Orbitron Ionization Gauge

Abstract

An ion gauge with high ionization efficiency and low input power is described. In this gauge, called the orbitron, electrons are injected by a small tungsten filament into the electrostatic field between two concentric cylinders, with energies and angular momenta such that a relatively long mean free path is achieved. Only 4 μA electron current is needed to produce the same ion current obtained from 8 mA emission in a conventional Bayard-Alpert gauge. X-ray and photocurrents are held to low values by locating the ion collector remotely from the main source of light and x rays. The ion current is linear with pressure below 1×10−5 Torr and has been tested down to 5×10−11 Torr. The lower pressure limit has not yet been determined.