Power voltage source synchronized with a spectrometer for real-time spectroscopic studies of pulsed discharges

The evolution of the species generated in a plasma may be characterized through real-time optical emission spectroscopy. Nevertheless, for experimental situations in which the light emission intensity is insufficient for acquisition times of several tens of milliseconds (typical resolution time of optical multichannel analyzers), some complementary instrumentation has to be incorporated. In this paper, we present the design of an experiment to study the spectroscopic evolution of a plasma during a switch-on of a dc discharge, and/or during its switch-off (afterglow). The solution consisted of a periodic discharge generated by a dc square wave voltage source, synchronized with the optical multichannel analyzer of the spectrometer through its TTL (transistor-transistor logic) level pulse. The periodicity of the discharge under similar physical conditions allows accumulation the spectroscopic information for each cycle, making possible a time resolution of tens of milliseconds by increasing the resulting intensity profile of the spectra.