Measurement of plasma parameters in He microdischarge by means of additional sensor electrode

The temperature and density of electrons are measured in a high pressure dc He microdischarge plasma. An additional electrode sensor, placed at the boundary of the discharge volume, is used to measure the sensor current-voltage characteristics and their first and second derivatives. The electron temperature is determined from the transition region of the sensor current-voltage characteristics, in particular from the slow part of the Electron Energy Distribution Function. The electron density is determined from the ion saturation current. The results from the measurements show that the temperature of the slow group of electrons is low about 0.2–0.3 eV and the electron density is about 1012–1014 cm−3.