Magnetic diffusivity

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The magnetic diffusivity is a parameter in plasma physics which appears in the magnetic Reynolds number. It has SI units of m²/s and is defined as:[1]


where is the permeability of free space and is the electrical conductivity of the material in question. In case of a plasma, this is the conductivity due to Coulomb or neutral collisions: , where

  • is the electron density.
  • is the electron charge.
  • is the electron mass.
  • is the collision frequency.

See also[edit]


  1. ^ W. Baumjohann and R. A. Treumann, Basic Space Plasma Physics, Imperial College Press, 1997.