Transcript Sub-keV Phenomena of Dayside Ring Current

Cold, keV, & MeV ion signatures
of westward moving auroral
bulge at L=4 in equatorial plane
M. Yamauchi1, I. Dandouras2, P.W. Daly3, H. Frey4, P.-A.
Lindquvist5, G. Stenberg6, Y. Ebihara7, R. Lundin1, H.
Nilsson1, H. Reme2, M. Andre6, E. Kronberg3, and A. Balogh8
(1) IRF, Kiruna, Sweden, (2) CESR, Toulouse, France, (3)
MPS, Katlenburg-Lindau, Germany, (4) UCB/SSL, Berkeley,
CA, USA, (5) Alfven Lab., KTH, Stockholm, Sweden, (6) IRF,
Uppsala, Sweden, (7) IAR, Nagoya U., Nagoya, Japan, (8)
Blackett Lab., ICL, London, UK
ICS-9, Graz, 2008-5 / revised for IMC-workshop, Espoo, 2008-7
overview
90 min
MeV
102 keV
Z=0 Re,
R=4 Re
0.01~40 keV
Cluster
perigee
(19 MLT,
R≈4 RE,
Z=0 RE)
25 min
H+
O+
H+
He+
What do these events indicate?
From 06:43 UT event
(a) Composition of cold plasma  plasmaspheremagnetosphere coupling in the inner magnetosphere.
(b) Mass-dependent filling of medium-energy ring
current ions (and by auroral bulge?)  drift motion
(c) Propagation of large DC electric field in the
equatorial plane.
(d) Inter-SC difference of energetics  non-gyrotropic
From 06:48 UT event (not today)
(d) Bi-parallel beams in the equatoral plane
(e) Equatorial signature of the transpolar arc.
Spacecraft
* Near equator (Z ≈ 0 RE)
* Perigee (R ≈ 4 RE)
S/C
* 19 MLT
SC1-SC4
≈ 25 sec
dusk
SC1-SC3
≈ 1 min
north
sun
dawn
U
tail
south
E
IMAGE/FUV
S/C
06:26~06:56 UT
06:26
UT
06:34 UT
06:42 UT
06:50
06:28
UT
06:36 UT
06:44 UT
06:5
2
06:30
UT
06:38 UT
06:46 UT
06:54
06:32
UT
06:40 UT
06:48 UT
06:56
IMAGE/FUV
S/C
06:26~06:56 UT
~06:43 event
06:26
UT
06:34 UT
06:42 UT
06:50
06:28
UT
06:36 UT
06:44 UT
06:5
2
06:30
UT
06:38 UT
06:46 UT
06:54
06:32
UT
06:40 UT
06:48 UT
06:56
IMAGE/FUV
S/C
06:26~06:56 UT
~06:43 event
~06:48 event
06:26
UT
06:34 UT
06:42 UT
06:50
06:28
UT
06:36 UT
06:44 UT
06:5
2
06:30
UT
06:38 UT
06:46 UT
06:54
06:32
UT
06:40 UT
06:48 UT
06:56
~06:26 UT: minor substorm
~06:38 UT: new glowing
#1
#2
MCQ = Cluster conjugate
Observation of 06:43 UT (#1) event
1. Sudden change in particle flux (> 40 keV, > 10 keV,
and < 100 eV) when aurora bulge arrived Cluster’s
conjugate ~19 MLT.
2. Change is simultaneous at all SC (SC-3 leading by 1~10 sec).
3. Simultaneous DC field change (tailward E~8mV/m, Pi2-like
rarefaction |B|≈|BZ| up to 20%) without special wave activity.
4. Increase in medium energy (~100 keV, mass dependent) ion
flux. Diamagnetic effect by ∆PP can quantitatively explain ∆PB.
5. Decrease in energetic e- (>30 keV) and ions (> 0.1 MeV)
6. Temporal (about 1 min) change of pitch-angle of 10-40 keV to
more field-aligned than perpendicular.
7. Bulk motion of cold He+ and H+ (no cold O+ or He++). The ion
velocity (20km/s, duskward) agrees with the ExB velocity.
overview
90 min
MeV
102 keV
Z=0 Re,
R=4 Re
0.01~40 keV
Cluster
perigee
(19 MLT,
R≈4 RE,
Z=0 RE)
25 min
H+
O+
H+
He+
keV ions of ionospheric origin?
06:43 UT
06:43 UT
//

