Measurement of Electron Temperatures in the Hollow Cathode Discharge

A system has been designed which will rapidly and conveniently measure the electron temperature in a hollow cathode discharge. The measurement system is based on the floating double probe technique. Preliminary results obtained with this system indicate that the electron temperature depends on lamp current, fill gas pressure, and cathode material. These results are compared to those found in the literature for low pressure, microwave, and radiofrequency discharges. The electron temperatures measured in the three types of discharges have similar values, but the different discharges show strikingly different dependences on plasma composition.