Plasma position measuring instrument for tokamak device

Purpose: To improve precision and safety of plasma position control by detecting abnormal signals from adjacent magnetic probes (by utilizing the fact that tangential and radial fields are smooth relative to a circumferential angle) and correcting the position measurements. Constitution: Signals from a plurality of plasma position detecting magnetic probes are converted to digital signals by an A-D convertor, before fed to an instantaneous abnormal detector. Tangential and radial field configurations of each probe are smooth relative to a circumferential angle. Measurements fed into the detector are compared with those of an adjacent probe. A stationary abnormal detector integrates the number of abnormality detections on each abnormal case, and when the integrated number surpass a limit, an alarm output part makes an alarm to personnel and emits a position calculation formula correction signal to the plasma position detector so that abnormal measurements are excluded from the measuring data. (Nakamura, S.)