Jefferson Lab is developing a 10MeV injector to provide an electron b e h for a high-power free-electron laser (FEL). To characterize the transverse phase space of the space-charged-dominated beam produced by this injector, we designed an interceptive multislit emittance diagnostic. It incorporates an algorithm for phase-space reconstruction and subsequent calculation of the Twiss parameters and emittance for both transverse directions at an update rate exceeding lHz, a speed th& will facilitate the transverse-phase-space matching between the injector and the FEL's accelerator that is critical for proper operation. This paper describes issues pertaining to the diagnostic's design. It also discusses the acquisition system, as well as the software algorithm and its implementation in the FEL control system. First results obtained from testing this diagnostic in Jefferson Lab's Injector Test Stand are also included.
Storage rings have served well as x-ray sources, achieving continued increases in flux and brilliance. While further improvements in performance may still be expected, the performance of these machines is constrained by radiation fluctuations and by the Touschek effect. The practical effect of the radiation fluctuations is to limit the minimum 6D emittance of the rings in general, and particularly the bunch length. The Touschek effect limits the lifetime and the bunch charge density. These effects can be ameliorated by using a linac to accelerate the beam to the requisite energy before passing it through undulators to produce the x-rays. If the beam is discarded after producing x-rays, radiation and collision effects are no longer limiting. This approach has not been used because prohibitive amounts of energy would be required to produce the beam. However, by using energy recovery in a superconducting linac, the energy can be recycled to accelerate new electrons. This would allow the use of currents comparable to those in storage rings, but with superior emittance, bunch length and flexibility. The concept of a 5-7 GeV facility using this principle is described and parameter goals given.
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