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The Search Coil Magnetometer for THEMIS


THEMIS instruments incorporate a tri-axial Search Coil Magnetometer (SCM) designed to measure the magnetic components of waves associated with substorm breakup and expansion. The three search coil antennas cover the same frequency bandwidth, from 0.1 Hz to 4 kHz, in the ULF/ELF frequency range. They extend, with appropriate Noise Equivalent Magnetic Induction (NEMI) and sufficient overlap, the measurements of the fluxgate magnetometers. The NEMI of the searchcoil antennas and associated pre-amplifiers is smaller than 0.76 pT \(/\sqrt{\mathrm{Hz}}\) at 10 Hz. The analog signals produced by the searchcoils and associated preamplifiers are digitized and processed inside the Digital Field Box (DFB) and the Instrument Data Processing Unit (IDPU), together with data from the Electric Field Instrument (EFI). Searchcoil telemetry includes waveform transmission, FFT processed data, and data from a filter bank. The frequency range covered depends on the available telemetry. The searchcoils and their three axis structures have been precisely calibrated in a calibration facility, and the calibration of the transfer function is checked on board, usually once per orbit. The tri-axial searchcoils implemented on the five THEMIS spacecraft are working nominally.

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  1. V. Angelopoulos et al., The THEMIS mission. Space Sci. Rev. (2008, this issue). doi:10.1007/s11214-008-9336-1

  2. J.W. Bonnell, F.S. Mozer, G.T. Delory, A.J. Hull, R.E. Ergun, C.M. Cully, V. Angelopoulos, The electric field instrument (EFI) for THEMIS. Space Sci. Rev. (2008, this issue)

  3. R.M. Bozorth, D.M. Chapin, Demagnetizing factors of rods. J. Appl. Phys. 13, 320–326 (1942)

  4. S.V. Bulanov, F. Pegoraro, A.S. Sakharov, Magnetic reconnection in electron dynamics. Phys. Fluids B 4, 2499–2508 (1992)

  5. C. Coillot, J. Moutoussamy, P. Leroy, G. Chanteur, A. Roux, Improvements on the design of search coil magnetometer for space experiments. Sens. Lett. 5, 1–4 (2007)

  6. N. Cornilleau-Wehrlin, P. Chauveau, S. Louis, A. Meyer, J. Nappa, S. Perraut, L. Rezeau, P. Robert, A. Roux, C. de Villedary, Y. de Conchy, L. Friel, C.C. Harvey, D. Hubert, C. Lacombe, R. Manning, F. Wouters, F. Lefeuvre, M. Parrot, J.L. Pinçon, B. Poirier, W. Kofman, P. Louarn, The cluster Spatio-temporal Analysis of Field Fluctuations (STAFF) experiment. Space Sci. Rev. 79, 107–136 (1997)

  7. N. Cornilleau-Wehrlin, G. Chanteur, S. Perraut, L. Rezeau, P. Robert, A. Roux, C. de Villedary, P. Canu, M. Maksimovic, Y. de Conchy, D. Hubert, C. Lacombe, F. Lefeuvre, M. Parrot, J.-L. Pinçon, P.M.E. Décréau, C.C. Harvey, P. Louarn, O. Santolik, H.St. Alleyne, M. Roth, T. Chust, O. Le Contel, STAFF team, First results obtained by the Cluster STAFF experiment. Ann. Geophys. 21, 437–456 (2003)

  8. C.M. Cully, R.E. Ergun, K. Stevens, A. Nammari, J. Westfall, The THEMIS digital fields board. Space Sci. Rev. (2008, this issue). doi:10.1007/s11214-008-9417-1

  9. P.R. Harvey et al., The THEMIS observatory. Space Sci. Rev. (2008, this issue)

  10. O. Le Contel, A. Roux, P. Robert, C. Coillot, A. Bouabdellah, B. de la Porte, D. Alison, S. Ruocco, V. Angelopoulos, K. Bromund, C.C. Chaston, C. Cully, First results of THEMIS Search Coil Magnetometers (SCM). Space Sci. Rev. (2008, this issue). doi:10.1007/s11214-008-9371-y

  11. M. Ludlam et al., The THEMIS magnetic cleanliness program. Space Sci. Rev. (2008, this issue). doi:10.1007/s11214-008-9423-3

  12. A.T.Y. Lui, Current controversies in magnetospheric physics. Rev. Geophys. 39(4), 535–563 (2001)

  13. A.T.Y. Lui, R.E. Lopez, B.J. Anderson, K. Takahashi, L.J. Zanetti, R.W. McEntire, T.A. Potemra, D.M. Klumpar, E.M. Greene, R. Strangeway, Current disruption in the near-Earth neutral sheet region. J. Geophys. Res. 97, 1461 (1992)

  14. M.E. Mandt, R.E. Denton, J.F. Drake, Transition to whistler mediated magnetic reconnection. Geophys. Res. Lett. 21(1), 73–77 (1994)

  15. J.A. Osborn, Demagnetizing factors of the general ellipsoid. Phys. Rev. 67(11–12), 351–357 (1945)

  16. P. Ripka, Magnetic sensors and magnetometers. Artech house (2001)

  17. A. Roux, S. Perraut, P. Robert, A. Morane, A. Pedersen, A. Korth, G. Kremser, B. Aparicio, D. Rodgers, R. Pellinen, Plasma sheet instability related to the westward traveling surge. J. Geophys. Res. 96, 17,697 (1991)

  18. E. Taylor et al., The THEMIS instrument data processing unit. Space Sci. Rev. (2008, this issue)

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Correspondence to A. Roux.

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Roux, A., Le Contel, O., Coillot, C. et al. The Search Coil Magnetometer for THEMIS. Space Sci Rev 141, 265–275 (2008). https://doi.org/10.1007/s11214-008-9455-8

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  • Search-coil magnetometer
  • Magnetospheric mission
  • Substorm physics