Surface potential mapping of an argon lamp during electrical breakdown

In this paper, we present measurements related to the early stages of electrical breakdown occurring in a low-pressure argon straight discharge tube. A capacitive probe was used to retrieve the evolution of the lamp electrostatic potential over time and space. The potential and calculated electric field, displayed in space-time diagrams, show that a region of strong potential gradient propagates from the cathode toward the anode and then backward. This is followed by a homogenization of the electric field in the inter-electrode space.