PAC09 - List of Authors (Freund, H.)

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Freund, H.

Paper	Title	Page
TU5RFP053	Efficiency and Spectrum Enhancement in a Tapered Free-Electron Laser Amplifier	1207
	X.J. Wang, D.A. Harder, J.B. Murphy, H.J. Qian, Y. Shen, X. Yang BNL, Upton, Long Island, New York H. Freund, W.H. Miner SAIC, McLean
	Funding: This work is supported in part by the Office of Naval Research (ONR), the Joint Technology Office, and U.S. Department of Energy (DOE) under contract No. DE-AC02-98CH1-886. We report the first experimental characterization of efficiency and spectrum enhancement in a laser-seeded free-electron laser (FEL) using a tapered undulator. Output and spectra in the fundamental and 3rd harmonic were measured versus distance for uniform and tapered undulators. With a 4% field taper over 3 m, a 300% (50%) increase in the fundamental (3rd harmonic) output was observed. A significant improvement in the spectra with the elimination of side-bands was observed for the first time using a tapered undulator. The experiment is in good agreement with predictions using the MEDUSA simulation code.

Paper

Title

Page

TU5RFP053

Efficiency and Spectrum Enhancement in a Tapered Free-Electron Laser Amplifier

1207

X.J. Wang, D.A. Harder, J.B. Murphy, H.J. Qian, Y. Shen, X. Yang
BNL, Upton, Long Island, New York
H. Freund, W.H. Miner
SAIC, McLean

Funding: This work is supported in part by the Office of Naval Research (ONR), the Joint Technology Office, and U.S. Department of Energy (DOE) under contract No. DE-AC02-98CH1-886.

We report the first experimental characterization of efficiency and spectrum enhancement in a laser-seeded free-electron laser (FEL) using a tapered undulator. Output and spectra in the fundamental and 3rd harmonic were measured versus distance for uniform and tapered undulators. With a 4% field taper over 3 m, a 300% (50%) increase in the fundamental (3rd harmonic) output was observed. A significant improvement in the spectra with the elimination of side-bands was observed for the first time using a tapered undulator. The experiment is in good agreement with predictions using the MEDUSA simulation code.