Reflection of Alfven waves in the solar wind
- Univ. of Alabama, Huntsville, AL (United States)
- NASA Marshall Space Flight Center, Huntsville, AL (United States)
The authors have revisited the problem of propagation of toroidal and linear Alfven waves formulated by Heinenmann and Olbert to compare WKB and non-WKB waves and their effects on the solar wind. They considered two solar wind models and showed that reflection is important for Alfven waves with periods of the order of one day and longer and that non-WKB waves exert a stronger acceleration force than WKB waves. The purpose of this paper is to study the origin of these discrepancies by performing parametric studies of the behavior of the waves under a variety of different conditions. In addition, they want to investigate two problems that have not been addressed by Heinemann and Olbert, namely, calculate the efficiency of Alfven wave reflection in different wind models. To achieve these goals, they investigated the influence of temperature, electron density distribution, wind velocity, and magnetic field strength on the waves. The obtained results clearly demonstrate that Alfven wave reflection is strongly model dependent and that the strongest reflection can be expected in models with the base temperatures higher than 10{sub 6} K and with the base densities lower than 7x10{sup 7} cm {sup {minus}3}. In these models as well as in the models with lower temperatures and higher densities, Alfven waves with periods as short as several minutes have negligible reflection so that they can be treated as WKB waves; however, for Alfven waves with periods of the order of one hour or longer reflection is significant, requiring a non-WKB treatment. They also show that non-WKB, Alfven linear waves are always less effective in accelerating the plasma than WKB Alfven waves. Finally, it is evident from these results that the region of strongest wave reflection is usually located at the base of the models and hence that interpretation of wave reflection based solely on the reflection coefficient can be misleading. 34 refs., 4 figs.
- OSTI ID:
- 91328
- Journal Information:
- Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A12 Vol. 99; ISSN JGREA2; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
Similar Records
ALFVEN WAVE REFLECTION AND TURBULENT HEATING IN THE SOLAR WIND FROM 1 SOLAR RADIUS TO 1 AU: AN ANALYTICAL TREATMENT
On WKB expansions for Alfven waves in the solar wind