Plasma properties and radiation signatures of current driven active region loops on the Sun
Abstract
The average plasma density in the coronal part of a loop is higher than in its surroundings but the ratio of the plasma kinetic pressure to magnetic pressure is less than one. These loop-like magnetic field lines may act as the energy transport lines from the internal layers of the Sun's photosphere to the chromosphere and the corona where the energy is stored and suddenly released or slowly dissipated. The photospheric disturbances which are associated with steady currents along the potential magnetic field lines were studied in order to identify the radiation signatures of the current density and its profile as well as the size of the loop in which the current flows. Three basic phenomena in which the current supposedly plays an important role are examined: the sudden release of energy in small loop-like structures (flares); the heating of loops of different sizes by anomalous current dissipation; and the sudden erosion of large scale loops (coronal transients). It is concluded that (1) the current driven from the fluid motions in the photosphere can, under certain conditions, trigger the tearing mode instability in a finite volume at the top of a small loop which may result in a sudden local heating and a transient electron acceleration; (2) the heating of a loop by 'anomalous' dissipation of currents is not feasible if the currents are driven from the photosphere and (3) it appears that under certain conditions the current flowing along a very large loop can force a loop upwards.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- May 1979
- Bibcode:
- 1979PhDT.........2V
- Keywords:
-
- Coronal Loops;
- Photosphere;
- Plasma Currents;
- Solar Flares;
- Solar Magnetic Field;
- Solar Radio Emission;
- Electron Acceleration;
- Energy Transfer;
- Magnetic Field Configurations;
- Pressure Distribution;
- Solar Activity;
- Solar Physics