Helicity, magnetic 8 Active regions, magnetic fields 6 Corona, structures 6 Helicity, observations 6 Active regions: magnetic fields 2 Active regions: structure 2 Active regions; magnetic fields 2 Corona: models 2 Coronal mass ejections 2 Coronal mass ejections; interplanetary 2 Flares; dynamics, relation to magnetic field 2 Helicity: magnetic 2 Helicity; magnetic 2 Magnetic fields, interplanetary 2