THM EFI Status - 1THEMIS SWT Meeting20 Dec 2008

THEMIS EFIInstrument Status Report

John Bonnell

Topics:• Instrument Performance and Configuration

• EFI• DFB (FBK, FFT, etc.)

• Ground Software and Documentation• Instrument Paper• Calibrations and Despin

THM EFI Status - 2THEMIS SWT Meeting20 Dec 2008

Performance and Config (EFI):

• EFI performance nominal across all probes:• all 30 sensors and preamps still in operation and in-spec after 22 months on-orbit.

• Cold plasma wake effects remain an issue for dayside data, for both DC and AC observations (see FFT section for examples).• Cold plasma wake effects can be an issue for inner magnetosphere DC observations (on-going work with Hori, Nishimura, Matsui).• Common-mode error (SC potential contamination) remains an issue for axial DC E field data.• FBK configuration update across constellation (Oct 2008).• Upcoming data quality interruptions:

• EFI sensor shadow season (~Apr 2008).

THM EFI Status - 3THEMIS SWT Meeting20 Dec 2008

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.• Switched to 32-bin on THA (Oct 2008)– no strong benefit.

• DQ (para, perp) SCM data still to be commanded.• DQ (para, perp) EFI may be commanded (only perp).

THM EFI Status - 4THEMIS SWT Meeting20 Dec 2008

Ground Software and Documentation:

• EFI Instrument paper accepted to SRR Special Issue (Dec 2008):• ftp://apollo.ssl.berkeley.edu/pub/THEMIS/SCI/Pubs/2008_Space_Science_Review

s/, thm_efi_instrument_paper_revAB.pdf.

• Read it, learn it, live it.•Additional mods to accommodate different offsets between booms in works (Oct 2008); significant at the 1-2 mV/m level.• Other items in the future:

• Frequency response correction.• Custom calibration (ala SDT).• THEMIS-EFI website update.• E-mail distribution of updates and corrections.

• Many teams working hard on DC and AC EFI data analysis – well done!• UCB: F. Mozer, J. McFadden, 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.• STELab, Nagoya: T. Hori, Y. Nishimura.• UNH: H. Matsui.

THM EFI Status - 5THEMIS SWT Meeting20 Dec 2008

Impact of ES wake contamination is variable, with plasma conditions. Performance often still great, and SCM-derived products are not impacted in any case.

THM EFI Status - 6THEMIS SWT Meeting20 Dec 2008

But, impact on EFI spectral products can be strong:

Spikes due to ES wake contaminate spectrum up to few hundred Hz