Double ionization of H- ions by electron impact in the solar atmosphere

Abstract

The double ionization of H- ions by the generalized Lorentzian distribution of electrons in the solar atmosphere is investigated. The Born-Bethe formula for the multielectron ionization cross section is employed in order to obtain the double-ionization rate for H- as a function of the spectral index and thermal energy. It is shown that the double-ionization rates of H- are greater in non-Maxwellian plasmas than in Maxwellian plasmas in the low-temperature region. It is also shown that the nonthermal character of the solar plasma increases the double-ionization rates of H- in the solar photosphere and chromosphere. In addition, we found that the double-ionization rates of H- in the solar photosphere and chromosphere increase with increasing the plasma temperature. It is also shown that the high-energy corrections enhance the double-ionization rates in non-Maxwellian plasmas, and that the high-energy corrections on the double-ionization rate increase with increasing the plasma temperature.