Heater-induced quenches in a superconducting HERA test dipole

Longitudinal and transverse quench-propagation velocities have been measured in a 1 m long superconducting dipole coil with the same cross section as the 9-m HERA (Hadron Electron Ring Accelerator) dipole magnet. By activating quench heaters in areas of different magnetic fields the quench velocities were determined as a function of current and field. Preheating of neighbouring turns by the initially quenched winding was observed leading to an accelerated quench propagation. Good agreement was found between measured and computed hot-spot temperatures assuming adiabatic heating. The data obtained in these experiments will be used as an input for computer studies on the quench safety in the HERA proton ring. >