GB1140798A - Improvements in and relating to high vacuum pumps - Google Patents

Abstract

1,140,798. Ion pumps. BALZERS PATENTUND BETEILIGUNGS-A.G. 17 March, 1967 [18 May, 1966], No. 12530/67. Heading H1D. [Also in Division F1] An electrode of a getter-ion pump operating with a magnetic field is maintained at a temperature below 20‹ K during operation. Cryogenic pumping is thus obtained in the absence of applied potentials. The anode of the pump shown is formed by annular discs 4 and part of the wall of a steel vessel 1 containing liquid helium and supported by a tube 2 from the wall 3 of a receptacle to be evacuated. Sheets 5 of getter metal Ti, Mo or Zr form cathodes which may be of multi-cellular construction and are supported by leads 6 and 7. A magnet coil 8 of superconductive wire or strip is located in the vessel 1 and supplied with current through leads 9 and 10 to establish the field which may then be maintained by a superconductive shunt. Modifications comprise: Superconductive concentrators e.g. of Nb-Zr or Nb-Ti alloys to concentrate the stray field of the magnet coil in the anode/cathode gap (Figs. 2a and 2b, not shown); an anode vessel consisting of three sections each containing a magnet coil, with cathodes mounted between the anode sections and the whole arrangement surrounded by a system of baffles allowing the passage of gas but screening the arrangement from heat radiation. The baffles may be cooled by liquid air while charging the anode vessel with liquid helium (Figs. 3a and 3b, not shown); a cylindrical arrangement of an annular anode containing a coil and surrounding a cylindrical cathode (Fig. 4, not shown); an arrangement of curved cathodes between radial anode chambers each containing a coil (Figs. 5a, 5b and 5c, not shown).