resonant optical wavelength can be estimated using λ=λ0(1+K2)/2γ2, where γ is the reativistic Lorentz factor and Emc2.The electron micropulse length is σz and in most cases is close to the optical pulse length. However, the opticalpulse can nbe up to five time longer than the electron micropulse,dependent on the adjustment of mirror position. The optical peak power can be estimated by P=IE/eN.

There are 41 existing or proposed FELs worldwide, with 22 in the United States, 8 in Japan, 3 in Russia, 2 in Germany, 3 in France, 1 in Holland, 1 in Italy, and 1 in China. Of these FELs, 21 are operating now, and the rest are proposed or under development.


Brau, C.A. 1988. Science 239:1115.

National Research Council. 1982. The Free Electron Laser. National Academy Press: Washington, D.C.

Pellegrini, C. 1994. Encyclopedia of Applied Physics 8:353.

Schawlow, A.L., and C.H. Townes. 1958. Phys. Rev. 112:1940.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement