As a result of eruptive events in the solar corona, large fluxes of energetic protons (and smaller fluxes of heavier ions) are produced which can impact spacecraft, these particles are known as Solar Energetic Particles (SEPs) and the enhancements are known as solar particle events (or SPEs). SEPs are encountered in interplanetary space as well as in the vicinity of solar system bodies.
The Earth’s magnetic field provides a varying degree of geomagnetic shielding for spacecraft in Earth orbits depending on their altitude and inclination. However, in interplanetary space there is no geomagnetic shielding afforded to the spacecraft so the environment is treated as (magnetically) unshielded. SEP radiation is usually considered to be isotropic in nature due to the scattering of such high energy particles dwarfing any streaming shortly after the commencement of an SPE although at high energies anisotropy can be significant.