Investigation of a glow discharge structure in 100 mbar argon

摘要

In this paper the evolution of a DC glow discharge is observed with the help of a high speed camera when the discharge current increases from 5 to 400 mA. The covering gas is argon, cylindrical tungsten electrodes have been used, the electrode gap is 25 mm. An electric device was conceived in order to study steady state and pulsed discharges. Different stages in the observed evolution appeared. The diffuse column evolves continuously toward a concentrated column with stable states showing partially diffuse and concentrated column. The anode root remains constricted in the whole current range considered. The change of the cathode arc root structure appears abruptly when a transition to an electric arc occurs.