment by the correction process of the disk can be performed by a small number of times, and the resonance frequency can be adjusted very easily. That is, it is possible to obtain an excellent effect that it is highly practical, can be easily adjusted to a desired resonance frequency at low cost.

  In addition, this invention is not limited to embodiment mentioned above, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

It is sectional drawing of the rotary joint for high frequency transmission which concerns on this invention. It is sectional drawing of the waveguide shown in FIG. It is a figure which shows the relationship between the thickness of the disk for frequency adjustment, and a resonance frequency. 1 is an overall schematic diagram of a “radiation therapy apparatus” in Patent Document 1. FIG. 10 is an explanatory diagram of a “rotary RF coupler” in Patent Document 1. FIG. 1 is a configuration diagram of a “resonance frequency adjusting device for a high-frequency acceleration cavity” of Patent Document 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotary joint 12, 14 Waveguide 12b, 14b Waveguide 15 Crevice 16 Cylindrical part 16a, 16c Block 16b Block (frequency adjusting disk)
17 End plate 18 Rectangular portion 20 Rotation support portion 21 Reinforcement piece 22 Bearing 23 Bearing housing 24 Gas seal 30 1/4 wavelength choke

Claims (3)

A resonance frequency adjusting method for a high-frequency transmission rotary joint, wherein a pair of waveguides having a hollow waveguide for high-frequency transmission therein are connected to each other so as to be relatively rotatable about a coaxial axis. ,
The cylindrical part of either one of the pair of waveguides is composed of at least three blocks arranged in series in the axial direction, and the frequency of the block located in the middle part in the axial direction is adjusted. A resonance frequency adjusting method for a rotary joint for high-frequency transmission, characterized in that an adjustment disc is adjusted to have a desired resonance frequency by adjusting an axial thickness of the frequency adjustment disc.   A waveguide is temporarily assembled by the respective blocks including the frequency adjusting disk, a rotary joint is configured using the waveguide, a resonance frequency of the rotary joint is measured, and the frequency based on the measurement result is measured. 2. The resonance frequency adjusting method for a rotary joint for high frequency transmission according to claim 1, wherein the axial thickness of the adjusting disk is finely adjusted. A high-frequency transmission rotary joint in which a pair of waveguides having a hollow waveguide for high-frequency transmission therein is connected to be rotatable relative to each other about a coaxial axis,
The cylindrical portion of one of the pair of waveguides is composed of at least three blocks arranged in series in the axial direction, of which the block located in the axially intermediate portion is A high-frequency transmission rotary joint which is a frequency adjusting disk and is adjusted to a desired resonance frequency by adjusting an axial thickness of the frequency adjusting disk.

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