Toroidal field and q₉₅ scalings on error field penetration in EAST

Toroidal field and q ₉₅ scalings of error field penetration are investigated with n = 1 resonant magnetic perturbation coil in EAST. The toroidal field scalings of error field penetration thresholds under fixed q ₉₅ are about $b_{r21}/B_T\propto B_T^{-1.0}$ in both ohmically and lower hybrid wave heated plasmas, where b _r21 is the vacuum error field at the q = 2/1 rational surface and B _T is the toroidal field. These scalings indicate a favorable tolerance on error field in ITER. To make clear the underlying physics on toroidal field scaling, the theoretical analysis is given. By subtituting penetration related scaling parameters into the theory, the obtained theoretical scalings are consistent with the experimental observations using the vacuum penetration thresholds. To further investigate penetration threshold in larger operation region, the q ₉₅ scaling on penetration threshold with $b_{r21}\propto q_{95}^{1.66}$ has also been observed. The rational surface radius r _s and magnetic shear s, which are crucial to q ₉₅ scaling, are included in the theoretical analysis. The theoretical analysis is also consistent with the experimental scalings using the vacuum penetration thresholds. Moreover, the obtained theoretical scalings are easy to compare with experimental scalings. These theoretical analyses will stimulate the extrapolation of error field tolerance towards future reactors. (paper)