IMPRS Lindau, Space weather and plasma simulation Jörg Büchner, MPAe Lindau Collaborators: B. Nikutowski and I.Silin, Lindau A. Otto, Fairbanks

IMPRS Lindau, Outline What is „Space Weather“: Manifestation, consequences, action at Earth and in space What is „Space Weather“: Manifestation, consequences, action at Earth and in space How does it work ? - Main scenarios of plasma heating and particle acceleration by artists‘s movies How does it work ? - Main scenarios of plasma heating and particle acceleration by artists‘s movies MODELING AND SIMULATION APPROACHES: MODELING AND SIMULATION APPROACHES: Force free magnetic fields -> lowest order solar fields Force free magnetic fields -> lowest order solar fields Ideal MHD -> large scale motion in the corona Ideal MHD -> large scale motion in the corona Resistive MHD -> reconnection in the transition region Resistive MHD -> reconnection in the transition region Kinetic simulation -> dissipation, structure formation Kinetic simulation -> dissipation, structure formation State of the art global simulation and outlook State of the art global simulation and outlook

IMPRS Lindau, Manifestation: Aurora

IMPRS Lindau, Action in Space

IMPRS Lindau, Space Weather: consequences

IMPRS Lindau, How does it work? Solar Wind and Magnetic Substorms

IMPRS Lindau, Source: motion of solar plasmas Solar plasma convection: Dynamo effect -> magnetic fields Dynamo effect -> magnetic fields Flows -> upward Poynting flux Flows -> upward Poynting flux Estimated energy fluxes: Active regions (0.5 -1) 104 W m-2 Quiet regions 300 W m -2 Coronal holes 800 W m -2

IMPRS Lindau, Typical dimensionless parameters If: L – Geometrical scale, n – Number density; T j – Temperature and B – Magnetic field, then: Ion-gyro radius: Mean-free path: Dreicer-field If E A > E D collisions don‘t prevent runaway: collisionless! << Magnetic Reynolds number E = v B ~

IMPRS Lindau, Typical values R m > 1 >> 1 >>>1

IMPRS Lindau, Force-free approximation 04: :40 i.e. Currents flow only parallel to the magnetic field ->

IMPRS Lindau, Ideal MHD (magnetohydrodynamics) E + v x B=0 -> „ideal“ magnetohydrodynamics, i.e. magnetic flux and plasma move together E + v x B=0 -> „ideal“ magnetohydrodynamics, i.e. magnetic flux and plasma move together SOHO-MDI photospheric B fields on 17./ “, 23Mm

IMPRS Lindau, MHD Simulation mit Dissipation und Neutralgas- Stößen Non-ideal MHD simulations

IMPRS Lindau, MHD Simulation mit Dissipation und Neutralgas- Stößen Non-ideal MHD simulations

IMPRS Lindau, MHD - simulations: example Eruptive magnetic Reconnection directly in the transition region The question remains open: what is the nature of dissipation? -> plasmakinetic investigation necessary

IMPRS Lindau, Next order - smaller - scales Electron equation of motion (“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/  pi c/  pe ee <- Scales Electron inertia Whistler waves kinetic Alfven waves <- Effects

IMPRS Lindau, Crucial point: current sheets

IMPRS Lindau, Hall currents in current sheets (Thin current sheet with  io ~> L)

IMPRS Lindau, Vlasov-code kinetic Simulation

IMPRS Lindau, From microscopic fluctuations and turbulence to a global instability: TIME

IMPRS Lindau, From microscopic fluctuations and turbulence to global instability: From microscopic fluctuations and turbulence to global instability: SPACE

IMPRS Lindau, Current sheet decay : from microscopic fluctuations to global instability

IMPRS Lindau, Microscopic dissipation Ionen distribution in the current direction Electron distribution in the current direction Ions drive waves → plateau - formation → electron-heating

IMPRS Lindau, Current reduction -> disspation Ion distribution function Electron distribution function

IMPRS Lindau, D current instability Plasma density wave

IMPRS Lindau, Transition to reconnection

IMPRS Lindau, D magnetic reconnection

IMPRS Lindau, State of the art: global MHD models

IMPRS Lindau, Multiscale processes in complex system -> plasma simulations necessary

IMPRS Lindau, Comparison with observations International program „Living With a Star“ (ILWS) International program „Living With a Star“ (ILWS) Missions : SUNRISE, STEREO, MMS, SDO... Missions : SUNRISE, STEREO, MMS, SDO... South Pole Sitter L2L2