Conceptual design of a single-ended MA cavity for J-PARC RCS upgrade

The Japan Proton Accelerator Research Complex (J-PARC) Rapid Cycling Synchrotron (RCS) employsMagnetic Alloy (MA) loaded cavities. The rf power is fed by vacuum tubes in push-pull operation. We realize the multi-harmonic rf driving and the beam loading compensation thanks to the broadband characteristics of the MA. However, the push-pull operation has disadvantages in multi-harmonics. A considerable amount of unbalance appears in the anode voltage swing at very high intensity beam acceleration. We propose a single-ended MA cavity for the RCS beam power upgrade, where no unbalance arises intrinsically.