THEMIS EFI Instrument Status Report Vassilis Angelopoulos for

Performance and Config (EFI): • EFI performance nominal across all probes: • all 30

Performance and Config – FBK and FFT: • DFB spectral products nominal. • Switch

Impact of ES wake contamination is variable, with plasma conditions. Performance often still great,

But, impact on EFI spectral products can be strong: Spikes due to ES wake

Ground Software and Documentation: • EFI Instrument paper finally complete and submitted (July 2008):

Summary Waveform Data from EFI, week of 12 -19 Sep 2008. Cluster-THEMIS-2008 22 -26

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THEMIS EFI Instrument Status Report Vassilis Angelopoulos (for John Bonnell) Topics: • Instrument Performance and Configuration • EFI • DFB (FBK, FFT, etc. ) • Ground Software and Documentation • Instrument Paper • Calibrations and Despin Cluster-THEMIS-2008 22 -26 Sep 2008 THM EFI Status - 1

Performance and Config (EFI): • EFI performance nominal across all probes: • all 30 sensors and preamps still in operation and in-spec after 19 months on orbit! • Cold plasma wake effects remain an issue for dayside data, for both DC and AC observations (see FFT section for examples). • Common-mode error (SC potential contamination) remains an issue for axial DC E field data. • Upcoming data quality interruptions: • Maneuver season (Oct 2008). • EFI sensor shadow season (Oct 2008). Cluster-THEMIS-2008 22 -26 Sep 2008 THM EFI Status - 2

Performance and Config – FBK and FFT: • DFB spectral products nominal. • Switch to 64 -bin FFP data partially successful: • Configuration change made across constellation. • Spectral contamination due to ES wake stronger than expected. • Change from DC- to AC-coupled inputs not significant. • Switch to 32 -bin in next few months. • DQ (para, perp) SCM data still to be commanded. • DQ (para, perp) EFI may be commanded (only perp). Cluster-THEMIS-2008 22 -26 Sep 2008 THM EFI Status - 3

Impact of ES wake contamination is variable, with plasma conditions. Performance often still great, and SCM-derived products are not impacted in any case. Cluster-THEMIS-2008 22 -26 Sep 2008 THM EFI Status - 4

But, impact on EFI spectral products can be strong: Spikes due to ES wake contaminate spectrum up to few hundred Hz Cluster-THEMIS-2008 22 -26 Sep 2008 THM EFI Status - 5

Ground Software and Documentation: • EFI Instrument paper finally complete and submitted (July 2008): • ftp: //apollo. ssl. berkeley. edu/pub/THEMIS/SCI/Pubs/2008_Space_Science_Re views/, thm_efi_instrument_paper_rev. AB. pdf. • Read it, learn it, live it. • Initial TDAS version of despin complete (Apr 2008). • Additional mods to accommodate different offsets between booms in works (Oct 2008); significant at the 1 -2 m. V/m level. • Other items in the future: • Frequency response correction. • Custom calibration (ala SDT). • Many teams working hard on DC and AC EFI data analysis – well done! • UCB: F. Mozer, J. Mc. Fadden, A. Hull. • UCLA: W. Li et al. ; VA and M. Feuerstein. • LASP: W. Liu, X. Li, L. Andersson, S. Eriksson, T. Johansson, R. Ergun, J. Tao. Cluster-THEMIS-2008 22 -26 Sep 2008 THM EFI Status - 6

Summary Waveform Data from EFI, week of 12 -19 Sep 2008. Cluster-THEMIS-2008 22 -26 Sep 2008 THM EFI Status - 7