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Space weather and plasma simulation

Space weather and plasma simulation. Jörg Büchner, MPAe Lindau Collaborators: B. Nikutowski and I.Silin, Lindau A. Otto, Fairbanks. Outline. What is „Space Weather“: Manifestation, consequences, action at Earth and in space

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Space weather and plasma simulation

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  1. Space weather and plasma simulation Jörg Büchner, MPAe Lindau Collaborators: B. Nikutowski and I.Silin, Lindau A. Otto, Fairbanks IMPRS Lindau, 6.2.2003

  2. Outline • 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 • MODELING AND SIMULATION APPROACHES: • Force free magnetic fields -> lowest order solar fields • Ideal MHD -> large scale motion in the corona • Resistive MHD -> reconnection in the transition region • Kinetic simulation -> dissipation, structure formation • State of the art global simulation and outlook IMPRS Lindau, 6.2.2003

  3. Manifestation: Aurora IMPRS Lindau, 6.2.2003

  4. Action in Space IMPRS Lindau, 6.2.2003

  5. Space Weather: consequences IMPRS Lindau, 6.2.2003

  6. How does it work? Solar Wind and Magnetic Substorms IMPRS Lindau, 6.2.2003

  7. Source: motion of solar plasmas • Estimated energy fluxes: • Active regions (0.5 -1) 104 W m-2 • Quiet regions 300 W m-2 • Coronal holes 800 W m-2 Solar plasma convection: • Dynamo effect -> magnetic fields • Flows -> upward Poynting flux IMPRS Lindau, 6.2.2003

  8. Typical dimensionless parameters If: L – Geometrical scale, n – Number density; Tj – Temperature and B – Magnetic field, then: Ion-gyro radius: Mean-free path: Magnetic Reynolds number E = v B ~ < Dreicer-field If EA > ED collisions don‘t prevent runaway: collisionless! IMPRS Lindau, 6.2.2003

  9. Typical values Rm > 1 >> 1 >>>1 IMPRS Lindau, 6.2.2003

  10. Force-free approximation i.e. Currents flow only parallel to the magnetic field -> 04:20 18.10.96 04:40 IMPRS Lindau, 6.2.2003

  11. Ideal MHD (magnetohydrodynamics) • E + v x B=0 -> „ideal“ magnetohydrodynamics, i.e. magnetic flux and plasma move together SOHO-MDI photospheric B fields on 17./18.10.1996 60“, 23Mm IMPRS Lindau, 6.2.2003

  12. Non-ideal MHD simulations MHD Simulation mit Dissipation und Neutralgas-Stößen IMPRS Lindau, 6.2.2003

  13. Non-ideal MHD simulations MHD Simulation mit Dissipation und Neutralgas-Stößen IMPRS Lindau, 6.2.2003

  14. Eruptive magnetic Reconnection directly in the transition region MHD - simulations: example The question remains open: what is the nature of dissipation? -> plasmakinetic investigation necessary IMPRS Lindau, 6.2.2003

  15. Next order - smaller - scales Electron equation of motion (“Ohm’s law”): e c/pe c/pi <- Scales kinetic Alfven waves Electron inertia Whistler waves <- Effects • Below c/pi electrons and ions decouple, i.e. electrons are • magnetized, ions not -> Plasma- Hall- Effect • Below c/pe : Electrons demagnetized as well IMPRS Lindau, 6.2.2003

  16. Crucial point: current sheets IMPRS Lindau, 6.2.2003

  17. Hall currents in current sheets (Thin current sheet with rio ~> L) IMPRS Lindau, 6.2.2003

  18. Vlasov-code kinetic Simulation IMPRS Lindau, 6.2.2003

  19. From microscopic fluctuations and turbulence to a global instability: TIME IMPRS Lindau, 6.2.2003

  20. From microscopic fluctuations and turbulence to global instability: SPACE IMPRS Lindau, 6.2.2003

  21. Current sheet decay: from microscopic fluctuations to global instability IMPRS Lindau, 6.2.2003

  22. Microscopic dissipation Ionen distribution in the current direction Electron distribution in the current direction Ions drive waves → plateau - formation → electron-heating IMPRS Lindau, 6.2.2003

  23. Current reduction -> disspation Electrondistribution function Ion distribution function IMPRS Lindau, 6.2.2003

  24. 3D current instability Plasma density wave IMPRS Lindau, 6.2.2003

  25. Transition to reconnection IMPRS Lindau, 6.2.2003

  26. 3D magnetic reconnection IMPRS Lindau, 6.2.2003

  27. State of the art: global MHD models IMPRS Lindau, 6.2.2003

  28. Multiscale processes in complex system -> plasma simulations necessary IMPRS Lindau, 6.2.2003

  29. Comparison with observations • International program „Living With a Star“ (ILWS) • Missions 2006-08: SUNRISE, STEREO, MMS, SDO ... L2 South Pole Sitter IMPRS Lindau, 6.2.2003

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