JP2017022051A - Impregnation type cathode body structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impregnation type cathode body structure which prevents first and second reflectors or an insulation material from being deteriorated.SOLUTION: A support inner cylinder 23 and a support outer cylinder 24 are provided on a rear face 11a of a cathode base 11, and a housing space 25 is formed between the support inner cylinder 23 and the support outer cylinder 24. An insulation material 14 is provided in the housing space 25, and a heater 13 is embedded in the insulation material 14. The support inner cylinder 23 includes a protrusion 26 that protrudes from a front face 14a of the insulation material 14. First and second reflectors 15 and 16 are formed in an annular shape including openings 37 and 37 and successively disposed oppositely to the front face 14a of the insulation material 14 while fitting their inner diameter sides to a peripheral surface of the protrusion 26. A spacer 39 is fitted to the peripheral surface of the protrusion 26 and interposed between the inner diameter side of the first reflector 15 and the inner diameter side of the second reflector 16. A fixing member 41 is fixed to the protrusion 26 while holding the inner diameter side of the first reflector 15, the spacer 39 and the inner diameter side of the second reflector 16 between the fixing member and the front face 14a of the insulation material 14.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an impregnated cathode assembly used in an electron gun of a microwave electron tube.

  An electron gun having an impregnated cathode structure is used in a microwave electron tube that converts direct current electron energy such as a klystron or a gyrotron into microwave power.

  For example, an impregnated cathode assembly used in an electron gun of a klystron has a cathode substrate, a support, a heater, an insulating material, a first reflector, a second reflector, and the like.

  An electron emitting surface impregnated with an electron emitting substance is formed on the cathode substrate.

  The support is provided on the back surface opposite to the electron emission surface of the cathode base, and plays a role of storing the heater and the insulating material in a storage space formed inside in addition to supporting the cathode base. The support has a support outer cylinder and a support inner cylinder that respectively protrude from the back surface of the cathode base. The support inner cylinder and the support outer cylinder are arranged coaxially (concentrically), and an annular storage space is formed between the support inner cylinder and the support outer cylinder.

  The heater is housed in the housing space and plays a role of heating the cathode substrate through the insulating material.

  The insulating material is filled in the storage space in which the heater is stored without a gap. The insulating material plays a role of holding the heater stored in the storage space in addition to transferring heat from the heater to the cathode base.

  The first reflecting plate and the second reflecting plate are disposed so as to face the surface of the insulating material. The first reflector and the second reflector serve to suppress heat dissipation from the surface of the insulating material and increase the heating efficiency of the cathode substrate.

  And the 1st reflecting plate is joined to the support outer cylinder and the support inner cylinder by arc welding so that the surface of an insulating material may be covered. The second reflecting plate is disposed outside the first reflecting plate via a cylindrical spacer, and is joined to the first reflecting plate by arc welding.

  However, since the first reflector and the second reflector are, for example, molybdenum (Mo) thin discs, they are embrittled by thermal stress or recrystallization caused by arc welding. In addition, since the support inner cylinder and the support outer cylinder are melted, the insulating material in the storage space may react and the insulation strength may deteriorate.

JP 2011-129361 A

  The problem to be solved by the present invention is to provide an impregnated-type cathode assembly that can prevent deterioration of the first and second reflectors and the insulating material.

  The impregnated-type cathode assembly of the present embodiment includes a cathode base, a support, an insulating material, a heater, a protrusion, first and second reflectors, a spacer, and a fixing member. The cathode substrate has an electron emission surface impregnated with an electron emission material. The support has a support inner cylinder and a support outer cylinder provided on the back surface opposite to the electron emission surface of the cathode substrate, and a storage space is formed between the support inner cylinder and the support outer cylinder. . The insulating material is provided in the storage space. The heater is embedded in the insulating material. The protruding portion is provided on the supporting inner cylinder so as to protrude from the surface of the insulating material exposed from between the supporting inner cylinder and the supporting outer cylinder. The first and second reflectors are each formed in an annular shape having an opening, and the inner diameter side is fitted to the peripheral surface of the protruding portion, and are sequentially arranged so as to face the surface of the insulating material. The spacer is fitted to the peripheral surface of the protrusion and is interposed between the inner diameter side of the first reflecting plate and the inner diameter side of the second reflecting plate. The fixing member is fixed to the protruding portion with the inner diameter side of the first reflecting plate, the inner diameter side of the spacer and the second reflecting plate being sandwiched between the surface of the insulating material.

It is the side view which notched a part of impregnation-type cathode structure which shows one Embodiment. It is the perspective view which notched a part of the impregnation type cathode structure same as the above.

