A threshold for excitation of neoclassical tearing modes

Gorelenkov, N. N.; Budny, R.; Chang, Z.; Gorelenkova, M.; Zakharov, L.

doi:10.1063/1.871614

Cited by 69 publications

(97 citation statements)

References 16 publications

(6 reference statements)

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“…Fig. 13 shows such a stabilization of electron trapped modes (ETM) by enhanced beta in IST configuration, calculated using the HINST code [32] Increase in β stabilizes modes as is shown in Fig. 13a.…”

Section: Magnetic Well Suppression Of Micro-instabilitymentioning

confidence: 99%

Plasma Physics Regimes in Tokamaks with Li Walls

Zakharo¹,

Gorelenkov²,

White³

et al. 2003

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Section: Magnetic Well Suppression Of Micro-instabilitymentioning

confidence: 99%

Plasma Physics Regimes in Tokamaks with Li Walls

Zakharo¹,

Gorelenkov²,

White³

et al. 2003

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“…3. Various theoretical treatments have estimated this constant to be as low as 3.17 [19] and as high as 9.26 [20]. The actual best fit of this parameter to experimental data has varied from as low as 1.7 [12,21] to 7 [14].…”

Section: Rutherford Equationmentioning

confidence: 99%

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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“…For sufficiently large magnetic islands, [30][31][32] the pressure profile in the vicinity of the rational surface is also a perturbed flux function, pϭp(⌿), which implies ͗‫ץ‬p/‫ץ‬x͘ϭ͗x͘dp/d⌿. Assuming a cross-field diffusion process and a pressure source located away from the rational surface, the pressure profile in the vicinity of the rational surface is given by 1-4,30,33 dp d⌿ ϭ dp d…”

Section: ͑7͒mentioning

confidence: 99%

“…For the purposes of this paper, we will restrict our calculation to be relevant for island widths larger than any characteristic threshold distances. [30][31][32]34,35 Using Eqs. ͑5͒-͑8͒ in the matching condition, Eq.…”

Section: ͑7͒mentioning

confidence: 99%

On the stabilization of neoclassical magnetohydrodynamic tearing modes using localized current drive or heating

1997

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The effectiveness of using localized current drive or heating to suppress the formation and growth of neoclassical magnetohydrodynamic ͑MHD͒ tearing modes is addressed. The most efficient way to use an auxiliary current source is to cause current to flow in the same direction as the equilibrium bootstrap current and phase the current relative to the magnetic island such that the current is deposited on the O-point of the island. Theoretical estimates for the amount of required current to suppress the formation of a large magnetic island is of order a few percent of the equilibrium current. If the suppression is successful, the magnetic island will saturate at a width of order the radial localization width of the current source. Localized heating at the O-point of the magnetic island can also produce stabilizing effects relative to magnetic island growth. The effects of the driven current or heating can be illustrated by using a phase diagram of the island growth. © 1997 American Institute of Physics.

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A threshold for excitation of neoclassical tearing modes

Cited by 69 publications

References 16 publications

Plasma Physics Regimes in Tokamaks with Li Walls

Plasma Physics Regimes in Tokamaks with Li Walls

Observation of Spontaneous Neoclassical Tearing Modes

On the stabilization of neoclassical magnetohydrodynamic tearing modes using localized current drive or heating

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