Penning gas mixture
A Penning gas mixture consists of a rare gas containing impurity atoms possibly at very low concentrations. The impurity atoms have an @I03208@ \(V_{\text{ion}}\) which is lower than or equal to the @M03872@ potential (\(V_{\text{meta}}\)) of the parent noble gas. The Penning effect in a Penning gas mixture is the @I03183@ by charge transfer (charge exchange) during collision between a @M03872@ atom and a neutral atom which decreases the average energy to form an @I03231@, e.g.
In a glow discharge, this results in an increase of the the @I03183@ @C01124@ (Townsend first @C01124@), a decrease in breakdown potential and a lowering of the @C00905@ fall potential. The magnetic Penning effect describes the increase of the @I03183@ @P04855@ of gas in a @L03636@ resulting from the helical (spiral) movement of electrons in a magnetic field placed normal to the @A00370@-@C00905@ electrical field.
Orange Book, 2nd ed., p. 148 [Terms]