Trapped Particles

Particles that bounce back and forth in the field's low-field region, tracing banana orbits.

In a torus the field is weaker on the outboard side, so some particles are magnetically mirrored and bounce rather than circulate, tracing 'banana' orbits. Trapped particles drive both neoclassical transport and the bootstrap current.

In a torus the field is weaker on the outboard side, so some particles are mirror-reflected and bounce rather than circulate, tracing banana orbits. Trapped particles drive both the neoclassical transport that sets the confinement floor and the bootstrap current that reduces external drive — two effects that come together in a well-designed plasma.