  Hereinafter, an embodiment will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the impregnated-type cathode assembly 10 is a cathode assembly used in an electron gun of a klystron. The impregnated-type cathode assembly 10 includes a cathode substrate 11, a support 12, a heater 13, an insulating material 14 that is an embedded material, first and second reflecting plates 15 and 16, a reflecting cylinder 17, and the like. Hereinafter, in the impregnated-type cathode assembly 10, the side on which the cathode base 11 is provided is referred to as one end, and the opposite side to the cathode base 11 is referred to as the other end.

The cathode substrate 11 is made of, for example, porous tungsten (W) having a porosity of 15 to 20%. The cathode substrate 11 is formed in a disk shape having a diameter of 70 mm, for example. On the surface on one end side of the cathode substrate 11, an electron emission surface 20 that is recessed in a curved shape with a predetermined curvature is formed. The holes of the cathode substrate 11 are impregnated with an electron emitting material including, for example, barium oxide (BaO), calcium oxide (CaO), and aluminum oxide (Al ₂ O ₃ ).

  When the electron emitting surface 20 is processed, the pores of the cathode substrate 11 are easily crushed, and the electron emitting substance may not be sufficiently impregnated in the cavities due to the crushing. In order to prevent this, it is preferable to impregnate the holes in the cathode base 11 with plastic before processing the electron emission surface 20 and to scatter the plastic after processing the electron emission surface 20. For example, when the cathode substrate 11 is heated in a hydrogen atmosphere or under vacuum, the plastic impregnated in the cathode substrate 11 is scattered. After the plastic is thus scattered, the holes of the cathode substrate 11 may be impregnated with an electron emitting substance.

  Further, the support 12 has a support inner cylinder 23 and a support outer cylinder 24. The support inner cylinder 23 and the support outer cylinder 24 are each made of, for example, molybdenum (Mo) and formed in a cylindrical shape. The support inner cylinder 23 and the support outer cylinder 24 are arranged coaxially (concentrically). An annular storage space 25 is formed between the support inner cylinder 23 and the support outer cylinder 24. The support inner cylinder 23 is formed to have a diameter of 20 mm, an axial length of 20 mm or more, and a plate thickness of 2 mm, for example.

  One ends of the support inner cylinder 23 and the support outer cylinder 24 are joined to the back surface 11 a of the cathode base 11. Specifically, one end of the support inner cylinder 23 and the support outer cylinder 24 and the back surface 11a of the cathode base 11 are brazed and bonded using, for example, a ruthenium-molybdenum (Ru-Mo) alloy. Here, the back surface 11 a of the cathode substrate 11 is a surface opposite to the electron emission surface 20. Therefore, one end side of the storage space 25 is closed by the back surface 11a of the cathode base 11, and the other end side of the storage space 25 is opened. The support 12 supports the cathode base 11 and further stores the heater 13 and the insulating material 14 in the storage space 25.

  At the other end of the supporting inner cylinder 23, a protruding portion 26 protruding from the surface 14a of the insulating material 14 stored in the storage space 25 is provided. That is, the protrusion 26 is integrally formed with the support inner cylinder 23. The protruding portion 26 of the supporting inner cylinder 23 protrudes from the supporting outer cylinder 24. Here, the surface 14a of the insulating material 14 is the surface of the insulating material 14 exposed from between the supporting inner cylinder 23 and the supporting outer cylinder 24, and is the surface of the insulating material 14 opposite to the cathode base 11 It is.

  The heater 13 is a filament formed in a linear shape, for example, a tungsten (W) wire having a diameter of 1.5 mm. An intermediate portion (heat generating portion) 29 of the heater 13 is wound in a coil shape and stored in the storage space 25 of the support 12. The winding shaft of the intermediate portion 29 of the heater 13 extends, for example, in the circumferential direction of the support 12. The heater 13 plays a role of heating the cathode base 11 via the insulating material 14.

  An end 30 on one end side of the heater 13 is electrically connected to the support inner cylinder 23. Therefore, the heater 13, the support 12 (the support inner cylinder 23 and the support outer cylinder 24), and the cathode base 11 are at the same potential.

  An end portion 31 on the other end side of the heater 13 extends through the alumina tube 32 to the outside of the impregnated-type cathode assembly 10 and is connected to a power supply device (not shown). The alumina tube 32 is provided to prevent the heater 13 from breaking near the surface 14a of the insulating material 14, and to insulate the heater 13 from the first and second reflectors 15 and 16. Yes.

  The insulating material 14 is, for example, an alumina sintered body, and fills the storage space 25 in which the intermediate portion 29 that is the heat generating portion of the heater 13 is stored without any gap. The surface 14a of the insulating material 14 is formed substantially flush with the other end of the support outer cylinder 24. The insulating material 14 plays a role of holding the heater 13 stored in the storage space 25 in addition to transferring the heat from the heater 13 to the cathode base 11.

