A Linac-Driven XUV Free-Electron Laser

An XUV free-electron laser (FEL) driven by a linear accelerator appears to be feasible for wavelengths as short as 50 nm. This projection is based upon the anticipated successful use of high peak-current (~100 A) linacs in forthcoming FEL oscillator experiments at infrared and visible wavelengths at Los Alamos and Boeing/Mathematical Sciences Northwest. As an alternative to schemes involving storage rings, a linac provides a train of individual electron bunches separated by 10-100 ns and duration of 10-30 ps. Further, electrons pass through the undulator magnet only once, but their remaining energy may be recovered in a separate decelerating structure and fed back into the primary accelerator.