JP2015141849A - high-frequency input coupler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency input coupler capable of securing a coaxial property of an inner conductor and an outer conductor, and of connecting between a loop and the inner and outer conductors without any gaps.SOLUTION: A high-frequency input coupler 10 comprises an inner conductor 20 and an outer conductor 21 coaxially arranged. An front end part of the inner conductor 20 and a front end part of the outer conductor 21 are connected with each other by a loop 22. Screws 28 and 29 are inserted into the loop 22 to fasten and fix the loop 22 to the inner conductor 20 and the outer conductor 21, respectively. Covering parts 36 and 37 respectively cover the screws 28 and 29 inserted into the loop 22.

Description

  Embodiments described herein relate generally to a high-frequency input coupler that injects a high-frequency wave (microwave) emitted from a high-frequency amplifier into an acceleration cavity.

  2. Description of the Related Art Conventionally, in a charged particle (electron, ion) accelerator, a high frequency input coupler is used to make a high frequency (microwave) emitted from a high frequency amplifier such as a klystron enter an acceleration cavity.

  The high-frequency input coupler includes an inner conductor and an outer conductor that are coaxially arranged, a loop that connects a tip portion of these inner conductors and a tip portion of the outer conductor, and further, an inner portion of a waveguide through which a high frequency passes. The structure is equipped with a high frequency input window that isolates the atmospheric pressure from the high vacuum in the acceleration cavity and efficiently transmits high frequencies.

  The loop is assembled by brazing the tip of the inner conductor and the tip of the outer conductor by brazing. In addition to ensuring the coaxiality of the inner conductor and the outer conductor, the loop, the inner conductor, and the outer conductor It is important not to create a gap between them. This is because if there is a gap between the loop and the inner conductor and the outer conductor, non-uniformity and concentration of the high-frequency electric field occurs, which may cause discharge. Therefore, when joining the loops, a large weight is placed on the loop while maintaining the coaxiality between the inner conductor and the outer conductor using various jigs, and there is a gap between the loop and the inner conductor and the outer conductor. The device is made to prevent it from occurring.

  In addition, it is possible to suppress the occurrence of deviation between the loop and the inner conductor and the outer conductor by adopting a concave-convex fitting structure at the joint portion between the loop and the inner conductor and the outer conductor. It is difficult to reliably prevent the generation of a gap between the loop and the inner conductor and the outer conductor due to a shift of the weight to be placed.

JP 2001-60500 A

  The conventional high-frequency input coupler has a problem that it is difficult to ensure the coaxiality between the inner conductor and the outer conductor and to connect the loop and the inner conductor and the outer conductor without any gap.

  The problem to be solved by the present invention is to provide a high-frequency input coupler capable of securing the coaxiality between the inner conductor and the outer conductor and connecting the loop, the inner conductor, and the outer conductor without any gap.

  The high-frequency input coupler according to the present embodiment includes an inner conductor and an outer conductor that are coaxially arranged, a loop that connects a front end portion of the inner conductor and a front end portion of the outer conductor, and the inner conductor that is inserted through the loop. And a screw that fastens and fixes the loop to the outer conductor, and a cover that covers the screw inserted through the loop.

It is sectional drawing of the high frequency input coupler which shows 1st Embodiment. It is a front view of a high frequency input coupler same as the above. It is sectional drawing of the decomposition | disassembly state of a high frequency input coupler same as the above. It is a front view of the high frequency input coupler which shows 2nd Embodiment.

  Hereinafter, a first embodiment will be described with reference to FIGS. 1 to 3.

  The high-frequency input coupler 10 couples, for example, a waveguide 11 that transmits a high frequency emitted from a high-frequency amplifier such as a klystron and an acceleration cavity 13 of the high-frequency cavity device 12, and the atmospheric pressure in the waveguide 11 And high vacuum in the acceleration cavity 13 are isolated from each other, and a high frequency is used to enter the acceleration cavity 13.

