Research On Protection Mechanism Of Magnetic Shielding For Space Radiation

Space radiation safety is a serious problem to be solved in deep space exploration for manned spaceflight.The traditional mass thickness shielding technology used in the earth's space radiation protection has been unable to meet the requirement of the typical galaxy cosmic rays with kinetic energy E>1GeV/n.Magnetic protection,with the advantages of flexible construction,low quality cost,strong protection ability and easy realization of engineering technology,has become the most promising development direction of space radiation active protection in the future.A few theoretical explorations have confirmed the effective protective ability of the active shielding magnetic field.But lack of a complete analysis of the shielding ability on the magnetic field configuration,the end-cap and barrel regions,the theory of magnetic protection needs to be further developed and perfected.In the thesis,eight kinds of shielded magnetic field configurations are designed,considering the factors such as the end-cap and the barrel regions' magnetic field structure,the shielding region's size,the shielding magnetic field strength and thickness,with a special focus on the promotion and reaction effect of combined magnetic field in the end-cap region and the barrel region.Then,a linear type shielding magnetic field configuration 3-A with the best protective effect is proposed for the typical GCRs.Through the Hoffman and 3-A configuration,the protection ability of each receiving surface is further explored,such as cylindrical side surface,the z and-z direction bottom(end-cap)surfaces.The results provide ideas for optimal designs of the shielding magnetic field protection.The main conclusions of the thesis are as follows:When the magnetic rigidity BL is given,the larger the shielding magnetic field intensity B is,the higher the cut-off kinetic energy is,and the better the protective effect is.The shielding efficiency of the elements with atomic number Z?2 is lower than H element.If there is no protection on the end-cap regions of the finite shielding magnetic field configuration,the overall shielding effect is very poor.The comprehensive shielding efficiency is influenced by the magnetic field configuration,thickness and intensity in the end-cap and the barrel regions.The combination configurations don't always improve the shielding efficiency.We found that the optimal magnetic field configuration is 3-A using linear magnetic field structure in barrel and end-cap regions.When L=1.5m and B=18T,shielding efficiency of the 3-A for the typical GCRs energy spectrum with kinetic energy less than 4GeV/n in Solar minimum is up to 94%.The weak protection ability regions of the Hoffman and 3-A magnetic field configuration is the –z direction bottom surface and the side surface,respectively.When the magnetic field becomes stronger,the most energetic particles enter into the protective region from these two regions.When the magnetic rigidity BL is fixed,magnetic field enhancement makes the gyration radius decrease and then the area of the weak shielding regions is reduced.But the increase of magnetic field thickness has no influence on the gyration radius,which does not change the weak regions.Maybe,sometimes,this will make the shielding ability decrease obviously.