Microwave Method for Measuring the Probability of Elastic Collision of Electrons in a Gas

Abstract
A plasma in a dc magnetic field has a transverse conductivity component whose reactive part depends, as to both magnitude and sign, on the strength of the magnetic field. By measuring the value of magnetic field that is necessary for bringing this reactive part to zero—and hence removing any resonant‐frequency shifts of a TE011 mode of a cylindrical cavity containing the plasma—determination of the probability of elastic collision of electrons in helium is obtained as a check on the method. The value of Pm=20±1 cm−1 mm Hg−1 for the electrons at room temperature thus obtained agrees substantially with the value obtained by previous workers. Sources of error in the measurement are discussed.