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Microphysical Plasma Processes in Astrophysics

Microphysical Plasma Processes in Astrophysics. Uppsala 2004. Matter. More than 99% of all visible matter in the Universe is in the plasma state

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Microphysical Plasma Processes in Astrophysics

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  1. Microphysical Plasma Processes in Astrophysics Uppsala 2004

  2. Matter • More than 99% of all visible matter in the Universe is in the plasma state • Invisible matter is unknown but weakly (i.e. mainly gravitationally) interacting, thus of importance for structure formation but not of primary importance for life and men • Locally almost all matter is in a collisionless (if understood as non-anomalous) state

  3. Main Thesis • If astrophysicist or astronomers could perform only one single measurement in situ this would have desastrous consequences for most astrophysical theories and models • Astrophysical theories and models would turn out to be basically wrong and would have to be overthrown and replaced by new local theories which should include basic aspects of microphysics • The relevant microphysics is kinetic plasma physics

  4. Justification • The paradigm is Space Physics • Almost all physical predictions which in space physics have been based on purely theoretical reasoning have turned out to be wrong (or at least only marginally correct) after the advent of rocket and spacecraft measurements in situ • In situ measurements have generated an entirely new and before unknown and unimaginable world of problems in space physics • This fact demonstrates the lack of imagination in human thinking and reasoning

  5. Problems • Reconnection • Jet stability • Interacting plasma shells Particle acceleration Radiation

  6. Reconnection • Reconnection in almost all astrophysical systems is collisionless • Resistive reconnection is a myth unless the matter is dominated by neutrals • If this is correct then MHD does not apply to reconnection independent of scales

  7. Presence of Neutrals mfp =1/ nnc For resistive reconnection: mfp < c/pi pi = ion plasma frequency n/nn < nc/pi Weakly ionized plasma only! Fully Ionized Plasma mfp = 64D(ND/lnND) ND» 1 Estimates 64D(ND/lnND) < c/pi ND < c/v Only satisfied for very low temperatures T~0 Reconnection in fully ionized plasma is always collisionless! W/nT > (m_e/m_i)1/2ve/c anomalous or Bohm diffusion

  8. Example: Reconnection on the Sun N~ 1016 m-3 T~50-100 eV ve ~ 10000 km/s e-i ~ 700 Hz c/pe ~ 10 cm c/pi ~ 5 m mfp ~ 1-10 km Solar atmosphere is absolutely collisionless what concerns any reconnection taking place there!

  9. Broadband Noise Spectra in Turbulence behind Shocks Pickett et al. Ann. Geophys. 10, 2003

  10. Solitons in Post-Shock-Turbulence and their Spectrum Pickett et al. Ann. Geophys. 10, 2003

  11. Parallel Electric Fields/Potential Drops and Particle Acceleration Ergun et al. PoP. 9, 2002

  12. Solitons in low-ß Regions McFadden et al. JGR. 108, 2003 Ergun et al. PoP. 9, 2002

  13. Electron Modulation in Solitons McFadden et al. JGR. 108, 2003

  14. Magnetospheric Field Line Structure (Empirical Tsyganenko Model) SolarWind Magnetosheath Z (RE) Bow Shock Lobes 3 2 X-point 1 1 3 Magnetopause B X (RE)

  15. The Meaning of Reconnection Axford 1984

  16. Generalized Ohm´s Law(Fluid Approach) Assumptions:two-fluid (protons/electrons) ideal conditions ~ collisionless me/mi <<1,   0 E + v  B - j = (0pe2)-1t j + (jv + vj – (en)-1j j)} + (en)-1{ j  B - Pe + Fepmf  Hall term Inertial term Wave pmf In quasi-equilibrium the electron pressure gradient term is the ion pressure term, for then: j  B -Pe ·Pi [ Wave ponderomotive force usually neglected without justification (?) May be important in a turbulent plasmasheet ]

  17. Reconstruction of Hall Current System in the Magnetotail (Nagai et al., 1998, 2001) Unmagnetised Electrons e Unmagnetised Ions Electron Hall Current System i

  18. Hall-Effect in Magnetotail 2 Oieroset et al., Nature 412, 416, 2001 Received 1. May 2001

  19. Electron Acceleration in Magnetotail Reconnection Reconnection Region Acceleration of Electrons FAC‘s connected to Hall Current Wrong ! No Hall current ! Oieroset et al. (2002)

  20. Lower-hybrid Waves at Magnetopause Bale et al., GRL 24, 2180, 2002

  21. Guide Field Simulation Drake et al. Science 299, 2003

  22. Solitons in Reconnection Connected Boundary Cattell et al. GRL 26, 1999

  23. M87 Radiolobes around a central Black Hole

  24. Cygnus A und B0218+357 Radiolobes

  25. Radiogalaxien Seyfert2G ESO428-g14 NGC6946 (6 cm) Halpha Bild M84 (4.9 GHz) Mk34

  26. Synchrotron Radiation in Reconnection Fe() Synch-spectrum EII P()

  27. Particle Acceleration by Electric Fields

  28. Particle Acceleration by Electric Fields

  29. Electric Wave Forms and Spectra

  30. Sol itons

  31. Radiation Fine Structure

  32. Phase Space Distribution

  33. Distributions and Holes

  34. Hole Dynamics in Radiation Source

  35. The Inefficiency of the Loss-cone Maser

  36. Small Growth of Loss-cone Maser

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