Low-pressure switching plasmas with axial magnetic field stabilization

Low pressure gas discharge switches of the usual pseudospark design are known to have rather large electrode erosion rates when operated at high current levels and long switching times. In order to improve the plasma confinement and to reduce the electrode erosion in high-current applications, an axial magnetic field has been used in a low-pressure pulsed switching device. For a pulse duration of 28 /spl mu/s and current amplitudes of up to 50 kA the plasma expands quickly, leading to a diffuse discharge mode. The radial expansion velocity increases with current amplitude and reaches up to 10 km/s at a peak current of 53 kA. With a further increase in current, a constricted plasma is superimposed onto the expanded diffuse part. These findings are compared with the case in which no magnetic field is applied.