Ionization instability
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An ionization instability is any one of a category of plasma instabilities which is mediated by electron-impact ionization. In the most general sense, an ionization instability occurs from a feedback effect, when electrons produced by ionization go on to produce still more electrons through ionization in a self-reinforcing way.
Ionization instabilities have been seen in such plasma physics apparatus as glow discharges,[1][2] Penning discharges,[3] magnetic nozzles,[4][5][6] and MHD generators.[7][8][9] Ionization instabilities may occur in magnetized or unmagnetized[10] plasma. They occur mostly when the plasma is relatively cold and only partially ionized, so that there is a lot of neutral gas mixed in with the plasma.
A glow discharge is a plasma-containing apparatus in which the plasma is formed by a large voltage placed across a rarefied gas. Glow discharges are used for electric lighting and materials processing. In a glow discharge, ionization instability takes the form of striations,[1] or bands of enhanced and suppressed light production. The distance between each striation is the distance required for an electron to gain enough energy to ionize a neutral gas particle.