AVS 46th International Symposium
    Vacuum Technology Division Tuesday Sessions
       Session VT-TuM

Paper VT-TuM7
A Compact Wide-Range Cold-Cathode Gauge

Tuesday, October 26, 1999, 10:20 am, Room 610

Session: Total and Partial Pressure Gauging
Presenter: B.R.F. Kendall, Elvac Laboratories
Authors: B.R.F. Kendall, Elvac Laboratories
E. Drubetsky, The Fredericks Company
Correspondent: Click to Email
Cold-cathode ionization gauges offer many advantages for routine high-vacuum measurements. They are simple and robust. Thermal outgassing and electron-stimulated desorption, both significant problems in hot-cathode gauges, are negligible. There are no x-ray effects to cause errors at low pressures. New design techniques have largely eliminated stray-field and starting problems. The design, development and testing of a compact wide-range cold-cathode gauge are discussed. Demountable and all-metal versions have small internal volumes ranging from 5 to 15 cm@super 3@, yet the sensitivity can exceed 10A Torr@super -1@ at 10@super -6@ Torr. Double inverted magnetron geometry and shielding rings reduce the external magnetic fields to very low levels. The anode contains thorium for easier starting at normal pressures. For UHV applications, Americium 241 or a carbon film cold emitter can be used for instant starting. Test data are given which illustrate the effects of varying anode voltages and magnetic fields upon sensitivity and starting time. Factors affecting stability and freedom from discharge discontinuities are also discussed. Design features allowing stable operation down to 10@super -11@ Torr and above 10@super -2@ Torr are described.