Enhancing ERL development in the UK

能量回收直线加速器（ERLs）有可能通过允许以仅适度的RF功率消耗产生高功率电子束来支撑未来高能物理实验的物理范围。这是通过使废束减速来提取废束的动能并使用该能量来加速新束来实现的，从而大大降低了加速器的总功耗。多匝ERL对于以成本有效的方式将电子加速到10 s GeV特别重要。ERLs被认为是未来高强度轻子-强子对撞机（FCC-eh，LHeC，EIC）和自由电子激光设施（UK-XFEL）的一项使能技术。在未来4-5年内，预计国际ERL社区将开始相关技术和测试设施的原型。该提案的主要目的是保持英国在与ERLs相关的加速器研发方面的国际领先地位。超导RF（SRF）技术对ERL的运行至关重要，并且高传输束功率要求开发机器保护和相关诊断。最后，光束线设计，包括拓扑结构和交错的新的和旧的束在多个回合的机器-被称为填充模式-是一个重要的新的研究领域，因为最近英国的研究表明，使用优化的束模式在性能上有重大改进的潜力。Cockcroft研究所在所有这些领域都拥有世界领先的专业知识，因此将这些领域确定为高度优先领域。PPTAP的英国加速器研发路线图将突出ERL的潜在社会应用，这些应用可能发生在比未来对撞机所需的规模更小的设施上。特别令人感兴趣的是那些在光源，即通过逆康普顿散射驱动的单能伽马源，和高平均功率自由电子激光器与UK-XFEL的协同作用。解决这些问题的中型ERL设施也可以成为及时部署未来对撞机项目所需关键技术的平台。在该路线图中，所有三个高优先级的研发主题都被提及，其中RF和ERL部分都提到了薄膜SRF，ERL部分强调了进一步加速器研发和诊断的需求。此外，关于诊断和薄膜SRF的研究可能会应用于安全和医疗加速器，从而产生额外的社会影响。

Energy recovery linacs (ERLs) have the potential to underpin the physics reach of future high-energy physics experiments by allowing the generation of high power electron beams with only modest RF power consumption. This is achieved by extracting the kinetic energy of the spent bunches by decelerating them and using this energy to accelerate new bunches, thus drastically reducing the overall power consumption of the accelerator. Multi-turn ERLs are of particular importance for accelerating electrons to 10s of GeV in a cost effective manner. ERLs are seen as an enabling technology for future high-intensity lepton-hadron colliders (FCC-eh, LHeC, EIC) and FEL facilities (UK-XFEL). Over the next 4-5 years, it is expected that the international ERL community will begin prototyping of relevant technologies and test facilities. The main purpose of this proposal is to maintain the UK's international leadership in accelerator R&D related to ERLs.Superconducting RF (SRF) technology is essential to the operation of an ERL, and the high delivered beam powers demand development of machine protection and related diagnostics. Finally, the beam line designs, including the topology and interleaving of new and old bunches in the machine over multiple turns - known as the filling pattern - are an important new area of study since recent UK studies have shown the potential for major improvements in performance using optimised bunch patterns. The Cockcroft Institute has world-leading expertise in all of these areas and accordingly have identified these areas as high priority. Hence the research undertaken within this project will address these areas to enhance the UK's continued leadership.The UK Accelerator R&D Roadmap by PPTAP will highlight potential societal applications of ERLs that could occur on smaller scale facilities than those required for future colliders. Of particular interest are those in light sources, namely a monoenergetic gamma source driven via inverse Compton scattering, and high average power Free Electron Lasers with synergies to a UK-XFEL. A mid-scale ERL facility addressing these could also be a platform for timely deployment of the key technologies required for future collider projects. Within this roadmap, all three high-priority themes of R&D are mentioned with thin film SRF mentioned in both the RF and ERL sections, and the ERL section highlighting the need for further accelerator R&D as well as diagnostics. Furthermore, the studies on diagnostics and thin film SRF are likely to have applications for security and medical accelerators, providing additional societal impact.