•Marion Kläser, Frank Hornung, Hanno Leibrock, Hans Müller und Theo Schneider
Institut für Technische Physik, Forschungszentrum Karlsruhe GmbH, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen

By means of the high magnetic field test facilities in the high-field laboratory (HFL) at the Forschungszentrum Karlsruhe the superconducting properties of low (NbTi, Nb₃Sn) and high (Bi2212, Bi2223) temperature superconductors were investigated at 1.8, 2.2 and 4.2 Kelvin in magnetic fields up to 20 Tesla. The electric field-current relation, E(I), is examined resistively using a high resolution four-point measurement technique. Detailed error analysis ensure the significance of the E(I)-characteristics and of the resultant critical current I_c and n-value. The outcomes are used e.g. to compare commercial conductors and to optimise the heat treatment of binary and ternary A15-superconductors.

These investigations are the base for the development and construction of superconducting high-field magnets for experimental high-field test facilities and new generations of NMR spectrometers.