Magnetic diffusivity

The magnetic diffusivity is a parameter in plasma physics. It appears in the Magnetic Reynolds number. The magnetic diffusivity is defined as^[1]:

$\eta = \frac{1}{\mu_0 \sigma_0}$ .

$\mu_0$ is the permeability of free space.
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
- $n_e$ is the electron density.
- $e$ is the electron charge.
- $m_e$ is the electron mass.
- $\nu_c$ is the collision frequency.

References

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