Investigation of random beam trips in a linear accelerator at the Japan proton accelerator research complex for the development of an accelerator-driven nuclear transmutation system

Abstract

ABSTRACT In a proton linear accelerator (linac), the proton beam is sometimes unexpectedly interrupted because of the electrical discharge caused by radio frequency, device/equipment failure, and other factors. Are these beam trips random? Traditionally, beam trips have been implicitly assumed to occur randomly. In this study, we investigated whether beam trips occur randomly in the Japan Proton Accelerator Research Complex (J-PARC) linac. The aim was to estimate the beam trip frequency in a superconducting proton linac for an accelerator-driven nuclear transmutation system. First, the J-PARC linac was classified into five subsystems. Then, the reliability function for the operation time in each subsystem was obtained by the Kaplan – Meier estimation, a reliability engineering method. This reliability function was used to investigate the randomness of beam trips. Analysis of operational data for five subsystems of the J-PARC linac for five years showed that beam trips occurred randomly in some subsystems. However, the beam trips did not occur randomly in many subsystems of the proton linac, including the ion source and the acceleration cavity, which are the primary subsystems of the proton linac.