Multi-point probing of universal plasma
processes in the Earth’s Magnetosphere
Göran Marklund
Space and Plasma Physics,
EES, KTH
SRS meeting, MISU, 24-25 mars 2010
Universal space plasma processes
• Magnetic reconnection
• Particle acceleration
• Auroral substorms
• Filamentation
• Cross-scale coupling
Explored by multi-probes in the Earth’s magnetosphere
Cluster 2000-2012
Operations
Themis 2007-2009
Operations
MMS 2014-2016
Design
Future missions
Planning
What drives Earth’s aurora?
DIRECTLY DRIVEN
LOADING-UNLOADING
X
SW power
generator
X
Dayside Reconnection
Impulsive penetration
Nightside Reconnection
& Current Disruption
What drives Earth’s Aurora ?
Magnetic reconnection Energy and
Momentum Transfer from B-field to particles
LABORATORY
MAGNETOSPHERE
Ren, 2005
SUN: SOLAR FLARE
Vaivads et al. Phys. Rev. Lett, 04
ASTROPHYSICS
Astrophysical jets
Magnetospheric Multi-Scale, MMS
Intense design & construction phase at present !
Scientific Objectives
To study fundamental space
plasma processes, such as
magnetic reconnection
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Ac
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Tu
Mission features
• NASA multi-s/c mission (4 identical s/c)
• Equatorial orbits in reconnection regions
• Design & construction phase, 2009-2010
• FM Delivery 2011-2012
• Launch & operations 2014-2016
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KTH / IRF contribution
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• Probes,
cable, wire boom deployer
• Electronics for E-field instrument
• Electronics for low-V power supply
Auroral Particle Acceleration by
”dc” and ”ac” Ell
Both ”dc” and ”ac” Ell act to produce discrete arcs & outflow of
energetic ion-and electron beams
Inverted-V
Black aurora
arc ”dc” Earc
”dc”/”ac”
Black arcEll
Inverted-V
ll
E⊥
E⊥
E⊥
E⊥
Arc
Inv-V
jllup
”dc”
Black Alfvénic
jlld
jllA
”dc/ac” ”ac”
Alfvénic
arc
”ac” E
Alfvénic
arc
ll
E⊥
”dc/ac”
Black
ar c
upward
current
downward
current
time-varying
current
FAST observations at 3500 km
Auroral particle acceleration
”dc” potential structures
Evolution
Cluster 2 t = t0 + 15 min
Cluster 1 t = t0
PSBL
Characteristics
CPS
dense plasma dense plasma
PSBL
CPS
thin plasma dense plasma
ΔΦll < -10 kV
E⊥ < 1 V /m
width ≈ 3-10 km
H ≈ 0.5-2 RE
ΔΦll+ < 3 kV
E⊥ < 1-2 V/m
width ≈ 1-10 km
H ≈ 0.2-0.6 RE
U-
S-
shape
shape
Marklund et al., 2004
PSBL thinning – boundary sharpens - Marklund et al. JGR 2007,
Cluster Top Story, Jan 07
U-potential change to S-potential
What triggers auroral substorms ?
Goal of NASA Themis mission
Themis
• Current disruption at 10 RE
• Reconnection at 20-30 RE
Onset > 90 s Expansion > 120s
Themis results support
reconnection scenario
Current disruption > 180 s
Reconnection t0
Angelopolous et al., Science, 2008
Colliding
auroras
Observed during a long-lasting
period of geomagnetic activity
Ionosphere
Fast moving
bright arc
Magnetotail
Fast jet rushing through
tail towards Earth
Slowly moving arc
All Sky Imaging
Network
stationary
convection
reversal
CR
jecloud
t
Collision
begins
+ 6 min
Light Eruption
+ 7 min
CR
jecloud
t
Eruption of waves and instabilities as the regions collide
Filamentation - characteristic
of space plasmas
Auroral oval 1000 km
Inverted-V’s 100 km
Arcs
10 km
Rays, curls
1 km
Filaments
0.1 km
ASK1
ASK1
ASK2
ASK3
Semeter & Blixt, 2006
ASK2
ASK3
Filaments 100 m widths
ASK narrow FOV images
multiple arc cascading
Multiple auroral curtains
Optical observations
Satellite
results
Filamentation - Auroral
Spatial Scales
Alfvénic arcs
FAST,
Chaston et al. 03
E⊥, Freja
E⊥, n/Δn, FAC, Cluster
Karlsson
et al., 96
Johansson et al, 07
Theoretical
widths,
Borovsky,
1993
Maggs and
Davis, 1968
Fine-structure in
Diffuse aurora
Partameis, 2008
Sandahl, 2008
Life time ∼ 1 min
km
Knudsen et
al, 2001
Life time
∼ 10 min
km
Summary of observed & predicted scales
Multi-scale auroral motions
Can be described by power-laws,
indicative of cross-scale coupling
& energy transport across scales
Chaston et al., GRL, 2010
Alfvénic
Alfvénic
Quasi-static
Vorticity
Quasi-static
Universal space plasma processes
acting in producing planetary aurora
Common Features
•
•
•
•
SW driven, non-continuous, aurora
Substorms, CD and tail reconnection
Acceleration by DL’s & Alfvén waves
Radio Emissions, AKR, SKR, DAM etc
Giant Planet Features
• Continuous aurora – corotating M-sphere
• Bright spots - moon-planet interactions
• Dawn storms - SW-driven convection &
corotation interactions
Earth, Jupiter, Saturn
aurora, after a SW shock
SUN
EARTH
JUPITER
SATURN
12 00
Prange et al, 2005
FUTURE - after MMS
Strong interest in the space physics community
for a mission focussed on multi-scale coupling,
e.g. SCOPE, Cross-scale
Scientific objectives
• reconnection
• acceleration
• shocks
• turbulence
using 3 s/c tetrahedrons
Electron
scale
Ion scale
Electron scale
Ion
sca
le
Fluid scale
Future-after MMS also strong
interest for multi-probe missions in LEO
Key components
• LEO Multi-Probes small s/c,
low-cost, short-term projects
• Global auroral imager
• Solar Wind monitor
FAST x 2
Scientific Objectives
• To study ubiqitous space plasma processes
acceleration, outflow, heating, filamentation,
feedback, cross-scale coupling
• In conjunction with GB global networks
Multi-probes also beneficial:
Auroral
Quartet
μ- sat swarm
• To develop competence in space engineering
• To test novel measurement techniques
• To ensure a continuity for the space activities
• To attract new students into the research area
Cascades-2
SRS meeting, MISU, 24-25 mars 2010