A microwave spectrometer to monitor discharge cleaning

Abstract A new type of gas monitor using microwave spectroscopy is applied for studying glow discharge cleaning in a toroidal plasma device. The amount of H 2 O partial pressure during the cleaning procedure is determined by the absoprtion of the microwave power with corresponding rotational spectra of 22.235 GHz for water molecules. By applying this method, it is possible to measure the relatively high gas pressure (up to 100 Pa) encountered during the cleaning. The rate of H 2 O production and the time history of H 2 O during the cleaning are monitored and the efficiency of the reduction of H 2 O is discussed.