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How do magnetic fields trap charged particles in the Van Allen radiation belts?

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Learn about magnetic fields and the levels of particles, atoms, crystals, and domains — magnet Magnetic fields and the levels of magnetism of particles, atoms, crystals, and domains.

The Van Allen radiation belts trap energetic charged particles, such as protons and electrons, through the interaction between these particles and Earth’s geomagnetic field.12

When charged particles enter the magnetic field, they are subject to the Lorentz force, which causes them to travel in spiral paths along the magnetic field lines. As these particles move toward the magnetic poles, they encounter regions where the field lines converge and the magnetic field strength increases.2314

This increase in field strength creates a magnetic mirror effect, which reflects the particles back toward the opposite hemisphere. Consequently, the particles bounce back and forth between these magnetic mirrors, effectively becoming trapped in the doughnut-shaped zones known as the Van Allen radiation belts. While trapped, the particles also drift longitudinally around the planet. They remain in these belts until they eventually collide with atoms in the thin upper atmosphere, which removes them from the trapped population.25461