An Ultra-Compact X-ray Free-Electron Laser
Recent advances in high gradient cryogenic Cu structure RF research open the door to use of surface electric fields between 250 and 500 MV/m. Such structures can enable a new generation of photoinjectors with brightness an order of magnitude beyond the state-of-the-art. Further, one may accelerate these beams to GeV scale in ~8 m. Such an injector, when combined with IFEL bunching techniques can produce multi-kA beams with 50 nm-rad emittance. These beams, when injected into short-period (1-10 mm) undulators enable ultra-compact X-ray FELs having university-scale-lab footprints*. We discuss the design and performance of this compact XFEL, which promises photon-per-pulse production a few percent of existing XFELs. In the context of a burgeoning project centered at UCLA to develop this instrument, we review implementation issues including collective beam effects, compact X-ray optics systems, and various technical challenges. To illustrate the potential of such a light source to fundamentally change the current paradigm of XFELs with their limited access, we examine transformative applications in biology, chemistry, materials, and atomic physics.
*J. B. Rosenzweig, et al., New Journal of Physics 22, 093067 (2020) https://doi.org/10.1088/1367-2630/abb16c
James Rosenzweig is a Distinguished Professor of Physics in the UCLA Department of Physics and Astronomy. He is the Director of a large research group at UCLA, termed the Particle Beam Physics Laboratory. This multi-disciplinary program concentrates on fundamental aspects of high brightness, ultra-fast electron beams, with application to advanced accelerators based on lasers, wakefields, and plasmas, and to radiation production, such as free-electron lasers and Compton scattering sources. This research program is based on-campus at the SAMURAI Laboratory, complemented by a large external program emphasizing wakefield acceleration at user facilities and collaborating institutions. Prof. Rosenzweig is the author of >530 scientific articles, has written a textbook on the physics of charged particle and laser beams. He is a lifetime member and Fellow of the American Physical Society. He has been the recipient of Sloan and Wilson Fellowships, and has received the International Free-electron Laser Prize. He has served five years as the Chair of the UCLA Dept. of Physics and Astronomy. He has also co-founded several industrial accelerator companies.