Development of a Smart Modulator and Efficiency Evaluation of 500-GeV   e+e- C-Band Linear Collider
  An e+e- linear collider at 500-GeV C.M. (center of mass) has been proposed as a future accelerator. The C-band linear collider has more than a thousand klystrons and matching modulators. The linear colliders require smart modulators with high reliability, compact and simple configuration, and good power efficiency. This study suggests solutions to problems expected in the future linear colliders. A C-band smart modulator has been developed using a constant-current inverter power supply. The smart modulator provides 350-kV pulses of the pulse-to-pulse stability of 0.35%, the pulse-width of 4.35 microseconds, and the repetition rate of 50 Hz. We also investigated the power efficiency for the C-band scheme. A pulse efficiency of 75% can be achieved by an optimized pulse transformer and the RF phase modulation. With pulsed klystrons of 60% power efficiency, it is possible to achieve the RF system efficiency of 32% with the wall-plug power of 170 MW. 
J. S. Oh, J. S. Bak, M. H. Cho, W. Namkung (PAL, Korea) K. H. Chung   (SNU, Korea) T. Shintake, H. Matsumoto(KEK, Japan)