Electrostatic Analyzer

The THEMIS ion and electron electrostatic analyzers (iESA and eESA) measure plasma over the energy range from a few eV up to 30 keV for electrons and 25 keV for ions. The instrument consists of a pair of "top hat" electrostatic analyzers with common 180 by 6 fields-of-view that sweep out 4Π steradians each 3s spin period. Particles are detected by microchannel plate detectors and binned into six distributions whose energy, angle, and time resolution depend upon instrument mode. On-board moments are also calculated and processing includes corrections for spacecraft potential.

Development Institution:ESA Leads
University of California, Berkeley (UCB)C. W. Carlson (UCB), J.P. McFadden (UCB)

The THEMIS ion and electron Electrostatic Analyzers (ESAs) are packaged together to provide a common field of view. The left-hand figure shows an ESA with the anode cover removed, revealing coupling capacitors. The LVPS (black) is mounted on the side and the nitrogen purge inlet (red) is exposed. The right-hand figure is an analyzer cutaway showing the common aperture mechanism and electronics packaging.

Click on the icon to download the paper by McFadden et al., 2008:
- Click on the icon to download the slides by Carlson et al., 2007 with the ESA highlights.

Here you may find some frequently requested information on ESA

THEMIS probes underwent many configuration changes during lifetime. ESA Event Log will help you in correct interpretation of ESA measurements.

MCP Test Results

For more information on ESA, go to the ESA instrument page of UC Berkeley THEMIS web site.

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