Initial performance of a 500 kV chopper prebuncher injection systemfor a 17 GHz linac

摘要

The design features of a 17 GHz chopper prebuncher injectionsystem are described, and initial test results operating with a 500 kVlow emittance electron gun and single section 17 GHz linac arepresented. The 17 GHz traveling wave relativistic klystron that providesthe RF power to the linac structure, and the 500 W electron gun thatforms the low emittance (βγε = 3π mm-mradian) sourcefor the injection system, are pulsed simultaneously using the MIT PlasmaScience and Fusion Center HV modulator. The HV injection system isdesigned to produce RF bunches of 15° to 20° for injection intothe linac structure, with subsequent compression to approximately 1degree to provide sub-picosecond bunch operation over an energy range of10 to 20 MeV with steady-state pulse currents of up to 250 mA. The useof an economical, on-line diagnostic system having the capability ofaccurately measuring the short RF bunch performance of the 17 GHz linacwould be highly advantageous; and a simple technique of accomplishingthis, using higher order mode 17 GHz cavities, is discussed