Analysis and Stabilization of AC Line Synchronized Timing System for SuperKEKB

TL;DR

This paper discusses the challenges and solutions for maintaining high-precision, AC line synchronized timing signals in the SuperKEKB accelerator, addressing issues caused by power line fluctuations and system complexity.

Contribution

It presents an analysis of the AC line synchronized timing system at SuperKEKB and proposes solutions to improve its robustness against power line drifts.

Findings

Identified trigger signal delivery errors due to AC power line drift.

Implemented solutions to enhance timing system stability.

Demonstrated improved robustness in the accelerator's timing signals.

Abstract

A timing system provides high-precision signals to allow the controls over a variety of hardware and software components in the accelerator complex. This is guaranteed by the radio frequency (RF) and trigger signal synchronization for subsystems such as klystrons, pulsed magnets, and beam monitors. The main trigger signal should be distributed throughout the facility and repeated at the beam repetition rate. This trigger signal is usually generated by the same phase of an AC power line to follow the source of the fluctuation of an electrical grid and reduce the unwanted variation of the beam quality. To fulfill the needs of the multi-accelerator facility at KEK, apart from the normal trigger synchronization and bucket selection injection control, a beam operation scheme called the pulse-to-pulse modulation is utilized; hence, the complexity of the timing system increases. Uncertainty in the system and a trigger signal delivery error caused by a drastic AC power line drift are observed. Further, the effort to establish a reliable timing system at KEK and several solutions to improve the system robustness are presented.