Multimachine Data–Based Prediction of High-Frequency Sensor Signal Noise for Resistive Wall Mode Control in ITER

Yueqiang Liu, S. A. Sabbagh, I. T. Chapman, S. Gerasimov, Y. Gribov, T. C. Hender, V. Igochine, M. Maraschek, G. Matsunaga, M. Okabayashi, E. J. Strait
2016 Fusion science and technology  
The high frequency noise measured by magnetic sensors, at levels above the typical frequency of resistive wall modes, is analyzed across a range of present tokamak devices including DIII-D, JET, MAST, ASDEX Upgrade, JT-60U and NSTX. Application of a highpass filter enables identification of the noise component with Gaussian-like statistics, that shares certain common characteristics in all devices considered. A conservative prediction is made for ITER plasma operation of the high-frequency
more » ... component of the sensor signals, to be used for resistive wall mode feedback stabilization, based on the multi-machine database. The predicted root-mean-square n=1 (n is the toroidal mode number) noise level is 10 4 − 10 5 Gauss/second for the voltage signal, and 0.1-1Gauss for the perturbed magnetic field signal. The lower cut-off frequency of the Gaussian pickup noise scales linearly with the sampling frequency, with the scaling coefficient of about 0.1. These basic noise characteristics should be useful for the modelling-based design of the feedback control system for the resistive wall mode in ITER.
doi:10.13182/fst15-207 fatcat:ghhkz7izwna65bqmchmn5r6p4u