Intrinsic flow and tearing mode rotation in the RFP during improved confinement

Craig, D.; Tan, E. H.; Schott, Benedikt; Anderson, J. K.; Boguski, J.; Hartog, D. J. Den; Nishizawa, T.; Nornberg, M. D.; Xing, Zichuan

doi:10.1063/1.5095620

Cited by 6 publications

(3 citation statements)

References 51 publications

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“…Despite the interest in the RFP plasma viscosity, no unique consensus on either the form of the viscous term or the viscosity coefficient evaluation in RFP plasmas still exists [1]. In fact, the experimental estimates [11,12,13,14,15] carried on according to classical [16] or turbulent transport [17,18] theory display orders of magnitude differences. In addition, a more recent study [19] has shown the electrostatic turbulence to play a central role in fusion plasmas momentum transport.…”

Section: Introductionmentioning

confidence: 99%

Kinematic viscosity estimates in reversed-field pinch fusion plasmas

Vivenzi

Spizzo

Veranda

et al. 2022

J. Phys.: Conf. Ser.

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This paper concerns the kinematic viscosity in reversed-field pinch fusion plasmas, including both the study of numerical magneto-hydrodynamics (MHD) simulations and the analysis of RFX-mod experimental data. In the first part, we study the role of non-uniform time-constant radial viscosity profiles in 3D non-linear visco-resistive MHD simulations. The new profiles induce a moderate damp (for the velocity field) and a correspondent enhancement (for the magnetic field) of the spectral components resonating in the regions where the viscosity is higher. In the second part, we evaluate the kinematic viscosity coefficient on a wide database of RFX-mod shots according to the transport theories of Braginskii (considering parallel, perpendicular and gyro viscosity coefficients), considering the action on viscosity of ITG modes (ion temperature gradient) and according to the transport theory of Finn. We then exploit the comparison with the visco-resistive MHD simulations (where the visco-resistive dissipation rules the MHD activity) to show that the classical Braginskii perpendicular viscosity produces the best agreement between simulations and data, followed by the Braginskii gyro-viscosity.

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Section: Introductionmentioning

confidence: 99%

Kinematic viscosity estimates in reversed-field pinch fusion plasmas

Vivenzi

Spizzo

Veranda

et al. 2022

J. Phys.: Conf. Ser.

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“…On the other hand, researches also indicate that the plasma flow is a crucial factor for the MHD control and it makes a significant impact on the MHD instabilities [34]. On the Madison Symmetric Torus, the result showed that the mode rotation was strongly affected by the toroidal flow at the resonant surface [35]. Recent simulations have also shown that the magnitude of the toroidal flow, rather than the flow shear, makes an influence on the dynamics of magnetic islands [36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Effect of the toroidal flow and flow shear on the m/n = 2/1 tearing mode in J-TEXT tokamak

Shao¹,

Liu²,

Xu³

et al. 2021

Plasma Phys. Control. Fusion

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The effect of the toroidal flow and flow shear on the m/n = 2/1 tearing mode (TM) has been investigated in J-TEXT tokamak, where m and n are the poloidal and toroidal mode numbers. It is found that the toroidal flow increment is linearly modulated by the bias current/return current. The frequency of the 2/1 TM is also found to be proportional to the toroidal flow during the bias phase, which is consistent with the theoretical expectation. The electron diamagnetic drift frequency is almost constant before and during the bias phase. Moreover, the statistical analysis shows that the saturated island width of the TM is more correlated to the toroidal flow amplitude than the flow shear, which reveals that the effect of the TM depends on the magnitude of the toroidal flow rather than the flow shear. This result may illustrate the process of the 2/1 TM controlled by the electrode biasing, and suggests that changing the magnitude of toroidal flow is a possible method for stabilizing the TM.

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“…In tokamaks, magnetohydrodynamic (MHD) instability modes often collapse with an abrupt transport of energy and particles. Notable examples are sawtooth crashes [1,2], the formation of tearing modes [3,4], and the burst of edge-localized modes (ELMs) [5][6][7]. On a larger scale, other examples include the ionospheric flows [8] and the sporadic explosion of the coronal loops on the surface of the Sun [9].…”

Section: Introductionmentioning

confidence: 99%

Cold-hot coupled waves in a flowing magnetized plasma

Lee

Yun

2020

Nucl. Fusion

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Nonlinear coupling of cold and hot waves in a flowing magnetized plasma is analyzed with the Vlasov equation. An analytical solution is obtained for cold waves of a small amplitude (weak flow) and a long wavelength. The distribution function is obtained by integrating the kinetic equation along a perturbed phase-space trajectory for a time-varying plasma flow. The kinetic description presents a generalized dispersion relation that involves resonances depending on cold and hot wave dispersions. Coherent fluid motion leads to radiation peaks in addition to the cyclotron harmonics, where the wavenumber of the cold wave determines the peak frequencies. The peaks appear narrow when the wave propagates perpendicular to the time-averaged flow while they become broad due to the Doppler effect when the wave propagates parallel to the flow. Fully kinetic particle-in-cell simulations corroborate the theoretical predictions. The dispersion relation and resulting wave spectra provide information about plasma parameters and flow properties.

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Intrinsic flow and tearing mode rotation in the RFP during improved confinement

Cited by 6 publications

References 51 publications

Kinematic viscosity estimates in reversed-field pinch fusion plasmas

Kinematic viscosity estimates in reversed-field pinch fusion plasmas

Effect of the toroidal flow and flow shear on the m/n = 2/1 tearing mode in J-TEXT tokamak

Cold-hot coupled waves in a flowing magnetized plasma

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