High-frequency window structure, high-frequency input coupler and high-frequency amplifier

Abstract

To provide a high frequency transmission window structure capable of preventing the damage of a high frequency transmission window.SOLUTION: The high frequency transmission window structure 17 includes a high frequency transmission window 40, an outer sleeve 42 joined to the outer periphery of the high frequency transmission window 40, and a holding member 44 wound around the outer periphery of a portion of the outer sleeve 42 to which the high frequency transmission window 40 is joined and joined to the outer periphery of the outer sleeve 42.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to a radio frequency transparent window structure, a radio frequency input coupler, and a radio frequency amplifier. [Background technology]

[0002] When a high frequency (microwave) is injected into an accelerating cavity, a high frequency input coupler is required which has a structure that can provide good coupling to the accelerating cavity.

[0003] The RF input coupler includes a RF-transparent window structure for injecting RF waves from the atmosphere into an accelerating cavity maintained at a high vacuum. The RF-transparent window structure includes a RF-transparent window that transmits RF waves while maintaining airtightness, an outer sleeve and an inner sleeve that are brazed to the outer and inner peripheries of the RF-transparent window to form a RF transmission path, and a wire wound around the outer periphery of the outer sleeve where the RF-transparent window is brazed.

[0004] The RF-transparent window is made of a ceramic such as alumina, and the outer sleeve is made of a metal such as copper. The surface where the RF-transparent window joins with the outer sleeve has a metallized layer, and the outer sleeve is joined via this metallized layer by brazing. This ensures airtightness in front of and behind the RF-transparent window.

[0005] Incidentally, the radio frequency transparent window structure is exposed to high temperatures of over 1000°C during the brazing process after assembly. It is also exposed to high temperatures of over 700°C during brazing when peripheral components are subsequently assembled to the radio frequency transparent window structure, as well as during baking, which is performed after completion. Because the thermal expansion coefficients of the radio frequency transparent window and the outer sleeve are different, tensile stress is generated in the radio frequency transparent window near the joint surface between the window and the outer sleeve when the temperature rises during brazing and baking. To prevent this, a wire made of a metal with a low thermal expansion coefficient is wrapped around the outside of the outer sleeve during assembly of the radio frequency transparent window structure, and then the radio frequency transparent window and the outer sleeve are brazed together.

[0006] However, if the wound wire loosens after the radio-frequency transmitting window and the outer sleeve are brazed together, when the temperature rises due to subsequent brazing or baking after the product is completed, the outer sleeve will have a larger amount of thermal expansion, and tensile stress will be generated in the radio-frequency transmitting window near the joint surface between the radio-frequency transmitting window and the outer sleeve.As a result, cracks will occur from the edge of the joint surface between the radio-frequency transmitting window and the outer sleeve toward the inside of the radio-frequency transmitting window, and these cracks may penetrate the radio-frequency transmitting window, causing the radio-frequency input coupler to lose its airtightness. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2018-113503 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a high frequency transparent window structure, a high frequency input coupler, and a high frequency amplifier that can prevent damage to the high frequency transparent window. [Means for solving the problem]

[0009] The radio-frequency-transmitting window structure of this embodiment comprises a radio-frequency-transmitting window, an outer sleeve joined to the outer periphery of the radio-frequency-transmitting window, and a retaining member wrapped around the outer periphery of the portion of the outer sleeve where the radio-frequency-transmitting window is joined and joined to the outer periphery of the outer sleeve. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a high-frequency input coupler having a high-frequency transparent window structure according to a first embodiment of the present invention. [Figure 2] FIG. [Figure 3] 3 is a cross-sectional view of the high-frequency input coupler provided with the same high-frequency transparent window structure. FIG. [Figure 4] FIG. 10 is a cross-sectional view of a high-frequency amplifier having a high-frequency transmitting window structure according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The first embodiment will be described below with reference to FIGS.

[0012] 1 shows a radio frequency input coupler (coupler) 10. The radio frequency input coupler 10 couples radio frequency (microwave) signals output from a radio frequency amplifier such as a klystron between a waveguide 11 and an accelerating cavity 13 of an accelerator 12, and also separates the atmospheric pressure in the waveguide 11 from the high vacuum in the accelerating cavity 13, allowing the radio frequency signals to enter the accelerating cavity 13.

