Measurement of ac cataphoresis

An apparatus and techniques are described for measurements of ac cataphoresis. The system uses a fiber optics light pipe driven along the discharge tube axis by a synchronous clock drive system. The collimated light signal is directed to a spectrometer whose output is processed using various methods to obtain desired types of information, including longitudinal time averaged scans of the discharge tube, longitudinal gated scans, and gated single cycle observations. Using these techniques one is able to study the time development of the ac effect as well as the presence of ionization waves. Examples are shown using noble gas mixtures of the various sampling procedures.