ipels, 29 june-3 july, 2003 whitefish, montana, usa
DESCRIPTION
A. Vaivads, M. Andr é , S. Buchert, N. Cornilleau-Wehrlin, A. Eriksson, A. Fazakerley, Y. Khotyaintsev, B. Lavraud, C. Mouikis, T. Phan, B. N. Rogers, J.-E. Wahlund. IPELS, 29 June-3 July, 2003 Whitefish, Montana, USA. The small scale structure of the magnetopause Current layers and waves. - PowerPoint PPT PresentationTRANSCRIPT
A. Vaivads, M. AndrA. Vaivads, M. Andréé, S. Buchert, N. Cornilleau-Wehrlin, , S. Buchert, N. Cornilleau-Wehrlin, A. Eriksson, A. Fazakerley, Y. Khotyaintsev, B. Lavraud, A. Eriksson, A. Fazakerley, Y. Khotyaintsev, B. Lavraud,
C. Mouikis, T. Phan, B. N. Rogers, J.-E. WahlundC. Mouikis, T. Phan, B. N. Rogers, J.-E. Wahlund
IPELS, 29 June-3 July, 2003Whitefish, Montana, USA
The small scale structure of the The small scale structure of the magnetopausemagnetopause
Current layers and waves
slide 2
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Why small scales and waves?
Importance for large scale phenomena
Decoupling of particles
Energy transport
Energy conversion, particle energization
Remote or local sensing tool
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 3
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
What we want to know?
Structure? sheet vs tubelocal vs globaldispersion relation
Transport plasma, energy (particles, Poynting flux)
Momentum equationGeneralized Ohm’s lawfree energy
Energy conversion j·E
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 4
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Cluster and magnetopause scales
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 5
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Cluster orbit, magnetopause crossings
Orbit in March
after Parks(1991)
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 6
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
2002-Feb-06 0810-0815UT
High latitude MP crossing
100km Cluster separation
s/c in burst mode
Magnetopause ~50 c/pi
Zoom into ~5 c/pi
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 7
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
s/c2a)p1040 29-Jun-2003 06:13:59
s/c4 s/c3s/c1
NV
ps [
cm-3
]
vnGSE
=105 [-0.76 -0.35 -0.54] km/s. dt= [0 0.19 0.72 -0.17] s.
1
2
3
4
5
b)
BN [
nT]
-10
0
10
c)B
M [
nT]
-20
0
20
d)
BL [
nT]
40
50
60
EyEx e) s/c 1
sc1
E [
mV
/m]
-40
-20
0
20
40
s/c 2f)
sc2
E [
mV
/m]
-40
-20
0
20
40
s/c 3g)
sc3
E [
mV
/m]
-40
-20
0
20
40
s/c 4h)
06-Feb-2002
sc4
E [
mV
/m]
08:11:56 08:11:57 08:11:58 08:11:59 08:12:00
-40
-20
0
20
40
Density dip ~1c/pi
Narrow current sheet (yellow) 5-10 e,e
Strongest E fields within the current sheet
Differences among s/c in E and B.
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 8
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
E [mV
/m] DS
Vps [V
]B [n
T] GSE
- 3 0- 2 0- 1 0
01 02 03 0
- 2 0
- 1 5
- 1 0
- 5
0
0 8 :11 : 4 0 0 8 :1 2 :0 0 0 8 :1 2 :2 0 - 5 0
0
5 0
0 6 -F e b -2 0 0 2
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 9
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Generalized Ohms law and Cluster
jjpE
jjpBjBvE
t
t
d
d
2e
2e
ne
m
ne
1ne
m
ne
1)(
ne
1
II
Spin resolution, ion scales
● B, E, n, pe, v, j
High time resolution, electron scales
● B, E, n (fpe)
● n (satellite potential), pe, j (curlometer, 1 s/c methods)
• v
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 10
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
5-10 e,e current sheet,jperp and jII
B and n gradients coincides
E~j x B
pe not important
e- beam carrying jII can generate waves
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 11
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
E~j x B, all 4 s/c
Potential drop across the current sheet of a few 100 V
p1039 29-Jun-2003 11:56:32
s/c4a) s/c1 s/c2 s/c3
s/c4. vMP
=105 [-0.76 -0.35 -0.54] km/s GSE, Te=150eV. E low pass filtered at 30 HzN - normal to MP, towards MSh, L - closest to the mean direction of B, M=LxN. dt= [0 0.19 0.72 -0.17] s.
