IMPRS Lindau, 6.2.2003 Space weather and plasma Space weather and plasma simulation simulation Jörg Büchner, MPAe Lindau Jörg Büchner, MPAe Lindau Collaborators: Collaborators: B. Nikutowski and I.Silin, B. Nikutowski and I.Silin, Lindau Lindau A. Otto, Fairbanks A. Otto, Fairbanks
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IMPRS Lindau, 6.2.2003 Space weather and plasma simulation Jörg Büchner, MPAe Lindau Collaborators: B. Nikutowski and I.Silin, Lindau A. Otto, Fairbanks.
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IMPRS Lindau, 6.2.2003
Space weather and plasma Space weather and plasma simulationsimulation
B. Nikutowski and I.Silin, LindauB. Nikutowski and I.Silin, Lindau
A. Otto, FairbanksA. Otto, Fairbanks
IMPRS Lindau, 6.2.2003
OutlineOutline What is „Space Weather“: Manifestation, What is „Space Weather“: Manifestation,
consequences, action at Earth and in spaceconsequences, action at Earth and in space How does it work ? - Main scenarios of plasma How does it work ? - Main scenarios of plasma
heating and particle acceleration by artists‘s moviesheating and particle acceleration by artists‘s movies MODELING AND SIMULATION APPROACHESMODELING AND SIMULATION APPROACHES:: Force free magnetic fields -> lowest order solar Force free magnetic fields -> lowest order solar
fieldsfields Ideal MHD -> large scale motion in the coronaIdeal MHD -> large scale motion in the corona Resistive MHD -> reconnection in the transition Resistive MHD -> reconnection in the transition
formationformation State of the art global simulation and outlookState of the art global simulation and outlook
IMPRS Lindau, 6.2.2003
Manifestation: Aurora Manifestation: Aurora
IMPRS Lindau, 6.2.2003
Action in SpaceAction in Space
IMPRS Lindau, 6.2.2003
Space Weather: consequencesSpace Weather: consequences
IMPRS Lindau, 6.2.2003
How does it work? How does it work? Solar Wind and Magnetic Solar Wind and Magnetic
Substorms Substorms
IMPRS Lindau, 6.2.2003
Source: motion of solar Source: motion of solar plasmasplasmas
Solar plasma Solar plasma convection:convection:
Dynamo effect -> magnetic fields Dynamo effect -> magnetic fields Flows -> upward Poynting flux Flows -> upward Poynting flux
Estimated energy fluxes:Estimated energy fluxes:Active regions (0.5 -1) 104 W m-2Active regions (0.5 -1) 104 W m-2 Quiet regions 300 W mQuiet regions 300 W m-2-2
E + v x B=0 -> „ideal“ magnetohydrodynamics, i.e.E + v x B=0 -> „ideal“ magnetohydrodynamics, i.e.magnetic flux and plasma move togethermagnetic flux and plasma move together
SOHO-MDI photospheric B fields on 17./18.10.1996 60“, 23MmSOHO-MDI photospheric B fields on 17./18.10.1996 60“, 23Mm
IMPRS Lindau, 6.2.2003
MHD Simulation mit MHD Simulation mit Dissipation und Dissipation und
Eruptive Eruptive magneticmagneticReconnection Reconnection directly in the directly in the transition regiontransition region
The question remains The question remains open: what is the nature open: what is the nature of dissipation?of dissipation?-> plasmakinetic -> plasmakinetic investigation necessaryinvestigation necessary
IMPRS Lindau, 6.2.2003
Next order - smaller - scalesNext order - smaller - scalesElectron equation of motion (Electron equation of motion (“Ohm’s law”“Ohm’s law”):):
• Below c/pi electrons and ions decouple, i.e. electrons are magnetized, ions not -> Plasma- Hall- Effect• Below c/pe : Electrons demagnetized as well
c/pic/pee <- Scales
Jpne1
BJnec1
Bvc1
EdtJd4
ei2pe
Electroninertia
Whistlerwaves
kinetic Alfvenwaves
<- Effects<- Effects
IMPRS Lindau, 6.2.2003
Crucial point: current sheets
Lznn /cosh 20
yx j
cz
B 4
IMPRS Lindau, 6.2.2003
Hall currents in current Hall currents in current sheets sheets
(Thin current sheet with io ~> L)
(Thin current sheet with io ~> L)
IMPRS Lindau, 6.2.2003
Vlasov-code kinetic Simulation
0)(1 ,
,
,,,
v
fBv
cE
m
e
r
fv
t
f ei
ei
eieiei
vdfvej
vdfe
ei
Veijei
V
eieij
ei
3,
,,
3,
,,
IMPRS Lindau, 6.2.2003
From microscopic fluctuations and From microscopic fluctuations and turbulence to a global instability: turbulence to a global instability:
TIMETIME
IMPRS Lindau, 6.2.2003
From microscopic fluctuations and From microscopic fluctuations and turbulence to global instability: turbulence to global instability: SPACE
IMPRS Lindau, 6.2.2003
Current sheet Current sheet decaydecay: from : from microscopic fluctuations to global microscopic fluctuations to global