Sub-kilometer thermal plasma structure near 1750 km altitude in the polar cusp/cleft

• We present Freja Cold Plasma Analyzer (CPA) measurements from an encounter with the low altitude (approx.1750 km) polar cusp during which the CPA measured 2-D images of the thermal (0-16 eV) particle distributions at 1.2 s time resolution, and simultaneously made rapid estimates (600/s) of integrated thermal particle flux into the instrument. The high resolution data show bursty ion flux enhancements of the order of tens of percent on time scales of tens of ms, or alternatively, hundreds of m spatial scales. The flux of electrons from 0-16 eV also varied by tens of percent and on temporal/spatial scales comparable to those in the ion cases. There is some evidence that the thermal particle flux variations are associated with intense low-frequency electromagnetic fluctuations with temporal/spatial scales identical to those seen by the CPA (tens of ms. hundreds of m).

Subject headings

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

Keyword

Data reduction

Detectors

Doppler effect

Electromagnetic wave interference

Electrons

Geomagnetism

Image processing

Ions

Plasma devices

Structure (composition)

Electromagnetic fluctuations

Freja cold plasma analyzer

Ion flux enhancements

Polar cusp/cleft

Thermal particle distributions

Thermal particle flux

Thermal plasma structure

Plasma theory

Publication and Content Type

ref (subject category)

art (subject category)