# permittivity_1D_Maxwellian

plasmapy.formulary.dielectric.permittivity_1D_Maxwellian(omega: Unit('rad / s'), kWave: Unit('rad / m'), T: Unit('K'), n: Unit('1 / m3'), particle, z_mean: Unit(dimensionless) = None)

Compute the classical dielectric permittivity for a 1D Maxwellian plasma.

This function can calculate both the ion and electron permittivities. No additional effects are considered (e.g. magnetic fields, relativistic effects, strongly coupled regime, etc.).

Parameters
• omega (Quantity) – The frequency in rad/s of the electromagnetic wave propagating through the plasma.

• kWave (Quantity) – The corresponding wavenumber, in rad/m, of the electromagnetic wave propagating through the plasma. This is often modulated by the dispersion of the plasma or by relativistic effects. See em_wave.py for ways to calculate this.

• T (Quantity) – The plasma temperature — this can be either the electron or the ion temperature, but should be consistent with density and particle.

• n (Quantity) – The plasma density — this can be either the electron or the ion density, but should be consistent with temperature and particle.

• particle (str) – The plasma particle species.

• z_mean (str) – The average ionization of the plasma. This is only required for calculating the ion permittivity.

Returns

chi – The ion or the electron dielectric permittivity of the plasma. This is a dimensionless quantity.

Return type

Quantity

Notes

The dielectric permittivities for a Maxwellian plasma are described by the following equations 1

\begin{align}\begin{aligned}χ_e(k, ω) = - \frac{α_e^2}{2} Z'(x_e)\\χ_i(k, ω) = - \frac{α_i^2}{2}\frac{Z}{} Z'(x_i)\\α = \frac{ω_p}{k v_{Th}}\\x = \frac{ω}{k v_{Th}}\end{aligned}\end{align}

$$χ_e$$ and $$χ_i$$ are the electron and ion permittivities, respectively. $$Z'$$ is the derivative of the plasma dispersion function. $$α$$ is the scattering parameter which delineates the difference between the collective and non-collective Thomson scattering regimes. $$x$$ is the dimensionless phase velocity of the electromagnetic wave propagating through the plasma.

References

1

J. Sheffield, D. Froula, S. H. Glenzer, and N. C. Luhmann Jr, Plasma scattering of electromagnetic radiation: theory and measurement techniques. Chapter 5 Pg 106 (Academic Press, 2010).

Examples

>>> from astropy import units as u
>>> from numpy import pi
>>> from astropy.constants import c
>>> T = 30 * 11600 * u.K
>>> n = 1e18 * u.cm**-3
>>> particle = 'Ne'
>>> z_mean = 8 * u.dimensionless_unscaled
>>> vTh = parameters.thermal_speed(T, particle, method="most_probable")
>>> omega = 5.635e14 * 2 * pi * u.rad / u.s
>>> kWave = omega / vTh
>>> permittivity_1D_Maxwellian(omega, kWave, T, n, particle, z_mean)
<Quantity -6.72809...e-08+5.76037...e-07j>