Plasma emission imaging of electrical breakdown in low-pressure argon

Time-resolved measurements of the breakdown process in a low-pressure argon discharge are presented. Light emission from the plasma was imaged onto an intensified charge coupled device camera. First, a weak pre-breakdown light flash occurred, which was thought to come from charges from previous discharges. Second, at the beginning of the main breakdown phase, a light front crossed the discharge gap. Finally, a striation-like pattern formed in the discharge gap.