Abstract

Many interesting applications of the free-electron laser (FEL) require the extension of the operating wavelength into the ultraviolet region of the spectrum. The introduction of a gas into the wiggler section of a FEL alters the phase velocity of the electromagnetic wave and so changes the synchronism condition relating wavelength to wiggler parameters and beam energy. This provides a means for tuning the frequency of an oscillator, and with the addition of 200 Torr of hydrogen gas the wavelength of a FEL operating in the near infrared without gas was reduced by 0.73 μm. The plasma generated from ionization of the hydrogen molecules by collisions with the electron beam diminished the oscillator gain, but this effect was eliminated by the addition of less than 0.1% of an electron attachment gas. Gain is also reduced by multiple scattering of the beam electrons, but this effect is not severe for a 1-m wiggler length. When hydrogen is used, a FEL with fixed wiggler parameters and electron energy can be tuned from the near infrared to ≈1200 Å, and with helium the wavelength can be reduced to 600 Å.

© 1989 Optical Society of America

Two-color free-electron laser driven by a radio-frequency linear accelerator

H. A. Schwettman and T. I. Smith
J. Opt. Soc. Am. B 6(5) 973-976 (1989)

Material applications of the far-infrared free-electron laser

John D. Simon, John E. Crowell, John H. Weare, and David R. Miller
J. Opt. Soc. Am. B 6(5) 1035-1044 (1989)

Application of a two-color free-electron laser to condensed-matter molecular dynamics

Dana D. Dlott and Michael D. Fayer
J. Opt. Soc. Am. B 6(5) 977-994 (1989)

Testing the photon–photon sector of quantum electrodynamics with free-electron lasers

W. Becker, J. K. McIver, and R. R. Schlicher
J. Opt. Soc. Am. B 6(5) 1083-1089 (1989)

Free-electron lasers in ultraviolet photobiology

Thomas P. Coohill and John C. Sutherland
J. Opt. Soc. Am. B 6(5) 1079-1082 (1989)