Turbulence intensity pulse propagation with self-consistent nonlinear noise

Wang, Z. H.; Diamond, P. H.; Gürcan, Ö. D.; Garbet, X.; Wang, X. G.

doi:10.1063/1.3567142

Cited by 4 publications

(4 citation statements)

References 36 publications

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“…In recent years, turbulence theories focusing on multiple-scaled nonlinear and statistical dynamics have gained traction in addressing this enigma. These include turbulence spreading models [18-20, 22, 25] and the concept of self-organized criticality (SOC) [23][24][25][26]. Moreover, several studies propose that the transition between trapped electron modes (TEMs) and ion temperature gradient modes (ITGs) may play a role in the critical nature of non-local effects [27].…”

Section: Introductionmentioning

confidence: 99%

Destabilization of toroidal Alfvén eigenmode during neutral beam injection heating on HL-2A

et al. 2017

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Toroidal Alfvén eigenmodes (TAEs) driven by fast ions during neutral beam injection heating have been observed on HL-2A. TAEs are found to be excited by the sideband resonance between fast ions and shear Alfvén waves. Their frequencies range from 90 kHz to 200 kHz, and toroidal mode numbers of the most unstable TAEs are n = 1–3. Nonlinear behaviours of TAEs, such as frequency chirping, pitch-fork splitting, and nonlinear mode-mode coupling, are also excited. In the down-chirping case, TAEs show typical ballooning mode structures and their amplitudes are around δBr = 3.25 × 10−4T at the edge of the plasma. The mode frequency is proportional to the square of time, i.e., f(t) ∼ t1∕2, which agrees well with the theoretical prediction. Pitch-fork splitting of TAEs has also been excited on HL-2A, and their growth rate is about γl ∼ 0.22 × 104 s−1. TAE coupling with a tearing mode results in the appearances of series of Alfvénic modes (AMs). The two AMs, which have the same absolute mode number but rotate in different diamagnetic drift directions, couple together and lead to the generation of a high frequency mode with a toroidal mode number of n = 0. The experimental results also indicate that nonlinear mode-mode coupling degenerates the confinement of fast ions.

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Section: Introductionmentioning

confidence: 99%

Destabilization of toroidal Alfvén eigenmode during neutral beam injection heating on HL-2A

et al. 2017

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“…Later, Gurcan et al [15] pointed out that the toroidal coupling and the zonalflow induced side-band coupling are not the necessary condition for the ballistic turbulence spreading. Such propagation of the turbulence energy front, proportional to the geometric mean of the growth and diffusion rates of turbulence, is possible via the nonlinear dynamics alone [15,20]. This result is further verified by a gyro-kinetic particle simulations of toroidal ion temperature gradient turbulence spreading from the edge to the core regions of tokamak [16].…”

Section: Introductionmentioning

confidence: 55%

Electromagnetic drift wave instability in tokamak plasmas with strong pedestal gradient

et al. 2023

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The linear eigenmode characterizations and the nonlinear turbulence energy spreading of the drift waves in a tokamak plasma with strong pedestal gradient are numerically investigated based on an electromagnetic Landau fluid model. By the linear eigenmode analysis, it is found that the dominant instability in the low $\beta$ regime is the ion-temperature-gradient (ITG$^c$) mode and the electron drift wave instability (eDWI$^p$) in the core and edge region with strong density gradient, respectively. Multiple eigenstates of the eDWI$^p$ with different peak locations in the poloidal direction can be obtained by the eigenvalue problem solver. The dominant one is the high order eDWI$^p$ corresponding to the unconventional ballooning mode structure with multiple peaks in the poloidal position, in contrast to the conventional modes that peak at the outboard mid-plane, and has been verified through initial value simulation. In the high $\beta$ regime, the dominant eigenmodes in the core and edge region are the conventional and unconventional kinetic ballooning modes respectively. In the nonlinear simulation, an inward turbulence spreading phenomenon during the quasi-saturation phase of the edge turbulence is clearly observed. The inward speed of the turbulence energy front in the high $\beta$ regime is much faster than that in the low $\beta$ regime. It is interestingly found that the speed of the turbulence energy front increases with the increase of the plasma $\beta$ in the low $\beta$ regime, while it is almost unchanged in the high $\beta$ regime. It is identified that the turbulence spreading in the low and high $\beta$ regimes are determined by the nonlinear dynamics and the linear toroidal coupling respectively.

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“…[16,17] In recent years, turbulence theories focusing on multiplescaled nonlinear and statistical dynamics have gained traction in addressing this enigma. These include turbulence spreading models [18][19][20]22,25] and the concept of self-organized criticality (SOC) [23][24][25][26] . Moreover, several studies propose that the transition between trapped electron modes (TEMs) and ion temperature gradient modes (ITGs) may play a role in the critical nature of non-local effects.…”

Section: Introductionmentioning

confidence: 99%

Long radial coherence of electron temperature fluctuations in non-local transport in HL-2A plasmas

Shi 石,

Fang 方,

Li 李

et al. 2024

Chinese Phys. B

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The dynamics of long-wavelength ($k_\theta<1.4 \mathrm{\ cm^{-1}}$), broadband (20-200 kHz) electron temperature fluctuations ($\tilde T_e/T_e$) of plasmas in gas-puff experiments were observed for the first time in HL-2A tokamak. In a relative low density ($n_e(0) \simeq 0.91 \sim 1.20 \times10^{19}/m^3$) scenario, after gas-puffing the core temperature increases and the edge temperature drops. On the contrary, temperature fluctuation drops at the core and increases at the edge. Analyses show the non-local emergence is accompanied with a long radial coherent length of turbulent fluctuations. While in a higher density ($n_e(0) \simeq 1.83 \sim 2.02 \times10^{19}/m^3$) scenario, the phenomena were not observed. Furthermore, compelling evidence indicates that $\textbf{E} \times \textbf{B}$ shear serves as a substantial contributor to this extensive radial interaction. This finding offers a direct explanatory link to the intriguing core-heating phenomenon witnessed within the realm of non-local transport.

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Turbulence intensity pulse propagation with self-consistent nonlinear noise

Cited by 4 publications

References 36 publications

Destabilization of toroidal Alfvén eigenmode during neutral beam injection heating on HL-2A

Destabilization of toroidal Alfvén eigenmode during neutral beam injection heating on HL-2A

Electromagnetic drift wave instability in tokamak plasmas with strong pedestal gradient

Long radial coherence of electron temperature fluctuations in non-local transport in HL-2A plasmas

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