Magnetic diffusivity

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]

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

,

while in Gaussian units it can be defined as

\eta ={\frac {c^{2}}{4\pi \sigma _{0}}}

.

In the above, $\mu _{0}$ is the permeability of free space, $c$ is the speed of light, and $\sigma _{0}$ is the electrical conductivity of the material in question. In case of a plasma, this is the conductivity due to Coulomb or neutral collisions: $\sigma_0=\frac{n_ee^2}{m_e\nu_c}$ , 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.

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

Magnetic diffusivity

See also

References