Notes on discharges in low-pressure iodine vapour

Some previous investigations of glow discharges in low-pressure iodine have been re-evaluated in the light of more recent work. The properties of the discharges are in many respects like those of discharges in oxygen at a little higher pressure. Some properties of the low-current form in iodine well away from the cathode may be governed by those of the negative sections of the discharge rather than by the positive column. Shortage of accurate data for collision cross-sections in iodine and the complexity of iodine discharges still makes it difficult to make full use of recent stability theory. The glow to are transition is discussed briefly, with particular reference to the growth of a precursor from the anode and the bridging and collapse of the cathode fall (dark) space.