Letter to the Editor

Collisional excitation and ionization of hydrogen by return current in solar flares

Astronomical Institute of the Academy of Sciences of the Czech Republic, 25165 Ondřejov, Czech Republic

Corresponding author: M. Karlický, karlicky@asu.cas.cz

Received: 5 December 2003
Accepted: 30 January 2004

Abstract

First a problem of the transport of electron beams with high energy fluxes into the cold chromosphere during the flare is presented. Then it is shown that the problem might be solved by the return current formed by superthermal (runaway) electrons. In such a case the return current electrons could influence hydrogen excitations and ionizations. Therefore, we computed collisional rates of such a return current and compared them with those of the thermal plasma and of a monoenergetic (10 keV) electron beam with the energy flux penetrating into the flare atmosphere described by the F1 model (Machado et al. [CITE]). We show that in this situation the return current collisional rates can be dominant for some transitions.