ABSTRACT
At the turn of the twentieth century the discovery of the electron and the advent of quantum mechanics as a new field of study gave birth to two schools for the study of electron-atom interactions. One school, led by Ramsauer and his colleagues, used beam techniques to measure scattering cross sections, which have been dealt with in earlier chapters. The other school, led by Townsend and his colleagues, adopted the swarm technique in which the electrons move in a gaseous medium under the influence of an applied electric field. The average properties of the electron swarm were studied and from these results the details of electron-atom collisions were theoretically deciphered. This chapter is devoted to the techniques adopted and the results obtained with regard to the diffusion and drift of electrons in gases. The emphasis will be on the data obtained, as they form the foundation on which the theory of electrical discharge, from corona to high density plasma, is developed. Theoretical treatment may be found in McDaniel,1 Hasted,2 and Huxley and Crompton.3
