Poloidal mode analysis of magnetic probe data in a spherical tokamak configuration.
A method to determine the poloidal mode number m in a spherical tokamak based on magnetic probe data was developed. Perturbed magnetic fields at Mirnov coils are calculated for distributed helical filamentary currents on rational surfaces assuming the maximum current amplitude, m and n (toroidal mode number), and the toroidal location of the filaments. These free parameters were determined from the best fit to the measured signals. The residual error was reduced by a factor of 2 by introducing helical filaments instead of toroidal filaments. Using this method, m/n=2/1 and 3/2 modes were identified in Mega-Ampere Spherical Tokamak discharges, and the time evolution of the tearing modes was derived.
Tojo
H
H
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan. tojo@fusion.k.u-tokyo.ac.jp
Ejiri
A
A
Gryaznevich
M P
MP
Takase
Y
Y
Adachi
Y
Y