//

//

No mass-energy
dispersion
Bi-directional
= not auroral ions
Observation of 06:43 UT (#1) event
1. Sudden change in particle flux (> 40 keV, > 10 keV, and < 100
eV) when aurora bulge arrived Cluster’s conjugate ~19 MLT.
2. Change is simultaneous at all SC (SC-3 leading by
1~10 sec).
3. Simultaneous DC field change (tailward E~8mV/m,
Pi2-like rarefaction |B|≈|BZ| up to 20%) without
special wave activity.
4. Increase in medium energy (~100 keV, mass dependent) ion
flux. Diamagnetic effect by ∆PP can quantitatively explain ∆PB.
5. Decrease in energetic e- (>30 keV) and ions (> 0.1 MeV)
6. Temporal (about 1 min) change of pitch-angle of 10-40 keV to
more field-aligned than perpendicular.
7. Bulk motion of cold He+ and H+ (no cold O+ or He++). The ion
velocity (20km/s, duskward) agrees with the ExB velocity.
Sudden change in ion and field
06:43:00 06:48:30
Timing (ion = 12sec resolution)
06:43:00 06:48:30
leading
60s behind
25s behind
Timing (E-field)
3 min
Timing (B-field)
Observation of 06:43 UT (#1) event
1. Sudden change in particle flux (> 40 keV, > 10 keV, and < 100
eV) when aurora bulge arrived Cluster’s conjugate ~19 MLT.
2. Change is simultaneous at all SC (SC-3 leading by 1~10 sec).
3. Simultaneous DC field change (tailward E~8mV/m, Pi2-like
rarefaction |B|≈|BZ| up to 20%) without special wave activity.
4. Increase in medium energy (~100 keV, mass
dependent) ion flux. Diamagnetic effect by ∆PP can
quantitatively explain ∆PB.
5. Decrease in energetic e- (>30 keV) and ions (> 0.1 MeV)
6. Temporal (about 1 min) change of pitch-angle of 10-40 keV to
more field-aligned than perpendicular.
7. Bulk motion of cold He+ and H+ (no cold O+ or He++). The ion
velocity (20km/s, duskward) agrees with the ExB velocity.
increase in
101~2 keV ion
flux
H+
< 90 keV
H+ > 160 keV
decrease in
102~3 keV
ion flux
increase in
1~2
10
keV ion flux
He < 350 keV
O < 0.9 MeV
O > 1.4 MeV
He > 700 keV
decrease in 102~3 keV ion flux
increase-decrease
combination
First increase,
then decrease
keV ion increase is NOT mass dependent
06:43 UT
No mass-energy
dispersion
(2~10 keV)
Observation of 06:43 UT (#1) event
1. Sudden change in particle flux (> 40 keV, > 10 keV, and < 100
eV) when aurora bulge arrived Cluster’s conjugate ~19 MLT.
2. Change is simultaneous at all SC (SC-3 leading by 1~10 sec).
3. Simultaneous DC field change (tailward E~8mV/m, Pi2-like
rarefaction |B|≈|BZ| up to 20%) without special wave activity.
