On priorities of cathode and anode contaminations in triggering the short-pulsed voltage breakdown in vacuum

Institute of High Current Electronic, Russian Academy of Sciences, Moskva, Moscow, Russia
IEEE Transactions on Dielectrics and Electrical Insulation (Impact Factor: 1.23). 03/2006; DOI: 10.1109/TDEI.2006.1593400
Source: IEEE Xplore

ABSTRACT Modern theoretical notations on electrical breakdown in vacuum consider cathode triggering mechanisms to be most responsible on short-pulsed (<1 μs) breakdowns while anode mechanisms to be responsible in a part on DC and long-pulsed breakdowns. Following those notations, we tried to reveal conditions at which either mechanism steps aside to another one. The study involved several experimental techniques including the anode-probe surface scanning, pulsed electron-beam surface melting in vacuum for surface cleaning, and intentional dust particle contamination of electrode surfaces. Breakdown tests were performed using a pulser capable of producing 220 kV quasi-square pulses that were adjustable to ∼30 to 80 ns pulse length. Our experiments showed that cathode emission sites are responsible for breakdowns at relatively low hold-off fields. At higher electric fields of up to 1 MV/cm, the anode share in the mechanism of triggering breakdown becomes probably more significant than the cathode mechanism.

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