Blobs and drift wave dynamics

Zhang, Yanzeng; Krasheninnikov, S. I.

doi:10.1063/1.4994833

Cited by 6 publications

(13 citation statements)

References 15 publications

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“…The iWKE dispersion relation (A4) is plotted in Fig. 2 for comparison with the NLSE dispersion relation (12) and the WM dispersion relation (18). To better understand the discrepancy between the them, let us also consider the traditional wave-kinetic equation (tWKE) [20].…”

Section: Appendix A: Limitations Of Wave-kinetic Modelsmentioning

confidence: 99%

Formation of solitary zonal structures via the modulational instability of drift waves

Zhou

Zhu

Dodin

2019

Plasma Phys. Control. Fusion

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The dynamics of the radial envelope of a weak coherent drift wave is approximately governed by a nonlinear Schrödinger equation, which emerges as a limit of the modified Hasegawa-Mima equation. The nonlinear Schrödinger equation has well-known soliton solutions, and its modulational instability can naturally generate solitary structures. In this paper, we demonstrate that this simple model can adequately describe the formation of solitary zonal structures in the modified Hasegawa-Mima equation, but only when the amplitude of the coherent drift wave is relatively small. At larger amplitudes, the modulational instability produces stationary zonal structures instead. Furthermore, we find that incoherent drift waves with beam-like spectra can also be modulationally unstable to the formation of solitary or stationary zonal structures, depending on the beam intensity. Notably, we show that these drift waves can be modeled as quantumlike particles ("driftons") within a recently developed phase-space (Wigner-Moyal) formulation, which intuitively depicts the solitary zonal structures as quasi-monochromatic drifton condensates. Quantumlike effects, such as diffraction, are essential to these condensates; hence, the latter cannot be described by wave-kinetic models that are based on the ray approximation.

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Section: Appendix A: Limitations Of Wave-kinetic Modelsmentioning

confidence: 99%

Formation of solitary zonal structures via the modulational instability of drift waves

Zhou

Zhu

Dodin

2019

Plasma Phys. Control. Fusion

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“…As opposed to previously exploited linearised models [28,37,38,45,46] we do not apply the OB approximation in the linearised Eqs. (6a), (6b) and (6c) or in the further course of the calculation.…”

Section: Linearised Gyro-fluid Modelmentioning

confidence: 99%

“…In spite of that, recent OB approximated analysis of large inhomogeneity effects on trapped electron or ion temperature gradient driven DW instabilities indicate their relevance for transport bifurcation in the edge of tokamaks [34][35][36]. Initial investigations of large density inhomogeneity effects on the stability and dynamics of collisional DWs rest partly upon the OB approximation and exploit further approximations in their linear analysis [37,38].…”

Section: Introductionmentioning

confidence: 99%

The collisional drift wave instability in steep density gradient regimes

2019

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The collisional drift wave instability in a straight magnetic field configuration is studied within a full-F gyro-fluid model, which relaxes the Oberbeck-Boussinesq (OB) approximation. Accordingly, we focus our study on steep background density gradients. In this regime we report on corrections by factors of order one to the eigenvalue analysis of former OB approximated approaches as well as on spatially localised eigenfunctions, that contrast strongly with their OB approximated equivalent. Remarkably, non-modal phenomena arise for large density inhomogeneities and for all collisionalities. As a result, we find initial decay and non-modal growth of the free energy and radially localised and sheared growth patterns. The latter non-modal effect sustains even in the nonlinear regime in the form of radially localised turbulence or zonal flow amplitudes. II. GYRO-FLUID MODELOur analysis is based on an energetically consistent full-F gyro-fluid model [39], which is derived by taking the gyro-fluid moments over the gyro-kinetic Vlasov-Maxwell equations [40]. In order to ease the following

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“…The critical (negative) temperature (3.47) and amplitude (3.50) of accumulation into the blob-hole mode are given quantitatively in closed form by solving exactly the free energy of the model. Although it remains a current topic of discussion in the plasma literature, the blob-hole structure is, according to a working definition, as follows (D 'Ippolito, Myra & Zweben 2011;Kosuga & Diamond 2013;Krasheninnikov 2016;Zhang & Krasheninnikov 2017): 'A blob-filament (or simply blob) is a magnetic-field-aligned plasma structure which is considerably denser than the surrounding background plasma and highly localized in the directions perpendicular to the equilibrium magnetic field B. In experiments and simulations, these intermittent filaments are often formed near the boundary between open and closed field lines, and seem to arise in theory from the saturation process for the dominant edge instabilities and turbulence.…”

Section: Introductionmentioning

confidence: 99%

Phase transition to blob-hole coherent structure in the Hasegawa–Mima model for plasmas

Lim¹

2021

J. Plasma Phys.

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An equilibrium statistical mechanics theory for the Hasegawa–Mima equations of toroidal plasmas, with canonical constraint on energy and microcanonical constraint on potential enstrophy, is solved exactly as a spherical model. The use of a canonical energy constraint instead of a fixed-energy microcanonical approach is justified by the preference for viewing real plasmas as an open system. A significant consequence of the results obtained from the partition function, free energy and critical temperature, is the condensation into a ground state exhibiting a blob-hole-like structure observed in real plasmas.

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Blobs and drift wave dynamics

Cited by 6 publications

References 15 publications

Formation of solitary zonal structures via the modulational instability of drift waves

Formation of solitary zonal structures via the modulational instability of drift waves

The collisional drift wave instability in steep density gradient regimes

Phase transition to blob-hole coherent structure in the Hasegawa–Mima model for plasmas

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