| Автор | Haerendel, Gerhard |
| Дата выпуска | 1986 |
| dc.description | The plasma flow in the cometary coma is described by a simple relation which results from the balance of magnetic stresses and drag forces, the latter being mainly due to ion mass loading. Inertial and pressure effects are not explicitly considered, but lumped into a correcting factor of order unity. The relation is used to infer the ionization rate due to the critical velocity effect. The limits, r<sub>crit</sub> and r<sub>lim</sub>, between which the effect dominates over photoionization are evaluated. Critical velocity ionization stabilizes the plasma flow speed at η<sup>−1/2</sup> v<sub>crit</sub>, where η is the overall efficiency of energy transfer to the ionizing electrons. This speed is estimated to be close to 20 km/s. At the outer limit, r<sub>lim</sub>, there is a strong rise of plasma density as seen from outside. Inside r<sub>crit</sub>, recombination and ion‐neutral friction come into play. The contact surface is found to be largely determined by ion‐neutral collisions. A second neutral component of the order of 10² cm<sup>−3</sup> is predicted to originate from recombination inside r<sub>lim</sub>. It is characterized by an antisunward flow with ∼ 20 km/s. Numerical values for the radial profile of n<sub>i</sub> and of the critical boundaries (except the bow shock) are given. The high plasma density found by ICE at the closest approach to comet Giacobini‐Zinner is interpreted as a result of the critical velocity effect. |
| Формат | application.pdf |
| Копирайт | Copyright 1986 by the American Geophysical Union. |
| Тема | Comets |
| Тема | Comets |
| Тема | Comets |
| Тема | Comets |
| Тема | Comets I |
| Тема | Planetary Sciences: Comets and Small Bodies |
| Тема | Planetology: Comets and Small Bodies: Interactions with solar wind plasma and fields |
| Тема | Space Plasma Physics |
| Тема | Space Plasma Physics: Ionization processes |
| Название | Plasma flow and critical velocity ionization in cometary comae |
| Тип | article |
| DOI | 10.1029/GL013i003p00255 |
| Electronic ISSN | 1944-8007 |
| Print ISSN | 0094-8276 |
| Журнал | Geophysical Research Letters |
| Том | 13 |
| Первая страница | 255 |
| Последняя страница | 258 |
| Аффилиация | Haerendel, Gerhard; Max‐Planck‐Institut für Physik und Astrophysik, Institut für extraterrestrische Physik |
| Выпуск | 3 |
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