Influence of DC electric field on Nd:YAG laser-induced breakdown in gases

Abstract

It is well known that pulsed laser can easily generate breakdown plasmas when the beam is focused. The laser-based gas breakdown phenomenon is caused by multiphoton ionization (MPI) and cascade ionization (CI) in a high-intensity electric field near the focal region. However, the phenomenon is complicated because it is affected by the purity of the gas and the focusing quality of the laser and optical systems. For a comprehensive understanding of the laser-induced breakdown phenomenon, the influence of an electric field on the threshold intensity of the laser-induced breakdown was investigated. The applied field disperses electrons generated in the focal area by the intense laser field, thereby increasing the laser-induced breakdown threshold intensity. The observed phenomenon is explained by a simple electron balance model.