Quench protection heater studies for the 1-m model magnets for the LHC low-beta quadrupoles

In superconducting magnets with large energies, quench protection heaters (QPHs) are necessary to prevent localized quenches. If the full energy of a magnet is dissipated into a small volume, the magnet may suffer irreparable damage. The QPHs are used to heat the surface of the coil to increase the volume of the normal zone so the heat is dissipated over a larger area. As a result, the maximum temperature after a quench will be reduced. The KEK low- beta quadrupole magnets for the Large Hadron Collider (LHC) have four QPHs on the outer surface of the coil. Several aspects of the performance of the QPHs for the KEK-LHC insertion quadrupole magnets have been studied. The time from firing the QPHs to quench vs. QPH-input-energy, the effects of varying quench-detection time on the magnet power supply, and the results of a normal training quench with no dump resistor and using the QPHs are reported and compared to a quench simulation code. (4 refs).