  The high-frequency input coupler 10 includes a coupler main body 16 and a window unit 17 installed at one end of the coupler main body 16 in the axial direction. As an example, the high-frequency input coupler 10 is formed with a total length of about 600 mm and a diameter of about 100 to 200 mm.

  The coupler body 16 includes a columnar inner conductor 20 and a cylindrical outer conductor 21 that are coaxially arranged. The inner conductor 20 and the outer conductor 21 are coaxially fixed by the window unit 17 on one end side of the coupler body 16, and the tip of the inner conductor 20 and the tip of the outer conductor 21 are on the other end of the coupler body 16. It is fixed coaxially by a loop 22. The coupler main body 16 including the inner conductor 20, the outer conductor 21, and the loop 22 is made of, for example, a copper material in consideration of facilitating current flow through the surface by a high frequency passing through the inside.

  Attachment holes 23 and 24 such as screw holes are formed at the distal ends of the inner conductor 20 and the outer conductor 21, respectively. The leading end portion of the inner conductor 20 protrudes beyond the leading end portion of the outer conductor 21.

  The loop 22 includes a joint portion 25 joined to the tip portion of the inner conductor 20, a joint portion 26 joined to the tip portion of the outer conductor 21, and a connecting portion 27 that connects the joint portion 25 and the joint portion 26. ing. The joints 25 and 26 protrude from the connecting part 27, and the joints 26 from the connecting part 27 correspond to the protruding amounts of the tip of the inner conductor 20 and the tip of the outer conductor 21 being different. Is larger than the protruding amount of the joint portion 25.

  The loop 22 is fastened and fixed to the distal end portion of the inner conductor 20 and the distal end portion of the outer conductor 21 by screws 28 and 29. The screws 28 and 29 have a shaft portion 30 and a head portion 31. The screw 28 for the inner conductor 20 and the screw 29 for the outer conductor 21 have different lengths of the tip of the inner conductor 20 and the tip of the outer conductor 21, and the length of the shaft portion 30 corresponds. Is different. The screws 28 and 29 are made of, for example, stainless steel or copper material. Since these stainless steel and copper do not change much in the coefficient of thermal expansion, any of them may be used as the material of the screws 28 and 29.

  Insertion holes 32 and 33 through which the screws 28 and 29 are inserted are formed through the joint portions 25 and 26, respectively. The insertion holes 32 and 33 have a small diameter hole portion 34 through which the shaft portion 30 is inserted and a large diameter hole portion 35 in which the head portion 31 is disposed.

  Cover portions 36 and 37 are used to cover the large-diameter hole portions 35 of the insertion holes 32 and 33 in which the heads 31 of the screws 28 and 29 are respectively disposed. The cover portions 36 and 37 are made of, for example, a copper material, and are joined to the loop 22 by brazing (wax joining) by sandwiching a brazing material and are flush with the surface of the loop 22. ing.

  On the outside of the outer conductor 21, a flange 38 for fixing to the high-frequency cavity device 12 is fixed so that the other end side of the coupler body 16 is disposed in the acceleration cavity 13.

  Further, the window unit 17 includes a cylindrical inner conductor portion 40 joined to the inner conductor 20, a cylindrical outer conductor portion 41 joined to the outer conductor 21, and the inner conductor portion 40 and the outer conductor portion 41. A high-frequency input window 42 is provided between them.

  The high frequency input window 42 is made of ceramics and is formed in a disc shape (annular shape) having a hole 43 in the center. The inner conductor portion 40 is inserted into the hole 43 of the high frequency input window 42, the high frequency input window 42 is inserted inside the outer conductor portion 41, and the joint surface between the high frequency input window 42 and the inner conductor portion 40 and the outer conductor portion 41 is formed. It is airtightly joined by brazing. The inner conductor portion 40 and the outer conductor portion 41 are coaxially fixed by the high frequency input window 42.

  The inner conductor portion 40 and the outer conductor portion 41 have a stress that is generated by a difference in expansion between the high-frequency input window 42 and the high-frequency input window 42 when current flows easily on the surface due to high-frequency waves passing through the inner conductor portion 40 and brazing / heating. Considering that it can be absorbed, it is made of a copper material.

