Radial Position Detection of Magnetic Islands and Electron Cyclotron Power Deposition in the FTU Tokamak

A tokamak is a magnetic confinement machine capable to hold a hot thermonuclear plasma for controlled nuclear fusion energy production. The confined plasma is subject to magneto hydro dynamic (MHD) instabilities. Active control of such instabilities is important in order to improve the tokamak performances. This paper describes a method for measuring the position in the plasma of MHD instabilities. The suppression of this type of instability can be obtained by localized heating using electron cyclotron heating (ECH) systems. In the paper is also described the measurement principle for measuring the position in the plasma where the ECH power is deposited. Using this diagnostic tools for the estimation of the MHD instability and the ECH power deposition, effective stabilization can be achieved tracking the MHD instability location with the ECH power deposition. Experimental work done on the Italian FTU tokamak in this field is reported.