Fishbone instability excited by circulating electrons

Wang, Z.T.; Long, Y. X.; Wang, A.K.; Dong, J. Q.; Long, Wang; Zonca, F.

doi:10.1088/0029-5515/47/9/030

Cited by 20 publications

(30 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Equations (4) and (12) generalize the electron fishbone dispersion relations, analyzed recently [12,13,31], to both trapped and barely circulating fast particles, including (s, α) model equilibrium effects onω d . A detailed discussion of the circulating electron effect on δŴ k was recently given in [32]. A further extension of Eqs.…”

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

confidence: 99%

“…That δŴ k,N L is predominantly imaginary, as it emerges from comparisons of Eqs. (32) and (39), suggests that the nonlinear fishbone cycle is essentially determined by the fast particle scattering out of the resonant region. Given the fluctuation level of the mode, the nonlinear time scale, τ N L , as derived from Eq.…”

Section: Nonlinear Amplitude Equationmentioning

confidence: 99%

“…When analyzing nonlinear fast particle behaviors, another source of symmetry breaking between bounce-averaged fast electron and ion dynamics emerges from Eqs. ( 27), (32) and (39): the term ∝ v exp i(1 − q)θ (v exp i(1 − q)θ = 0 for trapped particles), is responsible for the barely circulating fast particle radial transport due to the magnetic component of the fluctuations and clearly depends on the particle mass. For particle distribution functions that are symmetric in v , this term is unimportant.…”

Section: Nonlinear Amplitude Equationmentioning

confidence: 99%

See 2 more Smart Citations

Electron fishbones: theory and experimental evidence

et al. 2007

View full text Add to dashboard Cite

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.

show abstract

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

confidence: 99%

Section: Nonlinear Amplitude Equationmentioning

confidence: 99%

Section: Nonlinear Amplitude Equationmentioning

confidence: 99%

See 1 more Smart Citation

Electron fishbones: theory and experimental evidence

et al. 2007

View full text Add to dashboard Cite

show abstract

“…The instability is thought to be excited by the barely trapped electrons (BTEs) [32] or the barely circulating electrons (BCEs) at the negative magnetic shear [36,37]. To identify the resonance conditions, hard x-ray detectors (CdTe) were used to measure the energetic electron spectra on HL-2A.…”

Section: Internal Kink Mode Driven By Energetic Electronsmentioning

confidence: 99%

Overview of experimental results on HL-2A

et al. 2009

Self Cite

View full text Add to dashboard Cite

Abstract. Significant experimental advances have been made on HL-2A tokamak along with substantial improvement and development of hardware. The three dimensional spectral structures of the low frequency zonal flow, the geodesic acoustic mode (GAM), and quasi-mode-like low frequency fluctuations have been observed simultaneously for the first time. In addition, the spectral structure of the density fluctuation at GAM frequency is also identified. A spontaneous particle transport barrier has been observed in Ohmic discharges without any external momentum input. The barrier is evidenced by particle perturbation study using modulated SMBI and microwave reflectometry. The non-local transport effect with new features induced by SMBI has been investigated. The e-fishbone instability excited by energetic electrons of non-Maxwellian distribution has been investigated via 10-channel CdTe hard x-ray detector. It is found that the e-fishbone is correlated with the existence of energetic electrons of 30-70 keV. The experiment shows that the suppression of m/n = 2/1 tearing modes can be sustained by ECRH with low modulation frequency of about 10 Hz. Extended confinement improvement is obtained after the mode suppression.

show abstract

“…It was then found that resonance can occur between circulating energetic ions and the kink modes [24][25]. On the other hand, energetic electrons have similar effects on kink modes due to drift-reversal for the barely trapped electrons or due to the negative magnetic shear for the passing particles [26][27][28][29]. Moreover, energetic electrons in the trapped-passing boundary are recently found to interact with a tearing mode leading to chirping-down of magnetic island rotation frequency in the lower collision region [30][31][32].…”

Section: Introductionmentioning

confidence: 99%

The dynamics of a neoclassical tearing mode (NTM) influenced by energetic ions on EAST

Li¹,

Igochine²,

Xu³

et al. 2016

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

In the 2014 year's campaign of Experimental Advanced Superconducting Tokamak (EAST), a series of Magnetohydrodynamics (MHD) instabilities were observed as the launching of Neutral Beam Injection (NBI), the most interesting one of which is the neoclassical tearing mode (NTM). Evidence clearly shows that a kink mode present after a strong sawtooth-like (ST-like) crash leaves a perturbation near the location of the magnetic island, providing the initial seed. The interaction of energetic ions makes the magnetic island oscillate both in island width and in rotation frequency. Analysis indicates that the bulk plasma still 2 dominates the dynamics of NTM, and the orbit excursion of energetic ions induces a polarization current and modifies the width and rotation frequency of the neoclassical magnetic island.

show abstract

Fishbone instability excited by circulating electrons

Cited by 20 publications

References 15 publications

Electron fishbones: theory and experimental evidence

Electron fishbones: theory and experimental evidence

Overview of experimental results on HL-2A

The dynamics of a neoclassical tearing mode (NTM) influenced by energetic ions on EAST

Contact Info

Product

Resources

About