Plasma structuring in the polar cap

Technical Report · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6000544

Basu, S; Basu, S; Weber, E J; Bishop, G J

Propagation experiments providing scintillation, total electron content and drift data in the field of view of an all-sky imager near the magnetic polar in Greenland are utilized to investigate the manner in which ionospheric plasma becomes structured within the polar cap. It is found that under IMF Bz southward conditions, large scale ionization patches which are convected through the dayside cusp into the polar cap get continually structured. The structuring occurs through the ExB gradient drift instability process which operates through an interaction between the antisunward plasma convection in the neutral rest frame and large scale plasma density gradients that exist at the edges of the ionization patches. It is shown that with the increase of solar activity the strength of the irregularities integrated through the ionosphere is greatly increased. Under the IMF Bz northward conditions, the plasma structuring occurs around the polar cap arcs in the presence of inhomogeneous electric field or disordered plasma convection. In that case, the irregularity generation is caused by the competing processes of non-linear Kelvin-Helmholtz instability driven by sheared plasma flows and the gradient drift instability process which operates in the presence of dawn-dusk motion of arc structures. The integrated strength of this class of irregularities also exhibits marked increase with increasing solar activity presumably because the ambient plasma density over the polar cap is enhanced.

• Research Organization: Boston Coll., Chestnut Hill, MA (USA). Inst. for Space Research
• OSTI ID: 6000544
• Report Number(s): AD-A-227846/3/XAB; CNN: F19628-90-K-0007
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
CONVECTION
DRIFT INSTABILITY
EARTH ATMOSPHERE
ELECTRON DENSITY
ELECTRONS
ELEMENTARY PARTICLES
ENERGY TRANSFER
FERMIONS
GREENLAND
HEAT TRANSFER
HELMHOLTZ INSTABILITY
IMAGES
INSTABILITY
INTERPLANETARY MAGNETIC FIELDS
ION DENSITY
IONIZATION
IONOSPHERE
LEPTONS
MAGNETIC FIELDS
MASS TRANSFER
MEASURING INSTRUMENTS
MORPHOLOGY
PHOTOMETERS
PLANETARY IONOSPHERES
PLASMA
PLASMA DENSITY
PLASMA DRIFT
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA MICROINSTABILITIES
POLAR REGIONS
POLAR-CAP AURORAE
SCINTILLATIONS
SOLAR ACTIVITY
STABILITY
WAVE PROPAGATION