MEASUREMENTS OF QUENCH VELOCITY IN ADIABATIC NBTI AND NBSN COILS - COMPARISON BETWEEN THEORY AND EXPERIMENTS IN SMALL MODEL COILS AND LARGE MAGNETS

We investigated the quench propagation velocity in small epoxy impregnated NbTi and NbSn windings. Eventually we took data directly on a large epoxy impregnated NbTi magnet (phi(in) = 640 mm, B(max) = 8 T), where quenches were induced at 4,5 and 6 teslas and voltage across subsections were recorded at constant current by delaying the dumping system intervention. Results show a discrepancy with the predictions given by the usual formulas for turn to turn propagation, while good agreement was found for longitudinal one. In the paper the cable and magnet characteristics are reported in detail as well as some measured curves, such as to be compared with results of other researchers.