Ion-Electron Pair Production by the Impacts of Cometary Neutrals and Dust Particles on the Halley Probe Shield
Abstract
Current models for the number densities of cometary neutrals and dust particles for Halley at 1.5 AU pre-perihelion and suitable assumptions for ionization degrees are used to investigate the number of ions and electrons created by impacts of cometary neutrals and dust particles on the probe shield. A thin gold coating on the front sheet of an aluminum shield is proposed to reduce the number of ions produced by impacts of neutrals by several orders of magnitude. Depending on the mass of the impacting dust particle and the distance from the nucleus the impacts of dust particles on the probe shield can be conceived either as a quasi-continuous or a discrete phenomenon. In the first case the number of ions and electrons produced by dust particle impacts must be added to the number of ions and electrons produced continuously by impacting cometary neutrals to get the total impact-generated plasma around the probe; in the second case the dust particle impacts may cause discrete large probe potential pulses each lasting 0.1 ms.
- Publication:
-
The Comet Halley Probe. Plasma Environment
- Pub Date:
- May 1981
- Bibcode:
- 1981ESASP.155....7G
- Keywords:
-
- Cosmic Dust;
- Electron Impact;
- Ion Impact;
- Ions;
- Pair Production;
- Spacecraft Shielding;
- Aluminum;
- Gold Coatings;
- Halley'S Comet;
- Hypervelocity Impact;
- Ionization;
- Plasma Clouds;
- Space Probes;
- Astrophysics