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Glow discharge

(Science: radiobiology) Low-density, low-temperature plasma discharge (such as in a fluorescent light) which, well, glows. Sputtering in glow discharges is useful in plasma processing of materials. The voltage applied to the plasma must be greater than the ionisation potential of the gas used, most of the plasma voltage drop is near the cathode, where the majority of ionisation occurs. Discharge is sustained by secondary electrons emitted when ions or recombination radiation impact on the cathode, electrons are accelerated away from the cathode and ionize neutral gas in the discharge.