Miniature Explosively Driven High-Current Transverse-Shock-Wave Ferromagnetic Generators

Comprehensive studies of explosively driven ferromagnetic generators (FMGs) have been performed. It has been experimentally established that the initial magnetostatic energy stored in the magnetic element of the FMG (determined by the magnet´s maximum energy product (BH)_max and its volume), not the residual magnetic flux density Br, is the principal parameter that determines the output energy and the amplitude of the signals produced by the generator. Systematic studies were carried out with miniature high-current FMGs containing Nd₂Fe₁₄B high-energy hard ferromagnetic elements having a wide range of sizes. Utilization of transverse-shock demagnetization of Nd₂Fe₁₄B magnets (shock wave propagates across the magnetization vector mmb M) instead of longitudinal-shock demagnetization dramatically changed the design of the FMGs and reduced the mass of the explosives used by two orders of magnitude in comparison with that used in longitudinal FMGs. Data for the initial magnetic flux and shock-induced magnetic flux change in Nd₂ Fe₁₄B magnets are presented. It was shown that FMGs with a volume of 25 cm³ are capable of producing pulsed currents with amplitudes of up to 4.4 kA and rise times of 23 μs in the seed coil of a magnetic flux compression generator.