Comprehensive linear model for the <i>n</i> = <i>m</i> = 1 fishbone kinetic-MHD instability

Brochard, Guillaume; Dümont, R.; Garbet, X.; Lütjens, H.; Nicolas, T; Orain, F.

doi:10.1088/1742-6596/1125/1/012003

Cited by 9 publications

(46 citation statements)

References 13 publications

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“…The number of particle is integrated over unit surface (x and y directions are subdivided into 100 pieces for the integration). for similar conditions of fast particles of 1 MeV in ITER [20,21]. In this linear study, no resonance is found with passing particles but a resonance with trapped particles destabilize the n = 1 fishbone mode.…”

Section: Nbi Impact In An Iter-like Casementioning

confidence: 56%

“…Collision rate and NBI power are enhanced by a factor 10 to obtain in a reasonable time a slowing-down distribution, as explained above. The reason why NBI source #5 is chosen here is that a positive fast particle density gradient ∇n i,f ast > 0 is necessary to obtain the growth of a fishbone mode or the stabilization of a kink mode [20,21]. Otherwise, if a resonance occurs with ∇n i,f ast < 0, no resonant transport is induced and thus the resonance cannot be detected.…”

Section: Resonance Between Nbi-induced Fast Particles and The N = 1 M...mentioning

confidence: 99%

“…To answer this question, we need to compare the kink mode frequency with the particle frequencies. Let us first define the characteristic particle frequencies Ω 1−3 , as defined in the angle-action formalism [7,20]. Ω 1 is the cyclotron frequency:…”

Section: B Evidence Of Resonance Between Fast Particles and The N = 1...mentioning

confidence: 99%

“…Therefore, as explained in Refs. [20,21], the only resonance available with the n = m = 1 internal kink mode is the precessional resonance characterized by…”

Section: B Evidence Of Resonance Between Fast Particles and The N = 1...mentioning

confidence: 99%

“…For simplicity and for comparisons with the linear model for kink-fishbone stability described in Refs. [20,21], a circular cross-section is chosen. The resolutions taken in radial, poloidal and toroidal directions respectively are: 201, 128 and 32 points.…”

Section: Nbi Impact In An Iter-like Casementioning

confidence: 99%

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En route to realistic modeling of the kinetic-MHD interaction between macroscopic modes and fast particles induced by neutral beam injection in tokamaks

Orain,

Brochard,

Nicolas

et al. 2020

Preprint

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A new model of fast ion source induced by Neutral Beam Injection (NBI) in tokamaks has been implemented in the hybrid kinetic-magnetohydrodynamic code XTOR-K. This source, combined with the collisions also recently implemented, allows for the modeling of realistic slowing-down populations and their interplay with macroscopic modes. This paper describes the Neutral Beam injection and ionization model designed to reproduce experimental configurations and its validation for a typical discharge of the ASDEX Upgrade tokamak. The application to the interaction of NBI-induced fast particles with a kink mode in ASDEX Upgrade demonstrates a resonance between passing particles and the n = 1 mode. This resonance partially stabilizes the kink mode and induces a radial transport of fast particles. Preliminary results in ITER-like circular geometry show that NBI induces a toroidal torque but has little impact on the kink mode dynamics.

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Section: Nbi Impact In An Iter-like Casementioning

confidence: 56%

Section: Resonance Between Nbi-induced Fast Particles and The N = 1 M...mentioning

confidence: 99%

Section: B Evidence Of Resonance Between Fast Particles and The N = 1...mentioning

confidence: 99%

“…Therefore, as explained in Refs. [20,21], the only resonance available with the n = m = 1 internal kink mode is the precessional resonance characterized by…”

Section: B Evidence Of Resonance Between Fast Particles and The N = 1...mentioning

confidence: 99%

Section: Nbi Impact In An Iter-like Casementioning

confidence: 99%

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En route to realistic modeling of the kinetic-MHD interaction between macroscopic modes and fast particles induced by neutral beam injection in tokamaks

Orain,

Brochard,

Nicolas

et al. 2020

Preprint

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Excitation of 2/1 fishbone-like modes by trapped energetic ions

Zhang

Gao

Cai

et al. 2020

Plasma Phys. Control. Fusion

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A new branch of the m/n = 2/1 fishbone-like mode is found to be excitated by trapped energetic ions when the tearing mode is unstable. An energy-principle-based dispersion relation is derived and analyzed, which incorporates the wave-particle resonance and the resistive layer physics. Once the beta amplitude of trapped energetic ions exceeds a critical value, 2/1 fishbone-like instabilities would appear. The mode transition from tearing mode to 2/1 fishbone-like mode will be triggered with the increasing beta of trapped energetic ions. The total effects of the ideal magnetohydrodynamic potential energy and the adiabatic contribution of trapped energetic ions on the real frequency and growth rate of 2/1 fishbone-like modes are investigated; the effects of magnetic Reynolds number and magnetic shear are also studied. Both resistivity and magnetic shear play a stable role on 2/1 fishbone-like modes. An implication of the theory is conducive to understanding the 2/1 fishbone-like activities observed recently in HL-2A.

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Linear stability of the ITER 15 MA scenario against the alpha fishbone

et al. 2020

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The stability of the n = m = 1 alpha-fishbone kinetic-MHD mode on the ITER 15 MA baseline scenario (ITER Physics Expert Group on Energe Drive and ITER Physics Basis 1999 Nucl. Fusion 39 2471-95) is analyzed using the non-linear hybrid kinetic-MHD code XTOR-K. Quantitative agreement is found between the complex frequencies ω + iγ computed with the linear model in (Brochard G. et al 2018 J. Phys.: Conf. Series 1125 012003) and XTOR-K's linear simulations. Identical precessional resonance positions in phase space are also found between the linear model and XTOR-K. Linear hybrid simulations performed with XTOR-K on the ITER 15 MA scenario reveal that this configuration is likely to be unstable against the alpha fishbone mode. The fishbone thresholds for kinetic-MHD equilibria with flat q profiles with on-axis safety factor just below unity lies between βα,thres/βtot = 6 10%, whereas the expected beta ratio on ITER is βα/βtot = 15 20% (ITER Physics Expert Group on Energe Drive and ITER Physics Basis 1999 Nucl. Fusion 39 2471-95).

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Comprehensive linear model for the n = m = 1 fishbone kinetic-MHD instability

Cited by 9 publications

References 13 publications

En route to realistic modeling of the kinetic-MHD interaction between macroscopic modes and fast particles induced by neutral beam injection in tokamaks

En route to realistic modeling of the kinetic-MHD interaction between macroscopic modes and fast particles induced by neutral beam injection in tokamaks

Excitation of 2/1 fishbone-like modes by trapped energetic ions

Linear stability of the ITER 15 MA scenario against the alpha fishbone

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