Monte Carlo study of the escape of a minor species
| dc.contributor.author | Barakat, A.R. | |
| dc.contributor.author | Lemaire, J. | |
| dc.date | 1990 | |
| dc.date.accessioned | 2017-06-07T13:46:12Z | |
| dc.date.available | 2017-06-07T13:46:12Z | |
| dc.identifier.uri | https://orfeo.belnet.be/handle/internal/5724 | |
| dc.description | The understanding of some important space-physics problems (e.g., the Jeans escape of light atoms from a planetary atmosphere and the ion escape in the terrestrial polar wind) is related to the problem of the escape of a minor species through a nonuniform background. This latter problem was studied for different interparticle collision models (Maxwell molecule and hard sphere), for different minor-to major-species mass ratios, and for different values of the escape velocity (vc). The gravitational force was simulated by a critical escape velocity (vc), and the Lorentz forces were ignored. First, a simple variable change was used to transform the problem into a simpler one where the background medium is uniform. This simplified problem, which is similar to the Milne problem, was solved by a Monte Carlo simulation. In the collisionless region and for the case of zero escape velocity (vc=0), the velocity distribution function of the minor species (ft) showed large deviations from a Maxwellian, with large temperature anisotropy (parallel temperature less than the perpendicular temperature) and asymmetry in the parallel direction (upward tail), for both of the collision models. In the collision-dominated region the normalized density gradient was found to be independent of the mass ratio for the Maxwell molecule collision. For the hard-sphere cross section, it was reduced by a mass-ratio-dependent factor. This is due to the heat-flow contribution to the momentum balance, which vanishes only for the former collision model. The Monte Carlo results were compared with the moment-equations approach and the direct solution of the Boltzmann equation. This comparison confirms that the Monte Carlo method is a viable alternative and complementary to other techniques, especially in recent years, due to the large increase in the available computation power. | |
| dc.language | eng | |
| dc.title | Monte Carlo study of the escape of a minor species | |
| dc.type | Article | |
| dc.subject.frascati | Physical sciences | |
| dc.audience | Scientific | |
| dc.source.title | Physical Review A | |
| dc.source.volume | 42 | |
| dc.source.issue | 6 | |
| dc.source.page | 3291-3302 | |
| Orfeo.peerreviewed | Yes | |
| dc.identifier.doi | 10.1103/PhysRevA.42.3291 | |
| dc.identifier.scopus | 2-s2.0-0000928670 |
