GB1031766A - Vacuum pump - Google Patents

Abstract

1,031,766. Ion pumps. STANDARD TELEPHONES & CABLES Ltd. March 22, 1963 [March 29, 1962], No. 11477/63. Heading H1D. In a vacuum pump arrangement comprising an ion pump and a backing pump for scavenging gas from a low potential region of the ion pump, the ion pump has electron emissive surfaces 2 and 3 generating electrons which are accelerated and focused by anode portions 16 and 17 towards a central region in which a point 40 of minimum potential surrounded by a region of maximum potential is established. Gas entering at 26 is ionized, and ions which acquire energies sufficient to carry them over the said potential maximum pass through further positive potential electrode pairs 14 and 13 to a low potential region in a chamber 6 from which they are scavenged by a backing pump connected to outlet 27. A cold cathode of tungsten or rhenium may be used in conjunction with cathodes 2 and 3 to augment the electron current. Alternatively, the cathodes 2 and 3 may be secondary electron emissive so that a radiofrequency potential applied through a coil 37 to anode portions 16 and 17 will produce multifactor action between the cathodes 2 and 3. Electrodes 13, e.g. of platinum, are connected to a metal coating 12 in the chamber 6 if the latter is of glass or ceramic. Electrodes 14 may be bridged by a metal mesh 18. Cathodes 2 and 3 may be of stainless steel or beryllium copper which in addition to being secondary emissive will also getter any ions formed in their vicinity. Additional focusing rings 30 and 31 may be provided.