Interlocking and nonlinear saturation of double tearing modes in differentially rotating plasmas

Wang, Xianqu; Wang, Xiaogang; Xu, Wenbin; Wang, Jialei

doi:10.1063/1.3535371

Cited by 31 publications

(25 citation statements)

References 46 publications

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“…Besides, the interlocking and nonlinear saturation of DTMs in differentially rotating plasmas were also investigated, where the characteristics of threshold island width and locking frequency were analyzed. 26 Furthermore, the stabilization of DTMs by shear flow 27,28 concluded that the shear flow between both the resonant surfaces has a dominant effect on island suppression rather than that on an individual resonant surface. 29 Although the interactions between DTMs and shear flows have been well-studied and understood, the "error-field penetration" in the RMS configurations has been rarely explored.…”

Section: Introductionmentioning

confidence: 99%

Error-field penetration in reversed magnetic shear configurations

Wang

et al. 2013

Physics of Plasmas

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Error-field penetration in reversed magnetic shear (RMS) configurations is numerically investigated by using a two-dimensional resistive magnetohydrodynamic model in slab geometry. To explore different dynamic processes in locked modes, three equilibrium states are adopted. Stable, marginal, and unstable current profiles for double tearing modes are designed by varying the current intensity between two resonant surfaces separated by a certain distance. Further, the dynamic characteristics of locked modes in the three RMS states are identified, and the relevant physics mechanisms are elucidated. The scaling behavior of critical perturbation value with initial plasma velocity is numerically obtained, which obeys previously established relevant analytical theory in the viscoresistive regime. V C 2013 AIP Publishing LLC. [http://dx.

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Section: Introductionmentioning

confidence: 99%

Error-field penetration in reversed magnetic shear configurations

Wang

et al. 2013

Physics of Plasmas

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“…The linear results presented in this work are obtained in a cylindrical geometry by neglecting the toroidal mode coupling effect which may play an important role in the 'infernal' mode for a weak magnetic shear configuration in core plasmas (Charlton et al 1988(Charlton et al , 1989Nave and Wesson 1988;Ganesh and Vaclavik 2005;Chapman et al 2010). Moreover, the plasma mean E × B flow and diamagnetic flow, which also have an effect on tearing modes, are not considered in this work (Chen and Morrison 1990;Ofman et al 1991;Persson 1991;Ofman 1992;Shen and Liu 1998;Ishii et al 2009;Halpern et al 2011;Wang et al 2011aWang et al , b, 2012. The investigation of the linear and nonlinear drift DTMs, including the toroidal effect, is in progress.…”

Section: Discussionmentioning

confidence: 99%

Numerical study of collisionless q = 1 double tearing instability in a cylindrical plasma

Lai¹,

Yang

Zheng³

et al. 2012

J. Plasma Phys.

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The double tearing mode (DTM) instability with two q s = 1 rational surfaces is investigated by taking into account the collisionless effects, including electron inertia and electron viscosity in a cylindrical geometry. The calculations show that for q-profile with a small distance between two rational surfaces, Δr s , there exists a broad linear spectrum of collisionless DTMs. The collisionless effects not only can significantly increase the linear growth rate of DTMs but can also enlarge the width of spectrum of unstable modes. For the q-profile with fixed Δr s and fixed magnetic shears at two rational surfaces, the high-order harmonics with smaller wavelength, such as the m/n = 2/2, 3/3 and 4/4 modes, can be easily excited to have larger growth rates than the m/n = 1/1 mode by 'lifting' the safety factor value between two rational surfaces. The characteristics of eigenmode structures of the most unstable and secondly unstable DTMs with various mode numbers are analyzed in detail and the corresponding collisionless scalings are numerically obtained and verified theoretically based on the previous relevant analytical theories. In addition, the synergetic effects of plasma resistivity, electron inertia and electron viscosity on the linear growth rates of DTMs are analyzed.

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“…We find that the island at the outer rational surface quickly grows large enough to interlock the layer at the inner surface, which has been previously been observed in nonlinear differential rotation simulations. 22 Once recoupled, the separatrix merging event proceeds with only minor deviation from the force-free system. Thus locating a drift at the inner, sub-dominant rational surface results in more system kinetic energy (due to plasma flows near the inner surface) but is not an effective means of slowing DTM mode growth.…”

Section: A Inner Driftmentioning

confidence: 99%

Effect of electron diamagnetic drifts on cylindrical double-tearing modes

Abbott,

Germaschewski

2015

Preprint

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Interlocking and nonlinear saturation of double tearing modes in differentially rotating plasmas

Cited by 31 publications

References 46 publications

Error-field penetration in reversed magnetic shear configurations

Error-field penetration in reversed magnetic shear configurations

Numerical study of collisionless q = 1 double tearing instability in a cylindrical plasma

Effect of electron diamagnetic drifts on cylindrical double-tearing modes

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