Laser Plasma Interactions: Fusion, Particle Acceleration and Other Applications

提出的研究将研究高强度（10^18至10^21 W/cm2）激光等离子体相互作用在相对论体制中产生MeV电子和MeV质子，以及使用激光诱导击穿光谱（LIBS）检测饮用水中重金属污染的低强度激光等离子体相互作用。前一项调查的目标是一些申请，包括：(1)聚变能，其中这些MeV粒子可以用于压缩燃料颗粒中的激光聚变快速点火，大大减少标准自燃方法所需的激光系统能量；(2)超紧凑激光驱动的MeV粒子源用于(a)亚皮秒放射照相，(b)放射性同位素生产(c)质子癌症治疗和激光聚变能量系统的快速点火驱动器。低强度调查的目标是开发实地便携式激光系统，用于测量偏远地区和第三世界国家的水质，特别是重金属污染。我们正在探索的高强度激光等离子体应用的新方法之一是使用新开发的轨道角模（OAM）或“涡旋”模式光脉冲，它们在拉盖尔-高斯光束中携带额外的角动量。当光被吸收时，这个额外的角动量可以耦合到等离子体中的电子中，驱动圆形电流并产生百万高斯强度的轴向磁场。虽然这些领域已经在许多理论研究中得到了预测，但没有实验测量来验证这些预测。我们开发了一种简单的技术，在高强度激光系统中产生这种OAM模式，通过插入一个特殊设计的螺旋楼梯镜作为将光聚焦到目标上的最后旋转镜之一。我们已经与西班牙萨拉曼卡的强脉冲激光中心（CLPU）合作，在200太瓦（TW）激光系统的初步实验中成功地实现了这种反射镜。这种强大的磁场可以增强高密度等离子体中电子的引导，这对于激光聚变能系统的快速点火应用非常重要。此外，我们将研究与恒星内部相关的固体密度等离子体（称为热穴物质）中质子和电子束的传播，激光聚变点火和燃烧物理以及来自单个电子的高强度脉冲的汤姆逊散射，这些可以用作激光束的峰值强度诊断。我们还在开发下一代高效二极管泵浦高功率（多tw）激光器系统，适用于真正的科学和工业应用。这包括皮秒陶瓷盘啁啾脉冲放大（CPA） Yb:YAG激光器和飞秒光学参数啁啾脉冲放大激光器。

The proposed research will investigate high intensity ( 10^18 to 10^21 W/cm2) laser-plasma interactions in the relativistic regime for MeV electron and MeV proton production and low intensity laser-plasma interactions using Laser Induced Breakdown Spectroscopy (LIBS) for detection of heavy metal contamination in drinking water. The former investigations target a number of applications, including: (1) fusion energy where such MeV particles can be used for Fast Ignition of Laser Fusion in a compressed fuel pellet, significantly reducing the required laser system energies from the standard self ignition approaches and (2) super compact laser driven MeV particle sources for applications in (a) subpicosecond radiography, (b) radioisotope production (c) proton cancer therapy and Fast Ignition drivers for Laser Fusion Energy systems. The low intensity investigations are targeted at developing field portable laser based systems for measurements of water quality, specifically heavy metal contamination, in remote locations and third world countries. One of the novel approaches we are exploring for the high intensity laser plasma applications is the use of newly developed Orbital Angular Mode (OAM) or "Vortex" mode optical pulses which carry extra angular momentum in Laguerre-Gaussian beams. This extra angular momentum can be coupled into the electrons in the plasma when the light is absorbed driving a circular current and generating Megagauss strength axial magnetic fields. While these fields have been predicted in a number of theoretical investigations, there are no experimental measurements verifying these predictions. We have developed a simple technique to generate such OAM modes in high intensity laser systems by the insertion of a specially designed spiral staircase mirror as one of the final turning mirrors prior to focusing the light onto targets. We have successfully implemented such mirrors in collaborations with the Center for Intense Pulsed Lasers (CLPU) in Salamanca Spain in preliminary experiments with their 200 Terawatt (TW) laser system. Such powerful magnetic fields could lead to enhanced guiding of electrons in high density plasma which would be very important for applications in Fast Ignition of Laser Fusion Energy systems. In addition we will study the propagation of proton and electron beams in solid density plasmas (called warm dens matter) of relevance to the interior of stars and laser fusion ignition and burn physics and Thomson scattering of high intensity pulses from individual electrons which can then be used as a peak intensity diagnostic for laser beams. We are also developing the next generation of efficient diode pumped high power (multi-TW) lasers systems, suitable for real scientific and industrial applications. This includes both picosecond ceramic disk based chirped pulse amplification (CPA) Yb:YAG lasers and femtosecond Optical Parametric Chirped pulse amplification lasers.