plasmapy.formulary.braginskii.electron_thermal_conductivity(T_e, n_e, T_i, n_i, ion, m_i=None, Z=None, B: ~astropy.units.quantity.Quantity = <Quantity 0. T>, model='Braginskii', field_orientation='parallel', mu=None, theta: float | None = None, coulomb_log_method='classical') Quantity[source]

Calculate the thermal conductivity for electrons.

The electron thermal conductivity (\(κ\)) of a plasma is defined by

\[κ = \hat{κ} \frac{n_e k_B^2 T_e τ_e}{m_e}\]

where \(\hat{κ}\) is the non-dimensional electron thermal conductivity of the plasma, \(n_e\) is the electron number density of the plasma, \(k_B\) is the Boltzmann constant, \(T_e\) is the electron temperature of the plasma, \(τ_e\) is the fundamental electron collision period of the plasma, and \(m_e\) is the mass of an electron.


This is quite similar to the ion thermal conductivity, except that it’s for the plasma electrons. In a typical unmagnetized plasma, the electron thermal conductivity is much higher than the ions and will dominate, due to the electrons’ low mass and fast speeds.

In a strongly magnetized plasma, following the classical transport analysis, you calculate that the perpendicular-field thermal conductivity becomes greatly reduced for the ions and electrons, with the electrons actually being restrained even more than the ions due to their low mass and small gyroradius. In reality, the electrons and ions are pulling on each other strongly due to their opposing charges, so you have the situation of ambipolar diffusion.

This situation has been likened to an energetic little child (the electrons) not wanting to be pulled away from the playground (the magnetic field) by the parents (the ions).

The ultimate rate must typically be in between the individual rates for electrons and ions, so at least you can get some bounds from this type of analysis.

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