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。这项提议涉及对高强度激光与固体密度等离子体相互作用产生的巨大磁场的特征和动力学进行实验研究。以前，对高达0.7千兆高斯的磁场进行了原理证明测量，这些磁场是在超相对论入射激光强度下产生的，其中激光场中的电子振荡速度大于光速(这大约是实验室以前其他磁场测量的100倍)。目前的研究计划是将这些测量扩展到1000倍的强度，并通过开发使用a)单能相对论电子束和b)高次XUV谐波发射的独特的时间分辨探测诊断方法，对这些极端条件下的等离子体行为有一个清晰的物理理解。密歇根大学超快光学科学中心(CUOS)的500TW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。该激光系统是作为美国国家科学基金会物理前沿中心(Focus)的一部分而建造的。拟议工作的结果将促进在这些相互作用中磁场产生和演化的理论理解方面的进展。这样的理解不仅对于(在实验室和天体物理情况下)更好地理解相对论等离子体的动力学是至关重要的，而且对于这些激光束的几乎所有拟议的应用，如快速点火聚变、医疗放射治疗以及发展紧凑的X射线和高能粒子源，都是必需的。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.