A 20T pulse magnet with 80% field reversal for fast hysteresis measurements

For testing of magnetic materials and for magnetizing small permanent magne ts, it is desirable to have a set-up, generating fields well in excess of 1 0 T with a reasonable duration. Based on a 150 kJ capacitor bank, we have b uilt a compact magnet, which allows generating fields up to 20 T. A Cu sole noid with a bore of 22.3 mm is directly put into liquid nitrogen. The magne t is engaged by discharging a 10 mF capacitor bank with a maximal voltage o f 5.5 kV via an optically triggered thyristor stack. A diode stack anti-par allel to the thyristor allows for a full-sine-wave form. The self-inductanc e (i.e. the wire section) was chosen such that the full sine had a period o f about 200 ms to reduce the generation of eddy currents in the samples. Ma gnetization can be measured in the temperature range 77-400 K in a 4.5-mm-d iameter sample space. (C) 2001 Elsevier Science B.V. All rights reserved.