The design and initial testing of the beam phase and energy measurement system for DTL in the proton accelerator of CSNS

China Spallation Neutron Source (CSNS) is now in the process of research and design, in which the proton accelerator is an important part. This beam phase and energy measurement system imports the signal from the Drift Tube Linac (DTL) and calculates its phase and energy, which is feedback to tune the beam. The signals received from fast current transformer (FCT) are modulated pulses of high frequency (repetition rate is 352.2 MHz for ADS and 324 MHz for CSNS, while the leading edge is only hundreds of ps), and the dynamic range of the signal amplitude varies from 20 mv to 900 mv (peak to peak, before transmitted through cables); therefore, special techniques are required to obtain the phase information. Corresponding simulations and initial tests have been conducted, with the result of a phase resolution better than 0.1 degree over 57 dB input signal amplitude range (with the bandwidth of 367 kHz).