The effects of electrode cleaning and conditioning on the performance of high-energy, pulsed-power devices

High-energy pulsed power devices routinely access field strengths above those at which broad-area, cathode-initiated, high-voltage vacuum breakdown occur (>1E7-3E7 V/m). Examples include magnetically-insulated transmission lines and current convolutes, high-current density electron and ion diodes, high-power microwave devices and cavities and other structures for electrostatic and RF accelerators. Energy deposited in anode surfaces may exceed anode plasma thermal desorption creation thresholds on the time-scale of the pulse. Stimulated desorption by electron or photon bombardment can also lead to plasma formation on electrode or insulator surfaces. Device performance is limited above these thresholds, particularly in pulselength and energy, by the formation and expansion of plasmas formed primarily from electrode contaminants. In-situ conditioning techniques to modify and eliminate the contaminants through multiple high-voltage pulses, low base pressures, RF discharge cleaning, heating, surface coatings and ion- and electron-beam surface treatment allow access to new regimes of performance through control of plasma formation and modification of the plasma properties. Experimental and theoretical progress from a variety of devices and small scale experiments with a variety of treatment methods are reviewed and recommendations given for future work.