1
2
3
4
5
s/c 1b)
s/c1
, E
[m
V/m
]
-40
-20
0
20
EjxB/ne- T
e d
x n/n
s/c 2c)
s/c2
, E
[m
V/m
]
-40
-20
0
20
EjxB/ne- T
e d
x n/n
s/c 3d)
s/c3
, E
[m
V/m
]
-40
-20
0
20
EjxB/ne- T
e d
x n/n
s/c 4e)
06-Feb-2002
s/c4
, E
[m
V/m
]
08:11:56 08:11:57 08:11:58 08:11:59 08:12:00
-40
-20
0
20
EjxB/ne- T
e d
x n/n
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 12
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Numerical simulations of reconnection
Two fluid, reconnection with a guide field Te=0, t=0
Width of separatrix is a few c/pe
E is strong along the separatrix
E ~j x B, in most of the system
[Rogers]
n
Bz
E
-2 -1 0 1 2 c/pi
-2
-1
0
1
2
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 13
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
MP reference frame
EM>0, EN strong inside density dip
Inflow velocity ~ magnetopause velocity
Inf
7.3
Vps
[cm
-3]
0
1
2
3
4
5
n SC [
cm-3
]
08:11:56 08:11:57 08:11:58 08:11:59 08:12:00
06-Feb-2002
-200
0
200
400
600
V [
km/s
]M
PE
[mV
/m]
MP
LMN
0
10
20
30
40 LMN
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 14
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Waves strongest in the narrow current sheet (gradient in n and B)
Broad band
Spectral peaks f~fLH
Spectral peaks f~100 Hz, ’whistlers’
Poynting flux associated to both ’whistlers’ and ’LHD’
Waves generated by gradients or electron beams?
E
B
S-0.5
0
0.5
-2
0
2
-6
-4
-2
0
0.5
1
1.5
2
2.5
NV
ps [
cm-3
]
p1035spb 29-Jun-2003 12:43:35s/c 4
a)
-50
0
50
E [
mV
/m]
DS
I
Ex Eyb)
10
100
f [H
z]
E [
(mV
/m)2
/Hz]c)
10
100
f [H
z]
B [
nT2/H
z]
d)
10
100
f [H
z]
SII [
W/m
2H
z]1
/2
e)
08:11:57.0 .5 08:11:58.0 .5
-1
0
1
2
06-Feb-2002
SII [
W s
/m2]
whistler x100 LH x10 CS x1
f)
E
n
S
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 15
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
15-35 Hz band-pass filter (LH)
ke~1
low coherence
wave transports e- across the current sheet.
D10-9 m2/s, Diffusion?
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 16
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Diffusion at magnetopause
Treumann [2001]
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 17
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Laboratory observations [Carter et al. 2002]
LHD waves near the low- edge low coherence no clear correlation with
reconnection rate
Studies of B and narrow current sheets in progress
MRX – magnetic reconnection experiment
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 18
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
LHD waves in laboratory vs. space
Laboratory
Space
Broadband, fmax ~ fLH
ke ~ 1
Strongest at low- edge Low coherence Fast growth rate & damping ?
The propagation direction vDe ?along MP
emax/Te ~ 5% ~ 100%
Next step - to compare current sheets and whistlers
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 19
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Strong E (10s mV/m)within narrow current sheets ~10 c/pe
on magnetospheric side of MP
E~jxB, pe is not important
Separatrix of reconnectionOther explanations?
Strong lower hybrid drift waves and whistlers Electron transport due to LHD waves can be important only within
the current sheet D 109 m2/s, diffusion?
Comparisons with 3D numerical simulations Many more events Separatrix studies in lab
Summary
Future
Intro Cluster MP crossing E~jxB Separatrix Waves Summary
slide 20
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Particle diffusion, effective collision frequency
Diffusion approximation
j
jj
n
nD
v
Effective collision frequenacy
jyjyjj
jeff nE
Vmn
qv
,
Analytically - n,v (E+dispersion relation) Observations - n (satellite potential fluctuations)
- v=ExB (for electrons)
slide 21
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Other event
EE
BB
SS||||
2001-03-02
slide 22
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Aurora vs Magnetopause
Aurora - ion scales, can go down to electron scales Auroral field lines – narrow current sheets of Region I, II current systems
strong jII, particle acceleration, wavesoften boundary phenomena (PSBL)
Infering EII from measurements of Eperp
slide 23
Swedish Institute of Space Physics
Uppsala
IPELS, Whitefish27 June 2003
Scales
Parameter Magnetosheath Magnetosphere
B,n,Te,Ti 30nT, 10cm-3, 150eV, 1keV
30nT, 1cm-3, 1keV, 10keV
Gyroradius H+ 150km, e- 1.4 km H+ 480km, e- 3.5km
Inertial length H+ 72km, e- 1.7km H+ 230km, e- 5.3km
Gyrofequency H+ 0.46Hz, e- 840Hz H+ 0.46Hz, e- 840Hz
Lower hybrid 20Hz 20Hz
Small spatial scales between ion and electron scales and smaller
a few tens of km and below