The threshold potential,light-effect and chemical reactivity under electrical discharge
From an observation of a photo-increase of the minimum threshold potentialV m , that the currenti at a givenV should decrease under light was predicted by the author from a finding thati depends uponV-V m . Presumably, the magnitude of a chemical reaction under discharge does not depend appreciably on the corresponding high frequencies produced; these, however, constitute the main source of thelight-effect. Furthermore, in contrast with a chemical reaction which is minimum atV m , thelight-effect observed with a number of A.C. indicators, and expressed as percentage ofi is a maximum nearV m . This, together with a general finding that thelight-effect is not sensible belowV m , suggests that an optimum condition for its occurrence is a transition state, within which the conductivity of the gas changes from the dielectric to the ohmic type. The ‘electron affinity’ of the excited gas is another important determinant of this phenomenon.
KeywordsElectrical Discharge Electron Affinity Discharge Reaction Exciting Potential Silent Discharge
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