Reproducible Generation of Multimegagauss Magnetic Fields

Abstract

A method of reproducible ultrahigh magnetic field generation by cylindrical implosion is suggested. The method involves the use of an increased initial magnetic field and a decreased magnetic flux compression ratio. This method affords a possibility to eliminate the influence of some factors affecting the stability of magnetic field generation in flux compression systems and to facilitate investigations in these fields. A flux compression device has been developed which produces magnetic fields up to 10 MG with high reproducibility. It consists of a hollow liner which serves at the same time as an initial field coil, and a ring of high explosive around it. The liner produces initial fields up to 220 kG and efficiently traps and compresses the magnetic flux. Owing to small inductance it may be energized by an explosive high electric generator. Typical parameters of the generator are as follows: liner 14.0 cm i.d. and 30 cm long, liner weight per cm length ~90 g, implosion speed ~4 km/s, initial field 160 kG, peak field 9.5 ± 0.5 MG (in all shots); field volume around peak, 8.5 ± 0.5 mm diameter, ~100 mm long; efficiency of the liner kinetic energy conversion into magnetic field energy up to 40%. Two diagnostics have been used simultaneously in the experiments. The first diagnostics uses inductive loops, the second one is based on Faraday effect in heavy flintglass. The proposed device potentialities are illustrated by the results of investigations of magnetooptic effects and isentropic compression of some materials carried out in magnetic fields up to 10 MG.