Complications to Electron Landau Damping in the Solar Wind

Waves of interest have vphase|| ≈ vA

vA ≈ 54 km/s0.5mevA

2 ≈ 8×10-3 eV Very very low-energy electrons Landau resonate.

Borovsky and Gary, Electron-ion Coulomb scattering and the electron Landau damping of Alfven waves in the solar wind, J. Geophys. Res., 116, A07107, 2011.

This low energy leads to 3 complications:

(1). Alfven wave parallel voltages >> resonant energy of electrons. very broad resonance Linear Vlasov does not work for calculating Landau-damping rates.

Complications to Electron Landau Damping in the Solar Wind

(2). Slow electrons Coulomb scatter rapidly off solar-wind protons. (At 1 AU the timescale for electrons to collisionally scatter into and out of resonance is measured in seconds.)

a) collision << wave, Landau

Might not want to use the collisionless Vlasov equation.

b) Wave does not locally evolve the electron distribution function. Quasi-linear theory is insufficient.

(3). E|| of Alfven waves < heliospheric electric field. Must consider whether Eheliosphere disrupts Landau damping.

Note also: Ion beams near vA complicate Landau damping. Ion Landau damping (even at low ) may not be ignorable.