Post on 11-Jan-2016
description
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
Sub-keV Ring Current (RC)?
But, in reality, sub-keV ions exist
11 MLT
14 MLT
m>2
H+ cavity in sub-keV range
Traditional RC : > 5 keV only
15 MLT
Westward (magnetic) drift
Eastward (electric) drift
Viking statistics
6 MLT
9 MLT
12 MLT
15 MLT
18 MLT
Time-lag (hours)
(1) Moves eastward
(2) Decrease in time
Backward Superposed Epoch Analyses using 700 traversals. * 3h MLT bin & 3h window for time-lag* three categories: "clear structure", "marginal", and "quiet.
Morning: additional keV line= Eastward (electric) drift
Westward (magnetic) drift
Noon Early morning Late morning
(1) Total (wedge & >1 keV): Morning peak(2) > 1 keV: Morning only(3) Freja-Cluster difference: Mirror altitude?
only < 1 keV also > 1 keV also > 1 keV
day (12 MLT)
Midnigh (3 MLT)
UT 00:30 01:00 01:30 02:00
Substorm onset
difference
Case study : 2001-10-21
H+
O+South North
Substorm onset
+0.1° 0° -0.1°
SC-4 @ 23:50 UT: Yes
23:50 UT
23:40 UT
23:50 UT
SC-3 @ 23:40 UT: No
V(10 keV) = VE-VB << VE
V(0.1 keV) ~ VE
10 keV 0.1 keV
23:40 UT
Source estimation
∆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.
+0.1° 0° -0.1°
SC-4 @ 23:50 UT: Yes
23:50 UT
23:40 UT
23:50 UT
V(10 keV) = VE-VB << VE
V(0.1 keV) ~ VE
10 keV 0.1 keV
23:40 UTSC-3 @ 23:40 UT: No