Design of a compact race-track microtron source

We consider using a compact pulsed race-track microtron as an economical source of 30-40 MeV electron bunches with a charge/bunch of similar to 100 pC and bunch lengths of similar to 1 ps having low transverse emittance. The RTM has several advantages over a linar accelerator in this application including being more compact and requiring much less radio frequency power. We use permanent magnets which further increase the compactness and efficiency and provide the final bunch compression at the end of acceleration. Of the factors that can limit the RTM accelerated charge/bunch, we pay special attention to the coherent synchrotron radiation because the bunch wake field, which appears in the bends, can unacceptably increase the longitudinal and transverse emittance. We present our beam dynamics calculation results.