# Analogy between magnetic bottle and Van Allen's radiation belt

A magnetic bottle is an arrangement that permits to confine charged particles. Here you can find a review for charged particle rotating in a magnetic field and at the bottom of the page a description of the magnetic bottle:

Motion of a charged particle in magnetic field

Let's use this image since it's more clear

What results from this picture is that a particle inside a magnetic bottle makes a circular motion following magnetic field lines which have a sort of cylindrical symmetry as it's expressed by this simulation:

Magnetic Bottle 1

So you can imagine to put the earth in the middle of the picture: in this way the two rings are to the two magnetic poles.

In the case of a Van Allen's radiation belt motion simulation (Radiation Belt as a Magnetic Bottle), particles move around a magnetic field lines instead of moving around the earth.

But from this simulation:

you can see that a motion around a magnetic line is possible but i can't understand heuristically why.

So the questions are:

1. how a particle can move around a magnetic line if there is closed to it another one? so how can a particle choose around which line move (losing in this way the cylindrical symmetry)?
2. why the two type of motions are in disagreement?

Is the motion in the first picture just an approximation perhaps?

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