Quench Calculations and Measurements on the FAIR Super-FRS Dipole

Simplified Analytical Formulas of Quench Dynamics

“…5). Simulations presented in [3] give the maximum temperature of the coil, i.e., 85 K. Resistivity of copper at 85 K is about 2 × 10 −9 Ω × m, which in Fig. 5 gives the effective propagation velocity v ini ≈ 200 m/s, i.e., a value two orders of magnitude bigger than the physical propagation velocity v 0 ≈ 2 m/s computed for this case in [3].…”

“…Fig. 4 compares experimental data for quench current from [3] with our theory. Analytical formula (16) is fitted into the experimental data with the value τ = 10.6 s. The immediate conclusion that follows from this figure is that, qualitatively, analytical formula (16) is again in agreement with the experiment.…”

“…Next, we apply formulas (16)-(18) to the quantitative analysis of quench. One of the few publications that provides detailed data is [3]. Technical specifications of the magnet described in this article are reproduced in Table I.…”

“…Simulations presented in [3] give the maximum temperature of the coil, i.e., 85 K. Resistivity of copper at 85 K is about 2 × 10 −9 Ω × m, which in Fig. 5 gives the effective propagation velocity v ini ≈ 200 m/s, i.e., a value two orders of magnitude bigger than the physical propagation velocity v 0 ≈ 2 m/s computed for this case in [3]. In terms of our model, it means that the section of the winding heated to 85 K would spread along an isolated wire with the speed of 200 m/s, sweeping the entire volume of the coil with the same speed as the quench does in reality with transversal heat transfer.…”

“…The dashed curve with T max = 85 K is compiled from [3] for comparison. It takes into account heating not only the copper strip alone but also the NbTi superconducting filaments, copper matrix, and insulator around the wire.…”