In order to investigate working characteristics of traveling wave direct energy converter (TWDEC) to flux with wide energy spread, the second-phase experiments of the research project using end-loss flux of GAMMA 10 were performed. The end-loss flux of the normal operation and that of the one-side plugging operation of GAMMA 10 were introduced to a bias-type TWDEC. The variation of effect of TWDEC operation was examined on relative phase difference between the modulator and the decelerator voltages. Both deceleration and acceleration effect were found according to the relative phase difference for the end-loss flux of both normal and one-side plugging operations.