A high‐intensity CW photocathode electron injector test stand has been designed and is being built for a 200 MeV two‐pass recirculating CW superconducting accelerator. The accelerator is being designed to drive a high average power (1 kW) UV free‐electron laser (FEL). This FEL requires beam emittances as small as 11 mm mrad for the transverse normalized rms emittance and 30 deg‐keV for the longitudinal rms emittance. The electrons contained in a 135 pC charged bunch are compressed from an initial bunch length of 90 ps (6&sgr;) at the photocathode down to 1.2 ps (a factor of 75 compression) at the wiggler. In this paper, we present our studies on the space charge effects that determine the magnitude of beam emittance growth during the various stages of beam transport from the injector through the driver accelerator to the wiggler. ©1996 American Institute of Physics.