AVS 47th International Symposium
    Vacuum Technology Thursday Sessions
       Session VT-ThA

Paper VT-ThA4
Extending the Upper Pressure Limits of Cold-Cathode Gauges

Thursday, October 5, 2000, 3:00 pm, Room 201

Session: Pressure and Flow Measurements
Presenter: B.R.F. Kendall, Elvac Laboratories
Authors: B.R.F. Kendall, Elvac Laboratories
E. Drubetsky, Televac Division of the Fredericks Company
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Processes occurring in magnetron-type discharges at normal and elevated pressures are compared. As pressures rise into the micron range, an increasing fraction of electron-molecule interactions occur at less than ionizing energies, and more of the ions collide with molecules on their way to the cathode. This results in fundamental changes in the discharge behavior. Discharge currents have been measured as a function of pressure and voltage up to 1 Torr for a number of magnetron and inverted magnetron electrode configurations. Additional experiments covered AC and pulsed operation. Practical aspects of high-pressure operation such as sputtering, electrode heating and the formation of polymer films are reviewed. The possibility of operating a double inverted magnetron at pressures approaching 1 Torr is discussed. Simple extended-range gauges of this type could replace complicated hybrid gauge combinations in some applications.