Advanced pulsed power drive concepts for producing strong shocks in solids

大型脉冲功率设备的一个主要用途是将厘米尺度的飞片磁加速到极限速度，然后将其与目标相互作用以进行状态方程研究。例如，在Z设施上，铝制飞片的速度达到了100 - 40km -1，与碳样品的平面撞击产生了100 - 1tpa的压力。这种飞弹是第一光聚变正在探索的主要方法，用于在目标内部产生强大的平面冲击，其内部几何结构被设计成坍塌并引发聚变反应。目前，大多数磁驱动飞片的研究都是基于“条带线”几何，其设计是为了优化飞片的平面度。然而，还有一些其他的方案——比如环形发射装置正在探索的第一个轻聚变和锥形收敛方案，重定向磁驱动的内爆——这可能更适合产生所需的飞行加速/形状。此外，最近的研究表明，冲击波可以通过电流驱动的夯实导线爆炸极其有效地发射出来——这可以使冲击波在任何聚变目标上就地产生，而不是通过飞片。该博士研究生将探索利用脉冲功率在目标中产生强冲击波的新方法。从带状线开始，学生将探索几何形状的3D形状-特别是曲率的使用-可以用来改变发射和飞行，可能使更高的速度，更小的传单被发射。这项工作将随着锥形内爆棒的使用而扩展，在棒的末端有一个小区域发射飞片。在这些新的磁发射方案的同时，学生将研究爆炸导线负载的使用，以直接在目标材料中产生成形的高速冲击波。目前电线只在水浴中爆炸，因此这项研究将检查电线周围塑料和金属的使用，并探索新的方法来进一步提高产生的冲击波的速度。这项研究的大部分将在帝国理工学院的MACH发生器上进行，这是一个尖端的，~2MA， 400ns的脉冲功率腔，干燥空气绝缘。该学生将接受脉冲功率的使用培训，并利用多种诊断技术设计和执行冲击物理实验，包括多帧激光干涉测量和纹影摄影，条纹摄影，多点PdV，线VISAR和使用便携式X-pinch驱动器的硬x射线摄影。他们还将采取行动，支持在MAGPIE上工作的其他FLF学生，对那里的实验中产生的冲击波进行测速测量（MAGPIE目前无法提供诊断）。除了探索这些新的驱动技术，这项工作将产生高质量的定量数据，适用于流体力学代码的使用和比较。在博士课程中，学生将受益于帝国理工学院和第一光聚变之间已经建立的良好联系，使任何研究都能被第一光迅速利用。

One of the principle uses of large pulsed power facilities has been to magnetically accelerate cm-scale flyer plates to extreme velocities, then interact these with targets for equation of state studies. On the Z facility, for instance, aluminum flyers have been driven to velocities >40kms-1, and planar impacts with samples of carbon have produced >TPa pressures. Such flyers are the main method being explored by First Light Fusion to produce strong, planar shocks inside targets with an internal geometry designed to collapse and initiate fusion reactions.Presently most magnetically driven flyer research is based around 'strip line' geometries, which are designed to optimize planarity of the flyer. However there are several other schemes - such as the ring launcher being explored at first light fusion and conically convergent schemes that redirect a magnetically driven implosion - which could be more suited to producing the required flyer acceleration/shape. Further, recent research has demonstrated that shock waves can be launched extremely efficiently by the current driven explosion of tamped wires - which could enable the shock waves to be produced in situ to any fusion target rather than via flyer.This PhD studentship will explore new methods utilizing pulsed power to produce strong shock waves in targets. Starting with striplines, the student will explore how 3D shaping of the geometry - in particular the use of curvature - can be used to alter the launch and flight potentially enabling higher speed, smaller flyers to be launched. This work will be extended with the use of conically shaped imploding rods, with flyer launch from a small area at the end of the rod. Simultaneous to these new magnetic launch schemes, the student will examine the use of exploding wire loads to produce shaped high speed shock waves directly in a target material. Presently wires have only been exploded in water baths, and so this research will examine the use of plastics and metals around the wires, and explore new methods to further increase the speed of the shock waves produced. The majority of this research will be carried out on the MACH generator at Imperial College - a cutting edge, ~2MA, 400ns pulsed power cavity that is dry air insulated. The student would be trained in the use of pulsed power, and designing and performing shock physics experiments utilizing multiple diagnostic techniques including multi-frame laser interferometry and Schlieren photography, streak photography, multiple point PdV, line VISAR and hard X-ray radiography using a portable X-pinch driver. They would also act to support the other FLF student working on MAGPIE with velocimetry measurements of the shock waves produced in experiments there (diagnostics not presently available on MAGPIE). In addition to exploring these new drive techniques the work will produce high quality quantitative data suitable for use and comparison to hydrodynamics codes. Over the course of the PhD the student will be benefit from the good links already established between Imperial College and First Light fusion, enabling any research to be swiftly utilized by First Light.