Optogalvanic effect in a hollow cathode discharge with nonlaser sources

Several atomic emission sources were investigated for their potential to induce optogalvanic signals in hollow cathode lamps. The sources included an inductively coupled argon plasma, a H(2)-O(2) flame, a high-temperature furnace, electrodeless microwave discharge lamps, and hollow cathode lamps. Successful results were obtained with argon emission from the inductively coupled plasma focused into an argon-filled hollow cathode tube and with atomic emission from one hollow cathode discharge focused into a hollow cathode tube containing the same element. Very low level optogalvanic signals were observed from the other sources but could not be unambiguously ascribed to emission from a specific element. A problem encountered was the presence of a background signal due to photoelectric emission and possibly radiative heating of the cathode.