Tapering Enhanced Stimulated Superradiant Amplification

Over the last decade, Free Electron Laser (FEL) light sources have become an essential component of the world-wide scientific infrastructure, and deliver core research capabilities to Users across many scientific disciplines. However, the conventional FEL efficiency is usually limited to a small fraction of 1% at short wavelengths, which is a significant strain on the light source accessibility and performance. In response to this problem, RadiaBeam Technologies and UCLA are developing a novel concept, TESSA (Tapering Enhanced Stimulated Superradiant Amplification), which carries the promise to increase FEL efficiency by over an order of magnitude. By applying a high intensity radiation seed and a novel, strong-tapering algorithm, it was shown numerically that TESSA can achieve an energy exchange rate between laser and electron beam of 50 MeV/m, and an overall efficiency as high as 50%. The TESSA concept has only been validated experimentally at 10 µm wavelength, and in this project it will be extend it into the ultra-violet frequency range. During the Phase I, a detailed numerical study of the proposed TESSA experiment will be carried out, including optimization of the photoinjector operating regime, bunch compression dynamics, TESSA seeding, and amplification. The beamline components and subsystems will be designed and optimized, with particular effort placed on the initial design and cost engineering of the tapered helical undulator. Commercial Applications and Other Benefits A successful TESSA demonstration in the ultraviolet frequency range, can lead to development of novel and significant additional capabilities for the FEL Light Source community. It would also trigger a broader interest towards high efficiency FEL sources, including an interest from emerging industrial applications. For RadiaBeam the realization of TESSA concept, represents an exciting and potentially disruptive commercial opportunity.