CN111156141A

CN111156141A - Large-emission-current hollow cathode

Info

Publication number: CN111156141A
Application number: CN201911362861.3A
Authority: CN
Inventors: 谷增杰; 郭宁; 杨威; 贾艳辉
Original assignee: Lanzhou Institute of Physics of Chinese Academy of Space Technology
Current assignee: Lanzhou Institute of Physics of Chinese Academy of Space Technology
Priority date: 2019-12-26
Filing date: 2019-12-26
Publication date: 2020-05-15
Anticipated expiration: 2039-12-26
Also published as: CN111156141B

Abstract

The invention provides a large-emission-current hollow cathode which comprises a reserve type emitter, a cathode tube, a porous plug, a heater, a multi-layer heat-preservation heat-shielding cylinder, ceramics, a touch electrode, a mounting flange and an air inlet pipe, wherein the reserve type emitter is arranged on the cathode tube; the reserve type emitter is a cylinder, and axial through holes are uniformly distributed along the circumferential direction; the cathode tube is fixedly connected with the air inlet tube with the edge to form a cup-shaped part; the reserve type emitter is fixedly connected with the inner wall of the cup-shaped piece, and the bottom surface of the reserve type emitter is communicated with the air inlet pipe through the porous plug; a heater is arranged on the outer circumference of the cathode tube, and heat is preserved through a plurality of layers of heat preservation heat shielding cylinders on the periphery of the heater; the touch electrode is connected with the mounting flange through ceramic insulation to form a mounting space of a cup-shaped piece, a heater and a multilayer heat-preservation heat-shielding cylinder, an air inlet pipe of the cup-shaped piece penetrates through the mounting flange to be communicated with the outside, a cup opening of the cup-shaped piece is opposite to the touch electrode, a touch electrode hole in the top of the touch electrode is coaxial with the axial through hole, and electronic current is led out. The invention improves the emission capability and realizes the large emission current of the hundred ampere level.

Description

Large-emission-current hollow cathode

Technical Field

The invention relates to the technical field of electric propulsion systems, in particular to a large-emission-current hollow cathode.

Background

The large-emission current hollow cathode is the core of a large-power and ultra-high-power space electric propulsion system, is limited by the direct-current emission capacity of an electron emission substance under the condition of the prior art, and is difficult to improve the electron emission capacity of the hollow cathode to 100A magnitude by depending on the prior single-discharge channel hollow cathode technology. The barium-tungsten emitter needs to use a tungsten sponge body to be soaked with barium salt to store an emitting substance, and under the condition of the prior art, the uniformity and consistency of holes of a large-size tungsten sponge body are difficult to guarantee, so that the requirement for developing a large-emission-current hollow cathode in a Baian level cannot be met.

Disclosure of Invention

In view of this, the invention provides a hollow cathode with large emission current, which improves the emission capability and realizes large emission current of hundred amperes.

The technical scheme adopted by the invention is as follows:

a large-emission-current hollow cathode comprises a reserve type emitter, a cathode tube, a porous plug, a heater, a multi-layer heat-preservation heat-shielding cylinder, ceramics, a touch electrode, a mounting flange and an air inlet tube;

the reserve type emitter is a cylinder, and axial through holes are uniformly distributed along the circumferential direction; the cathode tube is fixedly connected with the air inlet tube with the edge to form a cup-shaped part; the reserve type emitter is fixedly connected to the inner wall of the cup-shaped piece, and the bottom surface of the reserve type emitter is communicated with the air inlet pipe through the porous plug; a heater is arranged on the outer circumference of the cathode tube, and heat is preserved through a plurality of layers of heat preservation heat shielding cylinders on the periphery of the heater; touch and hold utmost point and mounting flange and pass through ceramic insulation and be connected, form the installation space of a cup-shaped piece, heater, a multilayer heat preservation heat shield section of thick bamboo, the intake pipe of cup-shaped piece passes mounting flange and external intercommunication, the cup-shaped piece rim of a cup with touch and hold extremely relatively, touch that hold utmost point top and hold utmost point hole coaxial with axial through-hole, draw electronic current.

Further, the heater comprises a heating wire, an annular framework, a ceramic outer sleeve, a heating lead and a ceramic tube;

the heating wire is wound on the annular framework, a heating lead passes through the multilayer heat-preservation heat-shielding barrel and is connected with one end of the heating wire, and meanwhile, the contact part of the heating lead and the multilayer heat-preservation heat-shielding barrel is insulated through a ceramic pipe; the outer circumference of the annular framework is provided with a ceramic coat.