[0013] The high-frequency input coupler 10 includes a coupler body 16 and a high-frequency transmitting window structure 17 incorporated into the coupler body 16 .

[0014] The coupler body 16 has a cylindrical inner conductor (antenna) 20 and a cylindrical outer conductor 21 that are arranged coaxially. High frequency waves are transmitted between the inner conductor 20 and the outer conductor 21.

[0015] The inner conductor 20 has an atmosphere-side inner choke 23 and a vacuum-side inner choke 24 to which the inside of the high-frequency transparent window structure 17 is joined, and also has an antenna portion 25 that protrudes from the vacuum-side inner choke 24 into the accelerating cavity 13 of the accelerator 12.

[0016] The outer conductor 21 has atmosphere-side outer chokes 27 and vacuum-side outer chokes 28 to which the outside of the high-frequency transparent window structure 17 is joined, and has a connecting cylinder 29 that is joined to the outer peripheries of the atmosphere-side outer chokes 27 and vacuum-side outer chokes 28. An atmosphere-side flange 30 to which the waveguide 11 is attached is joined to the atmosphere-side outer choke 27, and a vacuum-side flange 31 is joined to the vacuum-side outer choke 28. An outer peripheral cylinder 32 is attached to the vacuum-side flange 31, and this outer peripheral cylinder 32 is attached to the accelerator 12.

[0017] The high-frequency input coupler 10 is assembled by combining a high-frequency transmitting window structure 17 and joining the various components together with the high-frequency transmitting window structure 17 by brazing.

[0018] 2 shows the radio frequency transparent window structure 17. The radio frequency transparent window structure 17 includes a radio frequency transparent window 40 that is airtight and transmits radio frequency waves, an inner sleeve 41 and an outer sleeve 42 to which the inside and outside of the radio frequency transparent window 40 are joined, a metal sheet 43 serving as an inner holding member joined to the inner periphery of the portion of the inner sleeve 41 to which the radio frequency transparent window 40 is joined, a metal wire 45 serving as an outer holding member 44 wrapped around the outer periphery of the portion of the outer sleeve 42 to which the radio frequency transparent window 40 is joined, and an atmosphere-side outer choke 27 joined to the outer sleeve 42. In this embodiment, the respective joints of the radio frequency transparent window structure 17 are joined by brazing, but other joining methods such as welding or adhesive may also be used.

[0019] The radio frequency transparent window 40 is made of a ceramic such as alumina. The radio frequency transparent window 40 is formed in a disk shape (annular) with a circular hole 46 in the center. The inner and outer peripheral surfaces of the radio frequency transparent window 40 serve as bonding surfaces with the sleeves 41, 42, and metallized layers are provided on these bonding surfaces.

[0020] The inner sleeve 41 is inserted into the hole 46 of the radio frequency transparent window 40, the radio frequency transparent window 40 is inserted inside the outer sleeve 42, and the radio frequency transparent window 40 and each sleeve 41, 42 are hermetically joined by brazing with a first brazing filler metal 48, which is a first joining material 47. The first brazing filler metal 48 has a lower melting point than the base materials of the radio frequency transparent window 40 and each sleeve 41, 42, and is a brazing filler metal type (material) that melts when exposed to high temperatures of, for example, 1000 degrees or higher.

[0021] As shown in FIG. 3( a), the first brazing material 48 is provided in a plate shape in the initial pre-melted state, and is arranged between the radio-frequency transmitting window 40 and each of the sleeves 41, 42 when the radio-frequency transmitting window structure 17 is assembled. As shown in FIG. 3( b), the first brazing material 48 melts when exposed to a high temperature of, for example, 1000°C or higher in the brazing process after assembly, and joins the radio-frequency transmitting window 40 and each of the sleeves 41, 42.

[0022] The inner sleeve 41 and the outer sleeve 42 are made of a metal such as copper. The inner sleeve 41 and the outer sleeve 42 are cylindrically shaped and arranged coaxially. One end of the outer sleeve 42 is attached to the atmosphere-side outer choke 27 by brazing, and the other end is attached to the vacuum-side outer choke 28 by brazing.

