Explosive-driven ferromagnetic generator
Encyclopedia
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. 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 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
, and the very sudden change induces a high-peak electric current
in the surrounding coil. Both the shock wave directions parallel to the vector of magnetization (longitudal) 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 generator
s and can be used for charging capacitor banks.
A generator coupling an EDFMG containing a 8.75 cm3 of magnetic material with a spiral vector inversion generator
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.
Ultra-compact generators with diameter less than 50 mm were developed.
Pulsed power
Pulsed power is the term used to describe the science and technology of accumulating energy over a relatively long period of time and releasing it very quickly thus increasing the instantaneous power.-Overview:...
generator, a device used for generation of short high-voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
high-current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
pulse by releasing energy stored in a permanent magnet. It is suited for delivering high-current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
pulses (kiloamperes) to low-impedance
Electrical impedance
Electrical impedance, or simply impedance, is the measure of the opposition that an electrical circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current circuit...
loads.
The FMGs consist of a permanent magnet (usually a neodymium magnet
Neodymium magnet
A neodymium magnet , the most widely-used type of rare-earth magnet, is a permanent magnet made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure. Developed in 1982 by General Motors and Sumitomo Special Metals, neodymium magnets are the strongest...
), a high explosive charge, and a pickup coil. They are a kind of phase transition
Phase transition
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another.A phase of a thermodynamic system and the states of matter have uniform physical properties....
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
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...
generated by explosion destroys the magnetic domains in the magnet, cause loss of the magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
, and the very sudden change induces a high-peak electric current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
in the surrounding coil. Both the shock wave directions parallel to the vector of magnetization (longitudal) 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 generator
Explosively pumped flux compression generator
An explosively pumped flux compression generator is a device used to generate a high-power electromagnetic pulse by compressing magnetic flux using high explosive....
s and can be used for charging capacitor banks.
A generator coupling an EDFMG containing a 8.75 cm3 of magnetic material with a spiral vector inversion generator
Vector inversion generator
A vector inversion generator 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...
yielded a pulse of amplitude over 40 kilovolts with a rise time
Rise time
In electronics, when describing a voltage or current step function, rise time refers to the time required for a signal to change from a specified low value to a specified high value...
of 6.2 nanoseconds. Generators delivering pulses over 50 kV and 5 kA were demonstrated.
Ultra-compact generators with diameter less than 50 mm were developed.
See also
- Explosively pumped flux compression generatorExplosively pumped flux compression generatorAn explosively pumped flux compression generator is a device used to generate a high-power electromagnetic pulse by compressing magnetic flux using high explosive....
- Explosive-driven ferroelectric generatorExplosive-driven ferroelectric generatorAn explosive-driven ferroelectric generator is a compact pulsed power generator, a device used for generation of short high-voltage high-current pulse...