Error field penetration in J-TEXT tokamak based on two-fluid drift-MHD model

An externally generated resonant magnetic perturbation can induce complex non-ideal MHD responses in their resonant surfaces. We have studied the plasma responses using Fitzpatrick’s improved two-fluid model and program LAYER. We calculated the error field penetration threshold for J-TEXT. In addition, we find that the island width increases slightly as the error field amplitude increases when the error field amplitude is below the critical penetration value. However, the island width suddenly jumps to a large value because the shielding effect of the plasma against the error field disappears after the penetration. By scanning the natural mode frequency, we find that the shielding effect of the plasma decreases as the natural mode frequency decreases. Finally, we obtain the m/n = 2/1 penetration threshold scaling on density and temperature.