A model of energetic ion effects on pressure driven tearing modes in tokamaks

Halfmoon, Michael; Brennan, D. P.

doi:10.1063/1.4984772

Cited by 15 publications

(14 citation statements)

References 29 publications

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“…A trans ition between the double tearing mode and fishbonelike mode can be triggered, depending on energeticion drive [20]. NIMROD code simulation results suggest the m/n = 2/1 low frequency mode can be driven by energeticions with weak shear in the core and high q min > 1.3 [21], and, subsequently this result is explained by a theoretical model, namely the TM is excited by trapped energeticions via precession resonance [22]. On devices, such as TFTR, neoclassical tearing modes (NTMs) have a chirping character, implying strong interaction with energeticions [23].…”

Section: Introductionmentioning

confidence: 90%

Resonant interaction of tearing modes with energetic-ions resulting in fishbone activities on HL-2A

Chen

Zhu²,

Wang³

et al. 2019

Nucl. Fusion

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The resonant interaction between energeticparticles and tearing mode is an unresolved physics issue at present. It is found for the first time in tokamaks that an unstable tearing mode with slowly rotating m/n = 2/1 helicity, where m/n represent poloidal/toroidal mode numbers, interacts with energeticions and results in amplitudebursting/frequencychirping fishbonelike activities. Nonlinear hybrid kineticMHD simulations with M3DK code prove that the copassing energeticions are responsible for the drive of tearing modes, and the wave particle resonance condition is satisfied at ω φ − 2ω θ − ω = 0, where ω φ , ω θ and ω are the toroidal, poloidal angular frequencies of energeticions and the mode frequency respectively. These findings can help the understanding of tearing mode induced energeticparticle loss and particle acceleration during the tearing mode reconnection in laboratory and space plasmas.

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Section: Introductionmentioning

confidence: 90%

Resonant interaction of tearing modes with energetic-ions resulting in fishbone activities on HL-2A

Chen

Zhu²,

Wang³

et al. 2019

Nucl. Fusion

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“…Experimentally, the observations on DIII-D reported by Heidbrink et al [22] indicate that some energetic-ion orbits resonate with TMs but that the density of resonances in the phase-space is sparse. Based on a DIII-D hybrid discharge with the weak shear in the core, a theory model proposed by Brennan shows that the resistive m/n = 2/1 mode is driven to be unstable by trapped EPs via precession resonance [23,24]. Despite all this, the study of resonant interaction between EPs and m > 1 resistive instabilities is still quite limited.…”

Section: Hybrid-kinetic Simulation Of Resonant Interaction Between En...mentioning

confidence: 99%

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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“…and are hence important for achieving advanced operation scenarios with high plasma pressure; on the other hand, they can significantly modify magnetohydrodynamic (MHD) stabilities via the wave-particle interactions. The roles played by EPs in various macroscopic MHD instabilities have been extensively investigated for decades [2][3][4][5][6][7][8][9][10][11][12]. For instance, EPs have been found to stabilize the ballooning mode [2] and the internal kink instability [3].…”

Section: Introductionmentioning

confidence: 99%

“…In fact, EPs do affect the TM by modifying the perturbed parallel current via interaction with either the inner resistive layer, which is generally a non-linear effect [7], or the outer ideal region for linear TMs [8,9]. Interestingly, it has also been reported that the effects of EPs on the TM depend on the magnetic shear [10], i.e. being stabilizing for equilibria with monotonic safety factor profiles (and hence positive shear) [8] while destabilizing for equilibria with slightly reversed magnetic shear in the plasma core [11].…”

Section: Introductionmentioning

confidence: 99%

Toroidal modeling of energetic passing particle drift kinetic effects on tearing mode stability

Bai¹,

Liu²,

Hao³

et al. 2022

Nucl. Fusion

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Drift kinetic effects of the neutral beam injection (NBI) induced passing energetic particles (EPs) on the linear stability of the n=1 tearing mode (with the dominant poloidal harmonic of m=2) are numerically investigated utilizing the MARS-K code [Liu et al., Phys. Plasmas 15, 112503 (2008)], in a tokamak plasma with finite equilibrium pressure and anisotropic thermal transport. In the low plasma pressure regime, it is found that co- (counter-) passing EPs stabilize (destabilize) the tearing mode, agreeing with previous studies. However, as the plasma pressure increases beyond a critical value, it is found that co-passing EPs also destabilize the mode. An in-depth analysis reveals that the net effect of co-passing EPs is a result of competition between the stabilizing contribution from the non-adiabatic drift kinetic terms and the destabilizing contribution associated with adiabatic terms, with the latter becoming more dominant at higher equilibrium pressure. Non-perturbative magnetohydrodynamic-kinetic hybrid modeling also finds that co- and counter-passing EPs modify the tearing mode eigenfunction differently, with the counter-passing EPs enhancing the sideband harmonics. Furthermore, effects of the plasma resistivity and toroidal rotation, as well as that of the equilibrium distribution of EPs in the particle pitch angle space, are also investigated, showing asymmetric results on the tearing mode stability between the co- and counter-passing EPs. The first order finite orbit width correction is found be to stabilizing with co-passing EPs and destabilizing with counter-passing particles. Finally, drift resonances between passing EPs and the tearing mode induces finite frequency to the mode and generate finite net torques inside the plasma, due to the neoclassical toroidal viscosity and the Reynolds stress associated with 3-D perturbations.

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A model of energetic ion effects on pressure driven tearing modes in tokamaks

Cited by 15 publications

References 29 publications

Resonant interaction of tearing modes with energetic-ions resulting in fishbone activities on HL-2A

Resonant interaction of tearing modes with energetic-ions resulting in fishbone activities on HL-2A

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

Toroidal modeling of energetic passing particle drift kinetic effects on tearing mode stability

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