@article{oai:repo.qst.go.jp:00082132,
 author = {坂東, 隆宏 and 井上, 静雄 and 篠原, 孝司 and 諫山, 明彦 and 若月, 琢馬 and 吉田, 麻衣子 and 本多, 充 and 松永, 剛 and 武智, 学 and 大山, 直幸 and 井手, 俊介 and Takahiro, Bando and Shizuo, Inoue and Koji, Shinohara and Akihiko, Isayama and Takuma, Wakatsuki and Maiko, Yoshida and Mitsuru, Honda and Go, Matsunaga and Manabu, Takechi and Naoyuki, Oyama and Shunsuke, Ide},
 journal = {Plasma and Fusion Research},
 month = {Mar},
 note = {We have investigated the excitation mechanism of n = 1 helical cores (HCs) with m/n = 2/1 neoclassical tearing modes (NTMs) in JT-60U. It is found that the n = 1 HC is observed with the mode frequency from several Hz to 6 kHz. This indicates that the resistive wall and the plasma control system do not induce n = 1 HCs because the both time scales are different from the mode frequency. In addition, n = 1 HCs appear to be the non-resonant mode from the two observations: n = 1 HCs do not rotate with the plasma around the q = 1 surface in the core and an n = 1 HC is observed even when qmin. > 1. It is also observed that the fluctuation due to an n = 1 HC in the core region disappears with the stabilization of an m/n = 2/1 NTM, implying that n = 1 HCs are driven by m/n = 2/1 NTMs. We revisit a quasi-linear MHD model where the n = 1 HC is induced directly by the sideband of the current for the m/n = 2/1 NTM, which potentially excites the non-resonant m/n = 1/1 mode.},
 title = {Non-Resonant n = 1 Helical Core Induced by m/n = 2/1 Neoclassical Tearing Mode in JT-60U},
 volume = {16},
 year = {2021}
}