Quench Detection and Protection of the Superconducting Fast Cycled Magnet

by Tiina Salmi (CERN - Technical Student)

Tuesday 3 Nov 2009, 02:00 → 03:00 Europe/Zurich

30/7-012 (CERN)

The superferric PS2 Fast Cycled Magnet (FCM) is designed for a peak central magnetic field of 1.8 T and for a field ramp rate of 1.5 T/s. The cable is internally cooled and based on a Cable-Around Conduit Conductor design. For designing the appropriate magnet protection system it is necessary to understand the quench processes in the cable. We have performed a physical analysis based on simulations of thermo-hydraulic transients in the coils, considering a cable option with a Nb-Ti:Cu strand. In this seminar we will present: 1) The stability margin that is computed at different operation conditions and for different perturbation types. 2) A parametric quench study that is performed by simulating a quench at different operation points and evaluating the maximum temperature, pressure, massflow and the resistive voltage for different combinations of the quench detection time and time constant for the following current decay. 3) The physical model is extended for estimating the expected response of different inductive voltage compensation methods. The simulation results are applied in defining an optimum voltage detection threshold for different protection voltages. It is shown that, for the investigated conditions, a balanced bridge detector can decrease the inductive noise level below the sufficient detection threshold limits in FCM operation.

Slides ts_ps2_quench_1109.pdf