Distinct turbulence sources and confinement features in the spherical tokamak plasma regime

Wang, W. X.; Ethier, S.; Ren, Y.; Kaye, S.; Chen, J.; Startsev, E.; Lu, Z.

doi:10.1088/0029-5515/55/12/122001

Title: Distinct turbulence sources and confinement features in the spherical tokamak plasma regime

Abstract

New turbulence contributions to plasma transport and confinement in the spherical tokamak (ST) regime are identified through nonlinear gyrokinetic simulations. The drift wave Kelvin-Helmholtz (KH) mode characterized by intrinsic mode asymmetry is shown to drive significant ion thermal transport in strongly rotating national spherical torus experiment (NSTX) L-modes. The long wavelength, quasi-coherent dissipative trapped electron mode (TEM) is destabilized in NSTX H-modes despite the presence of strong E x B shear, providing a robust turbulence source dominant over collisionless TEM. Dissipative trapped electron mode (DTEM)-driven transport in the NSTX parametric regime is shown to increase with electron collision frequency, offering one possible source for the confinement scaling observed in experiments. There exists a turbulence-free regime in the collision-induced collisionless trapped electron mode to DTEM transition for ST plasmas. In conclusion, this predicts a natural access to a minimum transport state in the low collisionality regime that future advanced STs may cover.

Authors:

Wang, W. X. ^[1]; Ethier, S. ^[1];

^[1]; Kaye, S. ^[1]; Chen, J. ^[1]; Startsev, E. ^[1]; Lu, Z. ^[2]

Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Univ. of California, San Diego, CA (United States). La Jolla, CA

Publication Date:: Fri Oct 30 00:00:00 EDT 2015

Research Org.:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:: 1256375

Alternate Identifier(s):: OSTI ID: 1238950

Report Number(s):: PPPL-5203
Journal ID: ISSN 0029-5515

Grant/Contract Number:: AC02-09CH11466; Contract No. DE-AC02-09CH11466

Resource Type:: Accepted Manuscript

Journal Name:: Nuclear Fusion

Additional Journal Information:: Journal Volume: 55; Journal Issue: 12; Journal ID: ISSN 0029-5515

Publisher:: IOP Science

Country of Publication:: United States

Language:: English

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma turbulence; transport; confinement; spherical tokamak; drift wave; instability; sheared flows

Citation Formats


                    Wang, W. X., Ethier, S., Ren, Y., Kaye, S., Chen, J., Startsev, E., and Lu, Z. Distinct turbulence sources and confinement features in the spherical tokamak plasma regime.  United States: N. p., 2015. 
Web.  doi:10.1088/0029-5515/55/12/122001.

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                    Wang, W. X., Ethier, S., Ren, Y., Kaye, S., Chen, J., Startsev, E., & Lu, Z. Distinct turbulence sources and confinement features in the spherical tokamak plasma regime.  United States.  https://doi.org/10.1088/0029-5515/55/12/122001

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                    Wang, W. X., Ethier, S., Ren, Y., Kaye, S., Chen, J., Startsev, E., and Lu, Z. Fri .  
"Distinct turbulence sources and confinement features in the spherical tokamak plasma regime".  United States.  https://doi.org/10.1088/0029-5515/55/12/122001.  https://www.osti.gov/servlets/purl/1256375.

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@article{osti_1256375,

  title        = {Distinct turbulence sources and confinement features in the spherical tokamak plasma regime},

  author       = {Wang, W. X. and Ethier, S. and Ren, Y. and Kaye, S. and Chen, J. and Startsev, E. and Lu, Z.},

  abstractNote = {New turbulence contributions to plasma transport and confinement in the spherical tokamak (ST) regime are identified through nonlinear gyrokinetic simulations. The drift wave Kelvin-Helmholtz (KH) mode characterized by intrinsic mode asymmetry is shown to drive significant ion thermal transport in strongly rotating national spherical torus experiment (NSTX) L-modes. The long wavelength, quasi-coherent dissipative trapped electron mode (TEM) is destabilized in NSTX H-modes despite the presence of strong E x B shear, providing a robust turbulence source dominant over collisionless TEM. Dissipative trapped electron mode (DTEM)-driven transport in the NSTX parametric regime is shown to increase with electron collision frequency, offering one possible source for the confinement scaling observed in experiments. There exists a turbulence-free regime in the collision-induced collisionless trapped electron mode to DTEM transition for ST plasmas. In conclusion, this predicts a natural access to a minimum transport state in the low collisionality regime that future advanced STs may cover.},

  doi          = {10.1088/0029-5515/55/12/122001},

  journal      = {Nuclear Fusion},

  number       = 12,

  volume       = 55,

  place        = {United States},

  year         = {Fri Oct 30 00:00:00 EDT 2015},

  month        = {Fri Oct 30 00:00:00 EDT 2015}

}

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Works referencing / citing this record:

