Development of new technologies to scale the average power (pulse energy and pulse rate) and efficiency of high average power DPSSL

世界上最强大的多焦耳二极管泵浦固体激光器DiPOLE100是由STFC的中央激光设备(CLF)[1]开发的，最近展示了以10赫兹(1.5kW)的脉冲频率将脉冲放大到150J，光-光效率为30%[2]。偶极气冷多板条放大器技术是CLF目前为极端光子学和应用中心(EPAC)开发的10赫兹拍瓦激光器的组成部分。偶极技术既被用于泵浦激光器，用于最终的高能Ti：Sa放大器(在频率转换为绿色之后)，也用于Ti：Sa放大器本身[3]。在国家点火设施最近演示点火后，人们对进一步扩大DPSSL系统的能源和效率的兴趣增加了[4]。此外，下一代激光驱动的等离子体加速器将需要以更高的效率和脉冲重复率(kHz方案)[5]运行高脉冲能量。本项目重点研究通过将脉冲频率提高到1 kHz并将脉冲能量提高到150 J来将平均功率扩展到千瓦级别以上所需的新技术，从而突破当前偶极子系统的界限。学生将致力于新的100赫兹偶极子系统的建模、设计、测试和表征，作为EPAC升级路径的一部分。他们将探索新的泵浦方案和替代的放大器几何结构，以提高效率，同时改进诊断和光束校正技术，以保持光束质量。还将对替代增益介质和热管理解决方案进行研究，以进一步调整能量和脉率。最后，学生将评估这项技术在基于激光的惯性约束聚变和激光驱动的等离子体加速器应用方面的未来。

The world's most powerful multi-Joule, diode-pumped solid-state laser (DPSSL), DiPOLE100, was developed by the Central Laser Facility (CLF) within STFC [1] and has recently demonstrated amplification of 10 ns pulses to 150 J at a pulse rate of 10 Hz (1.5 kW) with an optical-to-optical efficiency of 30% [2]. DiPOLE gas cooled multi-slab amplifier technology is integral to the 10 Hz petawatt laser currently being developed by the CLF for the Extreme Photonics and Applications Centre (EPAC). DiPOLE technology is utilised in both the pump laser for the final high energy Ti:Sa amplifier (after frequency conversion into the green) and for the Ti:Sa amplifier itself [3]. Interest in further energy and efficiency scaling of DPSSL systems has increased following the recent demonstration of ignition at the National Ignition Facility [4]. Furthermore, next generation laser-driven plasma accelerators will require high pulse energy operation at increased efficiency and pulse repetition rate (kHz regime) [5].This project focuses on pushing the boundaries of current DiPOLE systems by investigating new technologies required to scale average power beyond the kilowatt level by increasing pulse rate towards 1 kHz and pulse energies beyond 150 J. The student will work on modelling, design, testing and characterisation of new 100 Hz DiPOLE systems, as part of the upgrade path for EPAC. They will explore novel pumping schemes and alternative amplifier geometries to improve efficiency, whilst improving diagnostics and beam correction techniques for maintaining beam quality. Research into alternative gain media and thermal management solutions to scale energy and pulse rate further will also be undertaken. Finally, the student will evaluate the future of this technology for laser-based inertial confinement fusion and laser-driven plasma accelerator applications.