GB965102A - Improvements in ionic pump - Google Patents

Abstract

965,102. Ion pumps. GENERAL ELECTRIC CO. June 19, 1961 [June 21, 1960], No. 22037/61. Heading H1D. An ionic pump comprises a sputtering electrode 2 and an ion source 3, Fig. 1, at opposite ends of an evacuable envelope, a collector electrode 14 being disposed therebetween so that ions collected on its surface are trapped by the deposition of metallic particles ejected from the sputtering electrode by ion bombardment. As shown, the ion source includes a thermionic cathode 4 and an anode including a mesh or honeycomb structure 10 and a cylinder 12. A permanent or electromagnet 20, insulated from the envelope, provides an axial magnetic field B which increases the lengths of the electron paths. The electrodes are spaced and insulated from one another by ceramic envelope portions 16-18, or alternatively they may be mounted in a glass envelope, the radiallyextending electrode flanges being replaced by leads passing through the ends of the envelope, Fig. 3 (not shown). Sputtering electrode 2 is preferably a getter for chemically active gases and may be of titanium or zirconium. The anode and collector electrode may also be of titanium. Examples of dimensions and operating potentials are given. Electrodes 2 and 10 may be connected in series with resistances so that at higher pressures, when the electron and ion currents would be larger, lower potentials are applied to these electrodes. An alternative ionic pump includes a magnetron-type ion source comprising thermionic cathode 25, Fig. 2, and coaxial anode 24, associated with an ion accelerating electrode 23. This device may also be used as an ionization gauge by electrically connecting electrodes 2, 14 and 23 and applying thereto a small negative voltage. Specification 882,781 is referred to.