Saturation of the tearing mode

White, R. B.; Monticello, D.; Rosenbluth, M. N.; Waddell, B. V.

doi:10.1063/1.861939

Cited by 368 publications

(272 citation statements)

References 5 publications

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“…Their deleterious affect on confinement and potential to lead to disruptions has been well documented. A theoretical model, hereinafter referred to as the "classical" model, has been developed which describes the stability and evolution of islands in low beta plasmas [2][3][4]. This model generally predicts the 2/1 mode to be marginally stable and higher n modes to be stable, in reasonable agreement with observed tearing mode activity in early tokamak experiments.…”

Section: Introductionmentioning

confidence: 53%

Observation of Spontaneous Neoclassical Tearing Modes

Fredrickson¹

2001

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We present data in this paper from the Tokamak Fusion Test Reactor (TFTR) which challenges the commonly held belief that extrinsic MHD events such as sawteeth or ELMs are required to provide the seed islands that trigger Neoclassical Tearing Modes (NTMs). While sawteeth are reported to provide the trigger for most of the NTMs on DIII-D and ASDEX-U, the majority of NTMs seen in TFTR occur in plasmas without sawteeth, that is which are above the β threshold for sawtooth stabilization. Examples of NTMs appearing in the absence of any detectable extrinsic MHD activity will be shown. Conversely, large n=1 modes in plasmas above the NTM β threshold generally do not triggerNTMs. An alternative mechanism for generating seed islands will be discussed.2

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Section: Introductionmentioning

confidence: 53%

Observation of Spontaneous Neoclassical Tearing Modes

Fredrickson¹

2001

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“…This however does not explain the saturation of the instability, observed both in experiments [4] and in numerical simulations [5,6]. Saturation was found in a semi-analytical calculation by White et al [5].…”

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confidence: 66%

“…Saturation was found in a semi-analytical calculation by White et al [5]. They observed that in numerical simulations the perturbed' current behaves linearly with the total magnetic flux, inside the magnetic island.…”

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confidence: 71%

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Quasi-linear evolution of tearing modes

1984

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Abstract. 2014 The growth of a tearing instability in Rutherford's non-linear regime is investigated. Using a singular perturbations technique, we recover to lowest order Rutherford's result. To the following order we show that the mode generates a quasi-linear deformation of the equilibrium flux profile, whose resistive diffusion slows down the growth and shows the possibility of a saturation of the instability.

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“…Perhaps ironically, the confinement properties of tokamaks have become so good that various techniques are now being deployed to deliberately impair confinement locally in space and sometimes temporally, thereby either avoiding, or initiating controlled, destablization of MHD instabilities. Not doing so can lead to delayed but consequently larger perturbations, which in the case of edge-localized modes 2,3 can damage the vessel wall, and in the case of core-localized sawteeth 4 can trigger [5][6][7] globally confinement-limiting, and potentially disruption-causing, neoclassical tearing modes (NTMs) 8 .…”

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confidence: 99%

Control of magnetohydrodynamic stability by phase space engineering of energetic ions in tokamak plasmas

et al. 2012

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Virtually collisionless magnetic mirror-trapped energetic ion populations often partially stabilize internally driven magnetohydrodynamic disturbances in the magnetosphere and in toroidal laboratory plasma devices such as the tokamak. This results in less frequent but dangerously enlarged plasma reorganization. unique to the toroidal magnetic configuration are confined 'circulating' energetic particles that are not mirror trapped. Here we show that a newly discovered effect from hybrid kinetic-magnetohydrodynamic theory has been exploited in sophisticated phase space engineering techniques for controlling stability in the tokamak. These theoretical predictions have been confirmed, and the technique successfully applied in the Joint European Torus. manipulation of auxiliary ion heating systems can create an asymmetry in the distribution of energetic circulating ions in the velocity orientated along magnetic field lines. We show the first experiments in which large sawtooth collapses have been controlled by this technique, and neoclassical tearing modes avoided, in high-performance reactor-relevant plasmas.

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Saturation of the tearing mode

Cited by 368 publications

References 5 publications

Observation of Spontaneous Neoclassical Tearing Modes

Observation of Spontaneous Neoclassical Tearing Modes

Quasi-linear evolution of tearing modes

Control of magnetohydrodynamic stability by phase space engineering of energetic ions in tokamak plasmas

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