``Magic Eye'' Ionization Gauge

Abstract

An ionization vacuum gauge control and indicating circuit is described. It has the following features: (1) No meters whatever are required; the plate current of the gauge tube is indicated by a 6E5 tube, both during normal operation and during the outgassing operation. (2) The grid current in the gauge tube is held constant at any desired value, regardless of changes in line voltage, gas pressure, or the nature of gas in the vacuum system. (3) Outgassing of the grid of the gauge tube may be done by throwing one switch. (4) The grid current is controlled automatically during outgassing. (5) Any type of tube may be used as gauge tube proper, without changes in the control and indicating circuit. A note on leak testing with the ionization gauge is added.