A Basic Study on Propagation Mechanism of a Lasernduced Long Gap Leader Based on the Measurement of Electric Field

Abstract

In order to clarify the propagation mechanisms of the laser induced discharge, we measured the electric field due to a leader channel in a long air gap by using an optical electric field sensor based on the Pockels effect. We also calculated the electric field by simulating the leader with a line charge and applying the charge simulation method. The propagation velocity of the leader ranges from 2×105m/s to 1×106m/s for plasma channel produced by a high power carbon dioxide laser. The velocity depends on the number density of the plasmas produced by the laser. The velocity is about 10 times larger for a dense channel with plasmas more than 50per meter than without the plasma channel.