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Substorm-origin sub-keV ring current ions: wedge-like structure

Substorm-origin sub-keV ring current ions: wedge-like structure. M. Yamauchi , R. Lundin, H. Nilsson (IRF-Kiruna), Y. Ebihara (Nagoya U.) I. Dandouras, H. Reme (CESR, Toulouse). Substorm : production of plasma Sub-keV ring current : fossil of substorm

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Substorm-origin sub-keV ring current ions: wedge-like structure

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  1. Substorm-origin sub-keV ring current ions: wedge-like structure M. Yamauchi, R. Lundin, H. Nilsson (IRF-Kiruna), Y. Ebihara (Nagoya U.) I. Dandouras, H. Reme (CESR, Toulouse) Substorm : production of plasma Sub-keV ring current : fossil of substorm Question: source of sub-keV ring current? ICS-9, Graz, 2008-5-3~7

  2. Traditional RC : > 5 keV only Sub-keV Ring Current (RC)? m>2 H+ 15 MLT cavity in sub-keV range But, in reality, sub-keV ions exist Westward (magnetic) drift 11 MLT Eastward (electric) drift 14 MLT

  3. Viking statistics 6 MLT 9 MLT 12 MLT 15 MLT 18 MLT Time-lag (hours) Backward Superposed Epoch Analyses using700 traversals. * 3h MLT bin & 3h window for time-lag * three categories: "clear structure", "marginal", and "quiet. (1) Moves eastward (2) Decrease in time

  4. = Eastward (electric) drift Westward (magnetic) drift Morning: additional keV line Noon Early morning Late morning only < 1 keV also > 1 keV also > 1 keV (1) Total (wedge & >1 keV): Morning peak (2) > 1 keV: Morning only (3) Freja-Cluster difference: Mirror altitude?

  5. UT 00:30 01:00 01:30 02:00 day (12 MLT) Substorm onset Midnigh (3 MLT) difference

  6. Substorm onset Case study : 2001-10-21 H+ O+ South North V(10 keV) = VE-VB << VE 10 keV 0.1 keV 23:40 UT +0.1° 0° -0.1° 23:40 UT SC-3 @ 23:40 UT: No SC-4 @ 23:50 UT: Yes 23:50 UT V(0.1 keV) ~ VE 23:50 UT

  7. V(10 keV) = VE-VB << VE Source estimation 10 keV 0.1 keV 23:40 UT +0.1° 0° -0.1° 23:40 UT SC-3 @ 23:40 UT: No SC-4 @ 23:50 UT: Yes 23:50 UT V(0.1 keV) ~ VE 23:50 UT ∆t < 13 min (100 eV/C-3 & 10 keV/C-4)  t < 30 min  drift distance = VE * t < 20000 km started at 7~9 MLT.

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