Axial interelectrode breakdown in MHD channels

Results are reported for experimental studies of interelectrode breakdown in a Hall field in the U-02 installation and the U-25 power plant. It is found that Hall breakdown in Faraday channels can take place at both the anode and cathode walls, that conditions for breakdown are more favorable at the anode wall, and that breakdown there occurs at lower interelectrode voltages and electrode currents. The experiments in the U-02 installation confirm the possibility of two types of breakdown: 'fast' breakdown through the plasma and 'slow' breakdown on insulator surfaces. The voltage for 'fast' breakdown is shown to depend significantly on the width of the interelectrode insulator. It is concluded that intense Faraday arcs on the electrodes must be excluded in order to prevent damage due to interelectrode breakdown.