The determination of the electron collision cross sections for momentum transfer of argon and potassium by measuring the DC conductivity of a high pressure plasma

Argon at approximately atmospheric pressure is 'seeded' with small amounts of potassium vapour and heated to about 1300 K in a specially designed furnace. The DC conductivity of the thermally produced plasma is measured by means of two electrodes whose separation is variable and one of which is equipped with a guard ring. By measuring the DC conductivity of the plasma over a wide range of potassium pressures, the cross sections for momentum transfer of argon and potassium have been measured much more accurately than hitherto.