  By attaching the window unit 17 to the coupler body 16, the inner conductor portion 40 is combined with the inner conductor 20 to be flush with the outer surface of the inner conductor 20, and the outer conductor portion 41 is combined with the outer conductor 21. The inner conductor portion 40 and the outer conductor portion 41 are configured as a part of the inner conductor 20 and the outer conductor 21, respectively.

  The thus configured high frequency input coupler 10 is installed in the high frequency cavity device 12 by a flange 38 attached to the outer conductor 21, and is connected between the inner conductor 20 and the outer conductor 21 up to the high frequency input window 42. The part is in a vacuum state. The high-frequency input coupler 10 has a coaxial waveguide 11 fixed with screws, and guides high-frequency waves that have passed through the inside of the atmospheric pressure toward the high-frequency input window 42.

  Next, assembly of the loop 22, the inner conductor 20, and the outer conductor 21 will be described. The joining portions 25 and 26 of the loop 22 are arranged with a brazing material sandwiched between the tip portion of the inner conductor 20 and the tip portion of the outer conductor 21, respectively, so that brazing can be performed in a later joining step. At this time, if the heights of the inner conductor 20 and the outer conductor 21 do not fall within the specified tolerances and the loop 22 is inclined, either one of the joining portions 25 and 26 of the loop 22 is cut in advance to increase the protrusion amount. Adjust it.

  The screws 28 and 29 are inserted into the insertion holes 32 and 33 of the loop 22 and screwed into the mounting holes 23 and 24 of the inner conductor 20 and the outer conductor 21, and the loop 22 is connected to the inner conductor 20 and the outer conductor 21 by the screws 28 and 29. Tighten to and fix. The screws 28 and 29 are tightened firmly after the coaxiality and inclination of the inner conductor 20 and the outer conductor 21 are adjusted. At this time, in order to prevent the screws 28 and 29 from loosening, a brazing material is sandwiched between the heads 31 of the screws 28 and 29 and the loop 22 so that they can be brazed in a subsequent joining step.

  The cover portions 36 and 37 are fitted into the insertion holes 32 and 33 of the loop 22. At this time, a brazing material is sandwiched between the cover portions 36 and 37 and the loop 22 so that brazing can be performed in a later joining step. Moreover, the cover parts 36 and 37 have an initial shape higher than the height inserted into the insertion holes 32 and 33 of the loop 22 as indicated by a two-dot chain line in FIG. Therefore, when the cover portions 36 and 37 are fitted in the insertion holes 32 and 33 of the loop 22, the cover portions 36 and 37 protrude from the surface of the loop 22.

  In the joining process, between the joint portions 25 and 26 of the loop 22 where the brazing material has been arranged and the inner conductor 20 and the outer conductor 21, between the head portion 31 of the screws 28 and 29 and the loop 22, and the covering portion 36. , 37 and the loop 22 are joined by brazing with a brazing material interposed therebetween.

  After the joining step, the protruding portions of the cover portions 36 and 37 protruding from the surface of the loop 22 are cut and polished so as to be flush with the surface of the loop 22.

  In this way, in the high frequency input coupler 10, since the loop 22 is fastened and fixed to the inner conductor 20 and the outer conductor 21 with the screws 28 and 29, the coaxiality between the inner conductor 20 and the outer conductor 21 is secured, and the loop 22 And the inner conductor 20 and the outer conductor 21 can be connected without a gap.

  In addition, since the screws 28 and 29 inserted through the loop 22 are covered with the cover portions 36 and 37, the screws 28 and 29 are embedded in the loop 22, and it is possible to avoid disturbing the high-frequency electric field on the surface of the loop 22. it can. If the heads 31 of the screws 28 and 29 are exposed on the surface of the loop 22, local electric field concentration occurs in the head 31 part, and the head 31 may generate heat.

