Exploring the Limits in Ultrafast High Brightness Electron Beam Generation

加速器是促进科学研究的重要工具，在医学和工业中得到广泛应用，并且本身就是一个研究领域。加速器通常加速质子、反质子、电子和正电子（反电子）。强大的加速器导致了希格斯玻色子和顶夸克的发现，中等大小的加速器被用作x射线的来源来研究材料的性质，而较小的机器被用来提供癌症治疗或电子束显微镜。在加速器和束流物理学中，最近的一个新趋势是发展精确电子束，用于超快结构动力学研究的各种应用，并作为自由电子激光器或基于激光的加速器的驱动器。该奖项授予加州大学洛杉矶分校的目的是开发一种新的电子源，能够产生比以前使用最先进的射频光注入器更高亮度的电子束。通过推动更低的光束电荷，可以重新评估光注入腔的设计选择，结合阴极表面工程的最新进展，并采用不同的光束动力学解决方案。在技术上，具有极端光束参数的新型电子源的开发将对紧凑x射线自由电子激光器和超快电子衍射和显微技术产生重要影响。这些技术有望提供物质的实时原子尺度图像，并在凝聚态物理、化学、生物学和材料科学等各种科学领域产生深远的影响。在教育方面，这项工作本质上是跨学科的，将为学生提供全面的实践经验，为光电物理、激光和加速器技术、高亮度光束和光束诊断发展提供广泛的准备。在获得的项目中，UCLA小组计划研究电子源物理学中一些最紧迫的未解问题，如纵向发射度的增长和不相关的能量扩散以及阴极热发射度的极限。

Accelerators are important instruments for the advancement of scientific research, for their broad application in medicine and industry, and as a research area in their own right. Accelerators typically accelerate protons, antiprotons, electrons and positrons (anti-electrons). Powerful accelerators have lead to the discoveries of the Higgs Boson and the top quark, intermediate sized accelerators have been used as sources of x-rays to study properties of materials, and smaller machines are used to provide cancer therapy or for electron beam microscopy. A recent novel trend in accelerator and beam physics is the development of precise electron beams for diverse applications in the study of ultrafast structural dynamics, and as the drivers for Free Electron Lasers or laser-based accelerators. This award to UCLA aims to develop a new electron source capable of generating electron beams with an order of magnitude higher brightness than has been previously achievable using state-of-the-art radiofrequency photoinjectors. By pushing for lower beam charges, the design choices of a photoinjector cavity can be reevaluated, incorporating recent advances in cathode surface engineering and adopting different solutions for the beam dynamics. Technically, the development of a novel electron source with extreme beam parameters will have important impact on compact x-ray free-electron lasers and ultrafast electron diffraction and microscopy. These technologies have the prospect to provide real time atomic scale images of matter with the potential for profound impact in a variety of scientific fields such as condensed matter physics, chemistry, biology and material sciences. Educationally, the work with be intrinsically interdisciplinary and will provide full hands-on experience for students with a broad preparation in photoemission physics, laser and accelerator technology, and high brightness beam and beam diagnostic development.In the program as awarded, the UCLA group plans to study some of the most pressing unanswered questions in electron-source physics, such as the growth of the longitudinal emittance and uncorrelated energy spread and the limit in the cathode thermal emittance.