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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 14: Light Sources and FEL’s

AKBP 14.2: Talk

Thursday, March 21, 2024, 16:30–16:45, E 020

Power Buildup in a Strongly-Tapered FEL Oscillator — •Margarit Asatrian¹, Eugenio Ferrari², Andrew Fisher³, Georgia Paraskaki², Pietro Musumeci³, and Wolfgang Hillert¹ — ¹University of Hamburg, Hamburg, Germany — ²Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany — ³University of California at Los Angeles, Los Angeles, California, USA

Free-Electron Lasers (FELs) can deliver high-energy pulses at MHz repetition rates and wavelengths down to XUV – X-Ray regime by extracting a fraction of energy of ultrarelativistic electron bunches. This fraction, corresponding to the FEL efficiency, depends on the FEL setup and typically lies below 0.1%.

A promising scheme for its improvement – Tapering Enhanced Stimulated Superradiant Amplification (TESSA), proposes using a high-power seed laser pulse in combination with strongly-tapered undulators for extracting a significantly larger fraction of the energy from a pre-bunched beam. Since there is a lack of sufficiently powerful seed laser sources at shorter wavelengths, one can consider implementing the TESSA scheme in an FEL oscillator, so that the seed is generated and stored within the cavity.

We present a simulation study addressing the challenges of power buildup in such a strongly-tapered FEL oscillator. In particular, we look into the possibility of using fast control on the beam energy and the undulator phase shifters for accelerating the buildup process.

Keywords: FEL Oscillator; Tapering; High Efficiency; Phaseshifters; TESSA