When I read some discussion about exploration of Jupiter moons, or possibility of life there, a common argument is high dose of radiation in Jupiter's radiation belt (several orders of magnitude higher than outside Jupiter's magnetosphere). If we speak about charged particles, dangerous is just radiation faster than let's say 1 MeV ( other are shielded very easily by thin protection)
I would like to know what is the mechanism which create these fast particles inside Jupiter's magnetosphere. I would expect that particles from Sun/Cosmic radiation are rather repelled by the magnetosphere bubble, and the few which are caught slow down by emitting EM radiation oscillating around magnetic field lines (so ther would never accumulate much of them)
I found in some papers that the slow particles (~10 keV) are accelerated by plasma currents generated by the rotation of the magnetosphere/ moons and jupiter. However this does not explain the fast particles which only does matter for radiation hazard and are hard to shield.