Free-Electron Lasers in the X-Ray Region: General Design Considerations

Abstract

We consider possibilities for operating a free-electron laser at a wavelength of about 5 Å. At this wavelength a Bragg crystal ring resonator can provide feedback, but since the losses are large, large gain per pass is needed. We calculate the regimes of wiggler wavelength, wiggler length, and electron energy where large gain is obtainable.