Real-Time Betatron Tune Correction with the Precise Measurement of Magnet Current

TL;DR

This paper presents a real-time system that uses FPGA-based measurement of magnet current to correct betatron tune fluctuations in a ring accelerator, improving stability and reducing particle loss.

Contribution

The novel system enables real-time correction of betatron tune displacement by directly measuring magnet current with FPGA, enhancing accelerator stability.

Findings

Reduced betatron tune fluctuation from 5.2e-4 to 3.3e-4

Achieved real-time correction at frequencies below 250 Hz

Demonstrated effectiveness at J-PARC Main Ring

Abstract

The betatron tune, which is defined as the number of transverse oscillations in one turn of a ring accelerator, is one of the most important parameters. An undesired betatron tune increases the amplitude of the transverse oscillation so that many particles are lost from the ring sooner than designed. Since a betatron tune is controlled by the magnetic fields in the ring, the ripple of the magnet current directly displaces the betatron tune from its designated value. We have developed a system that corrects the betatron tune displacement using the measured magnet current at the J-PARC (Japan Proton Accelerator Research Complex) Main Ring. We adopted Field Programmable Gated Arrays (FPGA) to convert from the measured magnet current to the betatron tune in real time. Using the system, we have decreased the fluctuation of the betatron tune from 5.2e-4 to 3.3e-4 at the frequencies less than 250 Hz.