An explosive-driven ferromagnetic generator (EDFMG, explosively pumped ferromagnetic generator, EPFMG, or FMG) is a compact pulsed power generator, a device used for generation of short high- voltage high- current pulse by releasing energy stored in a

permanent magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, ...

. It is suited for delivering high- current pulses (kiloamperes) to low- impedance loads. The FMGs consist of a permanent magnet (usually a

neodymium magnet A hard_disk_drive.html"_;"title="Nickel-plated_neodymium_magnet_on_a_bracket_from_a_hard_disk_drive">Nickel-plated_neodymium_magnet_on_a_bracket_from_a_hard_disk_drive_ file:Nd-magnet.jpg.html" ;"title="hard_disk_drive_.html" ;"title="hard_disk_d ...

), a high explosive charge, and a pickup coil. They are a kind of phase transition generators, utilizing pressure-induced magnetic phase transition effect. By adjusting the number of turns of the coil, which can be as low as a single turn, the generator can be designed for delivery of high-current low-voltage pulses or, with more turns, low-current high-voltage pulses. The shock wave generated by explosion destroys the magnetic domains in the magnet, cause loss of the

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

, and the very sudden change induces a high-peak

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...

in the surrounding coil. Both the shock wave directions parallel to the vector of magnetization (longitudinal) and perpendicular (transverse) are possible to be used. One of the possible configurations is a ring magnet with the explosive charge in its center. EDFMGs are especially well suited as seed power sources for explosively pumped flux compression generators and can be used for charging capacitor banks. A generator coupling an EDFMG containing an 8.75 cm³ of magnetic material with a spiral

vector inversion generator A vector inversion generator (VIG) is an electric pulse compression and voltage multiplication device, allowing shaping a slower, lower voltage pulse to a narrower, higher-voltage one. VIGs are used in military technology, e.g. some directed-energ ...

yielded a pulse of amplitude over 40 kilovolts with a rise time of 6.2 nanoseconds. Generators delivering pulses over 50 kV and 5 kA were demonstrated.E.F. Talantsev ''et al.'
"Analytical Model for Explosive-Driven Ultracompact Shock-Wave Ferromagnetic Generators"
Vol. 115 (2009) Acta Physica Polonica A No. 6, Proceedings of the 2nd Euro-Asian Pulsed Power Conference, Vilnius, Lithuania,September 22–26, 2008 Ultra-compact generators with diameter less than 50 mm were developed.

References

{{reflist, 30em
Explosive pulsed power: an enabling technology

Analytical model for explosive-driven ultracompact shock-wave ferromagnetic generators
Pulsed power Ferromagnetism

See also

References