Speaker
Description
At J-PARC LINAC, cavity phase monitors (CPMs) monitor RF phase variation between neighboring cavities; existing system remains reliable but requires dedicated hardware per station and supports only two RF inputs per monitor. As LLRF DFB system has been upgraded from cPCI to MicroTCA.4, RF pickup signals are aggregated in a common rack, requiring CPM upgrade to multi-channel monitoring; as an initial step, we developed a MicroTCA.4-based CPM at MEBT1 with vector-sum capability. System acquires eight RF inputs from RFQ, Buncher 1/2 and Chopper 1/2; 324-MHz pickup signals are down-converted to 12 MHz on μRTM, digitized at 240 MHz, and converted to I/Q yielding amplitude/phase. Vector sums are formed for RFQ, Buncher 1/2, while Chopper 1/2 are single-channel; all phases referenced to RFQ. Existing LLRF firmware and EPICS IOC framework were adapted with modifications; new sequencer logic and GUI were developed. System is installed in the LLRF MicroTCA.4 environment, synchronized via shared ADC/FPGA clocks under temperature- and humidity-controlled conditions. Initial results demonstrate simultaneous multi-cavity monitoring with improved integration over the conventional distributed CPM.
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