Electrostatic Effect Mechanism Model And Experiment Research On Laser-Induced Plasma

The strong interaction of laser and material produces ultra hot electrons with high-energy who escape outwards, leading to the plasma has a dram of positive charges. Electrostatic effect mechanism was lucubrated in this paper. A testing method of the target electric potential without additional voltage was put forward, whose low-order equivalent circuit model was also established. Through changing laser energy, target characteristic parameter (material, length, section diameter), the detailed analysis of the signal was carried on from vaporization heat, vaporization temperature, plasma ionization rate, plasma absorbability coefficient, etc.It was found that Laser-induced plasma's electrostatic effect can be divided into four stages: The first stage, the target electric potential increases when ultra hot electrons escape, about 30ns ;The second stage, the target electric potential descends when the plasma decays and withers away , about 100ns ;The third stage, the target electric potential fluctuates when air mass diffuses, about 1μs;The fourth stage, the remainder charges discharges by the testing circuit, the target electric potential reduces exponentially. Equivalent circuit model accords with the experiment result, and the amount of the remainder positive charges of the laser-generated plasma is more than 10~8.The research of this paper lays a preliminary foundation for the mechanism and testing of the laser-generated plasma electrostatic effect in laser ablation and the energy transformation of laser-induced plasma shock wave.