Field Measurements in Glow Discharges with a Refined Electron Beam Probe and Automatic Recording

By using a very sensitive and fully automatic magnetically compensated electron beam probe, the design of which is described elsewhere, studies were made of the fields in glow discharges some 40 cm long in a tube 10 cm in diameter with aluminum and copper cathodes at from 0.03 to 1.0 mm Hg pressure with currents ranging from 0.1 to 10 ma in flowing air, nitrogen, hydrogen, helium, and argon which were pure to 99.5 percent, but contaminated by vapors from various stopcock greases, waxes, and clean, but not outgassed, metals. Simultaneously, wall potentials and luminosities of the glows were measured and spectra of the cogent parts of the discharges were observed. Emphasis centered on the fields in the Crooke's dark space for discharge currents ranging upwards from the normal cathode fall region. Some stationary striations were also studied. The high resolving power obtained resulted in details of the dark space fields hitherto unrecognized which are amenable to theoretical interpretations to be given in a subsequent paper. Only the observed results are reported here.