Coupling Losses in a Superconducting Model Magnet for the L.H.C.

Abstract

In the framework of a future Large Hadron Collider (L.H.C.) at C.E.R.N. high field (8–10 T) magnet models are in development. We have studied and measured the strand coupling losses in a single aperture, 1 meter long dipole. This dipole works at superfluid Helium temperature with a NbTi soldered cable. The calculations are based on the intrinsic decay time constant of the induced currents. This parameter has been obtained experimentaly on a stack of magnet cables. The shape factor has been calculated for any dipole. Modelling the magnet as a transformer with a lossless primary and a secondary short circuited on a resistance representing the induced currents losses we have shown that the losses during a discharge may be calculated only from the simple measurement of the tension of the dipole after the current of the magnet becomes zero. Calculations and measurements are performed for discharges of magnet at high current rates (80–200 A/s). The results from calculations and measurements are in good agreement.