Computerized system for investigation of electron energy distribution functions in decaying plasmas

A computerized PC-based system for measuring of electron energy spectra by means of the probe current modulation techniques is described. The block-diagram of the probe current second derivative curcuit is shown as well as the main programme algorithm. The system has been designed for control of the experiment, data acquisition and data processing. Its basic functions are to support the pulse operation of the discharge tube, to control the probe circuit, to produce the retarding potential for biasing the probe and to process the obtained information. Experimental results for two differnt time delays and temporal behaviour of the electron temperature in the afterglow of crypton plasma are presented. It is concluded that the system improves the signal-to-noise ratio and allows to mesure the electron temperature in the initial phase of afterglow at a comparatively low level of the differentiating signal. With its help the modern statistical methods for treatment of the obtained empirical evidence can be applied. 6 figs., 10 ref s