基于天光一号装置的激光直接驱动准等熵压缩研究

Study on Laser Direct Driven Quasi-isentropic Compression Loading on HEAVEN-Ⅰ Laser Facility

采用一种新型的激光驱动准等熵压缩方式,利用KrF准分子激光长脉宽的特点,在不经过脉冲整形的情况下在带窗口铝靶上实现了激光直接驱动准等熵压缩。实验前,对激光光束和靶结构进行了匹配设计。激光打靶获得的峰值压力为16.8GPa,压力上升前沿约为17.0ns,与辐射流体力学数值模拟结果一致,验证了实验方法的可行性和天光一号装置的稳定性和可重复性。通过分析受辐照后靶的损伤形貌与结构特征,发现受辐照区域铝膜完全气化,在辐照区域边缘形成溅射堆积状。辐照前后材料组织结构稳定,在高温高压作用下未形成新物质。最后,基于一维辐射流体力学模拟程序研究了不同激光功率密度对准等熵压缩加载过程影响规律,并采用热力学定律计算了其熵增,获得了其变化规律。

A new kind of laser direct driven quasi-isentropic compression experiment of aluminum without the temporal pulse shape was performed based on the long-pulsed KrF excimer laser.According to the simulated results,matched design of the laser and target structure was carried out.It’s demonstrated that ramp loading in aluminum foils is at pressure of 16.8 GPa with rise time of about 17.0 ns.The peak pressure was well reproduced by the 1D radiation hydrodynamics simulation.The stability and repeatability of HEAVEN-Ⅰlaser facility were verified.Through analyzing the damage morphology and microstructure of recovered sample,it shows that aluminium coating completely gasified in irradiated area,and lots of aluminium deposited on the edge of irradiated area.The phase structure in recovered sample is the same as the initial one,which implies that there are no new materials generated.Finally,to make the effect of the pulse intensity clear,quasi-isentropic compression process was calculated by 1D radiation hydrodynamics simulation.The entropy production was obtained based on law of thermodynamics,and some disciplinary conclusions were drawn.