I have been reading research papers on this topic, such as Evolution of the magnetic field in magnetars J. Braithwaite and H. C. Spruit 2006 http://www.aanda.org/index.php?opti...doi&doi=10.1051/0004-6361:20041981&Itemid=129 This is informative but takes the evolution through only the first thousand years or so. They do not deal with what occurs after the neutron star becomes superconductive. My understanding, such as it is, is this. The neutron star is created in a supernova with temperatures of trillions of degrees. At the this time the crust is about 1.5km of iron and highly conductive, the core neutrons and less conductive. The neutron star inherits a portion of the magnetic field of the parent star. The field has one hundred seconds or so to relax to mostly a twisted torus internal to the star with the rest a poloidal field. The crust then solidifies, locking the portion of the field in the crust into place. The portion of the field in the interior continues to diffuse. The stress between the crust and core can become so great that the crust ruptures. This is as far into the evolution as that paper seems to go. After the star cools for some time (one year?) the core becomes superconductive. It is a Type II superconductor and the magnetic field is strong enough that quantum flux tubes penetrate the core. After more time (1000 years?) the core is cool enough to become a combination of a neutron superfluid, a proton superfluid, and an ordinary electron fluid. Within the core appears an array of rotational vertices. At this point my view becomes hazy. Is a magnetic field generated in the core, what is its shape, how strong is it? My second question is, how does the magnetic field in the core find an equilibrium? By the energy slowing dissipating into the crust? Since the crust is very rigid this would be a very slow process. Surely the magnetic field in the superconductive core does not increase without bound. I suspect that this forum is not the place for this question. Any suggestions as to where an answer might be found?