[0023] The metal thin film 43 is made of a metal such as molybdenum or tungsten that has a smaller thermal expansion coefficient than the copper inner sleeve 41, and is joined by brazing to the inner periphery of the portion of the inner sleeve 41 where the radio frequency transparent window 40 is brazed.

[0024] The wire 45 is made of a metal such as molybdenum or tungsten that has a smaller coefficient of thermal expansion than the copper outer sleeve 42, and is wound around and tightened around the outer circumference of the portion of the outer sleeve 42 where the radio frequency transparent window 40 is brazed. After being wound around and tightened around the outer sleeve 42, both ends of the wire 45 are tied to prevent slack. The number of turns of the wire 45 around the outer sleeve 42 is optional.

[0025] The wire 45 is joined to the outer sleeve 42 by a second brazing filler metal 50, which is a second joining material 49. The second brazing filler metal 50 is of the same type as the first brazing filler metal 48, has a lower melting point than the base materials of the outer sleeve 42 and the wire 45, and is a brazing filler metal type that melts when exposed to high temperatures, for example, of 1000°C or higher.

[0026] As shown in Fig. 3(a), the second brazing filler metal 50 is provided in a linear shape in an initial pre-melted state, and is wound around the outer periphery of the outer sleeve 42 so as to be adjacent to the wire 45 wound around the outer periphery of the outer sleeve 42 during assembly of the radio frequency transparent window structure 17. As shown in Fig. 3(b) or 3(c), the second brazing filler metal 50 is exposed to a high temperature of, for example, 1000°C or higher in a brazing process after assembly, thereby melting and joining the wire 45 to the outer sleeve 42. In the brazed state shown in Fig. 3(b), the molten second brazing filler metal 50 penetrates the gap between the wire 45 and the outer sleeve 42 and joins them, and in the brazed state shown in Fig. 3(c), the molten second brazing filler metal 50 is joined to the outer sleeve 42 so as to cover the wound wire 45.

[0027] The radio frequency transparent window structure 17 is exposed to high temperatures, for example, of 1000°C or higher, during assembly by brazing the radio frequency transparent window structure 17 itself. It is also exposed to high temperatures of 700°C or higher when the radio frequency transparent window structure 17 and the components of the radio frequency input coupler 10 are subsequently assembled by brazing. It is also exposed to high temperatures, for example, during baking performed after completion. Because the thermal expansion coefficients of the radio frequency transparent window 40 and the outer sleeve 42 are different, tensile stress is generated in the radio frequency transparent window 40 near the joint surface between the radio frequency transparent window 40 and the outer sleeve 42 when the temperature rises during brazing or baking. To prevent this, when assembling the radio frequency transparent window structure 17, the radio frequency transparent window 40 and the outer sleeve 42 are brazed together with a wire 45, which has a low thermal expansion coefficient, wrapped around the outside of the outer sleeve 42.

[0028] However, if the wound wire 45 loosens after the radio frequency transmitting window 40 and the outer sleeve 42 are brazed together, when the temperature rises due to subsequent brazing or baking after the product is completed, the outer sleeve 42 will have a larger amount of thermal expansion, and tensile stress will be generated in the radio frequency transmitting window 40 near the joint surface between the radio frequency transmitting window 40 and the outer sleeve 42.As a result, cracks will occur from the edge of the joint surface between the radio frequency transmitting window 40 and the outer sleeve 42 toward the inside of the radio frequency transmitting window 40, and these cracks will penetrate the radio frequency transmitting window 40, potentially causing the radio frequency input coupler 10 to lose its airtightness.

[0029] In the radio frequency transparent window structure 17 of this embodiment, a wire 45 is wound around the outer periphery of the portion of the outer sleeve 42 where the radio frequency transparent window 40 is joined, and this wire 45 is joined to the outer sleeve 42 with the second brazing material 50. Therefore, the wire 45 does not loosen after the radio frequency transparent window 40 and the outer sleeve 42 are brazed together. When the temperature rises due to subsequent brazing or baking after the product is completed, tensile stress is less likely to occur in the radio frequency transparent window 40 near the joint surface between the radio frequency transparent window 40 and the outer sleeve 42, and as a result, vacuum leaks caused by this are less likely to occur.