4. Increase in medium energy (~100 keV, mass dependent) ion
flux. Diamagnetic effect by ∆PP can quantitatively explain ∆PB.
5. Decrease in energetic e- (>30 keV) and ions (> 0.1
MeV)
6. Temporal (about 1 min) change of pitch-angle of 10-40 keV to
more field-aligned than perpendicular.
7. Bulk motion of cold He+ and H+ (no cold O+ or He++). The ion
velocity (20km/s, duskward) agrees with the ExB velocity.
Decrease in > 40 keV electron flux
e- > 40 keV
cf. some decrease in < 30 keV ions
Observation of 06:43 UT (#1) event
1. Sudden change in particle flux (> 40 keV, > 10 keV, and < 100
eV) when aurora bulge arrived Cluster’s conjugate ~19 MLT.
2. Change is simultaneous at all SC (SC-3 leading by 1~10 sec).
3. Simultaneous DC field change (tailward E~8mV/m, Pi2-like
rarefaction |B|≈|BZ| up to 20%) without special wave activity.
4. Increase in medium energy (~100 keV, mass dependent) ion
flux. Diamagnetic effect by ∆PP can quantitatively explain ∆PB.
5. Decrease in energetic e- (>30 keV) and ions (> 0.1 MeV)
6. Temporal (about 1 min) change of pitch-angle of
10-40 keV to more field-aligned than perpendicular.
7. Bulk motion of cold He+ and H+ (no cold O+ or He++). The ion
velocity (20km/s, duskward) agrees with the ExB velocity.
Change in PA distirbution
06:43
06:48:30
Observation of 06:43 UT (#1) event
1. Sudden change in particle flux (> 40 keV, > 10 keV, and < 100
eV) when aurora bulge arrived Cluster’s conjugate ~19 MLT.
2. Change is simultaneous at all SC (SC-3 leading by 1~10 sec).
3. Simultaneous DC field change (tailward E~8mV/m, Pi2-like
rarefaction |B|≈|BZ| up to 20%) without special wave activity.
4. Increase in medium energy (~100 keV, mass dependent) ion
flux. Diamagnetic effect by ∆PP can quantitatively explain ∆PB.
5. Decrease in energetic e- (>30 keV) and ions (> 0.1 MeV)
6. Temporal (about 1 min) change of pitch-angle of 10-40 keV to
more field-aligned than perpendicular.
7. Bulk motion of cold He+ and H+ (no cold O+ or
He++). The ion velocity (20km/s, duskward) agrees
with the ExB velocity.
Composition
(2) TOF mass analyser: He+ rich
06:44:00 UT
06:48:30 UT
H+
contamination
He++
He+
No oxygen!
O+
0643
0644
0645
0646
0647
0648
0649
He+ convection  ExB velocity
ExB drift velocity = 25~50 km/s
4-15 eV for H+
=> 15-60 eV for He+
60-250 eV for O+
Detail on Ion dynamics
15-60 eV for He+
4-15 eV for H+
Cold ion moving in one
(perpendicular) direction
 (spin)
Ion drift direction vs E
//

