Plasma diffusion

Due to the presence of charged particles in plasma, plasma diffusion significantly differs from diffusion of gas or liquid. Even in the absence of externally applied fields, the interaction between the positive (ions) and negative (usually, electrons) plasma particles results in ambipolar diffusion with the diffusion coefficient that is dissimilar to that of either electron or ion species separately if the interaction is neglected.

Plasma diffusion across a magnetic field is an important topic in magnetic confinement of fusion plasma. It especially concerns how plasma transport is related to the strength of an external magnetic field B. Classical diffusion predicts the 1/B2 scaling, while Bohm diffusion, borne out of experimental observations from early confinement machines, was conjectured to follow the 1/B scaling. It is still an area of active research.