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Identifier 000022889
Title The magnetohydrodynamic nature of the solar atmosphere. Models for magnetized plasma loops with flows
Alternative Title Η μαγνητουδροδυναμική δομή της ηλιακής ατμόσφαιρας. Μοντέλα μαγνητικών βρόγχων πλάσματος με ροές
Author Σουρλαντζής, Γεώργιος Δ
Thesis advisor Τσίγκανος, Κ.
Abstract HIGH-RESOLUTION X-RAY IMAGES OF THE INHOMOGENEOUS SOLAR ATMOSPHERE BY SATELLITES AND ROCKETS, SEEM TO FIRMLY ESTABLISH THE NOTION THAT THE BUILDING BLOCKS OF THE CORONA OF THE SUN ARE MAGNETIZED PLASMA LOOPS OF VARIOUS SIZES AND PROPERTIES IN WHICH PLASMA FLOWS SEEM TO PLAY AN ESSENTIAL ROLE IN DETERMINING THE PHYSICAL AND GEOMETRIC CHARACTERISTICS OF THE LOOPS. IN THIS THESIS, THEREWERE STUDIED SOME FAMILIES OF EXACT SOLUTIONS OF THE MAGNETOHYDRODYNAMIC EQUATIONS. THEY HAVE BEEN DEVELOPED IN ORDER TO SOLVE THEM IN TWO DIMENSIONS IN THE LIMIT WHERE PLASMA PRESSURE IS MUCH LOWER THAN THE MAGNETIC PRESSURE - A REASONABLE ASSUMPTION FOR THE SOLAR CORONA - FOR ANY BOUNDARY CONDITIONS IMPOSED. IN PARTICULAR, IN SYMMETRICAL MAGNETIC CONFIGURATIONS, WHEN THE DISTRIBUTION OF PRESSURE AT THE FOOT POINTS IS SYMMETRICAL, THE FLOW IS NECESSARILY SUBSONIC. FOR COOL LOOPS THE FLOWS CAUSE THE DENSITY TO DROP FASTER ALONG FIELDLINES AS COMPARED WITH THE STATIC CASE, WHILE IN HOT LOOPS WITH FLOWS THE DENSITY CAN DROP SLOWER OR EVEN INCREASE WITH HEIGHT. IF THE PRESSURE AT THE TWO FOOTPOINTS ARE UNEQUAL THE FLOW BECOMES SUPERSONIC AT THE SUMMIT OF THE MAGNETIC FIELDLINE AND THEN PASSES THROUGH A SHOCK. IN ASYMMETRICAL LOOPS WITH FLOWS ONE LEG CAN BE MUCH DENSE THAN THE OTHER AND POORLY VISIBLE AS COMPARED WITH THE SITUATION WHERE FLOWS ARE ABSENT. HOWEVER, IF THE GAS PRESSURE IS COMPARABLE TO THE MAGNETIC ONE, MHD SOLUTIONS CAN BE FOUND FOR SPECIFIC BOUNDARY CONDITIONS.
Language English
Issue date 1995-04-10
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/2/5/9/metadata-dlib-1995DIS0154.tkl Bookmark and Share
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