Use of the curvature drift or the E × B drift of ions is studied in order to separate fusion protons from thermal components escaped from a FRC/D3He reactor. Orbital calculation is carried out to examine modulation, bunching, trapping and deceleration of the proton beam in a Traveling-Wave Direct Energy Converter (TWDEC). Results of numerical calculation show that energy conversion rate of the TWDEC increases up to 0.8 as a result of improvement of beam modulation. Computer simulation using a beam-circuit code clarifies desirable performance characteristics of the TWDEC