SPACE WEATHER, VOL.???, XXXX, DOI:10.1029/, Stormer Theory Applied to Magnetic Spacecraft Shielding

Abstract. The existence of a toroidal region from which charged particles are excluded was demonstrated by Stormer [1955] for a dipole magnetic eld geometry. Using a standard nu-merical code to trace the trajectories of particles in a magnetic eld, we nd excellent agree-ment with the predicted region for a variety of particle energies and masses. The ability of magnetic elds to shield certain regions from energetic particles, such as galactic cosmic rays (GCRs), has led to the suggestion that certain magnetic eld congurations could be used to shield the occupants of a spacecraft from the harmful effects of GCRs during interplanetary space travel. In particular, systems involving a deployed superconducting coil of wire that ex-tends well beyond the dimensions of the spacecraft have been proposed as a viable solution to shielding GCRs. The correct use of the analysis by Stormer [1955] requires that the ra-dius of such a coil be much smaller than the dimension of the region being shielded. Alter-natively, it is shown that the energy of the particles shielded from a given region decreases as the radius of a coil with a constant magnetic moment increases. The reality is that large magnetic elds, and thus currents, are necessary to adequately shield GCRs neither of which are provided by deployed magnetic shields. 1