首页   按字顺浏览 期刊浏览 卷期浏览 Transport toward Earth of ions sputtered from the Moon's surface by the solar wind
Transport toward Earth of ions sputtered from the Moon's surface by the solar wind

 

作者: J. B. Cladis,   W. E. Francis,   R. R. Vondrak,  

 

期刊: Journal of Geophysical Research: Space Physics  (WILEY Available online 1994)
卷期: Volume 99, issue A1  

页码: 53-64

 

ISSN:0148-0227

 

年代: 1994

 

DOI:10.1029/93JA02672

 

数据来源: WILEY

 

摘要:

The transport of typical ions from the surface of the Moon to the vicinity of Earth was calculated using a test particle approach. It was assumed that the ions were sputtered from the surface by the solar wind, with fluxes in the range determined experimentally by Elphic et al. (1991), and were accelerated initially to 10 eV by the potential of the Moon on its sunlit side. Si+and Ca+ions were selected for this transport analysis because their masses are within two prominent ion mass groups that have high sputtering yields. In the solar wind the ion trajectories were traced in the following superimposed fields: (1) a steady magnetic fieldB0at an angle of 45° to the solar wind velocityVsw, (2) the motional electric fieldE0= −Vsw× B0, and (3) turbulent magnetic and electric fields generated by hydromagnetic waves with ak‐space power spectrum of |k|−5/3propagating along both directions of the magnetic fieldB0. Interactions with Earth's bow shock and magnetosphere were included. Case histories of the ions were recorded in theXGSM,YGSMplane and in various planes perpendicular to theE0× B0drift direction of the ions between the Moon and Earth. The number density, energy and angular distributions, and directional and omnidirectional fluxes of the ions were constructed from the case histories. It was found that the diffusion of the ions increases rapidly as the amplitude of the turbulence δBrmsincreases beyond the value 0.04B0. The directional fluxes of Si+and Ca+in the solar wind, upstream from the bow shock, were found to be of the order of tens of ions cm−2s−1sr−1keV−1, with energies 35‐70 keV, for δBrms= 0.04B0,B0= 5 nT, andVsw= 400 km/s. The fluxes of Si+and Ca+ions that originate in the Moon's atmosphere were estimated to be smaller than the corresponding sputtered‐ion fluxes by about an order of magnitude. Recent measurements of lunar ions upstream of the bow shock by Hilchenbach et al. (1992) generally confirm the predicte

 

点击下载:  PDF (1135KB)



返 回