Further, the multilayer heat-preservation heat shield cylinder comprises a heat shield top plate, a heat shield cylinder, a circumferential heat shield and a bottom heat shield;

the heat shield top plate is in a ring shape and is fixed at the open end of the heat shield cylinder, and the circumferential heat shield is arranged inside the heat shield cylinder and is spaced from the heat shield cylinder by a certain distance; the bottom heat shield is arranged at the closed end of the heat shield cylinder and is spaced from the bottom surface of the heat shield cylinder by a certain distance.

Further, the reserve type emitter comprises a cathode top plate, an emitter barrel, an emitting substance, a tungsten sponge body and an emitter bottom plate;

the cathode top plate and the emitter bottom plate are fixed at two ends of the emitter barrel, the cylindrical tungsten sponge bodies are uniformly distributed in the emitter barrel along the circumferential direction, the inner surface of the tungsten sponge body is an electron emission surface, and emission substances are contained between the tungsten sponge body and the emitter barrel; and the cathode top plate is provided with a throttling hole, the emitter bottom plate is provided with an air inlet hole, and the throttling hole and the air inlet hole are coaxial with the tungsten sponge body.

Has the advantages that:

1. the invention increases the area of the emitting surface by utilizing the reserve type emitter with the axial through holes uniformly arranged along the circumferential direction, improves the emitting capability, realizes the large emitting current of the hundred ampere level by combining the heating and heat preservation functions of the heater and the multilayer heat preservation heat screen cylinder, does not introduce other complex processes, and has stronger realizability.

2. The reserve type emitter adopts a plurality of tungsten sponge bodies which are uniformly distributed in the circumferential direction to form an electron emission surface, and large-size tungsten sponge bodies do not need to be processed; and more emission materials are reserved in the cavity inside the emitter, and along with the consumption of the emission materials inside and on the surface of the tungsten sponge body, the reserved emission materials can be timely supplemented to the surface of the tungsten sponge body through a diffusion process, so that the coverage of the emission materials on the electron emission surface is maintained, and the foundation for ensuring the service life of the large-emission-current hollow cathode is provided.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIGS. 2(a) and (b) are a sectional view and a left side view of the reserve type projectile, respectively;

wherein, 1-cathode top plate; 2-orifice; 3-a projectile cartridge; 4-an emissive substance; 5-a tungsten sponge body; 6-emitter backplane; 7-air inlet holes; 8-a contact-holding pole hole; 9-a touch electrode; 10-a heat shield top plate; 11-a heat shield cylinder; 12-circumferential heat shield; 13-heating the ceramic tube; 14-bottom heat shield; 15-heating wire leading; 16-a contact-holder insulating ceramic; 17-mounting flange; 18-a fastener; 19-heating wire insulating ceramic; 20-an air inlet pipe; 21-a porous plug; 22-cathode tube; 23-heating wires; 24-an annular threaded skeleton; 25-ceramic jacket.

Detailed Description

The invention is described in detail below by way of example with reference to the accompanying drawings.

The embodiment provides a large-emission-current hollow cathode which comprises a reserve type emitter, a cathode tube 22, a porous plug 21, a heater, a multi-layer heat-preservation heat shield cylinder, a touch electrode insulating ceramic 16, a touch electrode 9, a fastener 18, a mounting flange 17 and an air inlet pipe 20.

As shown in fig. 1, the cathode tube 22 is fixedly connected with the air inlet tube 20 with the edge to form a cup-shaped member, the reserve type emitter is fixedly connected with the inner wall of the cup-shaped member, and the bottom surface of the reserve type emitter, namely the emitter bottom plate 6 is communicated with the air inlet tube 20 through the porous plug 21; a heater is arranged on the outer circumference of the cathode tube 22, and heat is preserved through a plurality of layers of heat preservation heat shielding cylinders on the periphery of the heater; the touch holding pole 9 is of a cylindrical structure with one open end, the open end is in insulated connection with the mounting flange 17 through touch holding pole insulating ceramic 16, the three are fixedly connected through a fastener 18 to form a cup-shaped piece, a heater and a mounting space of the multilayer heat-preservation heat-shielding cylinder, the air inlet pipe 20 penetrates through the mounting flange 20 to be communicated with the outside, the cup opening of the cup-shaped piece is opposite to the touch holding pole 9, the touch holding pole 9 is provided with a touch holding pole hole 8 at the closed end, the touch holding pole hole 8 is coaxial with the tungsten sponge body 5 of the reserve type emitter in the cup-shaped piece, and electronic current is led.

