Real-time control of the safety factor profile diagnosed by magneto-hydrodynamic activity on the Tore Supra tokamak

Imbeaux, F.; Lennholm, M.; Pastor, P.; Aniel, T.; Brémond, S.; Decker, J.; Devynck, P.; Dümont, R.; Giruzzi, G.; Maget, P.; Mazon, D.; Merle, A.; Molina, Diego Alonso Restrepo; Moreau, Ph.; Saint‐Laurent, F.; Ségui, J. L.; Zarzoso, D.

doi:10.1088/0029-5515/51/7/073033

Cited by 12 publications

(11 citation statements)

References 33 publications

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“…At the end of each P LH plateau the current profile has reached its stationary state. Several experiments have been carried out on Tore Supra to demonstrate the capability of this control scheme to obtain a desired stationary q-profile state and to sustain it in spite of preset variations of other plasma parameters such as plasma density, ion cyclotron resonant heating (ICRH) power or total current [14]. Successful experiments have been carried out featuring…”

Section: Rt Control Of Stationary States Of the Current Profilementioning

confidence: 99%

Contribution of Tore Supra in preparation of ITER

et al. 2011

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Tore Supra routinely addresses the physics and technology of very long duration plasma discharges, thus bringing precious information on critical issues of long pulse operation of ITER. A new ITER relevant LHCD launcher has allowed coupling to the plasma a power level of 2.7 MW for 78 s, corresponding to a power density close to the design value foreseen for an ITER LHCD system. In accordance with the expectations, long distance (10 cm) power coupling has been obtained. Successive stationary states of the plasma current profile have been controlled in real time featuring i) control of sawteeth with varying plasma parameters, ii) obtaining and sustaining a "hot core" plasma regime, iii) recovery from a voluntarily triggered deleterious MHD regime. The SOL parameters and power deposition have been documented during L-mode ramp-up phase, a crucial point for ITER before the X-point formation. Disruption mitigation studies have been conducted with massive gas injection, evidencing the difference between He and Ar and the possible role of the q=2 surface in limiting the gas penetration. ICRF assisted wall conditioning in the presence of magnetic field has been investigated, culminating in the demonstration that this conditioning scheme allows to recover normal operation after disruptions. Effect of the magnetic field ripple on the intrinsic plasma rotation has been studied, showing the competition between turbulent transport processes and ripple toroidal friction. During dedicated dimensionless experiments, the effect of varying the collisionality on turbulence wavenumber spectra has been documented, giving new insight into the turbulence mechanism. Turbulence measurements have also allowed quantitatively comparing experimental results to predictions by 5D gyrokinetic codes: numerical results simultaneously match the magnitude of effective heat diffusivity, rms values of density fluctuations, and wave-number spectra. A clear correlation between electron temperature gradient and impurity transport in the very core of the plasma has been observed, strongly suggesting the existence of a threshold above which transport is dominated by turbulent electron modes. Dynamics of edge turbulent fluctuations has been studied by correlating data from fast imaging cameras and Langmuir probes, yielding a coherent picture of transport processes involved in the SOL.

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Section: Rt Control Of Stationary States Of the Current Profilementioning

confidence: 99%

Contribution of Tore Supra in preparation of ITER

et al. 2011

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“…So, it leads to 19) is established. ✷ Theorem 1 Consider the error system (16) with the above assumptions and let (16) be driven by controller (17). Then the closed-loop system ( 18) is globally exponentially stable with respect to the induced norm .…”

Section: Disturbance-free Stabilizationmentioning

confidence: 99%

“…The closed-loop control of one single shape parameter, based on Single Input -Single Output (SISO) semi-empirical modelling, has been experimentally achieved (e.g control of plasma internal inductance [30] or non-inductive current drive profile width [3]). More recently, stationary states of the safety factor profile, defined by their MHD activity, were feedback controlled on Tore Supra [17]. However this is clearly not enough to match the main requirements of MHD stability and/or internal transport barriers issues [10].…”

Section: Introductionmentioning

confidence: 99%

stabilization of the current profile in tokamak plasmas via an LMI approach

et al. 2013

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This paper deals with the H∞ stabilization of the spatial distribution of the current profile of tokamak plasmas using a Linear Matrix Inequalities (LMIs) approach. The control design is based on the one dimensional resistive diffusion equation of the magnetic flux that governs the plasma current profile evolution. The feedback control law is derived in the infinite dimensional setting without spatial discretisation. The proposed distributed control is based on a proportional-integral state feedback taking into account both interior and boundary engineering actuators. Supporting numerical simulations are presented and tuning of the controller parameters attenuating uncertain disturbances is discussed.

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“…During the development of combined LH/IC scenarios, it was confirmed that the IC power had a stabilizing effect [5]. In several instances, accidental IC power switch-off have occurred, resulting in the triggering of MHD activity.…”

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confidence: 91%