Effects of collisional processes on the critical velocity hypothesis

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA04p04039· OSTI ID:5221817

Person, J C; Resendes, D; Petschek, H ^[1]; Hastings, D E ^[2]

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1. Physical Sciences Inc., Andover, MA (United States)
2. Massachusetts Inst. of Tech., Cambridge (United States)

Plasma production in a gas release from a body moving in low Earth orbit may occur via Alfven's critical ionization velocity (CIV) process. The effects of the collisional processes of charge exchange and elastic collisions of neutrals with ions and electrons are examined by numerical simulations of a plasma with a beam of fast neutral molecules. The rate of electron heating via plasma interactions increases as the fraction of ions in the fast beam increases. When the initial beam fraction is 0.005, increasing the neutral number density n{sub N} (for n{sub N} < 10{sup 12} cm{sup {minus}3}) increases the number of excitations and ionizations by electrons. This increased electron heating results from ambient charge exchange collisions increasing the fraction of beam ions. When the initial beam fraction is 0.5, the number of ionizations and excitations is shown to go through a maximum as n{sub N} increases. The initial increase is the result of the shorter collision times for the fast electrons, and the later decrease is the result of elastic collisions that disrupt the electron heating. In the higher density regime, the lower energy process of excitation is favored over ionization. Resonant charge exchange is an important process in maintaining the energy of the fast ion beam, and it lowers the threshold velocity for the CIV process.

• OSTI ID: 5221817
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:A4; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
&amp; Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AIRCRAFT
ATOM COLLISIONS
CHARGE EXCHANGE
COLLISIONS
CRITICAL VELOCITY
DEGASSING
EARTH ATMOSPHERE
EARTH PLANET
ELASTIC SCATTERING
ELECTRON COLLISIONS
ELECTRON-ATOM COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ENERGY
HEATING
ION COLLISIONS
ION-ATOM COLLISIONS
ION-MOLECULE COLLISIONS
IONIZATION
IONOSPHERE
KINETIC ENERGY
MOLECULE COLLISIONS
NUMERICAL SOLUTION
PLANETARY IONOSPHERES
PLANETS
PLASMA DENSITY
PLASMA PRODUCTION
SCATTERING
SPACE SHUTTLES
SPACE VEHICLES
VEHICLES
VELOCITY