ITER shape controller and transport simulations

Casper, T. A.; Meyer, William H.; Pearlstein, L. D.; Portone, A.

doi:10.1016/j.fusengdes.2007.09.009

Cited by 21 publications

(19 citation statements)

References 11 publications

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“…We note that during the rampdown it was necessary to change the control system algorithm in order to maintain vertical stability at low elongation with the current centroid, z cur , well below the midplane. Although vertical stability was demonstrated for these DIII-D discharges, we note that simulations of the ITER control system, power supplies, and plasma models [27][28][29][30] are necessary to extrapolate these results to ITER.…”

Section: Experimentally Simulating Iter Rampdownmentioning

confidence: 99%

Understanding and predicting the dynamics of tokamak discharges during startup and rampdown

Jackson¹,

Politzer²,

Humphreys³

et al. 2010

Physics of Plasmas

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Understanding the dynamics of plasma startup and termination is important for present tokamaks and for predictive modeling of future burning plasma devices such as ITER. We report on experiments in the DIII-D tokamak that explore the plasma startup and rampdown phases and on the benchmarking of transport models. Key issues have been examined such as plasma initiation and burnthrough with limited inductive voltage and achieving flattop and maximum burn within the technical limits of coil systems and their actuators while maintaining the desired q profile. Successful rampdown requires scenarios consistent with technical limits, including controlled H-L transitions, while avoiding vertical instabilities, additional Ohmic transformer flux consumption, and density limit disruptions. Discharges were typically initiated with an inductive electric field typical of ITER, 0.3 V/m, most with second harmonic electron cyclotron assist. A fast framing camera was used during breakdown and burnthrough of low Z impurity charge states to study the formation physics. An improved "large aperture" ITER startup scenario was developed, and aperture reduction in rampdown was found to be essential to avoid instabilities. Current evolution using neoclassical conductivity in the CORSICA code agrees with rampup experiments, but the prediction of the temperature and internal inductance evolution using the Coppi-Tang model for electron energy transport is not yet accurate enough to allow extrapolation to future devices.

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Section: Experimentally Simulating Iter Rampdownmentioning

confidence: 99%

Understanding and predicting the dynamics of tokamak discharges during startup and rampdown

Jackson¹,

Politzer²,

Humphreys³

et al. 2010

Physics of Plasmas

View full text Add to dashboard Cite

show abstract

“…In addition to algorithm verification, this capability also allows control optimization in the presence of delays introduced by the digital control as well as the ability to study tradeoffs in algorithm performance versus computational speed. In order to study nonlinearities and other complex physics associated with the plasma itself, TokSys simulations can make use of detailed nonlinear core plasma evolution modules derived from the LLNL Corsica [3] or TRINITI DINA [4] codes. Use of these codes in TokSys provides examples of cross-institution code interoperability, an essential process to maximize efficient use of control resources among ITER Parties and the broader control community.…”

Section: Toksys: Generic System For Tokamak Control Modelingmentioning

confidence: 99%

DIII-D Integrated plasma control solutions for ITER and next-generation tokamaks

Humphreys¹,

Ferron²,

Hyatt³

et al. 2008

Fusion Engineering and Design

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“…However, the computation to integrate magnetic field lines, for such magnetic configuration, is time-consuming [6][7][8]. On the other hand, simple models can delineate quite well dynamical properties of open and closed field lines near the separatrix.…”

Section: Introductionmentioning

confidence: 99%

Delineating the magnetic field line escape pattern and stickiness in a poloidally diverted tokamak

2014

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We analyze a Hamiltonian model with five wire loops that delineates the magnetic surfaces of the tokamak ITER, including a similar safety factor profile and the X-point related to the presence of a poloidal divertor. Non-axisymmetric magnetic perturbations are added by external coils, similar to the correction coils installed at the tokamak DIII-D and those that will be installed at ITER. To show the influence of magnetic perturbations on the field line escape, we integrate numerically the field line differential equations and obtain the footprints and deposition patterns on the divertor plate.Moreover, we show that the homoclinic tangle describes the deposition patterns in the divertor plate, agreeing with results observed in sophisticated simulation codes. Additionally, we show that while chaotic lines escape to the divertor plates, some of them are trapped, for many toroidal turns, in complex structures around magnetic islands, embedded in the chaotic region, giving rise to the so called stickiness effect characteristic of chaotic Hamiltonian systems. Finally, we introduce a random collisional term to the field line mapping to investigate stickiness alterations due to particle collisions. Within this model, we conclude that, even reduced by collisions, stickiness still influences the field line transport.

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ITER shape controller and transport simulations

Cited by 21 publications

References 11 publications

Understanding and predicting the dynamics of tokamak discharges during startup and rampdown

Understanding and predicting the dynamics of tokamak discharges during startup and rampdown

DIII-D Integrated plasma control solutions for ITER and next-generation tokamaks

Delineating the magnetic field line escape pattern and stickiness in a poloidally diverted tokamak

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