Abstract. The National Hypersonic Wind Tumel program requires an unprecedented electron beam source capable of 1-2 .MeV at a total average beam power of 100-200 MW for several seconds. Direct-current electron accelerator technology can readily generate high average power beams, however, due to the nature of research and industrial applications there has never been a requirement for a single module exceeding approximately 500 kW. Although a 100 MW module is a two-order extrapolation from demonstrated average power levels, the scaling of accelerator components appears reasonable. This paper will present an evaluation of component and system issues involved in the design of a 100 MW eleetron beam accelerator module with precision beam transport into a high pressure flowing air environment.