太赫兹驱动的电子加速：从亚相对论到完全相对论能量在阶梯式介质衬里波导中实现
Terahertz-driven electron acceleration from subrelativistic to fully relativistic energies in stepped dielectric-lined waveguides
- The Cockcroft Institute（科克沃尔研究所）
- Sci-Tech Daresbury（达尔斯伯里科学与技术中心）
- Department of Physics and Astronomy & Photon Science Institute, The University of Manchester（曼彻斯特大学物理与天文学系及光子科学研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出阶梯式介质衬里波导设计，结合多目标遗传算法与粒子模拟，实现太赫兹脉冲驱动电子从100 keV加速至1 MeV，束流质量优异，验证了太赫兹注入器可行性。
AI中文摘要：
太赫兹（THz）波的短波长使得将电子从典型的电子枪能量加速到完全相对论能量变得具有挑战性，原因在于需要在相当长的距离上匹配速度。然而，光电子枪与太赫兹驱动激光的固有激光同步性在时序至关重要的应用中提供了显著优势。我们提出了一种用于高梯度太赫兹驱动介质衬里波导注入器的新型设计流程，并展示了矩形和圆柱形几何结构的设计。这些结构利用新颖的锥形和阶梯化方案来操纵相速度，控制电子束相对于加速场相位的位置。我们展示了一种混合优化方法，首先利用基于波导加速模式解析模型的多目标遗传算法，然后进行高细节的粒子-in-cell模拟。我们的示例设计通过多周期0.5 mJ、0.2 THz脉冲相互作用，在20 mm距离内实现了电子从100 keV到1 MeV的加速，为基于太赫兹的注入器的实现铺平了道路。出射束表现出优异的束流质量，具有50 fs的束团长度、低于0.5%的能量展宽和低于0.15微弧度的发射度。我们还对设计对加工和操作参数误差的鲁棒性进行了分析，证明了该概念的可行性。我们表明，通过使用多目标遗传算法优化和稳健的设计流程，我们可以实现高质量的1 MeV束流。
英文摘要：
The short wavelength of terahertz (THz) waves makes the acceleration of electrons, from typical electron gun energies to fully relativistic energies, challenging due to the need to match the velocities over comparably long distances. However, the inherent laser synchronisation of a photogun to the THz drive laser offers significant advantage in applications where timing is critical. We present a novel design process for high-gradient THz-driven dielectric-lined waveguide injectors and demonstrate designs for rectangular and cylindrical geometries. These structures utilize novel tapering and stepping schemes to manipulate the phase velocity, controlling the position of the electron bunch relative to the phase of the accelerating field. We demonstrate a hybrid optimisation method utilizing firstly a multi-objective genetic algorithm based on analytic models of the waveguide accelerating modes, and then high-detail particle-in-cell simulations. Our example designs achieve electron acceleration from 100 keV to 1 MeV over a distance of 20 mm by interacting with a multicycle 0.5 mJ, 0.2 THz pulse, paving the way for the realisation of THz-based injectors. The exit beam shows excellent beam quality with 50 fs bunch lengths, sub 0.5% energy spread and emittances of under 0.15 μrad. We also present an analysis of the robustness of the designs to errors in machining and operational parameters demonstrating the feasibility of the concept. We show that using multi-objective genetic algorithm optimization and robust design process, we can achieve high-quality 1 MeV beams.
