太陽風に関するノート
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The quiet-day solar wind fully discussed by E.N, Parker on the basis of the fluid model of plasma. He found that it is a supersonic flow of the plasma in the solar gravitational field. We have here again discussed the solar wind using a two-fluid model of plasma.<BR>Two Bernoulli equations, which a : re coupled with the electric field each others, are complicated to analyse due to the many branches of the solutions. However, for the surface of the.sun, it is possible to apply the so-called quasi-linear approximation and to have relatively simple solution. In that approximation, two parameters play important rolles; one is γ related to the square of the initial velocity of ions and the other is β connected with the solar gravitational constant. When β=3-γ then the electric potential φ gradually decreases with increasing radious. When :β<3-γ or β>3-γ then φ changes steeply or takes an extreme value at a certain radious respectively. Furthermore, we have the conditions γ≥2β and γ>1; the former is necessary in order to keep the conservation of energy and the, latter is identical to the Bohm criterion leading to the stable ion sheath. Since small. change of γ or β results in a large change of φ, so a set of the special combination of (γ, β) is required in order to find the solar wind at the orbit of the earth.<BR>The results calculated by the quasi-linear approximation have been compared with ones computed by a machine. Finally it is, in this note, yet unclear whether "The electron Critical point" is present or not and we shall make it clear in the near future.
- 社団法人 プラズマ・核融合学会の論文