Quench simulations for superconducting elements in the LHC accelerator

The design of he protection system for he superconducting elements in an accel- erator such as the Large Hadron Collider (LHC),now under construction at CERN, requires a detailed understanding of the hermo-hydraulic and electrodynamic pro- cesses during a quench.A numerical program (SPQR -Simulation Program for Quench Research)has been developed o evaluate temperature and voltage dis ri- butions during a quench as a func ion of space and ime.The quench process is simulated by approximating the heat balance equation with the finite di fference method in presence of variable cooling and powering conditions.The simulation predicts quench propagation along a superconducting cable,forced quenching with heaters,impact of eddy curren s induced by a magnetic field change,and heat trans- fer hrough an insulation layer in o helium,an adjacen conductor or other material. The simulation studies allowed a better understanding of experimental quench data and were used for determining the adequate dimensioning and protection of the highly stabilised superconducting cables for connecting magnets (busbars),opti- mising the quench heater s rip layou for the main magnets,and s udying quench back by induced eddy curren s in he superconductor.After the in roduction of the theoretical approach,some applications of he simulation model for the LHC dipole and corrector magnets are presented and he outcome of he s udies is compared with experimental data.