Abstract
The high Rydberg spectra of atomic helium np 1P states were measured up to n=46 in the negative glow region of a discharge, with mJ=±1 polarization, by optogalvanic spectroscopy. The net electric field values in the negative glow region, in the transition region between the negative glow and the positive column, and also on the radial axis of the positive column were determined from series‐termination measurements. The spatial variations of the ion density in the negative glow region were also obtained from the net‐field measurements.