Magnetic fields in excess of 100 T can only be generated at the expense of a drastic reduction in pulse duration.
Invariably, they also lead to the destruction of the coil which, however, doesn’t prevent the use of Megagauss
magnetic fields (1 Megagauss = 100 Tesla) for scientific experiments.
The LNCMI Megagauss generator is one out of three platforms worldwide that are making use of capacitor-driven
single-turn coils (STC) to produce fields in the 150 to 250 T range for scientific applications. Although still
higher fields can be obtained with flux compression techniques, STCs have the advantage that the coil destruction
does not affect the experimentally useful volume: Samples, cryostats and other equipment generally survive and
experiments can therefore be performed reproducibly.
Magnetic forces and how to deal with them
Magnets are generating a force field that acts not only on magnetic objects in their vicinity, but also on
themselves: In a simple solenoid, for example, the so-called magnetic pressure tends to radially expand and
axially compress the windings. As a consequence, the maximum field that can be obtained in an electromagnet
without destroying it is limited by the mechanical strength of its components, that is, conductors and reinforcing
materials.
To reach a field of, say, 100 T, a magnet would have to sustain a pressure of 4 GPa, which corresponds to a weight
of 40 tons resting on a surface of 1 cm². So far this pressure level has prevented any successful attempt to build
a magnet that can generate fields approaching 100 T without exploding. This does not mean, however, that fields
above this threshold cannot be generated at all. One just has to resort to so-called destructive techniques.