Improved cathodes for magnetically-confined glow discharge apparatus

摘要

949,097. Ionisation chambers. VARIAN ASSOCIATES. Sept. 15, 1961 [Oct.11, 1960], No. 33248/61. Heading H1D. Electrical glow discharge apparatus, e.g. a getter-ion pump or an ionisation manometer, in which a glow discharge takes place between an anode 17, Fig. 5, and a cathode structure in a magnetic field, comprises a cathode grid 31 supported from a face of a cathode base-plate 24 and in good thermal contact with the baseplate. The cathode grid, which may be formed integrally with the base-plate, may comprise a plurality of parallel slats the spacing between adjacent slats being both wider and deeper than the thickness of the slats and they may be inclined at a substantial angle to the face of the base-plate. Alternatively, the slats may comprise a plurality of radially spaced coaxially disposed rings or frusto-conical rings, Fig. 10, a plurality of stacked mesh screens, or a single spiral-shaped slat. The anode is preferably of cellular form. In operation as a pump, ions accelerated from the anode cells either penetrate the well of the slats and are buried in sputtered material or impinge upon the top of the slats and enable sputtered material to build up in the well of the slats. The device may be used as a vacuum gauge by measuring the ion current which is a function of the pressure, aluminium or magnesium being used for the slatted cathode. A unidirectional magnetic field may be used or the fringing time-varying field of a Bevatron employed. Specification 883,189 is referred to.