【摘要】 以聚乙烯薄膜材料为研究对象,从实验物态方程出发,对强激光驱动薄膜材料时影响激光在薄膜后表面形成等离子体射流的主要因素,包括激光强度、波长、脉宽、气库膜材料及厚度,进行了理论和数值分析。研究表明,到达薄膜后表面的冲击波强度足够高时,能够产生气态或等离子体射流,否则卸载过程仍然为凝聚态;对于聚乙烯材料,形成等离子体射流的基本条件是到达薄膜后表面的冲击波强度达到约80 GPa以上;采用短波长、较高功率密度、较长激光脉宽的激光驱动具有低汽化温度、低电离阈值的薄靶,更容易实现等离子体射流。更多还原

【Abstract】 Laser-driven plasma jets provide a new way to simulate astrophysical jets and generate shockless loading in solids to high pressures,which are very important in the researches of high energy density physics.The experiments are all under the conditions with very high laser intensity in literatures,but there is no criterion of the basic condition under which the plasma jets can form from the rear surface of the driven film.The main objective of the current study is to investigate the effects of laser intensity,wavelength,pulse width,target material,and target thickness on plasma jet using analytic numerical methods.The results show that the shock strength before exiting the rear of the reservoir must be higher than a threshold value for jet formation.For polyethylene,this value is about 80GPa.The lower wavelength,boiling temperature,and ionization threshold value,and higher laser intensity,longer pulse width,thinner target,the plasma jet is more easily achieved for the thin target with low boiling temperature and small ionization threshold value when irradiated by a pulsed laser with high intensity,short wavelength and long pulse width.更多还原