RF Design and Tuning of Linac4 RFQ

Linac4 is scheduled to deliver 160 MeV H– beam to LHC injection chain by year 2015. The first stage of Linac4 is a 352 MHz, 3-meter long Radio Frequency Quadrupole (RFQ) accelerator [1]. It will accelerate the 70 mA, 45 keV H– beam from the RF source up to 3 MeV energy. Fabrication of RFQ, which started in 2009, is completed [2] and tuning operations are in progress. RF controls performed at each fabrication step have shown that RFQ electrical parameters are well within bounds specified after envelope of fabrication tolerances. Tuning operations have started with adjustment of so-called quadrupole rods inserted in end plates, in order to achieve adequate voltage boundary conditions at both RFQ ends. A preliminary slug tuning test demonstrates voltage percent accuracy after a few slug tuning iterations.