[0030] Furthermore, since the second brazing material 50 that joins the wire 45 to the outer sleeve 42 is the same type as the first brazing material 48 that joins the high-frequency transparent window 40 to each sleeve 41, 42, brazing can be performed simultaneously in the brazing process of the high-frequency window structure 17 itself.

[0031] Next, FIG. 4 shows a high-frequency amplifier 60 as a second embodiment.

[0032] Figure 4 shows a multi-beam klystron as an example of a high-frequency amplifier 60. The multi-beam klystron comprises an amplifier body 61 and a focusing magnetic field device (not shown) that is arranged around the amplifier body 61 and focuses an electron beam 62 traveling within the amplifier body 61. In Figure 4, 63 denotes the central axis of the multi-beam klystron.

[0033] The amplifier main body 61 includes an electron gun section 64 that generates multiple electron beams 62 on a circumference of a predetermined radius from a central axis 63, a high-frequency interaction section 65 that amplifies high-frequency power through the interaction between the electron beams 62 and a high-frequency electric field, an input section 66 that inputs high-frequency power to the high-frequency interaction section 65, an output section 67 that outputs the amplified high-frequency power from the high-frequency interaction section 65, and a collector section 68 that captures the electron beams 62 that have passed through the high-frequency interaction section 65.

[0034] The high-frequency interaction section 65 has a plurality of drift tubes 70, each arranged on a circumference of a predetermined radius from the central axis 63, through which the electron beams 62 pass, and a plurality of resonant cavities 71 connected to the drift tubes 70 along the traveling direction of the electron beams 62. The resonant cavities 71 include an input cavity 72 to which the input section 66 is connected, a plurality of intermediate cavities 73, and an output cavity 74 to which the output section 67 is connected.

[0035] A radio frequency transparent window structure 77 is provided in the output section 67 via a waveguide 76. The radio frequency transparent window structure 77 includes a holeless, circular plate-shaped radio frequency transparent window 78 that serves as an output window, and an outer sleeve 79 that is joined to the outer periphery of this radio frequency transparent window 78.

[0036] A wire 80 is wound around the outer periphery of the portion of the outer sleeve 79 to which the radio frequency transparent window 78 is joined, and this wire 80 is joined to the outer sleeve 79 by brazing.

[0037] In this case, too, in the radio frequency transparent window structure 77, the wire 80, which is the retaining member 44, is wound around the outer periphery of the portion of the outer sleeve 79 where the radio frequency transparent window 78 is joined, and this wire 80 is joined to the outer sleeve 79 by brazing. Therefore, the wire 80 does not loosen, and when the temperature rises due to subsequent brazing or baking after the product is completed, tensile stress is less likely to occur in the radio frequency transparent window 78 near the joint surface between the radio frequency transparent window 78 and the outer sleeve 79, and as a result, vacuum leaks caused by this are less likely to occur.

[0038] The holding member 44 is not limited to the wire 45, but may be in the form of a plate or a band.

[0039] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0040] 10 High frequency input coupler 16 Combiner body 17 High frequency transparent window structure 40 High frequency transparent window 42 Outer sleeve 44 Retaining member 47 1st bonding material 49 Second bonding material 60 High Frequency Amplifier 61 Amplifier body 67 Output section 77 High frequency transparent window structure 78 High frequency transparent window 79 Outer sleeve

Claims

1. a radio frequency transparent window; an outer sleeve joined to the outer periphery of the radio frequency transparent window; a holding member wound around an outer periphery of a portion of the outer sleeve to which the high frequency transparent window is joined and joined to the outer periphery of the outer sleeve; A high frequency transparent window structure comprising:

2. a first bonding material that bonds the outer sleeve to an outer periphery of the high frequency transparent window; a second bonding material that bonds the holding member to the outer periphery of the outer sleeve; Equipped with The first bonding material and the second bonding material are of the same type.

2. The high frequency transparent window structure according to claim 1.

3. a coupler body; a high-frequency transparent window structure according to claim 1 or 2, which is provided in the coupler body; A high-frequency input coupler comprising:

4. an amplifier body that amplifies high frequency waves; an output section that outputs the high frequency wave amplified by the amplifier body; a high-frequency transmitting window structure according to claim 1 or 2 provided in the output section; A high-frequency amplifier comprising:

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