  As shown in FIGS. 1 and 2, the first reflecting plate 15 is made of, for example, molybdenum (Mo), and is formed in a disc shape having an opening 35 at the center. The first reflecting plate 15 is disposed so that the inner diameter side is fitted to the outer peripheral surface of the protruding portion 26 and faces the surface 14 a of the insulating material 14. That is, the first reflecting plate 15 has the opening 35 fitted into the outer peripheral surface of the protruding portion 26 from the tip end side of the protruding portion 26 of the supporting inner cylinder 23, and the surface 14 a of the insulating material 14 and the end surface of the supporting outer cylinder 24. It is arranged to touch. A hole 36 through which the alumina tube 32 passes is formed in the first reflecting plate 15.

  The second reflecting plate 16 is made of, for example, molybdenum (Mo) and is formed in a disc shape having an opening 37 at the center. The second reflecting plate 16 is disposed so that the inner diameter side is fitted to the outer peripheral surface of the protruding portion 26 and faces the surface 14 a of the insulating material 14 through the first reflecting plate 15. That is, the second reflecting plate 16 has an opening 37 fitted to the outer peripheral surface of the projecting portion 26 from the front end side of the projecting portion 26 of the supporting inner cylinder 23, and has a predetermined distance from the first reflecting plate 15. It is arranged with a gap. The second reflecting plate 16 is formed with a hole 38 through which the alumina tube 32 passes.

  And between the inner diameter side of the first reflecting plate 15 and the inner diameter side of the second reflecting plate 16, the first reflecting plate 15 and the second reflecting plate 16 are held with a predetermined interval. A spacer 39 is interposed. The spacer 39 is made of metal and is formed in a ring shape having an opening 40 in the center. In the spacer 39, the opening 40 is fitted to the outer peripheral surface of the protruding portion 26 from the distal end side of the protruding portion 26 of the supporting inner cylinder 23. One end surface of the spacer 39 abuts on the inner diameter side of the first reflecting plate 15, and the other end surface abuts on the inner diameter side of the second reflecting plate 16.

  The inner diameter side of the first reflecting plate 15, the inner diameter side of the spacer 39 and the second reflecting plate 16 are sandwiched between the surface 14 a of the insulating material 14 and the fixing member 41 fixed to the protruding portion 26. The fixing member 41 is made of metal and is formed in a ring shape having an opening 42 in the center. In the fixing member 41, the opening 42 is fitted to the outer peripheral surface of the protruding portion 26 from the distal end side of the protruding portion 26 of the supporting inner cylinder 23. The fixing member 41 is joined to the tip of the protruding portion 26 by, for example, arc welding.

  The reflecting cylinder 17 is made of, for example, a rhenium-molybdenum (Re-Mo) alloy and is formed in a cylindrical shape. The reflection cylinder 17 is fixed to the outer periphery of the support outer cylinder 24 so as to cover the support outer cylinder 24. One end of the reflection cylinder 17 is brazed to the support outer cylinder 24 using, for example, a ruthenium-molybdenum-nickel (Ru-Mo-Ni) alloy. An annular flange member 45 is brazed to the other end of the reflecting cylinder 17 using, for example, a Ru—Mo—Ni alloy. The impregnated-type cathode assembly 10 is fixed to an electron gun portion (not shown) through the flange member 45.

  The first reflector 15, the second reflector 16, and the reflector cylinder 17 serve to suppress the heat radiation generated by the heater 13 from the storage space 25 to the outside and increase the heating efficiency of the cathode substrate 11. Fulfill.

  Next, a method for manufacturing the impregnated cathode assembly 10 will be described.

  First, the support 12 is placed on the back surface 11a of the cathode base 11 that is not impregnated with the electron emitting substance, and a Ru—Mo alloy is applied to the junction between the cathode base 11 and the support 12. At the same time, a Ru—Mo alloy is applied to the back surface 11 a of the cathode substrate 11. After the application, the Ru—Mo alloy is dissolved, the cathode base 11 and the support 12 are joined, and a Ru—Mo alloy film is formed on the back surface 11 a of the cathode base 11. This Ru-Mo alloy film prevents the electron emitting material from oozing out from the back surface 11a of the cathode substrate 11 into the housing space 25 when the electron emitting material 20 is impregnated from the electron emitting surface 20 of the cathode substrate 11. Is.

  Thereafter, the heater 13 is held at a predetermined position in the storage space 25 by a jig, and the storage space 25 is filled with the insulating material 14. This filling of the insulating material 14 is performed by, for example, pouring powdered alumina into an organic solvent containing a binder and stirring it into a storage space 25, and then dispersing the organic solvent by drying. Sintering is performed at a temperature of 1800 to 1850 ° C. in a vacuum or in a hydrogen atmosphere.

