AXIAL ELECTRON GUN

Abstract

The invention relates to the field of fabrication of new materials and coatings and may be used in plants designed for electron-beam heating, melting and evaporating of materials in vacuum or reactive gas atmosphere. The disclosed axial electron gun that comprises, in particular, the primary and secondary cathodes and features the figure-shaped holder used for maintaining a stable position of the secondary cathode relative to the electron-beam axis of the axial gun and the pulsed voltage that is applied between the cathodes for electron bombardment of the secondary cathode. The invention ensures an improved stability of process parameters and operation of the electron gun.

Claims

1. An axial electron gun comprising a primary cathode, a secondary cathode, an accelerating anode, a beam guide, a focusing coil, a deflecting system, a power supply system and a vacuum system characterized in that a figure-shaped holder of the secondary cathode is made of polycrystalline tungsten wire in the form of a plane regular triangle, quadrangle, pentagon or hexagon that put in an ring groove on the cathode's cylindrical side surface.

2. The axial electron gun as claimed in claim 1 in which for electron bombardment of the secondary cathode the pulsed voltage is applied between the secondary cathode and the primary cathode.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0023] The disclosed invention will be better understood but not restricted by reference to the drawings which show the following:

[0024] FIG. 1Main structural elements of the axial electron gun, the vertical section.

[0025] FIG. 2Design of the cathode assembly, the vertical section.

[0026] FIG. 3a-dLocation of a holder shaped as a plane regular polygon relative to the secondary cathode.

[0027] FIG. 4Secondary cathode, diagram of installation with the use of O-ring, the vertical and horizontal sections.

[0028] FIG. 5Secondary cathode, diagram of installation with the use of rod torsion holders, the vertical and horizontal sections.

[0029] FIG. 6Secondary cathode, diagram of installation with the use of a holder shaped as a plane regular triangle, the vertical and horizontal sections.

[0030] FIG. 7Compensation of high-temperature deformations of the secondary cathode with the use of a holder shaped as a plane regular triangle.

[0031] FIG. 8Diagram of relationship between the running time of the axial electron gun and the method of fastening of the secondary cathode.

PREFERRED EMBODIMENT

[0032] The axial electron gun (FIG. 1) comprising the cathode assembly (FIG. 2) operates as follows. Alternating voltage 4-10 VAC is applied to the current leads (11) so the heating current in the range 20 to 80 A runs through and heats the primary tungsten wire cathode (13). Bombarding voltage in the range 0.5 to ?2.5 kV is applied between the primary cathode (13) and the secondary cathode (20). Electrons emitted from the primary cathode bombard and heat the secondary cathode to the temperature of about 2800? C. The intensity of heating of the secondary cathode (20) depends on the heating current of the primary cathode (13) and the bombarding voltage. Accelerating voltage in the range 18 to 30 kV is applied between the secondary cathode (20) fixed by the holder shaped as a plane regular polygon and the anode (5). Under effect of this voltage electrons leave the cathode (20), are focused by the focusing electrode (15) and run to the beam guide of the axial electron gun (1) through the hole in the accelerating anode (5). An electron beam formed in such a manner is additionally focused by the focusing coil (4) and deflected by the deflecting system (2) in a proper direction. The deflecting system also performs scanning of the electron beam. In that way by changing the value of heating current of the primary cathode (13) it is possible to control the values of bombarding current of the secondary cathode (20) and also the gun beam current.

INDUSTRIAL APPLICABILITY

[0033] FIG. 8 shows the diagram of relationship between the running time in hours of the axial electron gun and the fastening method of the second cathode.

[0034] 1. Fastening of the cathode by the holder shaped as a ring.

[0035] 2. Fastening of the cathode by three separate torsions.

[0036] 3. Fastening of the cathode by the disclosed holder of regular triangular shape.

[0037] The presented diagram shows that the disclosed technical solution ensures an increase in the running time of the axial electron gun operated in the normal mode by a factor of three if compared with the prototype and by a factor of 1.5 if compared with the fastening of the secondary cathode by torsions.