Effect of toroidal magnetic field on n = 1 mode stability in rotamak plasmas

Yang, X.; Goss, J.; Kalaria, D.; Huang, T. S.
August 2011
Physics of Plasmas;Aug2011, Vol. 18 Issue 8, p080708
Academic Journal
To study the effect of toroidal magnetic field on n = 1 mode stability, a series of experiments with linearly ramping the axial current Iz, which makes field-reversed configuration (FRC) to spherical tokamak (ST) transition, have been conducted in rotamak. Results clearly demonstrate that the tilt mode can be completely suppressed by small Iz around 0.4 kA (in comparison with 2.0 kA plasma current). An unknown new mode with larger magnetic perturbations is triggered when Iz reaches 0.5 kA. This instability mode keeps saturation while plasma current is boosted when Iz is in the range of 0.6-1.4 kA. When Iz exceeds 1.6 kA, the new mode suddenly disappears and discharge is free from instability modes.


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