Sawtooth stabilization by barely trapped energetic electrons

Zhou, Deng; Wang, Shaojie; Zhang, Cheng

doi:10.1063/1.1929776

Cited by 4 publications

(13 citation statements)

References 18 publications

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“…A further extension of Eqs. (4) and (12) to a broader frequency range than that usually assumed near the ion diamagnetic gap [11] in the low-frequency shear Alfvén continuum is discussed in Section 2.2.…”

Section: Resonant Excitation By Trapped and Barely Circulating Supra-mentioning

confidence: 96%

“…with k s q s R 0 = ∆q s = q s − 1 in this case. Equations (4) and (12) are the basis for our linear stability studies of electronfishbones. Their general structure in is known; however, we want to emphasize two novel aspects: (i) that Eq.…”

Section: Mode Dispersion Relationsmentioning

confidence: 99%

“…Note that magnetic shear never enters in the accumulation point expression, as expected for local oscillations of the shear Alfvén continuum and explicitly shown by Eqs. (11) and (12).…”

Section: High-frequency Fishbonesmentioning

confidence: 99%

“…The peculiar roles of trapped and barely circulating particles will be further discussed in Section 2.2 in connection with the generalized inertia term, Λ, appearing in Eqs. ( 4) and (12).…”

Section: Resonant Excitation By Trapped and Barely Circulating Supra-...mentioning

confidence: 99%

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Electron fishbones: theory and experimental evidence

et al. 2007

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We discuss the processes underlying the excitation of fishbone-like internal kink instabilities driven by supra-thermal electrons generated experimentally by different means: Electron Cyclotron Resonance Heating (ECRH) and by Lower Hybrid (LH) power injection. The peculiarity and interest of exciting these electron fishbones by ECRH only or by LH only is also analyzed. Not only the mode stability is explained, but also the transition between steady state nonlinear oscillations to bursting (almost regular) pulsations, as observed in FTU, is interpreted in terms of the LH power input. These results are directly relevant to the investigation of trapped alpha particle interactions with low-frequency MHD modes in burning plasmas: in fact, alpha particles in reactor relevant conditions are characterized by small dimensionless orbits, similarly to electrons; the trapped particle bounce averaged dynamics, meanwhile, depends on energy and not mass.

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Section: Resonant Excitation By Trapped and Barely Circulating Supra-mentioning

confidence: 96%

Section: Mode Dispersion Relationsmentioning

confidence: 99%

“…Note that magnetic shear never enters in the accumulation point expression, as expected for local oscillations of the shear Alfvén continuum and explicitly shown by Eqs. (11) and (12).…”

Section: High-frequency Fishbonesmentioning

confidence: 99%

Section: Resonant Excitation By Trapped and Barely Circulating Supra-...mentioning

confidence: 99%

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Electron fishbones: theory and experimental evidence

et al. 2007

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“…11 and 12) with LHW injection. Some authors have proposed several theoretical models: the dominant notion proposed by Wong et al, 9 Zonca et al, 8 and Wang et al [13][14][15][16][17] is that the ideal kink mode resonates with barely trapped energetic electrons for they spend longer time on the high field side, resulting in their precessional direction reversing to the same as that of energetic ions.…”

Section: Introductionmentioning

confidence: 97%

Nonideal fishbone instability excited by trapped energetic electrons

2013

Physics of Plasmas

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It is shown that trapped energetic electrons can resonate with the collisionless m ¼ 1 nonideal kink mode, therefore exciting the nonideal e-fishbone, which would often lead to a drop in soft x-ray emissivity and frequency chirping. The theory predictions agree well with the experimental observations of e-fishbone on HL-2A. It is also found that the effects of MHD energy of background plasma might be the reason for the observed phenomena: frequency chirping up and down, and V-font-style sweeping. V C 2013 American Institute of Physics.

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Excitation of internal kink mode by barely trapped suprathermal electrons

et al. 2005

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The barely trapped suprathermal electrons can destabilize the internal kink mode when their density gradient is positive within the rational surface and the beta value of the suprathermal electrons exceeds a threshold value. With the assumption of two different models of energy distribution of the suprathermal electrons, the threshold beta value of the barely trapped suprathermal electrons, the real frequency, and the growth rate of the internal kink mode are found in this paper. The results are in reasonable agreement with the recent experimental observations on DIII-D tokamak [K. L. Wong, M. S. Chu, T. C. Luce et al., Phys. Rev. Lett. 85, 996 (2000)].

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Sawtooth stabilization by barely trapped energetic electrons

Cited by 4 publications

References 18 publications

Electron fishbones: theory and experimental evidence

Electron fishbones: theory and experimental evidence

Nonideal fishbone instability excited by trapped energetic electrons

Excitation of internal kink mode by barely trapped suprathermal electrons

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