Prebreakdown current growth in crossed electric and magnetic fields at low gas pressures: I. Effects of non-uniform applied fields

An experimental investigation of the spatial growth, in cylindrical geometry, of prebreakdown ionization currents in crossed electric and magnetic fields has been made in molecular hydrogen at gas pressures where the electron mean free path is much greater than the dimensions of the discharge chamber. Some unusual features have been observed in the current growth at very low gas pressures, and these have been attributed to instrumental effects, particularly non-uniformities in the applied electric and magnetic fields.