Photoelectrons are emitted from the surface of Mercury and take part in charge exchanges with the magnetosphere. We investigate the role of photoemission in closing field-aligned currents and in balancing the flow of magnetospheric electrons which precipitate to the surface. The conductance of the photoelectron sheath and sub-surface rock material are estimated and compared with that of the exosphere. It is shown that the loss cone angle is always larger than 30-40 degrees on the dayside, and that significant electron precipitation takes place. It is concluded that the closure of held-aligned current is unlikely because the conductance of the surface environment is too low, but that photoemission may alter the isotropy of the magnetospheric electron energy distribution and induce plasma instabilities. (C) 1999 Elsevier Science Ltd. All rights reserved.
|Number of pages||5|
|Journal||Planetary and Space Science|
|Publication status||Published - Dec 1999|
|MoE publication type||A1 Journal article-refereed|
|Event||Western Pacific Geophysics Meeting on Terrestrial Planets and Early Solor System Evolution - Taipei, Taiwan, Republic of China|
Duration: 21 Jul 1998 → 24 Jul 1998