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A multi-cell RF photoinjector design

A research and development effort has been underway to realize a high-brightness, low-emittance RF photoinjector to produce 1 to 3 nC bunch of photoelectrons at an energy of up to 20 MeV with a normalized RMS emittance of 10 /spl pi/ mm-mrad or less. It consists of a half cell at the photocathode and seven full cells, operating in 2856 MHz, K-mode, standing wave. Numerical calculations with POISSON/SUPERFISH and PARMELA codes indicate that the design goal can be achieved within realistic constraints on mechanical device tolerances and rf source availability. The latest among the series of numerical models is somewhat similar to the SLAC type accelerator in geometric dimensions, although the device characteristics are vastly different.