Experimental observation of multi-scale interactions among kink /tearing modes and high-frequency fluctuations in the HL-2A core NBI plasmas

Chen, W.; Jiang, M.; Xu, Yuhong; Shi, P.W.; Yu, Liming; Ding, X.T.; Shi, Z.B.; Ji, Xiao; Yu, D.L.; Li, Y.G.; Yang, Z.C.; Zhong, W.L.; Qiu, Zhiyong; Li, J.Q.; Dong, J. Q.; Yang, Qingwei; Liu, Yi; Yan, L.W.; Xu, M.; Duan, Xuru

doi:10.1088/1741-4326/aa7eee

Cited by 42 publications

(44 citation statements)

References 30 publications

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“…Recently, the interaction between an island and turbulence has been extensively studied [25,26]. Their interactions are known to result in coupled evolution between an island and turbulence [27,28,29,30,24]. Turbulence can be modified by the island associated change of the background pressure [31,32] and flow [33,34,35,36,37,38] profiles [39], which in turn affects the evolution of the island [27,28,29,30,24].…”

Section: Resultsmentioning

confidence: 99%

Stochastic fluctuation and transport of tokamak edge plasmas with the resonant magnetic perturbation field

Choi¹,

Kwon²,

Kim³

et al. 2021

Preprint

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The stochastic layer formation by the penetration of the resonant magnetic perturbation (RMP) field has been considered as a key mechanism in the RMP control of the edge localized mode (ELM) in tokamak plasmas. Here, we provide experimental observations that the fluctuation and transport in the edge plasmas become more stochastic with the more penetration of the RMP field into the plasma. The results support the importance of the stochastic layer formation in the RMP ELM control experiments.

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Section: Resultsmentioning

confidence: 99%

Stochastic fluctuation and transport of tokamak edge plasmas with the resonant magnetic perturbation field

Choi¹,

Kwon²,

Kim³

et al. 2021

Preprint

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“…This implies that the turbulent transport around an MI can be also modified, meaning that the evolution of plasma turbulence and the evolution of the MI are coupled. However, there has been relatively little experimental research progress 7 , 9 , 11 , 12 in addressing the effects of plasma turbulence on the MI evolution to date.…”

Section: Introductionmentioning

confidence: 99%

Effects of plasma turbulence on the nonlinear evolution of magnetic island in tokamak

et al. 2021

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Magnetic islands (MIs), resulting from a magnetic field reconnection, are ubiquitous structures in magnetized plasmas. In tokamak plasmas, recent researches suggested that the interaction between an MI and ambient turbulence can be important for the nonlinear MI evolution, but a lack of detailed experimental observations and analyses has prevented further understanding. Here, we provide comprehensive observations such as turbulence spreading into an MI and turbulence enhancement at the reconnection site, elucidating intricate effects of plasma turbulence on the nonlinear MI evolution.

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“…The amplitude and phase modulations associated with beating may contain useful information about possible nonlinear couplings between the interfering waves. This has been exploited, for instance, in studies of coexisting EP-driven Alfvén modes and rotating kink/tearing modes [52][53][54] 28 . Since different modes generally have different spatial structures, such cases exhibit not only temporal modulation but also spatial modulation.…”

Section: Summary Discussion and Outlookmentioning

confidence: 99%

On the Effect of Beating during Nonlinear Frequency Chirping

Bierwage

Roscoe

Duarte

2021

Plasma and Fusion Research

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Spectroscopic analyses of energetic particle (EP) driven bursts of MHD fluctuations in magnetically confined plasmas often exhibit chirps that occur simultaneously in groups of two or more. While the superposition of oscillations at multiple frequencies necessarily causes beating in the signal acquired by a localized external probe, self-consistent hybrid simulations of chirping EP modes in a JT-60U tokamak plasma have demonstrated the possibility of global beating, where the mode's electromagnetic field vanishes globally between beats and reappears with opposite phase [Bierwage et al., Nucl. Fusion 57, 016036 (2017)]. This implies that there can be a single coherent field mode that oscillates at multiple frequencies simultaneously when it is resonantly driven by multiple density waves in EP phase space. Conversely, this means that the EP density waves are mutually coupled and interfere with each other via the jointly driven field, a mechanism ignored in some theories of chirping. In this thesis-style treatise, we study the role of field pulsations in general and beating in particular using the Hamiltonian guiding center orbit-following code ORBIT with a reduced wave-particle interaction model in realistic geometry. Beating is found to drive the evolution of EP phase space structures. A key mechanism is the pulsation of effective phase space islands combined with the alternation of their effective O-and X-points due to phase jumps between each beat. Observations: (1) Beating causes density wave fronts to advance radially in a pulsed manner and the resulting chirps become staircase-like. (2) The pulsations facilitate convective transfer of material between neighboring layers of phase space density waves. On the one hand, this may inhibit the early detachment of solitary phase space vortices. On the other hand, it facilitates the accumulation of hole and clump fragments into larger structures. (3) Long-range chirping is observed when massive holes or clumps detach and drift away from the turbulent belt around the seed resonance. It is remarkable that the detached vortices remain robust and, on average, maintain their concentric nested layers while being visibly perturbed by the field's continued beating.

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Experimental observation of multi-scale interactions among kink /tearing modes and high-frequency fluctuations in the HL-2A core NBI plasmas

Cited by 42 publications

References 30 publications

Stochastic fluctuation and transport of tokamak edge plasmas with the resonant magnetic perturbation field

Stochastic fluctuation and transport of tokamak edge plasmas with the resonant magnetic perturbation field

Effects of plasma turbulence on the nonlinear evolution of magnetic island in tokamak

On the Effect of Beating during Nonlinear Frequency Chirping

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