Collision frequencies

Before being able to estimate the HF absorption through the Appleton-Hartree equation, the collision frequencies (electron-ions and electron-neutrals) must be computed. Due to the fact that neutrals are dominating the D-region, we expect the electron-neutrals collision frequency to be well over the electron-ions one. Only the collisions between positive ions and electrons are considered, the negative ions do not contribute to the total collision frequency.

The computation of those frequencies is done following the Schunk-Nagy collision frequencies [schunk1978] [schunk2009] as presented in [zawdie2017] . All of it is done through the two function in the lir_achem.compute_collision_frequency module.

import lir_achem.compute_collision_frequency as ccf

# Compute the different collision frequencies

# Electron-ion
veO2m = ccf.ei_collisionfreq(e_here, O2m_c)
veXm = ccf.ei_collisionfreq(e_here, Xm_c)
veNOp = ccf.ei_collisionfreq(e_here, NOp_c)
veO4p = ccf.ei_collisionfreq(e_here, O4p_c)
veYp = ccf.ei_collisionfreq(e_here, Yp_c)
veO2p = ccf.ei_collisionfreq(e_here, O2p_c)

# Electron-neutrals
ven = ccf.en_collisionfreq(e_here, n_here)