The temporal development of hollow cathode discharges

Summary Form only given, as follows. A linear discharge system with a plane anode and a hollow cathode was used to study discharges in He at pressures between 100 mtorr and several torr. A 10- mu s voltage pulse of variable amplitude was applied to the electrodes, and the discharge voltage and current were measured. Two distinct discharge modes were observed, a high-current (>100 A) mode and a low current (<500 mA) mode. The two modes represent different stages in the development of the hollow cathode discharge, which is described here. By applying an axial magnetic field it was possible to influence the transition from low-current to high-current mode. In a pressure range of about 200 mtorr the application of a magnetic field of greater than 0.15 T inhibited the occurrence of the high-current discharge. Magnetic fields below this value had no effect on the temporal development of the discharge. A possible explanation is that at lower fields the electrons in the hollow cathode exhibit cycloidal motion as in a magnetron where the hollow cathode discharge places a positive space-charge in the center of the hole. If the magnetic field is increased above a certain critical value the space-charge region can not be sustained.<>