冲击波点火中重要流体不稳定性问题研究

Indirect-driven center hot-spot ignition on the US National Ignition Facility (NIF) is recently fased on extreme scientifical challenge of the hydrodynamic instablity in the implosion and the laser-plasmas instability. Compared to the center hot-spot ignition,the shock ignition has the advantages in high implosive efficients, large fusion energy gain and economical and robust engineering features, thus is widely focused in the world. In this project,the critical issues of hydrodynamic instabilities in the shock ignition implosion are studied, mainly included: interaction between the ignition shock and the inner and outer surface perturbations largely grown before and the rule of later growth, the growth rule of hydrodynamic instabilities in the process of collision between the ignition shock and the compressive shock, and the impact on hydrodynamic instabilities arising from the intensity ratio and retarded time between the ignition shock and the compressive shock. Hydrodynamic instabilities in the shock ignition implosion is largely different in the center hot-spot ignition and is seldom studied in the world. This project pays more attention on the physical rule studied,and taking advantage of their strong physical background on the high-energy-density hydrodynamic instability, national top-ranking conditions of the numerical simulation and the laser facility experiment, studies the critical and based issues and expects international innovative results. These results will support the research and the design of shock ignition targets with the physical base, and reduce the challenge and pressure of technology in laser facility construction and target fabrication in our national important project of laser fusion.

目前美国国家点火装置(NIF)间接驱动中心点火面临内爆流体不稳定性和激光等离子体不稳定性科学风险的极大挑战。冲击波点火是近年提出的先进激光聚变点火方式，相比中心点火，具有内爆效率高、聚变能量增益大和工程经济皮实的特点，在国际上受到普遍重视。本项目研究冲击波点火中重要流体不稳定性问题，主要包括：点火冲击波与已有较大增长内外表面扰动的相互作用及后续增长规律、点火冲击波与压缩冲击波相碰过程中流体不稳定性增长规律、点火冲击波与压缩冲击波强度比和延迟时间对流体不稳定性增长的影响。冲击波点火与中心点火流体不稳定性问题有很大不同，且国际上还很少开展研究。本项目注重物理规律研究，利用已有高能量密度流体不稳定性扎实物理基础、国内一流数值模拟条件和激光装置实验条件，开展关键基础问题研究，期待获得国际创新成果，为我国冲击波点火靶研究和设计提供物理基础支持，减轻我国聚变点火重大专项驱动器和靶制作技术风险压力。

目前美国国家点火装置(NIF)间接驱动中心点火面临内爆流体不稳定性科学风险的很大挑战。相比中心点火，冲击波点火具有内爆效率高、聚变增益大的特点，但产生点火冲击波的3-6亿大气压的超高驱动压力难以在实验室产生。本基金项目在研究冲击波点火内爆基础上，充分吸收冲击波点火的优点，规避其缺点，创新提出了冲击波辅助间接驱动中心点火的稀疏再压缩(DR)新型点火物理方案。DR新型点火方案不仅提高了内爆效率，而且有效缓解了间接驱动点火内爆的流体不稳定性压力，较好解决了美国NIF上间接驱动点火遇到了流体不稳定性困难。利用该新型方案，本项目开展了我国激光间接驱动点火靶设计，获得了好的效果。与此同时，针对美国NIF间接驱动内爆高收缩流体不稳定性和烧蚀流体不稳定性等问题，开展了较多研究，获得了一些国际创新性成果。本项目获得的成果，对于我国激光间接驱动点火靶研究和设计，对于我国ICF内爆流体稳定性控制，对于我国高能量密度流体不稳定性研究，有十分重要的促进作用，并有重要的科学意义和实际应用价值。