  Further, since the cover portions 36 and 37 are embedded in the insertion holes 32 and 33 of the loop 22 through which the screws 28 and 29 are inserted, and the cover portions 36 and 37 are flush with the surface of the loop 22, Disturbing the high frequency electric field can be avoided.

  In addition, the assembly man-hour is increased by using the screws 28 and 29 and the cover portions 36 and 37. However, after brazing, the inclination of the loop 22, the flow of the brazing material, and the inner conductor 20 and the outer conductor 21 are coaxial. If a defect occurs every time, considering that correction is almost impossible, adjust the coaxiality and inclination of the inner conductor 20 and the outer conductor 21 in advance, and use the screws 28 and 29 to connect the loop 22 with the inner conductor 20. It is effective to perform brazing after fixing to the outer conductor 21.

  Further, in the high-frequency input coupler 10, the inner conductor 20, the outer conductor 21, and the loop 22 have a temperature rise due to exposure to a high frequency. The rise in temperature of these structures may cause deformation due to thermal expansion, variation in dimensions, and gas release from the surface of the structure, and there is a concern that this will have a considerable impact on the normal functioning of the equipment. For this reason, the high-input high-frequency input coupler 10 employs a configuration in which a water cooling jacket is provided on the outer peripheral portion of the outer conductor 21 and heat is removed by introducing a cooling pipe to the inner conductor 20 near the tip. However, since it is difficult to provide a water cooling mechanism in the loop 22 portion in terms of size, heat generated in the loop 22 portion is transferred to the inner conductor 20 and the outer conductor 21 by conduction. The inner conductor 20, outer conductor 21, and loop 22 are generally made of copper having excellent thermal conductivity, and the screws 28 and 29 are made of copper based on the same concept. Is preferred.

  Next, FIG. 4 shows a second embodiment. In addition, the same code | symbol is used about the same structure as 1st Embodiment, and the description about the structure and effect is abbreviate | omitted.

  In the high-frequency input coupler, when the loop 22 is brazed to the inner conductor 20 and the outer conductor 21, even if the screws 28 and 29 for fixing the loop 22 are tightened, the temperature of brazing increases (about 800 ° C. for silver brazing). There is a possibility that a minute shift occurs between the loop 22 and the inner conductor 20 and the outer conductor 21. With regard to this deviation, it is considered that the rotational deviation is most likely to occur at the joint surface between the loop 22 and the outer conductor 21 in consideration of the rotational stress when the screws 28 and 29 are tightened.

  In order to prevent such a shift, at least two portions in the circumferential direction are fixed with screws 29 at a portion where the loop 22 and the outer conductor 21 are connected. As a result, it is possible to suppress the occurrence of deviation in the rotational direction of the loop 22.

  Although there is a possibility that a deviation occurs at the joint surface between the loop 22 and the inner conductor 20, since the occurrence of rotational deviation between the loop 22 and the outer conductor 21 can be prevented, the loop 22 and the inner conductor 20 It is not necessary to increase the number of screws 28 for fixing the.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10 High frequency input coupler
20 Inner conductor
21 Outer conductor
22 loops
28, 29 screw
32, 33 insertion hole
36, 37 Cover

Claims (5)

An inner conductor and an outer conductor arranged coaxially;
A loop connecting the tip of the inner conductor and the tip of the outer conductor;
A screw that passes through the loop and fastens and fixes the loop to the inner conductor and the outer conductor;
A high-frequency input coupler comprising: a cover that covers the screw inserted through the loop. The high frequency input coupler according to claim 1, wherein the cover is joined to the loop by brazing and is flush with the surface of the loop. The loop has an insertion hole through which the screw is inserted,
The high frequency input coupler according to claim 1, wherein the cover is embedded in the insertion hole through which the screw is inserted. The high-frequency input coupler according to any one of claims 1 to 3, wherein the loop, the screw, and the cap are formed of a copper material. 5. The high-frequency input coupler according to claim 1, wherein two or more screws are provided for fastening and fixing the outer conductor and the loop.

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