| タイトル | The role of Coulomb collisions in limiting differential flow and temperature differences in the solar wind |
| 著者（英） | Neugebauer, M. |
| 著者所属（英） | Jet Propulsion Lab., California Inst. of Tech. |
| 発行日 | 1976-01-01 |
| 言語 | eng |
| 内容記述 | Data obtained by OGO 5 are used to confirm IMP 6 observations of an inverse dependence of the helium-to-hydrogen temperature ratio in the solar wind on the ratio of solar-wind expansion time to the Coulomb-collision equipartition time. The analysis is then extended to determine the relation of the difference between the hydrogen and helium bulk velocities (the differential flow vector) with the ratio between the solar-wind expansion time and the time required for Coulomb collisions to slow down a beam of ions passing through a plasma. It is found that the magnitude of the differential flow vector varies inversely with the time ratio when the latter is small and approaches zero when it is large. These results are shown to suggest a model of continuous preferential heating and acceleration of helium (or cooling and deceleration of hydrogen), which is cancelled or limited by Coulomb collisions by the time the plasma has reached 1 AU. Since the average dependence of the differential flow vector on the time ratio cannot explain all the systematic variations of the vector observed in corotating high-velocity streams, it is concluded that additional helium acceleration probably occurs on the leading edge of such streams. |
| NASA分類 | SOLAR PHYSICS |
| レポートNO | 76A19838 |
| 権利 | Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/444341 |
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