Finite Element Analysis of Magnetic Field Single-Turn Systems
Modelling of pulsed magnetic systems has extensive application in the optimisation of electromagnetic metal forming as well as in pulsed ultrahigh field generation systems. This paper presents a detailed three-dimensional finite element analysis model to be used in such power systems and compares simulated solutions with accurate experimental data.
Megagauss magnetic field generation in single-turn coils: new frontiers for scientific experiments
We report on the design and performance of a megagauss generator at the Humboldt High Magnetic Field Centre. The installation uses the fast capacitor discharge into single-turn coils to produce microsecond pulses of 260 T in 8 mm diameter suitable for low-temperature experiments and 310 T in 5 mm diameter. Simple concepts are applied to substantiate crucial design principles for the generator and the choice of components. The implementation of a high-power/low-inductance circuit operated at 60 kV and other technical questions are discussed in detail. The analysis of experimental field and current data is based on numerical simulations of the magnetic pressure and the nonlinear flux diffusion. It was carried out in order to investigate the limitations and characteristics of the Berlin generator in particular and the single-turn coil technique in general. The paper focuses primarily on field, generator and coil parameters, which can be used for performing routine, reproducible scientific experiments at low temperatures.
Reproducible Generation of Multimegagauss Magnetic Fields
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.