Emission Characteristics of the D.C., 100 kHz and 13.5 MHz Hollow Cathode Discharges

Hollow cathode discharges in argon at various pressures and currents have been studied by optical emission spectroscopy. The cathodes were made of copper, bronze and brass. The discharges were supplied by direct, 100 kHz and 13.5 MHz currents. Atomic and ionic spectra of plasma gas and elements of cathode materials and molecular bands of ZnH and PN formed due chemical reactions between plasma components have been excited and measured. Relations between emission intensities, excitation temperatures and discharge conditions have been analysed and discussed.