Optogalvanic and pseudosonic wave spectroscopies in oscillating d.c. discharges

The conditions under which spontaneously oscillating d.c. discharges may be formed are described, and two different experimental configurations with distinct operating properties are presented. Using these discharges, optogalvanic and pseudosonic wave frequency spectroscopies are performed in neon. Signal magnitude in both techniques is discussed in terms of the change in the discharge power spectra caused by laser excitation of an atomic neon transition. Both methods are used to observe H in a binary mixture of H2 and Ne.