AVS 45th International Symposium
    Vacuum Technology Division Monday Sessions
       Session VT-MoM

Paper VT-MoM5
Ultra-high Vacuum Instrumentation Development Studies

Monday, November 2, 1998, 9:40 am, Room 329

Session: Vacuum Gauging, Outgassing and Leak Detection
Presenter: C. Dong, Thomas Jefferson National Accelerator Facility and Old Dominion University
Authors: C. Dong, Thomas Jefferson National Accelerator Facility and Old Dominion University
G.R. Myneni, Thomas Jefferson National Accelerator Facility and Old Dominion University
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Measurements of both total and partial pressure in the ultra high vacuum range are known to be limited by several effects including the x-ray limit, electron stimulated desorption, cathode evaporation and thermal and chemical effects at hot cathodes. In order to understand the contributions of these effects, ultra high vacuum instrumentation development studies are in progress at the Jefferson Lab in collaboration with Teledyne Brown Engineering-Hastings Instruments. These studies include the modification of extractor gauges and RGAs by replacing the hot filaments with Spindt field emitters. The sensitivities of the modified instruments are determined in the Jefferson Lab’s vacuum gauge calibration apparatus. In this paper the sensitivities of the UHV instruments for nitrogen, helium and hydrogen with different cathode currents and for various electrode potentials are presented. In addition, the contributions of electron-stimulation desorbed ions are also measured with the help of a Watanabe ion spectroscopy gauge in an ion pump evacuated vacuum system and the results are also included here. This work supported by the U.S. DOE under contract No. DE-AC05-84ER40510