In this paper, we focused on the influence of gas pressure on the dynamic characteristics of laser-induced plasma (LIP) in air. The energy-dependent transmittances of a 1064 nm laser to LIPs generated at the pressure of 0.2–5 atm were measured. Laser Rayleigh scattering and Thomson scattering methods were applied to investigate the evolution of laser-produced shock wave and radial distribution of electron number density (n_e) and electron temperature (T_e) of LIP in air. The fraction of the shock wave energy to the total laser energy absorbed is about 40%–52% and increases upon increasing pressure. The higher the gas pressure, the greater n_e and T_e within the central of LIP and a faster decaying rate of T_e and n_e. The electron number density decays exponentially with time, and the decay index is between −0.891 and −1.177. A torus structure in LIPs is generated during the later stage of plasma decay and significantly affects the distribution of T_e, n_e and the intensity of plasma emission.

在本文中，我们重点研究气压对空气中激光诱导等离子体（LIP）动态特性的影响。测量了1064 nm激光对在0.2-5 atm的压力下产生的LIP的能量依赖性透射率。应用激光瑞利散射和汤姆森散射方法研究了激光产生的冲击波的演变以及空气中LIP的电子数密度（n _e）和电子温度（T _e）的径向分布。冲击波能量占吸收的总激光能量的比例约为40％–52％，并且随着压力的增加而增加。气压越高，n _e和T _e越大在LIP的中心处，并且T _e和n _e的衰减速率更快。电子数密度随时间呈指数衰减，并且衰减指数在-0.891至-1.177之间。LIP中的圆环结构在等离子体衰变的后期阶段产生，并显着影响T _e，n _e的分布和等离子体发射的强度。