Identification of new turbulence contributions to plasma transport and confinement in spherical tokamak regime

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

doi:10.1063/1.4933216

Identification of new turbulence contributions to plasma transport and confinement in spherical tokamak regime

Journal Article · Thu Oct 15 00:00:00 UTC 2015 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4933216· OSTI ID:1256376

Wang, W. X. ^[1]; Ethier, S. ^[1]; ^[1]; Kaye, S. ^[1]; Chen, J. ^[1]; Startsev, E. ^[1]; Lu, Z. ^[2]; ^[3]

Princeton Univ., Princeton, NJ (United States)
Univ. of California, San Diego, La Jolla, CA (United States)
Zhejiang Univ., Hangzhou (People's Republic of China)

Highly distinct features of spherical tokamaks (ST), such as National Spherical Torus eXperiment (NSTX) and NSTX-U, result in a different fusion plasma regime with unique physics properties compared to conventional tokamaks. Nonlinear global gyrokinetic simulations critical for addressing turbulence and transport physics in the ST regime have led to new insights. The drift wave Kelvin-Helmholtz (KH) instability characterized by intrinsic mode asymmetry is identified in strongly rotating NSTX L-mode plasmas. While the strong E x B shear associated with the rotation leads to a reduction in KH/ion temperature gradient turbulence, the remaining fluctuations can produce a significant ion thermal transport that is comparable to the experimental level in the outer core region (with no "transport shortfall"). The other new, important turbulence source identified in NSTX is the dissipative trapped electron mode (DTEM), which is believed to play little role in conventional tokamak regime. Due to the high fraction of trapped electrons, long wavelength DTEMs peaking around k_{θρ_s} ~ 0.1 are destabilized in NSTX collisionality regime by electron density and temperature gradients achieved there. Surprisingly, the E x B shear stabilization effect on DTEM is remarkably weak, which makes it a major turbulence source in the ST regime dominant over collisionless TEM (CTEM). The latter, on the other hand, is subject to strong collisional and E x B shear suppression in NSTX. DTEM is shown to produce significant particle, energy and toroidal momentum transport, in agreement with experimental levels in NSTX H-modes. Furthermore, DTEM-driven transport in NSTX parametric regime is found to increase with electron collision frequency, providing one possible source for the scaling of confinement time observed in NSTX H-modes. Most interestingly, the existence of a turbulence-free regime in the collision-induced CTEM to DTEM transition, corresponding to a minimum plasma transport in advanced ST collisionality regime, is predicted.

View Accepted Manuscript (DOE)

Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: DOE Office of Science; USDOE

Grant/Contract Number:: AC02-09CH11466

OSTI ID:: 1256376

Alternate ID(s):: OSTI ID: 1223570

Report Number(s):: PPPL--5202

Journal Information:: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 10 Vol. 22; ISSN PHPAEN; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

References (44)

