Development of LLRF control system for J-PARC RCS

Tamura, Fumihiko; Schnase, A.; Yamamoto, Masanobu; Nomura, Masahiro; Yoshii, Masahito*; Omori, Chihiro*; Takagi, Akira*; Hara, Keigo*; Anami, Shozo*; Ezura, Eiji*

no journal, , 

The J-PARC Rapid cycling synchrotron(RCS) requires a verystable and precise low level RF(LLRF) control system to handle theultra-high proton beam currents. The MA-loaded low-Q cavities for theRCS are driven by the superposition of the dual-harmonic RF signal forboth the acceleration and the longitudinal bunch shaping. We employ afull-digital system based on direct digital synthesis(DDS). Themulti-harmonic RF signals generated by the DDS are easily synchronizedwithout PLLs. We describe the design and the structure of the LLRFblocks. The common feedback loops are used for the stabilizing thebeam orbit and phase as well as the RF voltages of the cavity. Theheavy beam loading effect is compensated by using the beam feedforwardmethod. We also present the test results of the recently manufacturedmodules.