## FANDOM

137 Pages

Let us consider heat conduction in a dilute plasma. The calculation of the diffusion coefficient is similar to the calculation of the electrical conductivity. The effective collision rate is given by

$\omega \approx \frac{n q^4}{m^2 v^3}$

where $n$ is the number density, $q$ is the electric charge, $m$ is the electron mass and $v$ is the thermal velocity. The diffusion coefficient is given by

$D \approx v^2/\omega \approx \frac{m^2 v^5}{n q^4}$

The heat flux is given by Fick's law

$F_c \approx D \nabla \left(n k T \right ) \approx \frac{\left(k T \right )^{5/2}}{m^{1/2} q^4} \nabla \left(k T \right )$

where $T \,$ is the temperature and $k$ is the Boltzmann constant.