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Title: The ecology of flows and drift wave turbulence in CSDX: A model

Abstract

This paper describes the ecology of drift wave turbulence and mean flows in the coupled drift-ion acoustic wave plasma of a CSDX linear device. A 1D reduced model that studies the spatiotemporal evolution of plasma mean density $$\bar{n}$$, and mean flows $$\bar{v}$$y and $$\bar{v}$$z, in addition to fluctuation intensity ε, is presented. Here, ε = n ~ 2 + ( Φ ~ ) 2 + v ~ z 2 is the conserved energy field. The model uses a mixing length l mix inversely proportional to both axial and azimuthal flow shear. This form of l mix closes the loop on total energy. The model self-consistently describes variations in plasma profiles, including mean flows and turbulent stresses. It investigates the energy exchange between the fluctuation intensity and mean profiles via particle flux n ~ v ~ x and Reynolds stresses v ~ x v ~ y and v ~ x v ~ z Acoustic coupling breaks parallel symmetry and generates a parallel residual stress Π res xz . The model uses a set of equations to explain the acceleration of $$\bar{v}_y$$ and $$\bar{v}_z$$ via Π x y r e s n - and Π x y r e s n - . Flow dynamics in the parallel direction are related to those in the perpendicular direction through an empirical coupling constant σVT. This constant measures the degree of symmetry breaking in the 〈$$k_mk_z$$〉 correlator and determines the efficiency of ∇$$\bar{n}$$ in driving $$\bar{v}_z$$. The model also establishes a relation between ∇$$\bar{v}_y$$ and ∇$$\bar{v}_z$$, via the ratio of the stresses Π res xy and Π res xz . When parallel to perpendicular flow coupling is weak, axial Reynolds power P x z R e = - v ~ x v ~ z v - z is less than the azimuthal Reynolds power P x y R e = - v ~ x v ~ y v - y ∇$$\bar{v}_y$$. The model is then reduced to a 2-field predator/prey model where $$\bar{v}_z$$ is parasitic to the system and fluctuations evolve self-consistently. Finally, turbulent diffusion in CSDX follows the scaling: D CSDX = D B ρ * 0.6 , where D B is the Bohm diffusion coefficient and ρ * is the ion gyroradius normalized to the density gradient | n - / n - | - 1

Authors:
 [1];  [2];  [3]
  1. Univ. of California, San Diego, CA (United States). Center for Energy Research
  2. Univ. of California, San Diego, CA (United States). Center for Energy Research, Center for Astrophysics and Space Sciences; Center for Fusion Sciences, Southwestern Inst. of Physics, Chengdu, Sichuan (China)
  3. Univ. of California, San Diego, CA (United States). Center for Energy Research; Center for Fusion Sciences, Southwestern Inst. of Physics, Chengdu, Sichuan (China)
Publication Date:
Research Org.:
Univ. of California, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1524572
Alternate Identifier(s):
OSTI ID: 1420214
Grant/Contract Number:  
FG02-04ER54738
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 2; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Hajjar, R. J., Diamond, P. H., and Tynan, G. R. The ecology of flows and drift wave turbulence in CSDX: A model. United States: N. p., 2018. Web. doi:10.1063/1.5018320.
Hajjar, R. J., Diamond, P. H., & Tynan, G. R. The ecology of flows and drift wave turbulence in CSDX: A model. United States. https://doi.org/10.1063/1.5018320
Hajjar, R. J., Diamond, P. H., and Tynan, G. R. Thu . "The ecology of flows and drift wave turbulence in CSDX: A model". United States. https://doi.org/10.1063/1.5018320. https://www.osti.gov/servlets/purl/1524572.
@article{osti_1524572,
title = {The ecology of flows and drift wave turbulence in CSDX: A model},
author = {Hajjar, R. J. and Diamond, P. H. and Tynan, G. R.},
abstractNote = {This paper describes the ecology of drift wave turbulence and mean flows in the coupled drift-ion acoustic wave plasma of a CSDX linear device. A 1D reduced model that studies the spatiotemporal evolution of plasma mean density $\bar{n}$, and mean flows $\bar{v}$y and $\bar{v}$z, in addition to fluctuation intensity ε, is presented. Here, ε=〈n~2+(∇⊥Φ~)2+v~z2〉 is the conserved energy field. The model uses a mixing length lmix inversely proportional to both axial and azimuthal flow shear. This form of lmix closes the loop on total energy. The model self-consistently describes variations in plasma profiles, including mean flows and turbulent stresses. It investigates the energy exchange between the fluctuation intensity and mean profiles via particle flux 〈n~v~x〉 and Reynolds stresses 〈v~xv~y〉 and 〈 v~xv~z〉 Acoustic coupling breaks parallel symmetry and generates a parallel residual stress Π res xz . The model uses a set of equations to explain the acceleration of $\bar{v}_y$ and $\bar{v}_z$ via Πxyres∝∇n- and Πxyres∝∇n-. Flow dynamics in the parallel direction are related to those in the perpendicular direction through an empirical coupling constant σVT. This constant measures the degree of symmetry breaking in the 〈$k_mk_z$〉 correlator and determines the efficiency of ∇$\bar{n}$ in driving $\bar{v}_z$. The model also establishes a relation between ∇$\bar{v}_y$ and ∇$\bar{v}_z$, via the ratio of the stresses Π res xy and Π res xz . When parallel to perpendicular flow coupling is weak, axial Reynolds power PxzRe=-〈v~xv~z〉∇v-z is less than the azimuthal Reynolds power PxyRe=-〈v~xv~y〉∇v-y∇$\bar{v}_y$. The model is then reduced to a 2-field predator/prey model where $\bar{v}_z$ is parasitic to the system and fluctuations evolve self-consistently. Finally, turbulent diffusion in CSDX follows the scaling: DCSDX=DBρ*0.6, where DB is the Bohm diffusion coefficient and ρ* is the ion gyroradius normalized to the density gradient |∇n-/n-|-1},
doi = {10.1063/1.5018320},
url = {https://www.osti.gov/biblio/1524572}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 2,
volume = 25,
place = {United States},
year = {2018},
month = {2}
}

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Cited by: 3 works
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Figures / Tables:

FIG. 1 FIG. 1: A schematic of the ecology of drift wave turbulence, zonal, and axial flows. The first feedback loop relates the drift waves to the zonal flows via ( ~v x ~v y). A second feedback loop exists as a result of a potential relation between $$\bar{v}$$ y and $$\bar{v}$$more » z. The second loop relates the fluctuations to both mean flows.« less

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    Works referencing / citing this record:

    Generation of parasitic axial flow by drift wave turbulence with broken symmetry: Theory and experiment
    journal, May 2018


    How shear increments affect the flow production branching ratio in CSDX
    journal, June 2018


    Simultaneous measurements of turbulent Reynolds stresses and particle flux in both parallel and perpendicular directions in a linear magnetized plasma device
    journal, October 2018


    Scale selection and feedback loops for patterns in drift wave-zonal flow turbulence
    journal, August 2019


      Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.