Femtosecond Probing of Magnetic Fields Generated from Ultra-Intense Laser Plasma Interactions

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。本研究对高强度激光与固体密度等离子体相互作用时产生的巨大磁场的特性和动力学进行了实验研究。在此之前，在超相对论入射激光强度下产生的高达0.7千兆赫的磁场的原理验证测量已经完成，其中激光场中的电子振荡速度大于光速（这比之前在实验室中对磁场的其他测量大100倍）。目前的研究计划是将这些测量扩展到1000倍大的强度，并通过使用a)单能量相对论电子束和b)高阶XUV谐波发射开发独特的时间分辨探测诊断来获得对这些极端条件下等离子体行为的清晰物理理解。密歇根大学超快光学科学中心（CUOS）的500 TW大力神激光系统将使这些实验中使用的超高强度成为可能。该激光系统是美国国家科学基金会物理前沿中心（FOCUS）的一部分。提出的工作结果将促进对这些相互作用中磁场产生和演化的理论理解的进展。这种理解不仅对提高对相对论性等离子体动力学的基本理解至关重要（无论是在实验室还是在天体物理情况下），而且对于这些激光束的几乎所有拟议应用（如快速点火聚变、医疗放射治疗以及紧凑x射线和高能粒子源的发展）也是必需的。该提案已提交给NSF-DoE等离子体科学与工程合作伙伴联合征集。该奖项由物理系等离子体物理项目资助。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This proposal involves an experimental investigation into the characteristics and dynamics of the huge magnetic fields generated during high intensity laser interactions with solid density plasmas. Previously, proof-of-principle measurements of magnetic fields up to 0.7 Gigagauss were done which were generated at ultra-relativistic incident laser intensities where the electron oscillation velocity in the laser field is larger than the speed of light (this was about 100 times greater than other previous measurements of magnetic fields in the laboratory). The present research plan is to extend these measurements to intensities 1000 times larger and also to obtain a clear physical understanding of the behavior of plasma in these extreme conditions by developing unique time-resolved probing diagnostics using both a) mono-energetic relativistic electron beams and b) high order XUV harmonic emission. The ultra-high intensities to be used in these experiments will be made possible using the 500 TW Hercules laser system at the Center for Ultrafast Optical Science (CUOS) at the University of Michigan. This laser system has been constructed as part of an NSF Physics Frontier Center (FOCUS). The results of the proposed work will stimulate progress in the theoretical understanding of magnetic field generation and evolution in these interactions. Such understanding is critical not only for an improved fundamental understanding of the dynamics of relativistic plasma (both in the laboratory and in astrophysical situations) but is also required for almost all of the proposed applications of these laser beams such as fast ignition fusion, medical radio-therapy as well as for the development of compact x-ray and energetic particle sources.This proposal was submitted to the NSF-DoE Partnership in Plasma Science and Engineering joint solicitation. This award is being funded by the Plasma Physics Program in the Division of Physics.