QUENCHING OPTICAL-BREAKDOWN WITH AN APPLIED ELECTRIC-FIELD

Application of an external electric field across the focal volume of a high-pressure gas cell can increase the threshold for optical breakdown by electrostatic purification of the gas and by removal of free electrons from the laser focal volume in times that are short relative to the interpulse separation and/or the laser pulse duration. Experiments with 1.06-μm pulse trains (200-psec duration with a 7.5-nsec interpulse separation) demonstrate that electrostatic purification effectively quenches all optical breakdown in 20 atm of SF6 for the highest available single-pulse fluences of 140 J cm−2 (0.7 TW cm−2). © 1990 Optical Society of America.