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Real-time density profile measurements are essential for advanced fusion tokamak operation and interferometry is a proven method for this task. Nevertheless, as a consequence of edge localized modes, pellet injections, fast density increases, or disruptions, the interferometer is subject to fringe jumps, which produce loss of the signal preventing reliable(More)
Experiments were carried out in the JET tokamak to determine the critical ion temperature inverse gradient length (R/LTi=R|nablaTi|/Ti) for the onset of ion temperature gradient modes and the stiffness of Ti profiles with respect to deviations from the critical value. Threshold and stiffness have been compared with linear and nonlinear predictions of the(More)
—The real-time reconstruction of the plasma magnetic equilibrium in a Tokamak is a key point to access high performance regimes. Indeed, the shape of the plasma current density profile is a direct output of the reconstruction and has a leading effect for reaching a steady-state high performance regime of operation. In this paper we present the methodology(More)
Real time control of many plasma parameters will be an essential aspect in the development of reliable high performance operation of Next Step Tokamaks. The main prerequisites for any feedback scheme are the precise real-time determination of the quantities to be controlled, requiring top quality and highly reliable diagnostics, and the availability of(More)
1. Introduction Real-time control of the plasma profiles (current density, pressure and flow) is one of the major issues for sustaining internal transport barriers (ITB) in a high performance plasma, with a large bootstrap current fraction. Indeed, the controllability of the proposed advanced scenarii must be demonstrated to envisage steady state operation(More)
Preprint of Paper to be submitted for publication in Control Engineering Practice " This document is intended for publication in the open literature. It is made available on the understanding that it may not be further circulated and extracts or references may not be published prior to publication of the original when applicable, or without the consent of(More)
ITER magnetic diagnostics are now in their detailed design and R&D phase. They have passed their conceptual design reviews and a working diagnostic specification has been prepared aimed at the ITER project requirements. This paper highlights specific design progress, in particular, for the in-vessel coils, steady state sensors, saddle loops and divertor(More)
Eddy currents flowing in the conductive structures surrounding the plasma in a tokamak affect magnetic measurements (magnetic fields and fluxes at given points), which are used to estimate plasma quantities such as plasma toroidal current, position and shape. Due to their spatial distribution and their fast variations, eddy currents are difficult sources to(More)
We report the identification of a localized current structure inside the JET plasma. It is a field-aligned closed helical ribbon, carrying current in the same direction as the background current profile (cocurrent), rotating toroidally with the ion velocity (corotating). It appears to be located at a flat spot in the plasma pressure profile, at the top of(More)
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