RU2479884C2 - Axial electron gun - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: into an axial electron gun, comprising a cathode block, a filament unit with a tungsten spiral, an emitter, a focusing electrode, an anode, a magnetic system, a holder is introduced, which is arranged coaxially with the central axis of the gun, at one end of which there is an emitter arranged, and the opposite end is connected with the cathode block, the holder is arranged in the form of a hollow cylinder from a refractory metal, the side surface of which is perforated, and one of cylinder ends is connected with the cathode block by means of threading, the anode is made in the form of an insert connected with a water-cooled anode body with the help of threading, the focusing electrode is connected with the cathode block by means of threading, the magnetic system is arranged in the form of a short magnetic lens.

EFFECT: provision of stability of current and parameters of an electronic beam under conditions of performance of long-term technological processes, increased efficiency of using a gun, reduced negative effect of thermal speeds of electrons emitted with an emitter, resulting in smearing of bundle borders, increased laminarity of an electronic beam.

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Description

The invention relates to the field of coating, heating and melting of metal in vacuum.

There are known designs of axial guns, where the tasks of increasing the cathode service life are solved: Z. Schiller, U. Gising, Z. Papzer. Electron beam technology. Per. with him. M .: Energy, 1980.

A known electron gun containing a cylindrical insulator mounted coaxially with it is a cylindrical cathode assembly body, at the end of which a cathode disk electrode with a central hole is mounted, a tablet cathode mounted on the cathode electrode, and an anode characterized in that, in order to increase reliability and resource work due to the additional mutual alignment of the cathode and the anode and stabilization of the cathode position in the housing, a cylindrical potential quote screen is located in the gun, which is located on the outer surface of the cathode body can be moved along the axis of the gun, the cathode electrode is made with a radial clearance with respect to the tablet cathode, and an annular groove is made on the surface of the anode facing the cathode, the diameter of which is equal to the diameter of the end part of the adjustment screen. Patent of the Russian Federation No. 1572328, IPC: H01J 37/06, 1995

Known axial electron gun containing a thermal cathode, cathode assembly, heating the spiral cathode, anode, beam guide, magnetic lenses, scanning system, power source and vacuum system, characterized in that to maintain a given electronic thermal emission, the thermal cathode is constantly located on the central axis of the gun in a horizontal plane with the help of three spiral torsions located at an angle of 120 ° relative to each other and holding the thermal cathode along an annular groove on its lateral surface. Patent of the Russian Federation No. 2364980, IPC: H01J 37/065, 2009

Known electron injector containing a pumping system with a built-in getter pump and a cylindrical body in which there is an axial electron gun with a thermal cathode installed in a ceramic insulator on the anode flange, a solenoid covering the beam path, a working chamber and an accelerating voltage source connected to the cathode, in which the anode flange is made in the form of a cylindrical cavity into which a magnetic discharge pump of the pumping system is integrated, containing three plane-parallel lattice electrodes coaxial with by taking into account holes connected to an additional power source, the getter pump being located behind the magnetic discharge pump and covering the beam path coaxially with the injector body, and the height of the solenoid is not less than the distance from the cathode to the outlet of the getter pump. Patent of the Russian Federation No. 1447256, IPC: Н05Н 5/02, 1995. Prototype.

Known axial electron guns have several disadvantages that limit their stable long-term operation:

due to the influence of high operating temperatures, the thermal cathode may be displaced relative to the optical axis and the focus of the electron beam may be disturbed; at high temperatures, spiral tungsten torsions become embrittle and break; the formation of an electron beam in the drift space is carried out by several magnetic lenses, which are a bulky heavy system that complicates the operation of the gun.

This invention eliminates the disadvantages of analogues and prototype.

The technical task is to obtain a stable electron beam in a wide range of power values supplied to the axial electron gun, and to increase the efficiency of the gun.

The technical result of the invention is to ensure the stability of the current and the parameters of the electron beam in the conditions of long-term technological processes, increasing the efficiency of use of the gun; suppression of transverse thermal velocities of electrons in the accelerating gap of the emitter-anode of the gun and increasing the laminarity of the electron beam.

