The upgrade of J-PARC linac low-level radio frequency system

TL;DR

This paper discusses the development and testing of a new digital low-level RF system for J-PARC linac to improve stability, maintainability, and support increased beam current.

Contribution

The paper presents the architecture and performance results of a newly developed digital LLRF system for J-PARC linac, addressing aging hardware and future beam current upgrades.

Findings

Successful implementation of the new digital LLRF system

Achieved stable accelerating fields in tests

Enhanced system maintainability and future scalability

Abstract

The J-PARC linac was consist of 324MHz low-{\beta} section and 972MHz high-{\beta} section. There is a total of 48 stations. And each station was equipped with an independent LLRF (Low-Level Radio Frequency) system to realize an accelerating field stability of $\pm1$% in amplitude and $\pm1${\deg} in phase. For these llrf system, some of them, especially the 324MHz low-{\beta} section, had already been used for more than 10 years. Due to lack of supply, it had become more and more difficult to do the system maintain. And in the near future, the beam current of j-parc linac was planned to increase to 60mA. At that time, the current system will face a huge pressure in solving the beam loading effect. Considering these, a new digital llrf system was developing at j-parc linac. In this paper, the architecture of the new system will be reported. The performance of system with a test cavity is summarized.