Laser Plasma Interactions: Fusion, Particle Acceleration and Other Applications

这项拟议的研究将利用激光诱导击穿光谱(LIBS)研究相对论范围内产生MeV电子和MeV质子的高强度(10^18至10^21 W/cm2)激光-等离子体相互作用和低强度激光-等离子体相互作用，以检测饮用水中的重金属污染。以前的研究针对一些应用，包括：(1)聚变能源，这种MeV粒子可用于快速点燃压缩燃料颗粒中的激光聚变，大大减少标准自燃方法所需的激光系统能量，以及(2)用于以下应用的超小型激光驱动的MeV粒子源：(A)亚皮秒射线照相；(B)放射性同位素生产；(C)用于质子癌症治疗和激光聚变能源系统的快速点火驱动器。低强度调查的目标是开发野外便携式激光系统，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发展的轨道角模(OAM)或涡旋模光脉冲，这种光脉冲在拉盖尔-高斯光束中携带额外的角动量。当光被吸收时，这种额外的角动量可以耦合到等离子体中的电子中，驱动环形电流，产生兆高斯强度的轴向磁场。虽然在一些理论研究中已经预测了这些领域，但没有实验测量来证实这些预测。我们开发了一种在高强度激光系统中产生这种OAM模的简单技术，方法是在将光聚焦到目标之前插入一个特殊设计的螺旋阶梯镜作为最后的转镜之一。我们与西班牙萨拉曼卡的强脉冲激光中心(CLPU)合作，用他们的200太瓦(TW)激光系统进行了初步实验，成功地实现了这样的反射镜。如此强大的磁场可以增强电子在高密度等离子体中的导引，这对于激光聚变能量系统的快速点火具有重要的应用价值。此外，我们还将研究质子和电子束在与恒星内部相关的固体密度等离子体(称为温穴物质)中的传播，以及激光聚变点火和燃烧物理，以及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。我们还在开发适用于实际科学和工业应用的下一代高效二极管泵浦高功率(多TW)激光系统。这包括基于微微秒陶瓷圆盘的啁啾脉冲放大(CPA)Yb：YAG激光器和飞秒光学参变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.