Non-linear dynamics of compound sawteeth in tokamaks

Ahn, JH; Garbet, X.; Lütjens, H.; Marx, A.; Nicolas, T; Sabot, R.; Luciani, J. F.; Guirlet, R.; Février, O.; Maget, P.

doi:10.1063/1.4949342

Cited by 8 publications

(8 citation statements)

References 38 publications

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“…As argued in [9,10], partial sawtooth reconnection may be associated with non-monotonic q profiles with q min close to or smaller than unity. The pulsating island scenario observed in our simulations is associated with relatively flat, or slightly non-monotonic, q profiles.…”

Section: Benchmarking M3d Against Visco-tearing Regimementioning

confidence: 86%

“…However, as the value of V is increased, the nonlinear behaviour changes from complete reconnection to a pulsating m/n = 1 magnetic island at intermediate values of V, finally to a situation where a steady state m/n = 1 magnetic island is formed at large values of V > 100. As argued in section 6 of this article, the pulsating island scenario may be relevant to the interpretation of partial sawtooth reconnection [9,10] sometimes observed in the experiments, while the steady state magnetic island regime may be related to the observation of the snake phenomenon [11,12]. The viscosity parameter V is also refereed to as the magnetic Prandtl number [13].…”

Section: Introductionmentioning

confidence: 89%

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Linear and nonlinear simulations of the visco-resistive internal kink mode using the M3D code

Shen

Porcelli

2018

Nucl. Fusion

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Numerical simulations of visco-resistive internal kink modes with dominant poloidal and toroidal mode numbers m/n = 1 in tokamak plasma configurations have been carried out using the M3D code. The numerical scaling of the growth rate of linear visco-resistive internal kink is found to agree reasonably well with the analytical theory. The impact of toroidal effects is assessed. Nonlinear simulations show that when viscosity increases, the nonlinear evolution of resistive internal kinks transits from cyclic, Kadomtsev-like sawtooth oscillations at relatively low values of the viscosity parameter, to pulsating m/n = 1 magnetic islands at intermediate viscosity, to steady state islands at high viscosity. For the pulsating and steady state scenarios, the safety factor profile is nearly flat and almost equals to unity in the core region. Regimes with pulsating or steady state islands may be relevant to the interpretation of partial sawteeth and of the so-called snake phenomenon sometimes observed in tokamak experiments.

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Section: Benchmarking M3d Against Visco-tearing Regimementioning

confidence: 86%

Section: Introductionmentioning

confidence: 89%

Linear and nonlinear simulations of the visco-resistive internal kink mode using the M3D code

Shen

Porcelli

2018

Nucl. Fusion

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“…The occurrence of a q min indicates a non-monotonic q profile, like in JET reversed shear discharges. The appearance of such q profiles after a sawtooth crash was recently reported and studied by [42], in sawtooth simulations of Ohmic plasmas using the XTOR-2F code [1]. Hence, the evolution of postcrash q profiles depending on the values of the total current in XTOR-2F simulations can be used to examine Tore Supra measurements described in the previous section, even if fast ions are not included in the simulation.…”

Section: Reversed Q Profiles In Xtor-2f Sawtooth Simulationsmentioning

confidence: 84%

Determination ofqduring sawtooth from inverse evolution of BAEs in Tore Supra

et al. 2017

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Measuring the value of the safety factor (q) in the core during sawtooth cycles is still an open issue. A new method to measure q in Tore Supra plasma core is presented here. It relies on the analysis of the time evolution of a set of MHD modes detected after the sawtooth crashes. These modes are in the frequency range of previously observed Beta-induced Alfvén Eigenmodes, but with a frequency declining in time. The mode frequency analysis shows that the q profile is reversed when we have ICRH, after the sawtooth crash. In high current discharges ( I p > 1.15 MA), the q-profile remains reversed for a longer time compared with lower plasma current discharges. Non-linear 3D MHD simulations of sawteeth performed with the XTOR-2F code (Lütjens and Luciani 2010 J. Comput. Phys. 229 8130-43) exhibit features that are similar to these observations.

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“…A discussion on the mode resolution used in the XTOR-2F simulations to describe sawtooth cycles can be found in Refs. [27], [33], [34].…”

Section: Non-linear Mhd Model In the Xtor-2f Codementioning

confidence: 99%

Dynamics of heavy impurities in non-linear MHD simulations of sawtoothing tokamak plasmas

Ahn¹,

Garbet²,

Lütjens³

et al. 2016

Plasma Phys. Control. Fusion

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The effect of sawteeth on impurity dynamics is studied with the XTOR-2F code. Non-linear full 3D MHD simulations including appropriate fluid equations for heavy impurities show that the presence of regular sawtooth crashes affects the impurity behaviour. A spatial non-uniformity of 5% in post-crash impurity density profiles persists due to 2D structures of impurity density which appear during sawtooth crashes. They are shown to be mainly driven by the E × B velocity, and are responsible for the sudden impurity transport in the core plasmas.

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Non-linear dynamics of compound sawteeth in tokamaks

Cited by 8 publications

References 38 publications

Linear and nonlinear simulations of the visco-resistive internal kink mode using the M3D code

Linear and nonlinear simulations of the visco-resistive internal kink mode using the M3D code

Determination ofqduring sawtooth from inverse evolution of BAEs in Tore Supra

Dynamics of heavy impurities in non-linear MHD simulations of sawtoothing tokamak plasmas

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