激光间接驱动惯性约束聚变内爆物理实验研究

激光间接驱动惯性约束聚变利用辐射烧蚀驱动靶丸球形内爆,在减速阶段将内爆动能转化成热斑内能,同时压缩燃料,达到点火条件,实现聚变点火。根据目前认识,影响内爆压缩过程的主要因素包括内爆对称性、燃料熵增因子、内爆速度和混合。内爆物理实验研究的目的是发展对上述影响因素的实验表征方法,获取这些影响因素随靶设计参数的变化规律,建立相应的实验调控能力,最终达到不断提升内爆性能的目的。为此,在内爆对称性方面,开展了Bi球自发光实验,用于研究点火脉冲前2ns驱动不对称性;在内爆速度方面,开展了球面弯晶单能流线实验,测量得到内爆速度和剩余质量随时间的变化;在混合方面,开展了内壳层示踪涂层内爆混合实验,测量得到环形发光图像。为考察综合内爆性能,在神光Ⅱ和神光Ⅲ原型装置上开展了DT内爆实验,获得了中子产额随初始靶参数的变化规律。

Experimental studies of implosion physics of indirect-drive inertial confinement fusion

In the research of laser indirect-drive inertial confinement fusion, the capsule is imploded symmetrically using radiative ablation. Then, the implosion kinetic energy is converted into the hotspot thermal energy in the deceleration phase so as to achieve the ignition condition and the resulting burn propagation. According to current knowledge, the most important factors that determine the implosion performance are the implosion symmetry, adiabatic factor, implosion velocity, and mix. The purpose of the experimental studies of the implosion physics is to develop the methods that can quantitatively characterize these factors, to investigate the scaling laws of these factors as the design parameters are changed, and to establish the ways to tune these factors. Considering the implosion symmetry, Bi sphere reemission experiments were carried out in order to characterize the incident flux asymmetry in the first 2 ns of the ignition pulse. With respect to the implosion velocity, the platform of homochromatic stream-line using spherical bent crystal was developed to measure the implosion velocity and the remaining mass. In the subject of mix, we performed implosion experiment using the capsule of doped inner layer, and ring-shaped images were obtained. Finally, comprehensive implosion experiments using DT gas were conducted on SGⅡ and SGⅢ prototype laser facilities. The correlations between neutron yield and initial target parameters were studied.