Effect of photon density with varying transverse electro-magnetic modes in laserguided discharges

Experiments have been carried out to investigate the characteristics of a breakdown threshold voltage as a function of various transverse electro-magnetic modes (TEM) in laser-guided discharges (LGD). The electrical breakdown was effectively guided to the location of the laser focal spot on a metallic target by using a pulsed Nd:YAG laser radiation. It is found that the minimum breakdown voltage in LGD depends upon the average density of photons reaching the electrode surface as a function of the mode of the injected laser beam.