Minimization of charged particle background in X-ray telescopes is a well known issue. Charged particles (chiefly
protons and electrons) naturally present in the cosmic environment constitute an important background source when
they collide with the X-ray detector. Even worse, a serious degradation of spectroscopic performances of the X-ray
detector was observed in Chandra and Newton-XMM, caused by soft protons with kinetic energies ranging between 100
keV and some MeV being collected by the grazing-incidence mirrors and funneled to the detector. For a focusing
telescope like SIMBOL-X, the exposure of the soft X-ray detector to the proton flux can increase significantly the
instrumental background, with a consequent loss of sensitivity. In the worst case, it can also seriously compromise the
detector duration. A well-known countermeasure that can be adopted is the implementation of a properly-designed
magnetic diverter, that should prevent high-energy particles from reaching the focal plane instruments of SIMBOL-X.
Although Newton-XMM and Swift-XRT are equipped with magnetic diverters for electrons, the magnetic fields used
are insufficient to effectively act on protons. In this paper, we simulate the behavior of a magnetic diverter for
SIMBOL-X, consisting of commercially-available permanent magnets. The effects of SIMBOL-X optics is simulated
through GEANT4 libraries, whereas the effect of the intense required magnetic fields is simulated along with
specifically-written numerical codes in IDL.