  After the insulating material 14 is sintered, the first reflecting plate 15, the spacer 39, the second reflecting plate 16, and the fixing member 41 are fitted in order from the front end side of the protruding portion 26 of the supporting inner cylinder 23. With the inner diameter side of the first reflecting plate 15 and the inner diameter side of the spacer 39 and the second reflecting plate 16 sandwiched between the surface 14a of the insulating material 14 and the fixing member 41, the fixing member 41 and the protruding portion 26 Weld.

  One end of the reflecting cylinder 17 is brazed to the support outer cylinder 24 using a Ru-Mo-Ni alloy. An annular flange member 45 is brazed to the other end of the reflecting tube 17 using a Ru—Mo—Ni alloy.

  Finally, an electron emitting material is placed on the electron emitting surface 20 of the cathode substrate 11, the electron emitting material is melted at a temperature of 1600 to 1700 ° C. in a hydrogen atmosphere, and the electron emitting material is impregnated into the cathode substrate 11, The impregnated cathode assembly 10 is completed.

  According to the impregnated-type cathode assembly 10 of the present embodiment, the first and second reflectors 15 and 16 need only be fitted together with the protrusions 26 of the support inner cylinder 23 together with the spacers 39, and are welded to the support 12. Thus, thermal stress due to welding and embrittlement due to recrystallization are eliminated.

  Generally, when a spacer member is interposed between the first and second reflectors 15 and 16, the spacer member is disposed on the outer diameter side of the first and second reflectors 15 and 16. In many cases, it is necessary to fix the first and second reflectors 15 and 16 to the first and second reflectors 15 and 16, so that they are welded to the first and second reflectors 15 and 16. On the other hand, in this embodiment, the spacer 39 is disposed on the inner diameter side of the first and second reflectors 15 and 16 and is fitted to the outer peripheral surface of the protruding portion 26. Without positioning, positioning can be fixed.

  Further, by welding the fixing member 41 to the tip of the protruding portion 26 of the supporting inner cylinder 23, the first and second reflecting plates 15, together with the spacer 39 between the surface 14a of the insulating material 14 and the fixing member 41, 16 can be fixed in a sandwiched state, and by welding the tip of the protruding portion 26 of the support inner cylinder 23 and the fixing member 41, the insulating material 14 in the storage space 25 can be embrittled or deteriorated in insulation strength due to melting. Can be prevented.

  Moreover, since the spacer 39 is disposed along with the inner diameter sides of the first and second reflectors 15 and 16 while the surface 14a of the insulating material 14 and the fixing member 41 face each other, the surface of the insulating material 14 The first and second reflectors 15 and 16 can be securely held together with the spacer 39 between the spacer 14a and the fixing member 41, and the fixation of the first and second reflectors 15 and 16 can be stabilized. it can.

  Further, since the fixing member 41 is fitted to the peripheral surface of the protruding portion 26 and fixed to the protruding portion 26, the first and second reflecting plates 15, together with the spacer 39, are provided between the surface 14a of the insulating material 14. 16 can be securely clamped and fixed in its clamped state.

  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 Impregnated cathode structure
11 Cathode substrate
11a reverse side
12 Support
13 Heater
14 Insulation material
14a surface
15 First reflector
16 Second reflector
20 Electron emitting surface
23 Support inner cylinder
24 Support outer cylinder
25 Storage space
26 Protrusion
35, 37 opening
39 Spacer
41 Fixing member

Claims (2)

A cathode substrate having an electron emitting surface impregnated with an electron emitting material;
A support body having a support inner cylinder and a support outer cylinder respectively provided on the back surface opposite to the electron emission surface of the cathode base, and a storage space formed between the support inner cylinder and the support outer cylinder When,
An insulating material provided in the storage space;
A heater embedded in the insulating material;
A protrusion provided on the support inner cylinder so as to protrude from the surface of the insulating material exposed from between the support inner cylinder and the support outer cylinder;
First and second reflectors that are each formed in an annular shape having an opening, the inner diameter side of which is fitted to the peripheral surface of the protruding portion, and sequentially disposed so as to face the surface of the insulating material;
A spacer that is fitted to the peripheral surface of the protruding portion and interposed between the inner diameter side of the first reflecting plate and the inner diameter side of the second reflecting plate;
A fixing member fixed to the projecting portion with the inner diameter side of the first reflecting plate and the inner diameter side of the spacer and the second reflecting plate sandwiched between the insulating material and the surface of the insulating material. An impregnated cathode structure characterized by the above. The impregnated-type cathode assembly according to claim 1, wherein the fixing member is fitted to a peripheral surface of the protruding portion and fixed to the protruding portion.

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