Current
and future applications of high brightness electron beams, which include
advanced accelerators and beam-radiation interactions require both transverse
and longitudinal beam sizes on the order of tens of microns. Ultra-high
density beams may be produced at moderate energy (50 MeV) by compression
and subsequent strong focusing of low emittance, photoinjector sources.
We describe the implementation of this method used at LLNL?s PLEIADES
ICS x-ray source in which the photoinjector-generated beam has been
compressed to 300 fsec duration using the velocity bunching technique
and focused to 20 µm rms size using an extremely high gradient,
permanent magnet quadrupole (PMQ) focusing system.