saha_n1n0

PlasmaCalcs.mhd.multifluid.mhd_multifluid_ionization.saha_n1n0(*, ne, T, xi, g1g0, u=None)

return (n1/n0) for an element, via saha equation.

ne: number or array

number density of electrons.

T: number or array

temperature.

xi: number

first ionization potential.

g1g0: number

ratio of element’s g (degeneracy of states) for g1 (ions) to g0 (neutrals).

u: None or UnitsManager

units to use; determines expected units system for input & output.

Also will grab relevant physical constants (such as kB) directly from u.

None –> make new UnitsManager with SI units.

SAHA_EQUATION:

‘(n1/n0) = (1/ne) * (2.0 / lde^3) * (g1 / g0) * exp(-xi / (kB * T))

where the terms are defined as follows:

T : temperature ne: electron number density n1: number density of element’s once-ionized ions. n0: number density of element’s neutrals. g1: “degeneracy of states” for element’s once-ionized ions. g0: “degeneracy of states” for element’s neutrals. xi: element’s first ionization energy. lde: electron thermal deBroglie wavelength:

lde^2 = hplanck^2 / (2 pi me kB T)