Experimental study on air gap discharge triggered by pulsed laser under HVDC condition

Along with the application of combining the laser produced plasmas with gas discharge, the fundamental physics of laser triggered discharge are paid widely attention. In this work, the air breakdown triggered by the pulsed under the high voltage direct current (HVDC) condition were experimentally investigated. Special care was taken with the influences of the laser focus location as well as the laser incident mode on the occurrence probability of the gap breakdown. Plasmas evolution was visualized by the fast ICCD photography. Results revealed that the breakdown delay time and jitter would decrease pronouncedly when the laser focus location moved closer to the electrode surface from the gap middle. With the same incident laser energy, the average breakdown delay time decreased rapidly from 108 μs to 4.8 μs when the gap voltage was increased from 35 kV to 45 kV. In the end, a linear discharge channel was also found when the incident laser was introduced in the axial direction, and an average breakdown delay time as low as 800 ns was achieved.