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  • Vacuum measurements in small sealed systems
    Šetina, Janez ; Žumer, Marko, fizik ; Erjavec, Bojan, 1950-2023
    Single cell putter-ion pumps are often used for appendage pumping of small sealed systems such as electron tubes. After evacuation and pinching-off, the ion pump provides additional gas clean-up and ... thus extends the lifetime of the tube. Below ▫$10^{-2} Pa the discharge is magnetically confined and the current drawn by the sputter-ion pump is linearly proportional to the pressure. This phenomenon enables the use of the sputter-ion pump as a pressure gauge over a part of its operating range. Below 10^{-6} Pa the use of the pump as a gauge is limited due to the field emission and the insulator leakage currents. The latter overshadow the current drawn by the discharge at low pressures. Discharge ignition is yet another difficulty at low pressure use of the sputter-ion pumps. Single cell sputter-ion pumps, which are available on the market, hardly start below 10^{-5} Pa. In the electron tubes evacuated in our laboratory the pressure after pinch-off is below the striking pressure of appendage pumps. This problem is overcome by inserting hot cathodes in single cell sputter-ion pumps and by improving the insulation in order to minimize leakage currents. Modified ion pumps start and work at discharge currents below 10^{-10} A and indicate pressures below 10^{-8} Pa. Thus the monitoring of the vacuum in the electron tubes is possible after processing. The influence of different operating conditions on further degassing of the electron tube elements can be evaluated.$▫
    Vir: Vacuum. - ISSN 0042-207X (Vol. 38, no. 8-10, 1988, str. 946)
    Vrsta gradiva - prispevek na konferenci
    Leto - 1988
    Jezik - angleški
    COBISS.SI-ID - 18671621

vir: Vacuum. - ISSN 0042-207X (Vol. 38, no. 8-10, 1988, str. 946)
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