The High-gradient S-band Linac for Initial I. Acceleration of the Slc Intense

Although short lengths of S-band standing-wave, disk-loaded waveguide have been successfully RF-processed to accelerating gradients equivalent to about 175 MeV/m in a traveling-wave structure, the 20 MeV/m gradient of the SLC 50 GeV linac has been the highest gradient S-band accelerator in operation. However, the 1.5 m traveling-wave constant impedance capture section for the SLC positron source, operating with a dedicated 60 MW klyst,ron, is now routinely accelerating single-bunch beams of more than 7 x 10” e+/pulse at rates of up to 60 Hz with an accelerating gradient of 40 MeV/m. Design, processing techniques, and operation of the high-gradient section are described. DESCRIPTION OF SYSTEM Rapid acceleration of positrons produced by the 1 30 GeV electrons which are directed to the positron production target of the SLAC linear collider (SLC) is crucial in order to avoid phase lag and, consequently, bunch lengthening of the positrons.’ This acceleration is provided by a 1.5 m constant impedance, disk-loaded waveguide