fluxcompression

Flux compression is a physical phenomenon where the magnetic flux through a closed conductive loop increases when the loop's surface area decreases. This occurs due to the principles of electromagnetic induction, specifically Lenz's Law. When the area of the loop shrinks, the magnetic field lines passing through it are forced closer together, resulting in a stronger magnetic field. Since the magnetic flux is the product of magnetic field strength and the area it passes through, and the area is decreasing, the magnetic field strength must increase proportionally to conserve the total magnetic flux, assuming the loop is perfectly conducting and there are no resistive losses.

In practical applications, flux compression can be intentionally induced to generate very high magnetic fields. This is often achieved using explosive devices. A conductive liner, typically made of a metal like copper, is shaped around a coil carrying an initial magnetic field. When the explosive detonates, it rapidly compresses the liner inwards, drastically reducing the enclosed area. This rapid compression squeezes the magnetic field lines, leading to a significant amplification of the magnetic flux and consequently, a very intense magnetic field within the compressed volume. This technique has been used in research settings to study materials under extreme magnetic conditions and in some specialized applications requiring pulsed high magnetic fields. The effectiveness of flux compression is highly dependent on the conductivity of the liner material and the speed of compression.