Beam-Driven Accelerator Studies

要想在基本粒子物理学中有新的发现，就需要在加速器科学和技术上取得进步，实现这一目标的一条途径是设计出新的加速器，以提供高效率的高加速度。这个实验研究项目，在理论和计算的支持下，旨在确认一种基于双束概念的新加速器设计的基本方面，即一束具有大量粒子的光束提供能量，将一束较少的粒子加速到更高的能量。追求这样的路径对于增加未来以可接受的成本建造电子与正电子碰撞的多太电子伏特（即百万-百万电子伏特）机器的可能性至关重要。该项目以耶鲁大学束流物理实验室为基础，将支持建设一个独特的大学基础设施，用于探索一系列额外的束流驱动加速想法，并将为下一代急需的加速器科学家提供培训机会，包括学生、博士后研究人员和初级教师。本项目的技术目标是：(1)配置500千伏电子枪，并配套束流传输线路，提供长时间的大电流多安培束流；(2)利用束列作为驱动梁激励失谐双峰腔结构，实现高加速度梯度和高变比。该结构的两个微波模将被驱动光束激发，其中较高模的频率等于最低基模的三倍。这两种模式的频率与驱动光束或其三次谐波的频率失谐，以支持腔内电磁场的非常规时空分布。预计该策略将允许加速器在高加速度梯度下运行，同时具有低击穿率和极大的系统简化。预期的未来结果是一种可行的加速器结构设计的演变，可以支持一种新的双束加速方案，两束在结构中沿同一中心轴运动。

Advancement in accelerator science and technology is required to make possible new discoveries in elementary particle physics, and one path towards that goal is to devise new accelerator designs to provide high acceleration rates with high efficiency. This experimental research project, with theoretical and computational support, aims to confirm fundamental aspects of a new accelerator design based on a two-beam concept whereby one beam with a large number of particles provides energy to accelerate a beam of fewer particles to a higher energy. The pursuit of paths such as this is essential to increase the likelihood that a future multiple-tera-electron-volt (i.e. a million-million electron volt) machine to collide electrons with positrons will be built at an acceptable cost. This project, based at the Yale University Beam Physics Laboratory, will support construction of a unique university-based facility for exploring a range of additional beam-driven acceleration ideas and will provide training opportunities for the next generation of much-needed accelerator scientists, including students, postdoctoral researchers, and junior faculty.The technical objectives of this project are: (1) to configure a 500-kV electron gun with an associated beam transport line to provide a long high-current multi-Amp bunch train; and (2) to apply such a bunch train as the drive beam to excite a detuned bimodal cavity structure to achieve high acceleration gradient and high transformer ratio. Two microwave modes of this structure will be excited by the drive beam, with the frequency of the higher mode equal to three times that of the lowest fundamental mode. The frequencies of these two modes are detuned away from that of the drive beam or its third-harmonic, to support unconventional spatiotemporal distributions of the electromagnetic fields in the cavities. This strategy is predicted to allow the accelerator to operate at high acceleration gradient with low breakdown rates and great system simplification. The intended future outcome is the evolution of a viable accelerator structure design that can support a novel two-beam acceleration scheme with both beams moving along the same central axis in the structure.