Direct interlink of plasma in the convection zone and in the corona

Thursday, 18 December 2014: 5:30 PM
Kiyoto Shibasaki, Nobeyama Solar Radio Observatory, Nagano, Japan
Thermal plasma particles in a magnetic field have a magnetic moment due to Lorentz force. The magnetic moment is anti-parallel to the field direction (diamagnetic) and is inversely proportional to the field strength. It does not disappear even under highly collisional condition. The magnetic flux density (or magnetic field, B) in a magnetized media is determined as B = μ0(H+M), where μ0 is the magnetic permeability of the vacuum, H is the magnetic intensity, and M is the magnetic moment per unit volume. This means that the magnetic field in a plasma is a self-consistent field (B is a function of B itself) and has some restrictions. Under high plasma beta condition, this restriction results in spontaneous formation of magnetic flux tubes. Hence, in the solar convection zone where the gas pressure is high, the magnetic field can exists as concentrated flux tubes. Plasma particles inside and outside the tube are rather independent even in a low ionization degree plasma due to frequent collisions. Plasma particles inside the flux tube are pushed upwards along the field due to the diamagnetic moment (mirror force) against the gravity force. The hot coronal plasma can be supplied directly from below through magnetic flux tubes. Coronal heating and other important questions can be understood by this simple mechanism.