Experiment KM-7

Thermal plasma measurements in Plasmasphere

The primary purpose of KM-7 is to measure the temperature of cold electrons Te in Plasmasphere. As auxiliary parameter the instrument measures the difference of potentials between the floating spherical probe DET-P and the spacecraft. The spacecraft potential can be evaluated from these measurements. Frpm detailed measurements (only in STO mode) the ambient ion density can be determined also.

In the figures below only data from MRK are shown:

T_e

- electron temperature, ^oK

U_pk

- value of _sc not corrected for T_e

At lower part of the figures orbital and geophysical parameters are given:

UT

H

- height, km

Gmlat

- geomagnetic latitude

MLT

- Magnetic Local Time

Invl

- Invariant Latitude

L

- magnetic shell parameter (McIllwain L-parameter)

nOrb

- Orbit Number.

Fig.1

KM-7 measurements in MRK mode during the whole orbit 124, 27.IX.96.

Fig.2

Expanded part of fig.1 showing Upk variation with changing SC orientation near perigee.

Preliminary results

In period considered SC passed the plasmasphere at low and middle latitudes near L < 4 at heights = 8000-10000 km. At L > 4-5 and heights > 8000-10000 km SC was in auroral zone.

T_e inside plasmasphere is relatively low and does not exceed as a rule 3000-4000 K.
In auroral zone T_e is 1-2 eV and sometimes increases up to 3 eV. Fast variations are observed typically in after midnight sector, sometimes extending up to early morning sector (7-8 MLT). At MLT > 8 h T_e behaviour is smooth and fluctuations are negligible.

Fig.1

Fig.2