Tojo H, Ejiri A, Gryaznevich M P, Takase Y, Adachi Y
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan.
Rev Sci Instrum. 2008 Oct;79(10):10F120. doi: 10.1063/1.2965014.
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.
开发了一种基于磁探针数据确定球形托卡马克中极向模数(m)的方法。假设最大电流幅度、(m)和(n)（环向模数）以及细丝的环向位置，计算了在有理曲面上分布的螺旋状细丝电流在米尔诺夫线圈处的扰动磁场。这些自由参数通过对测量信号的最佳拟合来确定。通过引入螺旋状细丝而非环形细丝，残余误差降低了一半。使用该方法，在兆安球形托卡马克放电中识别出了(m/n = 2/1)和(3/2)模式，并推导了撕裂模的时间演化。
