The Kroll-Morton-Rosenbluth equations of motion for electrons in a linearly polarized, tapered wiggler are utilized to describe gain in free-electron laser amplifiers. The three-dimensional amplifier model includes the effects of density variation in the electron beam, off-axis variations in the wiggler magnetic field, and betatron oscillations. The input electromagnetic field is injected and subsequently propagated within the wiggler by computing the Fresnel-Kirchhoff diffraction integral using the Gardner-Fresnel-Kirchhoff algorithm. The injected optical beam used in evaluating amplifier performance is initially a Gaussian which in general may be astigmatic. The importance of the above effects on extraction effi-ciency is computed both with rigorous three-dimensional electromagnetic wave propagation and a Gaussian treatment of the field.

Date Published: 16 February 1984
PDF: 8 pages
Proc. SPIE 0453, Free-Electron Generators of Coherent Radiation, (16 February 1984); doi: 10.1117/12.947101

Published in SPIE Proceedings Vol. 0453:
Free-Electron Generators of Coherent Radiation
Charles A. Brau; Stephen F. Jacobs; Marlan O. Scully, Editor(s)