Study of Magnetically Driven Cylindrical Compression to Create Strongly Coupled Matter

该项目开发了一种新的实验平台，该平台将强磁场用于金属棒的压缩，并将高功率激光器用于高能X射线的产生作为诊断。当一种固体物质被逐渐压缩到超过一百万个大气压的高压时，固态可以转化为液体、气体，并最终转化为等离子体。这种高密度、低温度的物质状态被称为强耦合等离子体，就像在激光聚变核心和密集天体中发现的那样。在这种情况下，材料性质的建模是具有挑战性的，因为它太冷太密，不能应用理想等离子体理论，但热温度太高，不能用凝聚态物理处理。因此，物理模型的实验基准对于理解高压材料的基本性质是重要的。到目前为止，大多数压缩实验都是在国家实验室的大型激光或脉冲电流设备上进行的，发射次数有限。该项目将利用具有成本效益的大学规模的设备，探索磁力驱动圆柱压缩的可行性，以产生与大型设备上使用的平面压缩技术相当甚至更高的压力。激光产生的硬X射线穿透压缩的圆柱体，提供关于其密度分布和材料结构的信息。如果成功，具有紧凑脉冲功率的圆柱形压缩将允许研究人员在强耦合区域研究广泛的材料，用于基础科学和应用。该项目将为一名接受相对论激光-等离子体相互作用和脉冲功率等离子体物理培训的研究生提供全职支持。该项目的目标有两个：表征短脉冲激光产生的硬X射线，并演示磁压缩毫米直径铝棒的X射线探测。在同一真空室中同时使用兆安(MA)脉冲功率和高功率激光的耦合实验目前仅在内华达大学-里诺-内华达太瓦特设施(NTF)和桑迪亚国家实验室的Z-Machine提供。实验将充分利用NTF与1.0 MA斑马脉冲功率和50太瓦豹短脉冲激光的耦合能力。激光-靶相互作用产生的宽带和单色硬X射线(10keV)将用校准的x射线光谱仪和滤光片叠加谱仪进行测量。用X射线照相法和X射线衍射法研究了直径从几百微米到几毫米的固体铝棒的压缩。

This project develops a new experimental platform combining strong magnetic fields for compression of a metal rod, and a high power laser for high-energy x-ray generation as diagnostics. When a solid material is gradually compressed to high pressures above a million atmospheres, the solid state can be transformed to liquid, gas and eventually plasma. This high density, low temperature state of matter is called a strongly coupled plasma, as found in laser fusion cores and dense astrophysical objects. Modeling of material properties in this regime is challenging because it is too cold and dense to apply ideal plasma theory, but the thermal temperature is too high to be treated with condensed matter physics. Thus, experimental benchmarking of the physics models is important for understanding fundamental properties of high-pressured materials. So far, most compression experiments have been conducted on large laser or pulsed electrical current facilities at national laboratories with limited numbers of shots. Using a cost-effective, university-scale facility, this project will explore the feasibility of magnetically driven cylindrical compression to produce pressures comparable to or even higher than those with a planar compression technique used on large facilities. Laser-produced hard x-rays penetrate through a compressed cylinder, providing information on its density profile and material structure. If successful, the cylindrical compression with a compact pulsed power will allow researchers to study a wide range of materials in the strongly coupled regime for fundamental science and applications. This project will provide full-time support for a graduate student to be trained in relativistic laser-plasma interaction and pulsed power plasma physics.The goal of this project is twofold: characterization of short-pulse laser-produced hard x-rays and demonstration of x-ray probing of a magnetically compressed millimeter-diameter aluminum rod. Coupled experiments simultaneously using a Mega Ampere (MA) pulsed power and a high power laser in the same vacuum chamber are currently available only at the University of Nevada - Reno Nevada Terawatt Facility (NTF) and at the Z-Machine at Sandia National Laboratory. The experiments will fully utilize the NTF's coupled capability with the 1.0 MA Zebra pulsed power and 50 Terawatt Leopard short-pulse laser. Broadband and monochromatic hard x-rays ( 10 keV) produced in the laser-target interaction will be measured with calibrated x-ray spectrometers and filter stack spectrometers. Compression of a solid Al rod with a diameter ranging from several hundred microns to a few millimeters will be studied with x-ray radiography and x-ray diffraction.