Axial Pressure Gradients in dc Discharges with a Return or Bypass Connection

Measurements have been made of the effect of a bypass on longitudinal pressure differences in dc discharges of helium and xenon and for a 10% mixture of neon in helium. Comparison of the data in helium and xenon confirms the validity of previously predicted theoretical expressions for the pressure reduction. Measurements of the reduction of cataphoretic effects using the bypass are also reported for the mixture.