Testing Beam-Induced Quench Levels of LHC Superconducting Magnets

TL;DR

This paper investigates the thresholds at which beam-induced quenches occur in LHC superconducting magnets, combining experimental data and simulations to improve safety models for future high-energy operations.

Contribution

It provides a comprehensive analysis of quench levels through experiments and simulations, enhancing the understanding and prediction of beam-induced quenches in the LHC.

Findings

Eight quenches during tests, none during normal operation

Simulation models validated and refined against experimental data

Improved beam-dump threshold predictions for future runs

Abstract

In the years 2009-2013 the Large Hadron Collider (LHC) has been operated with the top beam energies of 3.5 TeV and 4 TeV per proton (from 2012) instead of the nominal 7 TeV. The currents in the superconducting magnets were reduced accordingly. To date only seventeen beam-induced quenches have occurred; eight of them during specially designed quench tests, the others during injection. There has not been a single beam- induced quench during normal collider operation with stored beam. The conditions, however, are expected to become much more challenging after the long LHC shutdown. The magnets will be operating at near nominal currents, and in the presence of high energy and high intensity beams with a stored energy of up to 362 MJ per beam. In this paper we summarize our efforts to understand the quench levels of LHC superconducting magnets. We describe beam-loss events and dedicated experiments with beam, as well as the simulation methods used to reproduce the observable signals. The simulated energy deposition in the coils is compared to the quench levels predicted by electro-thermal models, thus allowing to validate and improve the models which are used to set beam-dump thresholds on beam-loss monitors for Run 2.