Abstract
The effect of electron cyclotron current drive (ECCD) on the multi-helicity neo-classical tearing modes (2/1 and 3/2 NTMs) in tokamak plasmas is numerically studied by adopting a reduced magnetohydrodynamic (MHD) model. It is found that the control process of certain single helicity NTM by ECCD can be influenced by nonlinear multi-helicity interaction. In the case without plasma rotation, the ‘phase flip’ of 2/1 NTM, which happens in the control of single helicity situation, has been modified by multi-helicity interaction and consequently behaves periodicity. And the ‘phase flip’ of 3/2 NTM disappears. When plasma rotation is considered, the direct control of 3/2 NTM becomes difficult. Moreover, a dual role of 5/3 mode is found in the multi-helicity interaction between 2/1 and 3/2 modes. The nonlinear mode coupling among 2/1 and 3/2 modes through the 5/3 mode will increase the difficulty of the suppression of 3/2 mode by ECCD, while the competition effect between multi-helicity NTMs leads to the relatively weak amplitude of 2/1 mode. In addition, investigations of multiple ECCDs are also carried out. The numerical results indicate that the control strategy for controlling multi-helicity NTMs by ECCD in experiments may require well-designed aiming to gain high effectiveness and efficiency.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.