Plasma expansion characteristics of ionized clouds in the ionosphere: Macroscopic formulation

Journal Article · Fri Feb 01 04:00:00 EST 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JA02345· OSTI ID:5188674

Schunk, R W ^[1]; Szuszczewicz, E P ^[2]

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1. Utah State Univ., Logan (USA)
2. Science Applications International Corp., McLean, VA (USA)

The field-aligned expansion of Ba{sup +}, Li{sup +} and Ba{sup +}-Li{sup +} plasma clouds in the upper F region was modeled with a macroscopic hydrodynamic formulation in order to study the early-time (t {approx lt} 20 s) plasma expansion characteristics. The expansion scenarios were chosen to be similar to previous small-scale (Debye length), short-duration (plasma period) numerical simulations of collisionless plasma clouds. Since both the spatial and temporal scales differ by four orders of magnitude in the macroscopic and small-scale simulations, the comparison of results not only elucidates a broader domain of early-time plasma expansion characteristics and their extreme sensitivity to initial conditions but sheds light on the applicability of small-scale simulations to expanding plasma clouds in the ionosphere. The macroscopic simulations led to the following results: (1) An expanding Ba{sup +} cloud acts as an electrostatic snowplow, creating a hole in the ionosphere (factor of 10) as it pushes O{sup +} density bumps (factor of 1.8) ahead of it along the geomagnetic field. (2) For the same cloud half width a decrease in the cloud density leads to a weaker snowplow. (3) An initially weaker, longer lasting snowplow ultimately produces a larger hole in the ionosphere than a short-lived strong snowplow. (4) Elevated electron temperatures act both to speed the plasma cloud expansion and to strengthen the electrostatic snowplow. (5) A bulk velocity component along the magnetic field resulting from a rocket- or satellite- borne chemical release has several important effects on the plasma cloud expansion and the ionospheric response. (6) A Li{sup +} cloud expansion is qualitatively similar to a Ba{sup +} expansion but it is faster. (7) Without Li{sup +}-O{sup +} collisions the Li{sup +} snowplow is weaker than the comparable Ba{sup +} snowplow, but with collisions the reverse is true at early times.

• OSTI ID: 5188674
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:A2; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARIUM IONS
CATIONS
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
DIAGNOSTIC TECHNIQUES
EARTH ATMOSPHERE
ELECTRIC FIELDS
ELECTRON TEMPERATURE
EVALUATION
EXPANSION
F REGION
FLUID MECHANICS
HYDRODYNAMICS
ION DENSITY
IONOSPHERE
IONS
LITHIUM IONS
MATHEMATICAL MODELS
MECHANICS
OXYGEN IONS
PLANETARY IONOSPHERES
PLASMA EXPANSION
VELOCITY