Cryogenics of a superconducting LINAC : SPIRAL2 from commissioning to operation

TL;DR

This paper reviews the development and operation of the SPIRAL2 superconducting LINAC's cryogenic system, highlighting challenges, solutions, and the integration of modeling and machine learning for improved performance.

Contribution

It provides a comprehensive overview of cryogenic system evolution, addressing operational challenges and introducing advanced control and diagnostic techniques for superconducting LINACs.

Findings

Identification of thermo-acoustic oscillations as a key challenge

Implementation of thermodynamic modeling for system optimization

Use of machine learning for fault diagnosis and control

Abstract

The SPIRAL2 superconducting linear accelerator (LINAC), which has been operational since 2019, employs superconducting, independently phased RF resonators to deliver a wide range of particle beams. Designed for flexibility in particle types, intensities, and energies, it utilizes superconducting quarter-wave resonators (QWRs), whose performances are critically dependent on the reliability of the cryogenic operation. This paper reviews the evolution from commissioning to the routine operation of the SPIRAL2 cryogenic system, initially commissioned in 2017. It highlights the key challenges encountered, including thermo-acoustic oscillations, thermal management, and abnormal behavior of cavities. Furthermore, it explores the integration of thermodynamic modeling and machine learning techniques to enhance system control and diagnose issues. This work serves as a comprehensive resource for advancing the cryogenic operation and performance of superconducting LINACs.