Abstract
The disturbed air and the induced impulse discharge have been visualized by a shadowgraph technique when aTEA-CO2 laser is focused to breakdown air in a rod-plane electrode configuration. The air, which is instantaneously heated near the focal point, expands rapidly, and a low density region is produced between the electrodes. Thereafter, the disturbed air diffuses gradually due to the turbulent mixing. The induced discharge flows through the interior of the disturbed air. Although the laser-produced plasma is produced instantaneously, the sparkover voltage is still high immediately after the plasma formation, and considerably decreases in 20μs-1ms after the laser irradiation. The diffusion of the disturbed air is one of the important elements to trigger the discharge gap by laser-produced plasma.
