CAREER: Coherent Radiation Production in an Ion Channel Laser

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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.