Generation of high-intensity coherent radiation in the soft-x-ray and vacuum-ultraviolet region

An electron beam can be made to interact with an undulator magnet so that a collective unstable mode is excited. In this mode, the beam generates coherent radiation whose wavelength is determined by the undulator period and the electron energy. By proper choice of the electron-beam energy, energy dispersion, and density, one can obtain coherent radiation in the soft-X-ray region with peak and average power of the order of hundreds of megawatts and hundreds of milliwatts, respectively. Larger peak powers, of the order of a gigawatt, can be expected for UV radiation with lambda in the range of 500-2000 A. The physical principles of these systems are discussed and examples of how they might be built are given.