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. Technical Approach 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, strongtapering algorithm, it was shown numerically that TESSA can achieve 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 validated in the ultra-violet frequency range. Phase I Accomplishments During the Phase I, a detailed numerical study of the proposed TESSA experiment was carried out, including optimization of the beam dynamics, and TESSA system. The beamline components and subsystems were designed and optimized, with particular effort placed on the initial design and cost engineering of the tapered helical undulator. Phase II Plan Phase I demonstrated feasibility of the proposed TESSA demonstration at 266 nm, and the project is in a high degree of readiness for the transition into Phase II. In Phase II, the experimental system will be fully engineered and fabricated, and in Year 2 the entire system will be integrated and commissioned at the APS LEA facility. 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, such as EUV lithography. For RadiaBeam the realization of TESSA concept, represents an exciting and potentially disruptive commercial opportunity.