drift direction
- UxB (estimated E) direction
Y (duskward)
X (sunward)
 U ≈ -ExB in direction (but no guarantee of frozen-in
Observation Summary (06:43 UT)
1. Sudden change in particle flux (>40 keV, >10 keV, and <100
eV) when aurora bulge arrived Cluster’s conjugate ~19 MLT.
2. Change is simultaneous at all SC (SC-3 leading by 1~10 sec).
3. Simultaneous DC field change (tailward E~8mV/m, Pi2-like
rarefaction |B|≈|BZ| up to 20%) without special wave activity.
4. Increase in medium energy (~100 keV, mass dependent) ion
flux. Diamagnetic effect by ∆PP can quantitatively explain ∆PB.
5. Decrease in energetic e- (>30 keV) and ions (> 0.1 MeV)
6. Temporal (about 1 min) change of pitch-angle of 10-40 keV to
more field-aligned than perpendicular.
7. Bulk motion of cold He+ and H+ (no cold O+ or He++). The ion
velocity (20km/s, duskward) agrees with the ExB velocity.
Indications (conclusion)
E-field propagates together with the auroral bulge
at ground, which is in the same direction as
convection direction.
cold He+ flux >> cold O+ flux: plasmaspheric He+
at 4 RE.
No local acceleration: Mass dependent drift ?
How did they come on time?
Large-scale configuration change: pseudo-onset?
Energy source? / Can minor auroral activity
produce ring current ions?
ion-scale ?
All SC should observe the same behavior of ions
if ion gyro-radius (RB = mv/qB) >> inter-S/C
distance
RB for B ≈ 200 nT condition
10 keV
H+
v = 1400 km/s
RB = 70 km
He+ v = 700 km/s
RB = 140 km
O+ v = 350 km/s
RB = 300 km
100 keV
1 MeV
v = 4000 km/s
RB = 200 km
v = 2000 km/s
RB = 400 km
v = 1000 km/s
RB = 800 km
v = 14000 km/s
RB = 700 km
v = 7000 km/s
RB = 1400 km
v = 3500 km/s
RB = 3000 km
consolation
S/C distance
≈ 100 km in z direction
& 50 km in x-y direction
≈ RB for 10~20 keV H+
<< RB for Ring current ions
 H+ > 20 keV (O+ > 2 keV)
should behave the same at
all SCs if the gyrotropic
assumption is correct
RAPID (SSD) data
But, there is
inter-SC difference
Inter-SC difference: trapped H+ for CIS
inter-SC difference !
For flux increase:
(1) SC-2 < SC-1 < SC4=SC3
H+: 80~160 keV
He+: 200~300 keV
(2) SC-2 > SC-1 > SC4=SC3
H+: ~60 keV
O+: 500~600 keV
Hybrid:
(5) SC-2 > SC-1 > SC4 > SC3
O+: 400~500 keV
For flux decrease:
(3) SC-2 < SC-1 < SC4=SC2
He+: 400~700 keV
(4) SC-2 > SC-1 > SC4=SC3
O+: ~400 keV
Look at more carefully: energy dispersion
Energy dispersion =
magnetic drift? or shell shift?
End
Now is the time to analyse/simulate Inter-SC difference
of energetic particles with
ion gyro-radius (RB) >> inter-S/C distance
next is 06:48 event
IMAGE/FUV
S/C
06:26~06:56 UT
~06:43 event
~06:48 event
06:26
UT
06:34 UT
06:42 UT
06:50
06:28
UT
06:36 UT
06:44 UT
06:5
2
06:30
UT
06:38 UT
06:46 UT
06:54
06:32
UT
06:40 UT
06:48 UT
06:56
all at 06:48:30 UT
(12s resolution)
All info
SC-1: leading
ET
25~150 eV
5-25 eV
PA
25~150 eV
5-25 eV
SC-3: 60s behind SC-1
25~150 eV
ET
5-25 eV
PA
25~150 eV
5-25 eV
SC-4: 25s behind SC-1
ET
O+ 30~500 eV
PA
0642
0644
0646
0648
0650
0652
0654
0656
Observation of event #2
1. Simultaneous at SC-1, 4 and -3 within 1 sec  sudden
activation
2. Bi-directional along B, and DC E-field disturbance 
double parallel potential is carried by convection?
3. Wave with randomly changing Pointing flux direction (not
shown here)  wave is caused by the bi-parallel beam
4. Decrease 5~70 keV  large-scale configuration change
5. More O+ than He+  not from cold plasma
6. Filamentation in the transpolar arc  but, the relation is
not clear (?)
7. Only minor magnetospheric activity  Why do we
observed only once in 5 years ?
no wave@06:43 UT, wave@06:48 UT
ion
150 nT  ΩP = 4 Hz
ΩHe?
dE
dB
S//
E/B
dBZ
BB-EM
spin effects
stagnant
dBX
energetic
component
change: < 70 keV only
Composition from energy ratio
(1) From energy peak: plasmaspheric He+
rich

//
Precursor (06:44 UT)

18eV 70eV
H+
Heating (06:49 UT)
= 0°
//
H+ He+ O+
= 180°
He+
ratio=4: O+/He+ or He+/H+ = 360°
10
100 [eV]
10
100 [eV]
End
SC location
* Near equator (Z ≈ 0 RE)
* Perigee (R ≈ 4 RE)
* 19 MLT
* Short distance
(mainly in Z direction)
SC1-SC4 ≈ 25 sec
SC1-SC3 ≈ 1 min
Ground conj.
06:43 06:48
Nothing special
only 50 nT activity