New Frontiers of Direct Laser Acceleration in Megatesla Magnetic Fields

该项目通过分析和计算机模拟研究了一种新的机制，在该机制中，激光照射的固体密度目标中产生的前所未有的磁场增强了电子的加速，从而能够发射大量高能光子。超高强度的光与物质相互作用是先进加速器研究的下一个前沿，有潜力开发新型加速器和 X 射线源。 这种制度有可能颠覆现有的范式，并从根本上推进加速器科学。在激光与目标相互作用中产生大量高能光子的前景特别令人感兴趣，因为它有许多可能的应用，包括光核光谱、放射治疗和放射外科。 这项研究还与天体物理学具有根本性的相关性，因为它可以为从光中创造物质和反物质铺平道路，从而为宇宙的内部运作提供有价值的见解。该项目将为加速器科学、等离子体物理学和高性能计算方面的学生提供必要的培训。该项目研究的机制的新颖之处在于，极端磁场耦合了高强度激光-等离子体相互作用的三个关键方面：相对论透明度、直接激光加速和同步加速器光子发射。该项目研究的关键问题涵盖兆特斯拉级磁场中电子加速的基本方面，包括等离子体和激光脉冲参数的能量缩放，以及等离子体中产生如此强的激光驱动磁场的机制。该项目专门研究电子加速和光子发射之间的相互作用。这种相互作用是该机制的关键特征，因为虽然加速增强了光子发射，但光子发射本身对微观电子运动有强烈的反馈。除了同步加速器发射之外，该项目还解决了轫致辐射的作用。由于高等离子体密度，轫致辐射可能变得相关，但巨特斯拉磁场的存在可以产生深远的缓解作用，抑制光子发射。

This project examines analytically and using computer simulations a novel regime in which an unprecedented magnetic field, generated in a laser-irradiated solid density target, enhances acceleration of electrons and, as a result, enables emission of copious very energetic photons. Light-matter interactions at ultra-high intensities are the next frontier of the advanced accelerator research with the potential to enable development of novel accelerators and x-ray sources. This regime has the potential to disrupt existing paradigms and advance accelerator science at a fundamental level. The prospect of generating copious quantities of energetic photons in laser-target interactions is of particular interest due to its many possible applications, including photo-nuclear spectroscopy, radiation therapy, and radio surgery. The study is also of fundamental relevance to astrophysics, as it can pave the way to creation of matter and antimatter from light, thus providing valuable insights into the inner workings of the universe. The project will provide essential student training in accelerator science, plasma physics and high performance computing.The novelty of the regime investigated by this project is that the extreme magnetic field couples three key aspects of laser-plasma interactions at high intensities: relativistic transparency, direct laser acceleration, and synchrotron photon emission. The key questions investigated by the project cover fundamental aspects of electron acceleration in Megatesla-level magnetic fields, including energy scaling with plasma and laser pulse parameters, and the mechanism underpinning generation of such a strong laser-driven magnetic field in a plasma. The project specifically examines the interplay between electron acceleration and photon emission. This interplay is the key feature of this regime, because, while the acceleration enhances the photon emission, the photon emission itself has a strong feedback on the microscopic electron motion. In addition to the synchrotron emission, the project also addresses the role of bremsstrahlung. The bremsstrahlung emission can become relevant due to high plasma density, but the presence of the Megatesla magnetic field can have a profound mitigating effect, suppressing photon emission.