Laser-Guided Discharge Characteristics of Long Air Gaps and Observation of the Discharge Progressing Feature

Abstract

Laser-guided discharge is promising for protection of power transmission systems against lightning. Several experiments concerning the laser induced electrical discharge have been performed up to now. However, it is necessary to understand the mechanism of the laser induced electrical discharge to achieve the laser-triggered lightning.
When a high power laser beam is focused in air, a high degree of ionization is produced as brilliant beams nearby the focus. In this paper, the electrical discharge induced up to 2-meter with a high power CO₂ laser focused by a 10-meter focal length mirror is described.
Experiments of the laser-guided discharge were carried out by application of an impulse voltage to a rod-rod gap after laser radiation. This paper deals with the effects of delay times and polarity of the impulse voltage on 50% flashover voltage characteristics and the observation results of discharge phenomena taken by a still camera, a special camera named ALPS (Automatic Lightning Discharge Progressing Feature Observation System) and an image converter camera.