Interaction of relativistic intensity laser with a compressed plasma

激光技术的巨大进步使制造相对论性等离子体成为可能。利用这一进展，提出了激光聚变的快速点火方案。本项目的目的是研究压缩等离子体中的激光等离子体相互作用，并阐明快速点火的物理性质。首先，研究了利用超短脉冲对压缩燃料边缘进行加热的钻孔工艺。在一个例子中，我们利用大型并行计算机求解Vlasov-Maxwell方程，研究了激光和等离子体的相对论相互作用物理。结果表明，激光束在传输过程中由于维贝尔型不稳定性而发生破裂，并不是总能实现自聚焦。这一事实在粒子码的研究中也得到了证实。针对压缩堆芯的点火和燃烧问题，用二维内爆码和粒子输运码阐明了给定压缩堆芯聚变增益的标度规律。无论是在核心中心还是边缘触发点火，都获得了几乎相同的点火条件，并且发现在兆焦耳激光照射的情况下，原则上可以获得200左右的目标增益。利用强激光可以设计天文现象的模型实验。这一主题与本项目有关，并在报告中作了简要描述。

Drastic progress of laser technology have made it possible to produce a relativistic plasma. By use of this advance, the fast ignition scheme has been proposed in laser fusions. The purpose of this project is to study the laser plasma interactions in a compressed plasma and to clarify the physics of fast ignition.At first, we have studied the hole boring process to guide a ultra-short pulse to heat the edge of a compressed fuel. In one case, we have studied the relativistic interaction physics of laser and plasma by solving Vlasov-Maxwell equations with massive parallel computer. As the result, it is found that the self-focusing is not always expected, while the propagating laser beam breaks up due to the Weibel-type instability. This fact is also confirmed in the study with a particle code.Concerning the ignition and burn in the compressed core, we have clarified a scaling law of fusion gain of a given compressed core by use of 2-dimensional implosion code with alpha-particle transport code. Regardless whether ignition is triggered at the core center or edge, almost the same ignition condition has been obtained, It is also found that the target gain about 200 can be obtained in principle for the case of Mega Joule laser irradiation.Model experiments of astronomical phenomena can be designed with the intense laser lights. This topics is related to the present project and is briefly described in the report.