Research on high energy density plasmas produced by peta watt laser

2003年，我们开始了这个项目，在五年内开创了一个新的研究领域——佩塔瓦激光等离子体。在实验方面，由于引入了新的OPCPA前端，将预脉冲电平从10^<-4>降低到10^<-8>，改进的GMII已应用于质子加速。通过使用箔靶，我们实现了高达约20MeV的加速度。我们还对固体刨床靶进行了辐照，测量了未加预脉冲时斜坡温度低于加预脉冲时斜坡温度的相对论电子能谱。通过这一成果，我们可以进行良好的控制实验，并对实验数据进行理论和仿真的精确分析。在理论和仿真研究中，我们将辐射流体动力学模拟与水力代码pinocchio结合起来，采用集体PIC模拟和Fokker Planck模拟，对激光聚变和中子源研究中的快速等离子体加热进行了模拟。作为FI3 + h快速点火实验靶设计，模拟了锥形靶实验的内爆等离子体加热过程。特别地，引入双锥靶来改善锥内的相对论性电子约束，并将它们引导到锥的尖端。PIC模拟结果表明，真空间隙中产生的强磁场长时间地限制了相对论性电子。结果表明，耦合效率提高了1.5倍。我们还研究了预等离子体对高能电子输运的影响。当预等离子体的尺度长度超过几μm时，电子斜率温度过高，不利于等离子体的有效加热。为了克服这一困难，我们研究了预脉冲产生等离子体的工艺。根据仿真，要求预脉冲强度小于10^<11>W/cm^2。总之，经过5年的项目，开发并验证了集成仿真代码。仿真研究有助于实验设计和分析。在实验中，对GMII短脉冲超强激光器进行了改进，并应用于质子和电子束加速实验。澄清了自生磁场和相对论性电子引导。少

In 2003, we started this project to create a new field in the research of peta watt laser plasmas within five years. As for the experiments, since the new OPCPA front end was introduced to reduce the pre-pulse level from 10^<-4> to 10^<-8>, the improved GMII has been applied to the proton acceleration. By using a thin foil target, we achieved the acceleration of up to about 20MeV. We also irradiated solid planer targets to measure the relativistic electron spectrum of which slope temperature without pre-pulse is lower than that with pre-pulse. By this achievement, we can carry out well controlled experiments and analyze experimental data precisely with theory and simulation.In the theory and simulation research, we combined a radiation hydrodynamic simulation with the hydro code PINOCO, a collective PIC simulation, and a Fokker Planck simulation to simulate the fast plasma heating for laser fusion and neutron source researches. As the target design for the fast ignition experiments wit … More h of FI3, we simulated the imploded plasma heating processes for the cone target experiment. In particular, the double cone target was introduced to improve the relativistic electron confinement in the cone and guiding them to he tip of the cone. The PIC simulation indicated that the strong magnetic fields in the vacuum gap are generated which confine relativistic electrons for a long time. As the results, the coupling efficiency is enhanced by 1.5 time. We also investigated the pre-plasma effects on the high energy electron transport. It is found that when the scale length of the pre-plasma exceeds a few μm, the electron slope temperature is too hig for the efficient plasma heating. In order to overcome this difficulty, we investigated the plasma production processes by the pre-pulse. According to the simulations, prepulse intensity is required to be lower than 10^<11>W/cm^2.In conclusion, after 5 year project, the integrated simulation code was developed and validated. The simulation research contributed to the experiment design and analysis. In the experiment, the GMII short pulse ultra intense laser was improved and applied to the proton and electron beam acceleration experiments. The self-generated magnetic field s and the relativistic electron guiding have been clarified. Less