Vortex dynamics studies in pulsed magnetic fields

We have studied the vortex dynamics of High-Temperature Superconductors (HT S) in pulsed magnetic fields up to 50 T. Due to the very high sweep rates i nvolved (mu(0)dH(a)/dt approximate to 10(4) T/s), the induced current densi ty j approaches the non-relaxed critical current density j(c0). Turning the sweep rate during a high-field pulse makes it possible to vary the voltage criterion at which j is determined. Furthermore, the use of pulsed magneti c fields substantially increases the experimentally accessible region in th e H-T phase diagram. (C) 2000 Elsevier Science B.V. All rights reserved.