Efficiency and spectrum enhancement in a tapered free-electron laser amplifier.
We report the first experimental characterization of efficiency and spectrum enhancement in a laser-seeded free-electron laser using a tapered undulator. Output and spectra in the fundamental and third 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 (third harmonic) output was observed. A significant improvement in the spectra with the elimination of sidebands was observed using a tapered undulator. The experiment is in good agreement with predictions using the MEDUSA simulation code.
Wang
X J
XJ
National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA.
Freund
H P
HP
Harder
D
D
Miner
W H
WH
Murphy
J B
JB
Qian
H
H
Shen
Y
Y
Yang
X
X