We have measured the total soft‐x‐ray power from a transition radiator composed of a stack of 25 beryllium foils each 1.0 &mgr;m thick which were penetrated by a relativistic electron beam whose maximum power was approximately 7 kW. The maximum total soft‐x‐ray power was measured to be 15.2 mW for a 245 MeV, 37 &mgr;A electron beam. The bandwith of the radiation at the full width half maximum points was calculated to be between 0.6 and 1.6 keV. In addition, we have exposed photoresist‐coated silicon wafers at a distance of 3 m from the radiator. Exposure times of the bare resist were as short as 120 s for 5 cm2of wafer are (resist sensitivity is 55.6 mJ/cm2). The shortest time for mask/wafer exposure was 180 s for 5 cm2.