Study of the discrepancy between electron temperature and gas temperature in the vicinity of the anode of an electric arc

Summary form only given. Several studies of arc plasma in the vicinity of the electrodes revealed inconsistencies due to departure of local thermodynamic equilibrium. To analyze this phenomenon we studied the plasma near the copper anode of a wall-stabilized arc and of a transferred arc, running in argon and in nitrogen at atmospheric pressure. We measured the difference between electron temperature and gas temperature, using a relaxation method based on their different rates of decrease. With a spectroscope we observed the intensities of the line 510.5 nm of copper and of the line 696.5 nm of argon at a distance of 2 mm from the anode. Arc interruption was produced by using a fast thyristor connected to the electrodes which short-circuits the discharge with a turn on time close to 1 /spl mu/s. The signal is stored with a transient recorder.