| 研究実績の概要 |
1) We completed a thorough sensitivity study on magnetic reconnection induced by energetic particle (EP)-driven modes. Magnetic reconnection during Abrupt Large-amplitude Events (ALE) in JT-60U is found to be a robust feature of the resistive MHD model. 2 papers are in preparation: one focusing on numerical convergence tests and the other reporting physics results concerning the role of resistivity. 1 invited and 1 oral presentation were given.
2) The PI joined a collaboration examining instabilities observed in the DIII-D tokamak in the low-frequency band associated with Beta-induced Alfven-Acoustic Eigenmodes (BAAE). We expected insights concerning self-heating and enhanced EP losses. However, the results are negative: further experiments showed that the enhanced EP transport may have been caused by other modes at higher frequencies. Moreover, our simulations indicate that the observed low-frequency modes may be Alfvenic continuum modes rather than BAAEs, which means ignorable coupling to ion sound waves and, thus, ignorable bulk ion heating.
3) In July 2019, the PI visited colleagues at ENEA Frascati and IPP Garching in Europe. We developed a new interface between our codes, enabling gyrokinetic stability analyses with realistic EP distributions from long-time hybrid simulation. We also reexamined our earlier discovery of EP-induced continua and found it to be relevant only for plasmas driven by tangential (strongly anisotropic) beams. Finally, the construction of self-consistent equilibria with EP effects seems to be presently beyond reach according to our evaluation.
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