Spatial distributions of laser-induced air plasmas

The spatial distributions were explored in the laser-induced air plasmas for clearer understanding of the micromechanism. A column of plasmas were formed by focusing Nd:YAG laser beam at 1.06 μm (energy is about 500 mJ/pulse, pulse width 10 ns,and frequency 30 Hz ). The column was about 8 cm long and 5 cm in diameter. The spectra of the column in different position have been detected from vertical and parallel direction of laser beam respectively. From these data, the electron densities and the electron temperature distributions in the laser-induced air plasmas can be estimated. The experimental results indicate that the laser-induced air plasma exists in the shape of a tear drop, symmetrical in the vertical direction but not symmetrical in the horizontal direction. The largest electron d