Half a Century of Kinetic Solar Wind Models

TL;DR

This paper reviews the evolution of four generations of kinetic solar wind models, highlighting improvements in their ability to match observed solar wind velocities through the incorporation of self-consistent electric potentials.

Contribution

It provides a historical overview and technical analysis of how successive kinetic models have enhanced understanding of solar wind acceleration.

Findings

First kinetic model failed to produce supersonic velocities.

Inclusion of self-consistent electric potential yields supersonic flows.

Later models better match observed slow and fast solar wind streams.

Abstract

I outline the development of four generations of kinetic models, starting with Chamberlain's solar breeze exospheric model. It is shown why this first kinetic model did not give apposite supersonic evaporation velocities, like early hydrodynamic models of the solar wind. When a self-consistent polarization electric potential distribution is used in the coronal plasma, instead of the Pannekoek-Rosseland's one, supersonic bulk velocities are readily obtained in the second generation of kinetic models. It is outlined how the third and fourth generations of these models have improved the agreement with observations of slow and fast speed solar wind streams.