Study of fast magnetic reconnection with multi-scale plasma magnet-hydrodynamic simulations

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Fast magnetic reconnection is an explosive energy conversion mechanism in plasma, by which the magnetic energy is converted to the plasma kinetic energy. With recent space satellite observations, fast magnetic reconnection is considered to play a crucial role in solar flares and geomagnetic substorms. The major difficulty of the plasma physics is that the mechanisms of many phenomena are controlled through coupling of more than two basic mechanisms in an extremely wide range of space and time, i.e. from the gyration motion of electron to interplanetary space. In this study, in order to research the fast magnetic reconnection process, some multi-scale plasma simulation codes were developed and the existence of the Petschek type fast reconnection model was tried to be examined by the numerical simulations. The followings were revealed.1: On the basis of MHD (Magneto-hydrodynamic) theoretical study, the propagation speed of plasmoids ejected from the fast magnetic reconnection region is u … More niquely controlled by the upstream plasma beta value and the opening angle of the slow shock around the plasmoid.2: On the basis of MHD multi-scale simulation code, two-dimensional fast magnetic reconnection is unstable for a small amount of perturbations in the sheet-current direction and is spontaneously developed to three-dimensional fast magnetic reconnection which is strongly localized in the sheet current direction. And, the reconnection process is intermittently repeated and continues to randomly eject the three-dimensional plasmoids. This simulation result seems to be consistent with plasma downflowing phenomena in solar flares detected in TRACE satellite observations.3: The combination of the MHD and particle (kinetic) simulation codes was also studied. The code itself was constructed and it was revealed that the code is very useful to save the computer memory to simultaneously simulate the electron-ion behaviors at the magnetic neutral point and the MHD behaviors around there. But, the computational speed is still insufficient to examine the full simulation for the fast magnetic reconnection. The development of the simulation code is continued. Less