Magnetic reconnection

Summary

Magnetic reconnection is a change in the connectivity of magnetic field lines in a conducting fluid or plasma. In an ideal conductor field lines are frozen into the fluid by Alfvén's theorem, so their topology cannot change. Reconnection happens in thin regions where resistivity or other non-ideal effects break this rule. It quickly converts magnetic energy into heat, flows and fast particles. It drives solar flares, magnetic substorms in the Earth's magnetosphere and sawtooth crashes in tokamaks.