Study and development of CW room temperature rebuncher for SARAF accelerator

The SARAF 176  MHz accelerator is designed to provide CW proton/deuteron beams up to 5  mA current and 40  MeV accelerated ion energy. Phase I of SARAF (up to 4-5  MeV) has been installed, commissioned, and is available for experimental work. Phase II of SARAF is currently in the design and first prototyping stage and will contain longer MEBT with three rebunchers and four cryomodules, each consisting of SC HWRs and solenoids. Phase II MEBT line is designed to follow a 1.3  MeV/u RFQ, is 4.5  m long, and contains three 176  MHz rebunchers providing a field integral of 105  kV. Different rebuncher configurations have been studied in order to minimize the RF losses and maximize the shunt impedance. Different apertures have also been tested with the 40  mm diameter required by beam dynamics. The simulations were done using CST Microwave Studio. CEA leads the design for SARAF phase II linac including the MEBT rebunchers and has studied a mixed solid copper and Cu plated stainless steel, 3-gap cavity. SNRC is developing a 4-gap OFHC copper rebuncher as a risk reduction. Both designs are presented and discussed in the paper.