A low level radio frequency system drift compensation technique by time-multiplexing pick-up/reference signals.

The Low Level radio frequency system long-term stability is critical for the operation of accelerator facilities. The RF cavity field phase drift observed at the Tsinghua Thomson scattering X-ray source showed the correlations with devices temperature characteristic. We proposed a drift compensation technique by time-multiplexing cavity pick-up and phase reference signals, which guaranteed that they shared the same route with the same change. The preliminary ∼84 h Dual-Receiver out-of-loop stability test showed phase drift of 100 fs peak-peak (∼45 fs rms) when the reference signal phase changed ∼40 ps peak-peak.