The technical result is achieved by the fact that in an axial electron gun containing a cathode block, a filament assembly with a tungsten helix, an emitter, a focusing electrode, an anode and a magnetic system, a holder is installed coaxially with the central axis of the gun, an emitter is placed at one end of the holder, and the opposite the end is connected to the cathode block, and the holder is made in the form of a hollow cylinder of refractory metal, the side surface of which is perforated, and one of the ends of the cylinder is connected to the cathode block in the middle Twomey thread, a magnetic system made in the form of a short magnetic lens, the anode is configured as an insert, coupled to the water cooled anode body by threads, a focusing electrode is connected to the cathode block by a screw.

The invention is illustrated in figure 1.

Figure 1 shows a structural diagram of an axial electron gun, where 1 is a basic high-voltage insulator, 2 is a cathode block, 3 is a filament assembly, 4 is a tungsten spiral, 5 is a screen, 6 is a hollow cylinder, 7 is an emitter, 8 is a focusing electrode , 9 — anode insert, 10 — water-cooled anode body, 11 — short magnetic lens.

Figure 2 shows the appearance of an axial electron gun.

Figure 3 shows a photograph of an electron beam in the drift space.

Axial electron gun works as follows.

The main elements of the axial electron gun: cathode block 2, filament assembly 3, tungsten spiral 4, screen 5, hollow cylinder 6 and emitter 7, are protected by a base high-voltage insulator 1.

The emitter 7 is heated by bombardment by electrons emitted by a heated flat tungsten spiral 4 when an accelerating voltage is applied between the spiral 4 and the emitter 7. The formation of the electron beam and its conduction in the drift space is carried out by a short magnetic lens 11. The magnetic lines of force of the magnetic lens 11 coincide with the electron paths (magnetic beam tracking) in the space emitter 7 - anode 9, 10 of the electron gun, which suppresses the transverse thermal velocities of the emitted electrons and is improved ju laminar electron flow.

In addition, the magnetic lens 11 serves to form an extended electron beam with a small angular divergence in the drift space. The emitter 7 and the focusing electrode 8 are under the same negative potential of 10 kV. The spherical shape of the working surface of the emitter 7, the focusing electrode 8, the anode insert 9, located in the body of the anode 10, cooled by water and a short magnetic lens 11 provide focusing of the electron beam with minimal power loss.

In case of failure of the emitter 7 or coil 4, the cylinder 6 is turned out of the cathode block 2 and the emitter 7 or coil 4 is replaced. Then the hollow cylinder 6 is set to its previous position. In this case, the emitter 7 occupies a standard position, ensuring complete preservation of interelectrode gaps and alignment of the optical system.

Due to threaded connections, the axial electron gun is quickly assembled and does not require adjustment. Elements of the optical system occupy a standard position and the parameters of the gun are stable.

The working electron acceleration voltage is 10 kV. The power of the electron beam is changed by the voltage between the tungsten spiral 4 and the emitter 7 at a constant current of the spiral 4.

The axial electron gun was tested for sixteen hours of continuous operation at a maximum electron beam power of 10 kW.

During this time, the parameters of the axial electron gun did not undergo any changes, breakdowns by high voltage were absent. The lifetime of spiral 4 or emitter 7 is ~ 300 hours.

The axial electron gun is installed in the vacuum working chamber or outside it, depending on the technological process scheme. In the second case, differential pumping is used, which ensures stable gun operation when the process gas is poured into the working chamber to a pressure of 1.3 × 10 ^-1 Pa.

Claims (1)

An axial electron gun containing a cathode block, a filament assembly with a tungsten helix, an emitter, a focusing electrode, an anode and a magnetic system, characterized in that the holder has a holder located coaxially with the central axis of the gun, at one end of which there is an emitter, and the opposite end connected to the cathode block, and the holder is made in the form of a hollow cylinder of refractory metal, the side surface of which is perforated, and one of the ends of the cylinder is connected to the cathode block by a thread, itnaya system is designed as a short magnetic lens, and the anode is configured as an insert, coupled to the water cooled anode body by threads, a focusing electrode is connected to the cathode block by a screw.

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