PROFESSOR HIROAKI ISOBE

The solar atmosphere is full of dynamic and explosive phenomena. The most spectacular example is solar flares, and recent high-resolution observations have revealed a lot of similar explosions occurring in the entire atmosphere in various scales. Most, if not all, of these phenomena are driven by explosive release of magnetic energy via "magnetic reconnection" mechanism. Magnetic reconnection is a concept of plasma physics in which magnetic field lines are "cut and glued" due to the finite electric resistivity of the plasma. The newly reconnected field lines accelerate the plasma by their tension force in a similar way to a catapult, thus causing rapid conversion of magnetic energy to the kinetic and, eventually, thermal energy of the plasma. It is believed to play important roles in various plasmas in the universe, e.g, flares in stars and accretion disk, auroral substorms in the terrestrial and planetary magnetosphere, and also in the lab plasmas. However, there remains fundamental difficulties in the physics of magnetic reconnection, such as "why magnetic reconnection occurs so fast in plasmas with extremely small resistivity?" and "how to connect the huge gap between the kinetic scale and the global (MHD) scale?". In this talk, the speaker will review the state-of-art of the magnetic reconnection studies and how solar observations can contribute to this interdisciplinary field.