Redistribution of Suprathermal Electrons due to Fishbone Frequency Jumps

Macor, A.; Goniche, M.; Artaud, Jean-François; Decker, J.; Elbeze, D.; Garbet, X.; Giruzzi, G.; Hoang, G. T.; Maget, P.; Mazon, D.; Molina, Diego Alonso Restrepo; Nguyen, C.; Peysson, Y.; Sabot, R.; Ségui, J. L.

doi:10.1103/physrevlett.102.155005

Cited by 34 publications

(44 citation statements)

References 23 publications

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“…that this is an 1/1 mode. Also, the profile of the mode at 6 kHz (figure 6(c)) agrees with the simulated structure of the m = 2 modes (figure 6(h)), which agrees with the previous identification of this mode as m/n = 2/2 [7,8]. However, the 9 kHz mode (figure 6(b)) clearly exhibits the profile of an m = 3 mode (figure 6(g)), but previously this mode was identified as 1/1 [7,8].…”

Section: Reanalysis Of the Wavenumbers In Tore Suprasupporting

confidence: 90%

“…Also unexpected, the continuous evolution for the E • g λ product during the frequency jumps obtained in the case of Tore Supra ( figure 7(d)) is substantially different from the values presented in [7,8]: the E • g λ of the 9 kHz mode was estimated as ∼70 keV, while for the 11 and 6 kHz modes, E •g λ ∼ 30 keV was obtained (the 3 kHz mode was not considered in [7,8]).…”

Section: Continuous Evolution Of the Resonant Conditions During Frequmentioning

confidence: 56%

“…In Tore Supra, modes with frequencies up to 20 kHz are observed in plasmas with moderate values of LH power (∼1 MW) and low density (n 0 ∼ 2.5 × 10 19 m −3 ) [7,8]. The frequency evolution of these modes often displays discontinuities (frequency jumps), which are related to abrupt changes between modes with different structures (poloidal and toroidal wavenumbers) [7,8]. The influence of the LH power on the stability of these modes was studied in [8], which presents an experimental bifurcation diagram describing the observed modes according to the LH power.…”

Section: Mode Evolution In Tore Supramentioning

confidence: 99%

“…An analysis of the phase of the induced T e oscillations measured by ECE clearly shows that the poloidal parity of the 3 kHz mode is odd (figure 6(d)), the m/n = 1/1 mode being a natural candidate. However, as in the previous analysis [7,8], the 9 kHz mode was identified as 1/1, and a reanalysis of the wavenumbers was performed.…”

Section: Mode Evolution In Tore Supramentioning

confidence: 99%

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Electron fishbones in FTU and Tore Supra tokamaks

et al. 2012

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This work presents a comparative study of the experimental observation of MHD instabilities identified as electron fishbone-like modes that appear in plasmas with lower hybrid current drive in FTU and Tore Supra tokamaks. Initially, the mode-induced electronic temperature oscillations measured by electron cyclotron emission were used to study the evolutions of the frequency and position of these modes. In FTU, where fishbones with and without bursting behaviour are observed, it was found that the evolutions of the mode position and frequency follow opposite trend in the two regimes. In Tore Supra, where abrupt changes between modes with different mode structures are often observed, it was found that the mode position evolves continuously and the wavenumbers follow an inverse cascade starting from an m/n = 4/4 mode and finishing in an 1/1 mode. In a second step, the energy of resonant electrons was estimated from the resonant condition of the precession drift frequency. It was found that in Tore Supra the resonant condition does not change during the frequency jumps. The relevance of the correction due to the pitch angle of the resonant electrons and the possible role of the energetic passing particles in the drive of these modes are discussed from the results obtained in both machines.

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Section: Reanalysis Of the Wavenumbers In Tore Suprasupporting

confidence: 90%

Section: Continuous Evolution Of the Resonant Conditions During Frequmentioning

confidence: 56%

Section: Mode Evolution In Tore Supramentioning

confidence: 99%

Section: Mode Evolution In Tore Supramentioning

confidence: 99%

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Electron fishbones in FTU and Tore Supra tokamaks

et al. 2012

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“…Electron fishbones driven only by HFS off-axis (near q = 1) ECRH were observed also in HL-1M tokamak [20]; applying LH waves was found to enhance the fishbone, but only in conjunction with ECRH. Meanwhile, the observation of fishbone oscillations driven by only LH waves has been reported on FTU [7,21,22] and Tore Supra [23,24].…”

Section: Experimental Evidences Of Energetic Electron Driven Fishbonesmentioning

confidence: 99%

Theory and modeling of electron fishbones

et al. 2016

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Internal kink instabilities exhibiting fishbone like behavior have been observed in a variety of experiments where a high energy electron population, generated by strong auxiliary heating and/or current drive systems, was present. After briefly reviewing the experimental evidences of energetic electrons driven fishbones, and the main results of linear and nonlinear theory of electron fishbones, the results of global, self-consistent, nonlinear hybrid MHD-Gyrokinetic simulations will be presented. To this purpose, the extended/hybrid MHD-Gyrokinetic code XHMGC will be used. Linear dynamics analysis will enlighten the effect of considering kinetic thermal ion compressibility and diamagnetic response, and kinetic thermal electrons compressibility, in addition to the energetic electron contribution. Nonlinear saturation and energetic electron transport will also be addressed, making extensive use of Hamiltonian mapping techniques, discussing both centrally peaked and offaxis peaked energetic electron profiles. It will be shown that centrally peaked energetic electron profiles are characterized by resonant excitation and nonlinear response of deeply trapped energetic electrons. On the other side, off-axis peaked energetic electron profiles are characterized by resonant excitation and nonlinear response of barely circulating energetic electrons which experience toroidal precession reversal of their motion.

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Energetic Particle Physics Experiments With High Power ECRH on HL-2A

Ding

Chen

et al. 2012

EPJ Web of Conferences

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Abstract. The MHD instabilities driven by the energetic-particles are of particular importance for future burning plasma devices, where energetic particles will be abundantly produced by high power heating and fusion reaction. In this paper, some new phenomena induced by high power ECRH are presented.The high frequency (200kHz-350 kHz) instabilities have been observed during the high power ECRH or NBI. The frequencies of the modes are proportional to Alfvén velocity and very close to the TAE frequency in the plasma core. In the lower frequency range from 10 kHz to 35 kHz, the coexistence of multi-mode has also been found during the high power ECRH. The frequencies of the modes are proportional to Alfvén velocity, but much lower than it. Between the two frequency ranges, a new mode with the frequency from 50 kHz to 100 kHz has been observed with high power ECRH and NBI heating together. The modes have obvious frequency chirping within short time, which is the feature of the EPM like modes.The fishbone instability excited by energetic electrons during ECRH has been identified in HL-2A. It is interested to find the frequency jump phenomena in the high power ECRH. The frequency jumps between 8 kHz and 15 kHz within about 25ms periodically, when the power is 1.2MW. The new results are different from the phenomena on Tore-Supra, because the trapped particle dominates in this case.

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Redistribution of Suprathermal Electrons due to Fishbone Frequency Jumps

Cited by 34 publications

References 23 publications

Electron fishbones in FTU and Tore Supra tokamaks

Electron fishbones in FTU and Tore Supra tokamaks

Theory and modeling of electron fishbones

Energetic Particle Physics Experiments With High Power ECRH on HL-2A

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