CAREER: Coherent Radiation Production in an Ion Channel Laser

这项由CAREER奖支持的研究将通过研究一种利用电子束和等离子体源之间相互作用的方法来推进x射线激光生产的物理学。高亮度x射线激光光源代表了科学成像的前沿，能够在原子尺度上解决超快速动力学问题，同时也为从材料科学到制药研究等技术追求提供了关键能力。大型x射线激光设备被安置在国家实验室，如SLAC国家加速器实验室的线性相干光源。这个项目将为更紧凑和灵活的x射线激光源铺平道路，对于缺乏国家实验室空间和财政资源的大学和其他机构来说，这将是负担得起的。此外，该项目将努力增加非裔美国人在物理学博士项目中的代表性，为从历史上的黑人学院和大学招募的学生提供强大的本科研究经验，与美国国家科学基金会资助的本科生暑期实习研究经验项目相协调。最后，本项目将为在科罗拉多州学习的研究生等离子体物理学学生建立一个新的年度暑期学校静修，以扩大学生对等离子体物理学不同子领域的教育接触，提供交流机会，增强他们作为等离子体物理学家的社区意识。本研究的目的是测量和模拟相对论性电子束与等离子体通过离子通道激光（ICL）机制相互作用产生的相干辐射。这将通过在SLAC国家加速器实验室的先进加速器实验测试设施- ii （FACET-II）进行的实验工作来实现。首席研究员的研究小组是FACET-II等离子体加速器研究合作的一部分，并将利用该计划的众多协同效应来开展工作。迄今为止，ICL理论已被提出，但尚未在实验中进行研究。该项目将测量在FACET-II实验中可以实现的两个区域的辐射增益长度和亮度：1)800 nm波长的大振荡幅度区域，可以借助FACET-II Ti：蓝宝石激光系统进行播种；2)1 nm波长的小振荡幅度区域，以了解ICL产生x射线激光脉冲的能力。由于束流能量扩散的容忍度相对较低，ICL可以容纳来自等离子体加速器的电子束。此外，当电子束进入等离子体源时，通过调整电子束的初始横向偏移和角度，可以以相对微不足道的方式在逐射基础上改变ICL产生的辐射的偏振。通过利用ICL的这些独特功能，这项研究可能会导致新型紧凑的、基于等离子体的x射线激光源在学术界、国家实验室和工业中广泛使用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The research enabled by this CAREER award will advance the physics of X-ray laser production by studying a method that utilizes interactions between an electron beam and a plasma source. High-brightness X-ray laser light sources represent the cutting edge of scientific imaging, capable of resolving ultra-fast dynamics at the atomic scale, while also providing critical capabilities in service of technological pursuits ranging from materials science to pharmaceutical research. Large-scale X-ray laser facilities are housed at national laboratories, such as the Linear Coherent Light Source at the SLAC National Accelerator Laboratory. This project will pave the way toward a more compact and flexible X-ray laser source that would be affordable to universities and other institutions lacking the space and financial resources of a national lab. In addition, this project will work to increase African American representation in physics Ph.D. programs by providing a strong undergraduate research experience to students recruited from Historically Black Colleges and Universities in coordination with the NSF-funded Research Experience for Undergraduates summer internship program run by the University of Colorado. Finally, this project will establish a new annual summer school retreat for graduate-level plasma physics students studying in Colorado to broaden the students’ educational exposure to different sub-fields of plasma physics, provide networking opportunities, and enhance their sense of community as plasma physicists.The objective of the research is to measure and model the generation of coherent radiation from the interaction between a relativistic electron beam and a plasma via the ion channel laser (ICL) mechanism. This will be achieved through experimental work carried out at the Facility for Advanced Accelerator Experimental Tests-II (FACET-II) at the SLAC National Accelerator Laboratory. The principal investigator’s research group is a part of the FACET-II plasma accelerator research collaboration and will leverage numerous synergies with that program to carry out the work. To date, the ICL has been proposed theoretically, but not yet studied in experiment. This project will measure the gain length and brightness of radiation that can be achieved in two regimes that are experimentally accessible at FACET-II: 1) the large oscillation amplitude regime at 800 nm wavelength, which can be seeded with the aid of the FACET-II Ti:sapphire laser system, and 2) the small oscillation amplitude regime at 1 nm wavelength to understand the ICL’s capability of producing X-ray laser pulses. The ICL is accommodating to electron beams originating from plasma-based accelerators due to a relatively loose tolerance on the beam energy spread. Further, the polarization of the radiation produced by the ICL can be changed in a relatively trivial manner on a shot-by-shot basis by adjusting the initial transverse offset and angle of the electron beam as it enters the plasma source. By leveraging these unique features of the ICL, this research may lead to novel forms of compact, plasma-based X-ray laser sources for broad use in academia, national labs, and industry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.