Research Note

A detailed calculation of neutral hydrogen ionization frequencies used in turbulence transport models in the heliosphere

¹ South African National Space Agency, 7200 Hermanus, South Africa
e-mail: n.eugene.engelbrecht@gmail.com
² Center for Space Research, North-West University, 2790 Potchefstroom, South Africa
e-mail: 12580996@nwu.ac.za
³ On sabbatical leave at the Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 3585, USA

Received: 9 March 2015
Accepted: 7 June 2015

Abstract

It is generally accepted that the solar wind is significantly heated beyond ~10 AU by the turbulent decay of pickup ion generated Alfvénic fluctuations. Here, we present a detailed and general calculation of the pickup ion ionization frequencies, and we evaluate these quantities within the solar wind termination shock along the stagnation line. For this supersonic solar wind region, inside of the solar wind termination shock, our results compare well with earlier estimates of these frequencies. When, in the future, turbulence transport models are extended into the heliosheath, the methodology outlined in this paper can be used to calculate ionization frequencies in this hot and dense plasma region where the resulting calculations become more complex.