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Thermal Plasma Flow

NSSDCA ID: 1977-029A-02

Mission Name: ESA-GEOS 1
Principal Investigator:Dr. Gordon L. Wrenn


This instrument (ESA experiment S-302) employed two hemispherical electrostatic analyzers mounted on one of the locking booms for the measurement of electrons or protons over the range 0.5 to 500 eV arriving close to parallel and close to perpendicular to the local magnetic field. The energy range was covered in 64 steps with a relative energy resolution of 0.11. One analyzer had its aperture pointing along the negative Z spin axis with an opening angle of 18 deg x 18 deg providing a geometrical factor (G) of 6.0E-4 sq cm sr. The other analyzer made an angle of 100 deg with respect to the +Z axis with an opening angle of 8 deg x 30 deg providing a G of 5.0E-4 sq cm sr. Both detectors had to measure the same type of particles at the same time. The collimators of these instruments could be set at any voltage from -28 to +32 V in steps of 0.1 V to compensate for the potential difference between the instrument and the undisturbed plasma environment. This voltage was used to determine the spacecraft potential.

Alternate Names

  • ESA-GEOS1/ThermalPlasmaFlow
  • Study of Thermal Plasma, Experiment Number S302

Funding Agency

  • European Space Agency (International)


  • Space Physics: Magnetospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Mr. Keith NormanOther InvestigatorUniversity College, London
Sir Robert L. F. BoydOther InvestigatorUniversity College, London
Dr. W. John RaittOther InvestigatorUtah State
Dr. Gordon L. WrennPrincipal InvestigatorUniversity College, London
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