Abstract
The energy of electrons crossing the glow boundary of a cylindrical hollow cathode discharge has been directly controlled in a small, test region by the use of a wall probe installed in the side of the cathode cylinder. Varying the potential of this probe disclosed that some electrons ejected from the probe surface and hence from all cathode walls penetrate into the dark space opposite to the surface of their origin. These electrons can reach the opposite wall if the pressure and the cathode diameter are too low, in which case they will be removed. This removal causes the hollow cathode discharge to extinguish at higher pressures than is the case for linear discharges. Electrons that cross the cathode cavity entirely can pass through a small hole in the cathode wall into a high vacuum chamber and be analysed energetically. The same experiment also discloses the energy distribution of electrons leaving the cathode surface. A comparison with the theory recently published 3 shows that pendelelectrons can be responsible for the currrent amplification observed in the hollow cathode discharge.