Nonlinear dynamics of toroidal Alfvén eigenmodes in the presence of tearing modes

Zhu, Jia; W., Z.; Wang, S.; Zhang, W.

doi:10.1088/1741-4326/aaae7e

Cited by 15 publications

(20 citation statements)

References 29 publications

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“…These findings can help us to understand the TM-induced energetic-ion losses and particle acceleration during the TM reconnection in the laboratory and space plasmas and motivate the incorporation of a kinetic description of energetic-ions in TM models. Furthermore, some experimental and simulated results suggest that the TM can couple with EP-driven Alfvén modes and create the new physical phenomena [45,46], as well as the simulation shows that the large-amplitude Alfvénic fluctuations may nonlinearly drive TM reconnection and induce macroscopic magnetic islands [47]. These corresponding physical processes should be paid more attention in all respects, including the experiment, theory and simulation.…”

Section: Conclusion and Discussionmentioning

confidence: 92%

Hybrid-kinetic simulation of resonant interaction between energetic-ions and tearing modes in a tokamak plasma

et al. 2020

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The effect of energetic-ions on magnetohydrodynamic instabilities is pivotal in the basic physics that will be vital in burning plasma experiments. Recently, it has been found in the HL-2A tokamak that an m/n = 2/1 unstable tearing mode (TM) interacts with energeticions, resulting in amplitude-bursting and frequency-chirping fishbone-like activities, and it is numerically identified that the co-passing energetic-ions play a dominant role in the waveparticle resonances (Chen et al 2019 Nucl. Fusion 59 096037). Motivated by fully and deeply understanding such a resonant interaction between energetic-ions and TM, a more detailed study of global nonlinear hybrid kinetic-MHD simulations with M3D-K code is performed in the present work. The kinetic effect of co-passing energetic-ions from non-adiabatic response is interestingly found to be strongly destabilizing, while the net effect with both adiabatic and non-adiabatic contributions is weakly destabilizing. For passing energeticions, the m/n = 2/1 TM is found to be most unstable in the case of q 0 1.5, where q 0 is the central safety factor. Effects of energetic-ion beta β h and pinch angle Λ 0 determining different energetic-ion fractions on the resonance features, such as the growth rate, frequency chirping and mode structure, are discussed in detail. The relevant simulation results are consistent with the observations on HL-2A. Furthermore, the effects of both counter-passing and trapped energetic-ions on the TM have also been explored, but the corresponding resonance phase space is found to be very narrow in the P φ − E plane. In addition, the redistribution and loss induced by the resonant interaction between TM and energetic-ions are analyzed in multiplemode simulations. Significant redistribution and loss are clearly observed, and the scaling of energetic-ion loss fraction with the fluctuation amplitude is found to be f loss ∝ √ A max , indicating that the loss is convective. These discoveries are conducive to understanding the mechanisms of TM-induced energetic-ion loss through the resonant interaction.

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Section: Conclusion and Discussionmentioning

confidence: 92%

Hybrid-kinetic simulation of resonant interaction between energetic-ions and tearing modes in a tokamak plasma

et al. 2020

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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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“…CLTx has been successfully applied in studying the influence of toroidal rotation (Wang and Ma 2015), external driven current (Wang, Ma, and Zhang 2016;, and Hall effect on resistive tearing modes in Tokamaks. Its hybrid kinetic-magnetohydrodynamic version 4 / 31 code, CLT-K, has also been developed to investigate dynamics of toroidal Alfvé nic eigenmodes in Tokamak (Zhu, Ma, and Wang 2016;Zhu et al 2018).…”

Section: Overview Of Cltxmentioning

confidence: 99%

“…Magnetic confinement fusion is a method of using a magnetic field to confine a high-temperature fusion fuel, deuterium-tritium plasma, to generate thermonuclear fusion energy. There are different kinds of magnetically confined fusion devices in operation or under construction around the world, mainly Tokamaks, such as the DIII-D Tokamak (Evans et al 2005) in the U. S., the Joint European Torus (JET) Tokamak (Liang et al 2007) in 4 / 31 code, CLT-K, has also been developed to investigate dynamics of toroidal Alfvé nic eigenmodes in Tokamak (Zhu, Ma, and Wang 2016;Zhu et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Acceleration of three-dimensional Tokamak magnetohydrodynamical code with graphics processing unit and OpenACC heterogeneous parallel programming

Zhang

Zhu

et al. 2019

International Journal of Computational Fluid Dynamics

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In this paper, the OpenACC heterogeneous parallel programming model is successfully applied to modification and acceleration of the three-dimensional Tokamak magnetohydrodynamical code (CLTx). Through combination of OpenACC and MPI technologies, CLTx is further parallelized by using multiple-GPUs. Significant speedup ratios are achieved on NVIDIA TITAN Xp and TITAN V GPUs, respectively, with very few modifications of CLTx. Furthermore, the validity of the double precision calculations on the above-mentioned two graphics cards has also been strictly verified with m/n=2/1 resistive tearing mode instability in Tokamak.

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Nonlinear dynamics of toroidal Alfvén eigenmodes in the presence of tearing modes

Cited by 15 publications

References 29 publications

Hybrid-kinetic simulation of resonant interaction between energetic-ions and tearing modes in a tokamak plasma

Hybrid-kinetic simulation of resonant interaction between energetic-ions and tearing modes in a tokamak plasma

On the Effect of Beating during Nonlinear Frequency Chirping

Acceleration of three-dimensional Tokamak magnetohydrodynamical code with graphics processing unit and OpenACC heterogeneous parallel programming

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