Plasma Diagnostics V

A simple three-channel probe system for low temperature plasma diagnostics has been proposed and tested. The system works on the principle of recording the probe current-voltage characteristics by using a sawtooth voltage generator and a high resolution digital oscilloscope. By double numerical differentiation of the measured current-voltage characteristics, electron energy distribution functions for a hollow cathode glow discharge in helium are obtained at three points along the axis of the discharge tube. It was clearly observed that inside the hollow cathode, the signals from Penning electrons have a step-like shape, while outside they appear as peaks. The data obtained using this system was compared with the results from a commercial probe diagnostic system, and the findings show that the proposed system can reliably and accurately reproduce the high-energy part of the electron distribution function. This probe system has the potential to be used for plasma electron spectroscopy, as it provides a simple and effective method for studying the properties of plasmas.