STRONG PULSED MAGNETIC-FIELDS COMBINED WITH VERY LOW-TEMPERATURES

New types of pulsed field coils have been developed: optimized reinforcement by fibre composites has yielded ultimate peak fields of 67 T in a 12 mm bore and 58 T in a 20 mm bore, and a coil made with a newly developed cable of pearlitic steel wires around a copper core has reached 55 T in a 17 mm bore. The temperature range of pulsed field experiments has been extended into the 400 mK range by means of top-loading He-3 cryosts. Experiments with the fractional quantum Hall effect have shown that sample heating due to eddy currents can be kept within acceptable limits but it becomes critical for a pulse duration of 10 ms or less.