Speaker
Description
At the Anhui University infrared free-electron laser (FEL) facility, an optical beam-loss monitor (oBLM) diagnostic system is under development for spatially continuous beam-loss monitoring along the accelerator beamline. To meet the stringent position-resolution requirements of compact accelerators and to mitigate event ambiguity under multi-bunch operation, an optical fibre is installed parallel to the beamline and coupled to photomultiplier tubes (PMTs) at both ends. Cherenkov light generated by beam losses propagates along the fibre to the two PMTs. After conditioning with a transimpedance amplifier and a high-speed comparator, the signals are digitized by an FPGA-based time-to-digital converter (FPGA-TDC) to obtain precise timestamps. The differential arrival times measured at both ends enable accurate reconstruction of the bunch ID and the longitudinal beam-loss position. To satisfy the oBLM requirements on timing precision and short inter-event intervals, we propose a low-dead-time FPGA-TDC architecture. First, by optimizing the clock distribution path, we implement a four-edge, dual-sampling TDC within a single clock domain. Second, we develop an encoding scheme based on sub-event aggregation, which reduces the system-level dead time of the WaveUnion-TDC to one system clock cycle. The proposed design has been implemented on a Xilinx Zynq UltraScale+ ZU3EG development board, achieving a timing precision of approximately 3.34 ps and a dead time of 1.333 ns.
| Minioral | Yes |
|---|---|
| IEEE Member | Yes |
| Are you a student? | No |