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Title: Integrated Study of the Nonlinear Dynamics of Collisional Drift Wave Turbulence

Abstract

An existing linear magnetized plasma device, the Controlled Shear Decorrelation experiment (CSDX) was used to study the transition from a state of coherent wave like activity to a state of turbulent activity using the magnetic field and thus magnetization of the plasma as the control parameter. The results show the onset of coherent drift waves consistent with linear stability analysis. As the magnetization is raised, at first multiple harmonics appear, consistent with wave steepening. This period is then followed by the beginning of nonlinear interactions between different wave modes, which then results in the formation of narrow frequency but distributed azimuthal wave number fluctuations that are consistent with the formation of long-lived coherent nonlinear structures within the plasmas. These structures, termed quasicoherent modes, persist as the magnetic field is raised. Measurements of turbulent momentum flux indicate that the plasma is also forming an azimuthally symmetric radially sheared fluid flow that is nonlinearly driven by smaller scaled turbulent fluctuations. Further increases in the magnetic field result in the breakup of the quasicoherent mode, and the clear formation of the sheared flow. Numerical simulations of the experiment reproduce the formation of the sheared flow via a vortex merging process, and confirm thatmore » the experiment is providing the first clear experimental evidence of the formation of sheared zonal flows from drift turbulent fluctuations in a magnetized plasma.« less

Authors:
Publication Date:
Research Org.:
Univ. of California, San Diego, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1038867
Report Number(s):
DOE-ER54773- Final Report
TRN: US201210%%116
DOE Contract Number:  
FG02-04ER54773
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; FLUCTUATIONS; FLUID FLOW; HARMONICS; MAGNETIC FIELDS; MAGNETIZATION; PLASMA; SHEAR; STABILITY; TURBULENCE; plasma turbulence; transport; magnetic fusion; confinement

Citation Formats

Tynan, George R. Integrated Study of the Nonlinear Dynamics of Collisional Drift Wave Turbulence. United States: N. p., 2012. Web. doi:10.2172/1038867.
Tynan, George R. Integrated Study of the Nonlinear Dynamics of Collisional Drift Wave Turbulence. United States. https://doi.org/10.2172/1038867
Tynan, George R. 2012. "Integrated Study of the Nonlinear Dynamics of Collisional Drift Wave Turbulence". United States. https://doi.org/10.2172/1038867. https://www.osti.gov/servlets/purl/1038867.
@article{osti_1038867,
title = {Integrated Study of the Nonlinear Dynamics of Collisional Drift Wave Turbulence},
author = {Tynan, George R},
abstractNote = {An existing linear magnetized plasma device, the Controlled Shear Decorrelation experiment (CSDX) was used to study the transition from a state of coherent wave like activity to a state of turbulent activity using the magnetic field and thus magnetization of the plasma as the control parameter. The results show the onset of coherent drift waves consistent with linear stability analysis. As the magnetization is raised, at first multiple harmonics appear, consistent with wave steepening. This period is then followed by the beginning of nonlinear interactions between different wave modes, which then results in the formation of narrow frequency but distributed azimuthal wave number fluctuations that are consistent with the formation of long-lived coherent nonlinear structures within the plasmas. These structures, termed quasicoherent modes, persist as the magnetic field is raised. Measurements of turbulent momentum flux indicate that the plasma is also forming an azimuthally symmetric radially sheared fluid flow that is nonlinearly driven by smaller scaled turbulent fluctuations. Further increases in the magnetic field result in the breakup of the quasicoherent mode, and the clear formation of the sheared flow. Numerical simulations of the experiment reproduce the formation of the sheared flow via a vortex merging process, and confirm that the experiment is providing the first clear experimental evidence of the formation of sheared zonal flows from drift turbulent fluctuations in a magnetized plasma.},
doi = {10.2172/1038867},
url = {https://www.osti.gov/biblio/1038867}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Apr 24 00:00:00 EDT 2012},
month = {Tue Apr 24 00:00:00 EDT 2012}
}