Design of the magnetic diagnostic for ITER

Kock, L. de; Walker, Chris; Coccorese, E.; Costley, A. E.; Dremin, M. M.; Gernhardt, J.; Kasai, S.; Senda, I.; Shoji, T.; Leuer, J.A.; Snider, R. T.; McCarthy, Patrick J.; Portone, A.; Stott, P.E.; Young, K. M.

doi:10.1063/1.1149390

Cited by 9 publications

(11 citation statements)

References 3 publications

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“…HL-2A [30] is a medium-sized tokamak, with R/a = 165 cm/40 cm, operated in limiter or single divertor configuration with maximum plasma current I p ~ 450 kA, the achieved toroidal magnetic field B t ~ 2.7 T, and line-averaged electron density up to n e ~ 5.5 × 10 19 m −3 . For those disruptive discharge concerned in this study, the parameter regime for current is from 170 to 200 kA, the total plasma current is measured using continuous Rogowski loops [31]. The toroidal magnetic field is in the range of 1.3 T ~ 1.4 T. The line-averaged electron density varies throughout the discharge, its value just before disruption ranges from 0.5 × 10 19 m −3 to 4.5 × 10 19 m −3 .The available auxiliary heating and current drive power includes 1.5 MW NBI at 45 keV for 2 s, 3 MW ECRH at 68 GHz for 1 s and 1 MW LHCD at 2.45 GHz for 1 s. The key diagnostics for this experiment are electron cyclotron emission (ECE), the soft-x ray (SXR) detector, Mirnov coils, Bolometer and a D detector arrays.…”

Section: Methodsmentioning

confidence: 99%

Synchronous oscillation prior to disruption caused by kink modes in HL-2A tokamak plasmas

Jiang

Wang

et al. 2015

Nucl. Fusion

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A class of evident MHD activities prior to major disruption has been observed during recent radiation induced disruptions of the HL-2A tokamak discharges. It can be named SOD, synchronous oscillations prior to disruption, characterized by synchronous oscillation of electron cyclotron emission (ECE), core soft x-ray, Mirnov coil, and a D radiation signals at the divertor plate. The SOD activity is mostly observed in a parametric regime where the poloidal beta is low enough before disruption, typically corresponding to those radiationinduced disruptions. It has been found that the m/n = 2/1 mode is dominant during the SODs, and consequently it is the drop of the mode frequency and the final mode locking that lead to thermal quench. The mode frequency before the mode locking corresponds to the toroidal rotation frequency of the edge plasma. It is also found that during SODs, the location of the q = 2 surface is moving outward, and most of the plasma current is enclosed within the surface. This demonstrates that the current channel lies inside the rational surface during SOD, and thus the resistive kink mode is unstable. Further analysis of the electron temperature perturbation structure shows that the plasma is indeed dominated by the resistive kink mode, with kink-like perturbation in the core plasma region. It suggests that it is the nonlinear growth of the m/n = 2/1 resistive kink mode and its higher order harmonics, rather than the spontaneous overlapping of multiple neighboring islands, that ultimately triggered the disruption.

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Section: Methodsmentioning

confidence: 99%

Synchronous oscillation prior to disruption caused by kink modes in HL-2A tokamak plasmas

Jiang

Wang

et al. 2015

Nucl. Fusion

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“…This largely eliminated the effect of currents induced in the wall. In ITER, the coils will be placed behind the blanket modules [29]. Eddy currents have decay times in the range 7-17 ms [30].…”

Section: Wave Measurementsmentioning

confidence: 99%

Resolving the wave–particle–plasma interaction: advances in the diagnosis, interpretation and self-consistent modelling of waves, particles and the plasma configuration

Hole¹,

Fitzgerald²

2014

Plasma Phys. Control. Fusion

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The purpose of this review is to present the state-of-the-art in diagnosis, interpretation and modelling of waves, particles and the magnetic configuration in fusion plasmas. Knowledge of the magnetic configuration underpins all confinement, stability and transport physics, as well as being an essential prerequisite for the inference of plasma parameters from many diagnostics. As the effect of fast particles become important enough to modify the macroscopic variables of the plasma, the macroscopic fluid equations for equilibrium need to be modified to encapsulate the effects of pressure anisotropy, particle and heat flow. We present a review of such modifications in tokamak geometry, and review probabilistic validation techniques of different equilibrium models. In the last decade new spectral tools have also emerged to characterize the linear behaviour of waves and wave-modes, such as SVD, Fourier-SVD, data-mining and the bispectrum. An emerging trend is the use of statistics to characterize the nonlinear wave population of the plasma from wave field data. Finally, progress is reported on developments in understanding the physics of wave-particle resonant interactions, and the emerging science of the wave-particle-plasma interaction.

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“…The following parameters obtained by magnetic measurements are essential for the determination of the plasma equilibrium [23,282].…”

Section: Equilibriummentioning

confidence: 99%

“…It can be relaxed to 3 % in case of an EFIT reconstruction [23,282,302]. The plasma current measurements have been specified to be accurate to 1 % or at least 10 kA absolute in the low current range (< 1 MA).…”

Section: Equilibriummentioning

confidence: 99%

“…Elongated tokamak plasmas have to be stabilized actively and the plasma shape reconstruction is essential for the avoidance of first wall element overloading and the divertor control. A comparison of different reconstruction methods with respect to the plasma shape accuracy has been performed for ITER [23] comprising artificial neural networks, function parameterisation and EFIT. Dedicated fast algorithms for plasma shape determination are reported for tokamaks based on a filament representation of the plasma current, in particular for plasma control and stabilization [336], but also EFIT [337] has been used for shape control at DIII-D [338].…”

Section: Automated Analysismentioning

confidence: 99%

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Diagnostics for steady state plasmas

Hartfuß¹,

König²,

Werner³

2006

Plasma Phys. Control. Fusion

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Problems related to the development of diagnostics for steady state fusion plasma experiments are being discussed. The paper concentrates on those necessities already appearing in nowadays non-burning plasma fusion experiments when extending pulse lengths beyond 10 s, i.e. thermal load, erosion, deposition, and long-time signal integration in magnetic diagnostics. Problems arising from high power ECRH under conditions of incomplete absorption are outlined. Individual standard diagnostic systems are discussed to identify their specific problems as well as the opportunities connected with long pulse operation. Burning plasma experiments characterized by intense n-and g-radiation are briefly reviewed for reasons of completeness, dealing with radiation induced processes in windows, fibres, cables, and mirrors. Methods of data handling, real time monitoring, and plasma control are outlined. Index

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Design of the magnetic diagnostic for ITER

Cited by 9 publications

References 3 publications

Synchronous oscillation prior to disruption caused by kink modes in HL-2A tokamak plasmas

Synchronous oscillation prior to disruption caused by kink modes in HL-2A tokamak plasmas

Resolving the wave–particle–plasma interaction: advances in the diagnosis, interpretation and self-consistent modelling of waves, particles and the plasma configuration

Diagnostics for steady state plasmas

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