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Cold Plasma Analyzer (CPA)

NSSDCA ID: 1992-064A-04

Mission Name: Freja
Principal Investigator:Dr. David J. Knudsen


The cold plasma experiment utilized a spherical plate, electrostatic energy analyzer to monitor electrons and ions of E/Q upto 200 eV/Q with the help of a Microchannel Plate (MCP). The incident location of the deflected particle on the plate provided eV/Q (radial distance) and the arrival angle (azimuth angle at the plate). The energy resolution (delta-E/E) could be programmed to be in the range of 0.05 to 0.20. The angular resolution of the arrival direction could be programmed to be as small as 10 deg in azimuth and 5 deg in elevation. Typical temporal resolution is about 10 ms,occasionally extended to 0.1 ms. A built-in Sun sensor enabled location of the actual direction of arrival. Monitored data were telemetered either directly as a matrix of 16 (angle) x 16 (energy), or processesd in house to provide number density, temperature and drift velocity for telemetering. The high temporal and spatial resolution enabled identification of waves of upto 3 kHz, and currents down to 10 micro Amperes per square meter. The instrument is inoperative since 25 May 1994.

Alternate Names

  • CPA
  • F3C
  • Freja/CPA

Facts in Brief

Mass: 5.5 kg
Power (avg): 8.4 W
Bit rate (avg): 16.384 kbps

Funding Agency

  • National Research Council of Canada (Canada)


  • Space Physics: Ionospheric Studies
  • 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
Dr. James A. KoehlerCo-InvestigatorUniversity of
Dr. Donald J. McEwenCo-InvestigatorUniversity of
Prof. Rickard LundinCo-InvestigatorSwedish Institute for Space
Dr. Andrew W. YauCo-InvestigatorNational Research Council of
Dr. Lars EliassonCo-InvestigatorSwedish Institute for Space
Dr. David J. KnudsenGeneral ContactUniversity of
Dr. David J. KnudsenPrincipal InvestigatorUniversity of
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