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FWF Project workshop [October 18-20 2010, Vienna]

"Solar partially ionized plasmas and related energetic phenomena"


Workshop Minutes: FWF_Project_workshop_Minutes.pdf

Workshop Information: WS_agenda.pdf


Workshop Details:

Within the frame of FWF project (P21197-N16) a small, 2.5 days workshop took place, dedicated to the subject of solar partially ionized plasmas and related energy release phenomena. The primary goal of the workshop was exchange of ideas, establishing of cooperation links and development of a joint strategic working plan for further tackling of the problems of dynamics and energetics of the solar plasmas. The Workshop took place in Vienna at the Institute of Astronomy at premises of the Astronomy Commission of the Austrian Academy of Sciences.

In view of the fundamental character of the basic plasma physics and wave phenomena in the solar atmosphere discussed during the workshop, this event was open for attending by students and everyone curious about the subject. 
A possibility to publish the workshop contributions in a special issue of the Solar Physics journal is considered. 


Scientific background:

In order to understand the solar activity and its variability, it is essential to determine and to understand the mechanisms by which the energy generated in the Sun's core is released into space. As important components in the chain of the solar energy transformations and transport appear the solar chromosphere and corona. Until now there is no clear understanding of the mechanism of coronal heating and energizing. Certain difficulties exist also with the explanation of the sharp temperature increase in the thin transition region between the upper chromosphere and the low corona. By this, among the major heating mechanisms in the solar atmosphere, the absorption of powerful energy flux carried by MHD waves generated in the photospheric convection, and the energy dissipation of the coronal electric currents, are widely considered.

The majority of existing so far attempts to study (theoretically and numerically) propagation and energy dissipation of MHD waves and electric currents in the low solar atmosphere, as well as in the solar corona, were made under the assumption of an ideal fully ionized plasma case. At the same time, it is well known that the plasma of solar photosphere and chromosphere is a partially ionized medium. The presence of even a small amount of neutral atoms in plasma may significantly change its physical properties and dynamics, which will strongly differ from the fully ionized case. Different interaction of the partially ionized plasma species with the magnetic field and each other, play crucial role in the processes of electric currents energy dissipation and MHD waves damping. The collisions between ions and neutrals have been shown to be of high importance in that respect. Because of the slippage between the ionized and neutral components, the magnetic field cannot be easily considered as being frozen into the material flow. An external magnetic field causes the essential anisotropy of electric conductivity in the partially ionized plasma. Correct and self-consistent modelling of MHD waves and electric currents transport and dissipation processes in the solar magnetized and partially ionized plasmas, requires the inclusion of an appropriate generalized Ohm's law and the corresponding magnetic induction equation into the set of MHD equations.


Colloquium (Okt.18,2010, 15:00) 

  • 16:30 - General discussion: planning of cooperations


FWF project Workshop (Okt.19,2010, 09:00 - 18:30)
(presentations followed by discussion)

  • 12:00-13:30 Lunch break
  • 16:30-18:30 General discussion


Discussion topics:

  • Formulation of the multi-fluid plasma description appropriate for solar photospheric and chromospheric cases.
  • Correct form of the Ohm's law and the induction equation, and the importance of several terms appearing in these equations.
  • Formation of stable magnetic field concentration in partially ionized plasmas; wave propagation and dissipation in these structures.
  • MHD waves in partially ionised plasmas in general.
  • Modelling of the neutral fraction without having to solve for the full rad-hydro problem.
  • Possibilities for performing realistic numerical simulations of multi-fluid magneto-convection.
  • Partial ionisation vs spicule formation