Solenoid for megagauss magnetic fields: Non-collapsing windings design problems

The maximum stability of electromagnets with azimuthal currents was obtaine d using equal-loaded windings. In these cases the ratio of the external rad ius of the magnet to the inner one increases as exp((B-i/B-m)(2)), where B- i is the magnetic induction amplitude value on the solenoid axis and B-m is "the magnet limit of the material stability". It would be possible to esse ntially reduce the external magnet radius by using a combination of a force -free winding with an equal-loaded section which has only the azimuthal ind uction component. This idea promises to ensure the field production with th e magnet induction values above 100 T and pulse duration about 10(-3)-10(-2 )s. The possibility of creating "quasi force-free" winding with discrete cu rrent layers in the real system is shown in this paper.