Radiation Belt Presentation Skeleton:
What (and where) are the radiation belts:
The radiation belts are the regions of the earth's inner magnetosphere in which high-energy particles are trapped.
High energy particles. Precipitation and where it comes from.
How do storms effect them:
It's hard to say [maruk, 2013]. Storms are often caused by coronal mass ejections from the Sun, last for a few days, happen a dozen times a year, and increase hot ion populations from 2 – 6 RE (Earth radii). Sometimes the outer belts increase in population during storms, sometimes they're unchanged, sometimes they decrease.
How does solar activity effect them:
We're not sure [maruk, 2013]. Increased solar activity usually causes geomagnetic storms, which often triggers population loss (and sometimes not). It's also known, however, that other planets with much weaker solar influence (like Jupiter) experience similar radiation belt activity, so perhaps the sun is a much less important factor than one would think.
What kinds of precipitation do we see from them, and when:
From balloon observations, we see evidence of high energy electron auroral precipitation is observed by the principle of Bremsstrahlung theory.
Bremsstrahlung theory is the idea that when high energy electrons are deflected through collisions with other charged particles, the loss in kinetic energy is released through photons. These photons (of all kinds of energies) can be measured by ground (or high atmosphere) EM radiation-detecting instruments. This is how we can gather data on high-energy electron precipitation from instruments that are not in-situ: such as riometers and high altitude balloons.
Whistlers and observed precipitation relationship. (parks)
How do relativistic electrons escape?
Electromagnetic whistler and ion cyclotron anisotropy instabilities change dramatically at the plasmapause. (It's thought that these instabilities are driving factors in proton and electron loss though we're uncertain how strongly.) These instabilities change because the energies of parallel motion to the magnetic field (needed for cyclotron resonance) scale with magnetic energy/particle, and the plasmapause experiences a strong variation in plasma particle number density.
There's a strong correlation between the inner edge of the proton ring current and the instantaneous location of the plasmapause. In the high density zones of the plasmapause, ring current protons should be highly unstable to ion-cyclotron turbulence, so fluxes coming from the outer zones to the plasmasphere should be quickly depleted via pitch angle scattering producing the sharp inner edge of ring current and thus a highly localized, intense ion-cyclotron turbulence just on the inner edge of the plasmapause. (Populations coming from outer zones into the plasmapause will be kicked out again right away. This is because the plasmapause inner boundary is a sharp and sudden intensity of ring current, which causes ion-cyclotron turbulence, which makes ring current protons highly unstable, thus quickly and intenstly scattering their pitch angles, kicking them out.)
More recent works [maruk, 2013] suggest that there may be a lot of other factors in play as well.
Microbursts: connected to whistlers?
“Microbursts” are radiation belt precipitation spikes, observed at low altitudes in less than 20 millisecond timescales. They might be a very significant fraction of active belt losses. They occur in the same times (dawn-morning quadrant) as chorus/whistler waves are active, so are they connected?
Typical particle behaviour: lifetimes, precipitaiton zone, trapping behaviour, energies, velocities, etc.
Charged particles (mostly protons) in the region of 3-5 RE drifting longitudinally around the Earth create ring currents which, accoridng to Lenz's law, decrease the strength of the magnetic field.
How to the belts become re-populated?
There must be a source of re-population, as auroral precipitation would have already depleted these populations unless there was a continuous source of them [parks, 1970]
Where and how are these electrons accelerated to the energies we see them at?
Electrons come from the ionosphere and solar wind, at energy scales of 0.1 and 10-60 eV respectively. Magnetospheric interactions extract and energize electrons ranging from 1 to 10's of eV and send them out to the outer magnetosphere (>9RE). Processes at the bow shock and magnetopause energize and transport electrons into the magnetosphere. Reconnection (and other processes in the magnetotail) accelerate electrons further. This causes plasmasheet populations of around 5keV.
One would expect the radiation belts to push these electrons into the inner magnetosphere in a way that preserves the 1st adiabatic invariant and perhaps the 2nd too (gyrating and bouncing motion respectively). Conserving the 1st would cause an increase of about 40 times, but their energies increase by far more than this would account for. Where is this energy coming from? What factors are we missing?
A current hypothesis (among others) is that quasi-linear interactions with whistler plasma waves take energy from low eV electrons and transfer it to high eV electrons. This requires further testing.
Short answer: we don't know.
