Plasma diamagnetism and solar coronal activity
Kiyoto Shibasaki
Gyration of charged particles around magnetic lines of force creates
ring current. The equivalent magnet is anti-parallel to the surrounding
magnetic field. This is the origin of diamagnetism of plasma. The
magnetic moment of thermal plasma is proportional to plasma pressure and
is inversely proportional to magnetic flux density (M = P/B). When
magnetic field has gradient, plasma particles are pushed toward weak
field region (F = - M dB/dr). In closed magnetic loops, plasmas are
confined around the loop top. In open magnetic field, plasmas are pushed
outwards against the gravity. Even in the closed magnetic loop, plasmas
tend to get out from the loop top when the plasma beta value is high
(high-beta disruption). In general, magnetic field strength decreases
outwards; hence plasmas are pushed outwards against gravity by magnetic
force. This is the origin of solar coronal activity.
Correspondence
Kiyoto Shibasaki (shibasaki@nro.nao.ac.jp),
Nobeyama Solar Radio Observatory
presentation
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