Free-electron laser sources of extreme-ultraviolet radiation and their vacuum requirements

Recent development of free-electron laser (FEL) component technologies should enable these devices to operate in the extreme-ultraviolet, well below 100 nm. When fully developed, FELs represent the next generation of coherent-radiation sources with peak- and average-power outputs surpassing those of any existing, continuously tunable photon source by many orders of magnitude. An rf-linac-based, multiple-FEL facility, spanning the spectral range from 1 nm to 100 μm, is proposed. To enable such a facility to operate without significant degradation over long periods, contamination of certain of the FEL components must be prevented. Requirements for ultra-high vacuum and restricted contamination from outgassing from chamber walls are discussed. 73 refs., 11 figs., 4 tabs