A simple, nearly 2D explosively shocked NdFeB(52) permanent magnet and a comparison to a cale calculation suggesting the mechanism for magnetic flux release and subsequent EMF pulse

Several groups have investigated the phenomenon of the generation of pulsed electrical energy realized from the shocking of modern strong permanent Ferro magnets. The Care´n Co., together with Hyperspectral Sciences, Inc., have performed several experiments, one of which this paper discusses in detail. The shot design and the diagnostics are described in the paper. The subject magnets (NdFeB(52)) in these investigations were 25 mm long by 25 mm diameter cylindrical solids with the magnetic direction along the cylindrical symmetry axis. Most of the experiments were with the shock front vector aligned along the axis as well. This type of shot has been done and well published by others1. The shot described by this paper aligned the shock wave vector perpendicular to the axis and by shaping, entered the magnet in a nearly radial inward fashion. Because the radial velocity of the shock was so much larger than the relief wave from the two ends, the behavior had strong 2D character. This allowed an approximate modeling with the 2D hydro-code CALE in the x-y mode. CALE has a magneto-hydrodynamic modeling capability, but these were not used in the described simulations. The authors were interested in the suggested temperature in the magnetic material behind the shock and how that compared to the magnetic phase diagram. It seems likely that the flux is released due to the material being heated beyond the magnetization boundary but maybe below the Curie temperature. These observations are discussed.