Global δf particle simulation of neoclassical transport and ambipolar electric field in general geometry Wang, W. X.; Tang, W. M.; Hinton, F. L. Computer Physics Communications, Vol. 164, Issue 1-3 https://doi.org/10.1016/j.cpc.2004.06.027	journal	December 2004
Parallel velocity shear instabilities in an inhomogeneous plasma with a sheared magnetic field Catto, Peter J. Physics of Fluids, Vol. 16, Issue 10 https://doi.org/10.1063/1.1694200	journal	January 1973
Kelvin—Helmholtz Instability in a Fully Ionized Plasma in a Magnetic Field D'Angelo, Nicola Physics of Fluids, Vol. 8, Issue 9 https://doi.org/10.1063/1.1761496	journal	January 1965
Role of nonlinear toroidal coupling in electron temperature gradient turbulence Lin, Z.; Chen, L.; Zonca, F. Physics of Plasmas, Vol. 12, Issue 5 https://doi.org/10.1063/1.1894766	journal	May 2005
Nonlocal neoclassical transport in tokamak and spherical torus experiments Wang, W. X.; Rewoldt, G.; Tang, W. M. Physics of Plasmas, Vol. 13, Issue 8 https://doi.org/10.1063/1.2244532	journal	August 2006
Gyro-kinetic simulation of global turbulent transport properties in tokamak experiments Wang, W. X.; Lin, Z.; Tang, W. M. Physics of Plasmas, Vol. 13, Issue 9 https://doi.org/10.1063/1.2338775	journal	September 2006
Nonlocal properties of gyrokinetic turbulence and the role of E×B flow shear Wang, W. X.; Hahm, T. S.; Lee, W. W. Physics of Plasmas, Vol. 14, Issue 7 https://doi.org/10.1063/1.2750647	journal	July 2007
Numerical study of linear dissipative drift electrostatic modes in tokamaks Romanelli, M.; Regnoli, G.; Bourdelle, C. Physics of Plasmas, Vol. 14, Issue 8 https://doi.org/10.1063/1.2755981	journal	August 2007
The role of plasma elongation on the linear damping of zonal flows Angelino, P.; Garbet, X.; Villard, L. Physics of Plasmas, Vol. 15, Issue 6 https://doi.org/10.1063/1.2928849	journal	June 2008
Effects of plasma shaping on nonlinear gyrokinetic turbulence Belli, E. A.; Hammett, G. W.; Dorland, W. Physics of Plasmas, Vol. 15, Issue 9 https://doi.org/10.1063/1.2972160	journal	September 2008
Implementation and application of two synthetic diagnostics for validating simulations of core tokamak turbulence Holland, C.; White, A. E.; McKee, G. R. Physics of Plasmas, Vol. 16, Issue 5 https://doi.org/10.1063/1.3085792	journal	May 2009
Nonlinear flow generation by electrostatic turbulence in tokamaks Wang, W. X.; Diamond, P. H.; Hahm, T. S. Physics of Plasmas, Vol. 17, Issue 7 https://doi.org/10.1063/1.3459096	journal	July 2010
Suppressing electron turbulence and triggering internal transport barriers with reversed magnetic shear in the National Spherical Torus Experiment Peterson, J. L.; Bell, R.; Candy, J. Physics of Plasmas, Vol. 19, Issue 5 https://doi.org/10.1063/1.4718456	journal	May 2012
Gyrokinetic analysis of ion temperature gradient modes in the presence of sheared flows Artun, M.; Tang, W. M. Physics of Fluids B: Plasma Physics, Vol. 4, Issue 5 https://doi.org/10.1063/1.860118	journal	May 1992
Kinetic quasitoroidal ion temperature gradient instability in the presence of sheared flows Dong, J. Q.; Horton, W. Physics of Fluids B: Plasma Physics, Vol. 5, Issue 5 https://doi.org/10.1063/1.860898	journal	May 1993
Nonlinear gyrokinetic equations Dubin, Daniel H. E. Physics of Fluids, Vol. 26, Issue 12 https://doi.org/10.1063/1.864113	journal	January 1983
Gyrokinetic approach in particle simulation Lee, W. W. Physics of Fluids, Vol. 26, Issue 2 https://doi.org/10.1063/1.864140	journal	January 1983
Nonlinear interaction of toroidicity-induced drift modes Similon, P. L.; Diamond, P. H. Physics of Fluids, Vol. 27, Issue 4 https://doi.org/10.1063/1.864682	journal	January 1984
Momentum‐energy transport from turbulence driven by parallel flow shear Dong, J. Q.; Horton, W.; Bengtson, Roger D. Physics of Plasmas, Vol. 1, Issue 10 https://doi.org/10.1063/1.870477	journal	October 1994
Toroidal gyro‐Landau fluid model turbulence simulations in a nonlinear ballooning mode representation with radial modes Waltz, R. E.; Kerbel, G. D.; Milovich, J. Physics of Plasmas, Vol. 1, Issue 7 https://doi.org/10.1063/1.870934	journal	July 1994
Flow shear induced fluctuation suppression in finite aspect ratio shaped tokamak plasma Hahm, T. S.; Burrell, K. H. Physics of Plasmas, Vol. 2, Issue 5 https://doi.org/10.1063/1.871313	journal	May 1995
Collisional δf method Chen, Yang; White, Roscoe B. Physics of Plasmas, Vol. 4, Issue 10 https://doi.org/10.1063/1.872254	journal	October 1997
Structure of parallel-velocity-shear-driven mode in toroidal plasmas Dong, J. Q.; Xu, W. B.; Zhang, Y. Z. Physics of Plasmas, Vol. 5, Issue 12 https://doi.org/10.1063/1.873143	journal	December 1998
