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28 October 1996 Gases evolved from the common cold cathode
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One of the contributing factors to rf pulse shortening in long-pulse high-power microwave sources is gas evolution from the cathode surface during the explosive emission process. Theory of ecton formation, models of expanding are plasmas, and high-speed diagnostics are leading to a better understanding of the contributing factors to the cold- cathode emission processes. While technological leaps often result from applications of new materials, it is worthwhile to characterize and understand the effects of existing cathode materials commonly used in pulsed power systems. This paper describes the use of a residual gas analyzer to measure the atomic mass spectrum and total pressure of the background gas evolved from the cathode surface in a repetitively-pulsed electron beam vacuum chamber. Cathode materials studied include carbon fiber, velvet, copper, and stainless steel. The increase in the background pressure and the constituents of the background pressure are catalogued for the four cathode material samples. The simultaneous narrowing of voltage-pulse width with increase in background pressure is also measured. The carbon fiber cathode contributes least to the background pressure, and maintains the most stable and repeatable diode impedance.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Marc S. Litz, Daniel C. Judy, George A. Huttlin, and Carl J. Lazard "Gases evolved from the common cold cathode", Proc. SPIE 2843, Intense Microwave Pulses IV, (28 October 1996);


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