Solid-state hybrid modulator for the next linear collider

Under a recently completed SBIR grant from the Department of Energy, DTI delivered a hybrid modulator to the Stanford Linear Accelerator Center (SLAC) in October 2002 for assessing the use of solid-state switching in the next generation linear collider. The modulator uses a solid-state series IGBT switch and a conventional pulse transformer to drive two klystrons. It provides 3.5 kA pulses into a 6.33:1 pulse transformer at 80 kV, resulting in 500 kV, 530 A output pulses with tight voltage regulation and pulse flattop. During 2003 SLAC has been evaluating the hybrid modulator´s performance and using it as a test stand for a new generation of high voltage X-band klystrons. Under an ongoing SBIR effort, DTI is developing a new pulse transformer to reduce losses in this modulator, and will incorporate improvements in solid state switch design to improve the pulse risetime and efficiency of the hybrid modulator. This paper describes results from the hybrid modulator development and initial operation at SLAC.