Force-Reduced Superconducting Toroidal Magnet Coils
Force-free or force-reduced magnets have long been proposed as a means to overcome strength of material limitations in high fields. The basic idea involved is that conductors which are parallel to a magnetic field experience no forces since J × B = 0. The total structure, of course, cannot be force free. If a finite set of current-carrying conductors produces a magnetic field, then there is field energy and mechanical forces must exist to hold the magnet turns in place. Levy  has shown for the general case that the minimum structural mass necessary to hold magnets together either force-free or ordinary magnets, is proportional to the stored energy. Mills  and associates at Princeton have designed and constructed many force-free configurations with copper conductors in which forces were greatly decreased in a force-free subsection and transferred to the non-force-free magnet subsections.
KeywordsPitch Angle Longitudinal Field NASA Lewis Research Superconductor Wire 180A 236A 240A 184A 360A
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