100T magnet developed in Osaka

A non-destructive pulsed magnet for 100 T has been developed to carry out precise magnetic measurements at extremely low temperatures and under high pressures. Our record magnet has generated 80.3 T in a 10 mm bore with 7 ms pulse duration and then is called a 80 T magnet. The 80 T magnet consists of inner and outer coils, both of these are made by winding with Cu-Ag wire and reinforced by maraging steel. The inner coil is a single-layer coil backed up with a thin maraging pipe and the outer coil is made with nine layers reinforced by a thick maraging ring. Magnetization and magnetoresistance measurements at 1.3 K have been carried out up to 70 T in the 80 T magnet. The outer coil of the 80 T magnet has an 18 mm bore and can generate 71.3 T as a record and then is called a 70 T magnet. The 18 mm bore of the 70 T magnet is a useful space for introducing an extremely low temperature into high magnetic field, this was used to carry out both magnetization and magnetoresistance measurements at 80 mK up to 60 T. We have examined the lifetime of the 70 T magnet at various maximum fields in ordinary use. The results show that about 100 shots can be made with 60 T and 500 shots at 55 T. We have developed another 70T magnet with longer pulse duration of about 20 ms for magnetization measurements under high pressure up to 10 kbar. The 70 T magnet for high-pressure experiments has an 18 mm bore and an inductance of about 3 mH. The magnet consists of an inner five-layer coil backed up with a thick maraging steel pipe and the outer has 11 layers and a maraging ring. As the pressure cell used for the measurement is made of Be-Cu, a longer pulse is necessary to allow penetration of the pulsed field into the cell. Magnetization measurements under high pressure have been carried out successfully up to 55 T although the pulse duration is not long enough to keep the temperatures very low. A new pulsed magnet with higher field and longer pulse duration is proposed. (C) 2001 Elsevier Science B.V. All rights reserved.