Angular distribution of mass and charge flows in far zone of plasma beams generated by nanosecond vacuum surface flashover at 70 kV

In this work, we measure directional patterns of charge flow of ions and mass flow of neutrals in particle beam generated by vacuum surface flashover in linear configuration at voltage of 70 kV. We used a generator, which provide a discharge current of 2.8 kA. The samples used are polymethylmethacrylate, polytetrafluorethylene and polyethylene. We found that the directional patterns of mass and charge flows in linear configuration have distinct axial asymmetry. The corresponding angular distributions are significantly wider in the plane which is normal to the discharge than in the plane which contains the discharge. Angular distributions of charge flow are wider than distributions of neutral mass flow in the same planes. Besides, the asymmetry in ion current amplitudes at the cathode side and at the anode side is observed. We found that the share of low-velocity ions in ion current drops drastically in the plane which contains the discharge at the angles of 15 degrees and larger for all the tested materials.