AVS 52nd International Symposium
    Vacuum Technology Tuesday Sessions
       Session VT-TuM

Paper VT-TuM2
New Ignition Devices for Cold-Cathode Gauges

Tuesday, November 1, 2005, 8:40 am, Room 200

Session: Total and Partial Pressure Gauging
Presenter: B.R.F. Kendall, Elvac Laboratories
Authors: B.R.F. Kendall, Elvac Laboratories
E. Drubetsky, Televac Division of The Fredericks Company
Correspondent: Click to Email
The discharge in a cold-cathode gauge does not start immediately when power is applied. In the absence of special starting devices the delay may be quite long, with large variations between successive starts. Average values typically range from seconds at 10@super -6@ Torr to hours or even days at 10@super -11@ Torr. For this reason, gauges which require frequent starting at very low pressures have sometimes been fitted with either radioactive or thermionic emitters to ensure relatively quick and predictable starting. Although effective, these solutions can cause other problems. Many laboratories are now reluctant to handle even weak radioactive sources, while the disturbance to the background pressure caused by some thermionic emitters can be significant. In an attempt to resolve these difficulties, we have tested diamond-like film emitters and electron generator arrays, both of which offer suitable fluxes of cold electrons for gauge starting. We have also made a detailed study of the physical processes occurring during gauge starting with thermionic electron sources. This has led to a very compact low-power emitter which greatly reduces thermal desorption during the starting process. The test gauges were double inverted magnetrons operating at pressures down to the 10@super -11@ Torr range.