Effect of Surface Condition of Electrode on the Surface Melting of Material by Laser-Guided Micro-Arc Discharge

This paper studies the surface melting in the atmosphere by YAG laser-guided micro-arc discharge. In three kinds of surface conditions (free, oiled, and polyethylene covered), we try to control the diameter and the power density of discharge pit. It is found that the power density of 3 times 10⁶ W/cm² of discharge pit on the oiled surface is moderate to form the melted layer thicker than that of the others, adapting to strengthen the surface of material, and the power density of 1.07 times 10⁷ W/cm² of discharge pit on the polyethylene-covered surface is highest to form the deepest discharge pit among them, adapting to remove the material.

I. Introduction

Nowadays, many people study the mechanism of laser plasma guiding discharge [1], [2] and succeed some studies of laser-guided lightning and laser-guided discharge (LGD) at long distance of atmosphere [3], [4]. It was also reported that the LGD was applied to processing. For example, Gilgenbach et al. [5] performed the LGD boring in aluminum foil in the atmosphere by laser, Hoshi et al. [6], [7] studied the LGD marking and processing inside of workpiece at low air pressure by 532-nm YAG laser, and we have also succeeded the similar study in electrode gap of less than 1-mm by 1.06- YAG laser [8], [9].