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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.

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Actually, this question is not yet clear even to experts. There is some recent discovery concerning this question: http://www.nature.com/news/mystery-of-earth-s-radiation-belts-solved-1.13452

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OK, some explanation is on wikipedia for Earth's Van Allen radiation belt

It is believed that proton energies exceeding 50 MeV in the lower belts at lower altitudes are the result of the beta decay of neutrons created by cosmic ray collisions with nuclei of the upper atmosphere. The source of lower energy protons is believed to be proton diffusion due to changes in the magnetic field during geomagnetic storms.[14]


This suggests the Van Allen belts confine a significant flux of antiprotons produced by the interaction of the Earth's upper atmosphere with cosmic rays.[19] The energy of the antiprotons has been measured in the range from 60-750 MeV.


It is generally understood that the inner and outer Van Allen belts result from different processes. The inner belt, consisting mainly of energetic protons, is the product of the decay of so-called "albedo" neutrons which are themselves the result of cosmic ray collisions in the upper atmosphere. The outer belt consists mainly of electrons. They are injected from the geomagnetic tail following geomagnetic storms, and are subsequently energized through wave-particle interactions.


However, I'm not quite sure, if this processes are responsible for the acceleration of these particles, Or if they just inject relatively slow particles into magnetic trap, which are then accelerated by other processes

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