Langmuir probe measurements in commercial plasma plants

We developed and tested a Langmuir double-probe system suitable for measurement in industrial environments, where quick and easy-to-handle methods are required. Data acquisition and calculation of plasma parameters are controlled by a personal computer. An evaluation algorithm is presented and its properties are briefly discussed. Successful operation of the system can be proved in a variety of different plasma configurations, namely in radiofrequency driven, pulsed direct current and microwave plasmas. Typical measurements and the conclusions that have been drawn are presented. Plasma densities were in the range 10⁸-10¹³ cm^-3. From the end user's point of view the main application areas are trouble-shooting, on-line process control and plasma source characterization during the development stages of a plasma plant.