The reserve type emitter comprises a cathode top plate 1, an emitter barrel 3, an emitting material 4, a tungsten sponge body 5 and an emitter bottom plate 6; the cathode top plate 1 is made of high-purity high-density metal tungsten, and the material is high-temperature resistant and strong in ion sputtering resistance; the emitter barrel 3 and the emitter soleplate 6 can adopt high-temperature resistant materials such as tantalum or molybdenum-rhenium alloy and the like; the emissive substance 4 may be an electron emissive substance such as a ternary aluminate or scandate, and the emissive substance 4 may be diffused to the inner surface of the tungsten sponge body through the porous tungsten sponge body 5 to form an electron emissive surface having a low work function on the inner surface.

As shown in fig. 2(a) and (b), the cathode top plate 1 and the emitter bottom plate 6 are fixed at two ends of the emitter barrel 3, the cylindrical tungsten sponge bodies 5 are uniformly distributed in the emitter barrel 3 along the circumferential direction, and the emitting material 4 is contained between the tungsten sponge bodies 5 and the emitter barrel 3; an orifice 2 is processed on the cathode top plate 1 to keep the inside of the emitter to have higher gas density; an air inlet hole 7 is processed on the emitter bottom plate 6, and the throttling hole 2 and the air inlet hole 7 are coaxial with the tungsten sponge body 5.

The heater comprises a heating wire 23, an annular thread framework 24, a ceramic outer sleeve 25, a heating lead 15 and a heating wire ceramic tube 13; the heating wire 23 is wound on the annular thread framework 24, the heating lead 15 penetrates through the heat shield cylinder 11 and the bottom heat shield 14 of the multi-layer heat-insulation heat shield cylinder to be connected with one end of the heating wire 23, meanwhile, the contact parts of the heating lead 15, the heat shield cylinder 11 and the bottom heat shield 14 are insulated through the outer sleeve heating wire ceramic tube 13, the heating lead 15 penetrates through the contact electrode insulating ceramic 16 and the mounting flange 17 to be connected with an external power supply, and the contact parts of the heating lead 15 and the mounting flange 17 are insulated through the outer sleeve heating wire insulating ceramic 19; the outer circumference of the annular thread framework 24 is provided with a ceramic coat 25.

The multilayer heat-preservation heat shield cylinder comprises a heat shield top plate 10, a heat shield cylinder 11, a circumferential heat shield 12 and a bottom heat shield 14; the heat shield top plate 10 is annular and is fixed at the open end of the heat shield cylinder 11, and the circumferential heat shield 12 is arranged inside the heat shield cylinder 11 and is spaced from the heat shield cylinder 11 by a certain distance; the bottom heat shield 14 is arranged at the closed end of the heat shield cylinder 11 and is spaced from the bottom surface of the heat shield cylinder 11 by a certain distance.

The coaxial arrangement of each tungsten sponge body 5, the throttling hole 2 and the contact electrode hole 8 ensures that the temperature distribution of each tungsten sponge body 5 is the same when the hollow cathode works, and the electronic current led out from each hole is uniformly distributed. Hollow cathodes with different emission currents can be obtained by designing the inner diameter and the number of the tungsten sponge bodies 5.

In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A large-emission-current hollow cathode is characterized in that the hollow cathode comprises a reserve type emitter, a cathode tube, a porous plug, a heater, a multi-layer heat-preservation heat-shielding cylinder, ceramics, a touch electrode, a mounting flange and an air inlet pipe;

2. The large emission current hollow cathode according to claim 1, wherein the heater comprises a heating wire, an annular frame, a ceramic sheath, a heating lead wire and a ceramic tube;

3. The large emission current hollow cathode according to claim 1, wherein said multi-layer heat shield cylinder comprises a heat shield top plate, a heat shield cylinder, a circumferential heat shield, and a bottom heat shield;

4. The large-emission current hollow cathode according to claim 1, wherein the reserve emitter comprises a cathode top plate, an emitter barrel, an emitting material, a tungsten sponge body and an emitter bottom plate;