The determination of the electron collision cross sections for the momentum transfer in potassium by measuring the DC conductivity of a plasma

The DC conductivity of a thermally produced plasma in a plasma diode has been measured in pure potassium vapour. A simple theory for determining the influence of the plasma sheaths on the measured conductivity was developed and experimental conditions were established under which the potential drops across the sheaths could be neglected. By measuring the DC conductivity of the plasma at temperatures ranging from 1250 to 1600K the potassium momentum-transfer cross section has been obtained. The measured cross section (2.37+or-0.24)*10 -14 cm 2 at 1500K is in good agreement with the recent experimental results of Beynon and Brooker (1972). Good agreement with the two-state exchange close-coupling calculation by Karule (1965) was found.