Kinetic description of electron beams in the solar chromosphere

GÓMEZ, DANIEL O.; MAUAS, PABLO J.D.

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Año: 1992 vol. 398 p. 682 - 691

0004-637X

We formulate the relativistic Fokker-Planck equation for a beam of accelerated electrons interacting with a partially ionized plasma. In our derivation we conserved those terms contributing to velocity diffusion and found that this effect cannot be neglected a priori. We compute the terms accounting for elastic and inelastic collisions with neutral hydrogen and helium. Collisions with neutral hydrogen are found to be dominant throughout the chromosphere, except at the uppermost layers close to the transition region. As an application, we compute the loss of energy and momentum for a power-law beam impinging on the solar chromosphere, for a particular case in which the Fokker-Planck equation can be integrated analytically. For comparison, we also computed the energy deposition rates obtained from a test particle approach. We find that most of the beam energy is deposited in a relatively thin region of the chromosphere, a result which is largely insensitive to the theoretical method employed to compute the energy deposition rate.