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The spontaneous emission of positive ions from a heated tungsten filament occurs as pulses, a single pulse releasing as many as 106 ions in less than 100 μsec. The pulses are composed mainly of potassium ions, present as impurities in the tungsten lattice. It is suggested that the emission of positive ions in the form of bursts is dependent upon the existence of edge dislocations in the metal. At temperatures where the formation of an adsorbed layer is possible, oxygen has a very pronounced effect upon the rate of emission of positive ion pulses.
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Minturn et al. (1960) studied this question.
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