Development and testing of an unstructured mesh method for whole plasma gyrokinetic simulations in realistic tokamak geometry
journal, December 2019

Lu, Z. X.; Lauber, Ph.; Hayward-Schneider, T.
Physics of Plasmas, Vol. 26, Issue 12
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Title: Distinct turbulence sources and confinement features in the spherical tokamak plasma regime

Abstract

Citation Formats

L-mode validation studies of gyrokinetic turbulence simulations via multiscale and multifield turbulence measurements on the DIII-D tokamak journal, May 2011

Parameter dependences of ion thermal transport due to toroidal ITG turbulence journal, November 2001

Progress in simulating turbulent electron thermal transport in NSTX journal, August 2013

Parallel shear flow instability in the tokamak edge journal, August 2011

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Role of nonlinear toroidal coupling in electron temperature gradient turbulence journal, May 2005

Chapter 2: Plasma confinement and transport journal, June 2007

Nonlinear interaction of toroidicity-induced drift modes journal, January 1984

Nonlinear flow generation by electrostatic turbulence in tokamaks journal, July 2010

Gyro-kinetic simulation of global turbulent transport properties in tokamak experiments journal, September 2006

Kinetic quasitoroidal ion temperature gradient instability in the presence of sheared flows journal, May 1993

Numerical study of linear dissipative drift electrostatic modes in tokamaks journal, August 2007

Gyrokinetic analysis of ion temperature gradient modes in the presence of sheared flows journal, May 1992

Stability of the trapped electron mode in steep density and temperature gradients journal, May 2006

Effects of Collisional Zonal Flow Damping on Turbulent Transport journal, November 1999

Parallel velocity shear instabilities in an inhomogeneous plasma with a sheared magnetic field journal, January 1973

Nonlocal properties of gyrokinetic turbulence and the role of E×B flow shear journal, July 2007

Kelvin–Helmholtz instabilities in tokamak edge plasmas journal, October 1999

Implementation and application of two synthetic diagnostics for validating simulations of core tokamak turbulence journal, May 2009

Trapped particles in toroidal magnetic systems journal, January 1971

Suppression of turbulence and transport by sheared flow journal, January 2000

Loss of static equilibrium, flow generation and the development of turbulence at the edge of tokamaks journal, September 1992

Turbulent Transport in Tokamak Plasmas with Rotational Shear journal, April 2011

Zero-Turbulence Manifold in a Toroidal Plasma journal, December 2012

Nonlinear toroidal mode coupling: a new paradigm for drift wave turbulence in toroidal plasmas journal, November 2005

Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak journal, April 2011

Gyrokinetic analysis of ion temperature gradient modes in the presence of sheared flows report, January 1992

Gyrokinetic analysis of ion temperature gradient modes in the presence of sheared flows report, January 1992

Zero-Turbulence Manifold in a Toroidal Plasma text, January 2012

Development and testing of an unstructured mesh method for whole plasma gyrokinetic simulations in realistic tokamak geometry journal, December 2019

L-mode validation studies of gyrokinetic turbulence simulations via multiscale and multifield turbulence measurements on the DIII-D tokamak
journal, May 2011

Parameter dependences of ion thermal transport due to toroidal ITG turbulence
journal, November 2001

Progress in simulating turbulent electron thermal transport in NSTX
journal, August 2013

Parallel shear flow instability in the tokamak edge
journal, August 2011

Experimental study of parametric dependence of electron-scale turbulence in a spherical tokamak
journal, May 2012

Nonlocal neoclassical transport in tokamak and spherical torus experiments
journal, August 2006

Role of nonlinear toroidal coupling in electron temperature gradient turbulence
journal, May 2005

Chapter 2: Plasma confinement and transport
journal, June 2007

Nonlinear interaction of toroidicity-induced drift modes
journal, January 1984

Nonlinear flow generation by electrostatic turbulence in tokamaks
journal, July 2010

Gyro-kinetic simulation of global turbulent transport properties in tokamak experiments
journal, September 2006

Kinetic quasitoroidal ion temperature gradient instability in the presence of sheared flows
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Numerical study of linear dissipative drift electrostatic modes in tokamaks
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Gyrokinetic analysis of ion temperature gradient modes in the presence of sheared flows
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Stability of the trapped electron mode in steep density and temperature gradients
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Effects of Collisional Zonal Flow Damping on Turbulent Transport
journal, November 1999

Parallel velocity shear instabilities in an inhomogeneous plasma with a sheared magnetic field
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Nonlocal properties of gyrokinetic turbulence and the role of E×B flow shear
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Kelvin–Helmholtz instabilities in tokamak edge plasmas
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Implementation and application of two synthetic diagnostics for validating simulations of core tokamak turbulence
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Trapped particles in toroidal magnetic systems
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