Scaling of heat transport with collisionality Petty, C. C.; Luce, T. C. Physics of Plasmas, Vol. 6, Issue 3 https://doi.org/10.1063/1.873330	journal	March 1999
Kelvin–Helmholtz instabilities in tokamak edge plasmas Garbet, X.; Fenzi, C.; Capes, H. Physics of Plasmas, Vol. 6, Issue 10 https://doi.org/10.1063/1.873659	journal	October 1999
Trapped particles in toroidal magnetic systems Kadomtsev, B. B.; Pogutse, O. P. Nuclear Fusion, Vol. 11, Issue 1 https://doi.org/10.1088/0029-5515/11/1/010	journal	January 1971
Loss of static equilibrium, flow generation and the development of turbulence at the edge of tokamaks Drake, J. F.; Hassam, A. B.; Guzdar, P. N. Nuclear Fusion, Vol. 32, Issue 9 https://doi.org/10.1088/0029-5515/32/9/I15	journal	September 1992
Parameter dependences of ion thermal transport due to toroidal ITG turbulence Dimits, A. M.; Cohen, B. I.; Nevins, W. M. Nuclear Fusion, Vol. 41, Issue 11 https://doi.org/10.1088/0029-5515/41/11/322	journal	November 2001
Physics of non-diffusive turbulent transport of momentum and the origins of spontaneous rotation in tokamaks Diamond, P. H.; McDevitt, C. J.; Gürcan, Ö. D. Nuclear Fusion, Vol. 49, Issue 4 https://doi.org/10.1088/0029-5515/49/4/045002	journal	March 2009
Momentum transport in electron-dominated NSTX spherical torus plasmas Kaye, S. M.; Solomon, W.; Bell, R. E. Nuclear Fusion, Vol. 49, Issue 4 https://doi.org/10.1088/0029-5515/49/4/045010	journal	March 2009
Study of turbulent fluctuations driven by the electron temperature gradient in the National Spherical Torus Experiment Mazzucato, E.; Bell, R. E.; Ethier, S. Nuclear Fusion, Vol. 49, Issue 5 https://doi.org/10.1088/0029-5515/49/5/055001	journal	April 2009
L-mode validation studies of gyrokinetic turbulence simulations via multiscale and multifield turbulence measurements on the DIII-D tokamak Rhodes, T. L.; Holland, C.; Smith, S. P. Nuclear Fusion, Vol. 51, Issue 6 https://doi.org/10.1088/0029-5515/51/6/063022	journal	May 2011
The dependence of H-mode energy confinement and transport on collisionality in NSTX Kaye, S. M.; Gerhardt, S.; Guttenfelder, W. Nuclear Fusion, Vol. 53, Issue 6 https://doi.org/10.1088/0029-5515/53/6/063005	journal	April 2013
Electron-scale turbulence spectra and plasma thermal transport responding to continuous E × B shear ramp-up in a spherical tokamak Ren, Y.; Guttenfelder, W.; Kaye, S. M. Nuclear Fusion, Vol. 53, Issue 8 https://doi.org/10.1088/0029-5515/53/8/083007	journal	July 2013
Progress in simulating turbulent electron thermal transport in NSTX Guttenfelder, W.; Peterson, J. L.; Candy, J. Nuclear Fusion, Vol. 53, Issue 9 https://doi.org/10.1088/0029-5515/53/9/093022	journal	August 2013
Transport phenomena in Alcator C-Mod H-modes Greenwald, M.; Schachter, J.; Dorland, W. Plasma Physics and Controlled Fusion, Vol. 40, Issue 5 https://doi.org/10.1088/0741-3335/40/5/044	journal	May 1998
Nonlinear toroidal mode coupling: a new paradigm for drift wave turbulence in toroidal plasmas Chen, L.; Zonca, F.; Lin, Z. Plasma Physics and Controlled Fusion, Vol. 47, Issue 12B https://doi.org/10.1088/0741-3335/47/12B/S06	journal	November 2005
Stability of the trapped electron mode in steep density and temperature gradients Connor, J. W.; Hastie, R. J.; Helander, P. Plasma Physics and Controlled Fusion, Vol. 48, Issue 6 https://doi.org/10.1088/0741-3335/48/6/012	journal	May 2006
Suppression of Electron Temperature Gradient Turbulence via Negative Magnetic Shear in NSTX Yuh, H. Y.; Kaye, S. M.; Levinton, F. M. Physical Review Letters, Vol. 106, Issue 5 https://doi.org/10.1103/PhysRevLett.106.055003	journal	February 2011
Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak Ren, Y.; Kaye, S. M.; Mazzucato, E. Physical Review Letters, Vol. 106, Issue 16 https://doi.org/10.1103/PhysRevLett.106.165005	journal	April 2011
Turbulent Transport in Tokamak Plasmas with Rotational Shear Barnes, M.; Parra, F. I.; Highcock, E. G. Physical Review Letters, Vol. 106, Issue 17 https://doi.org/10.1103/PhysRevLett.106.175004	journal	April 2011
Zero-Turbulence Manifold in a Toroidal Plasma Highcock, E. G.; Schekochihin, A. A.; Cowley, S. C. Physical Review Letters, Vol. 109, Issue 26 https://doi.org/10.1103/PhysRevLett.109.265001	journal	December 2012
Suppression of turbulence and transport by sheared flow Terry, P. W. Reviews of Modern Physics, Vol. 72, Issue 1 https://doi.org/10.1103/RevModPhys.72.109	journal	January 2000
Foundations of nonlinear gyrokinetic theory Brizard, A. J.; Hahm, T. S. Reviews of Modern Physics, Vol. 79, Issue 2 https://doi.org/10.1103/RevModPhys.79.421	journal	April 2007

Cited By (8)

Radial properties of the geodesic acoustic mode Li, Zhenqian; Dong, Jiaqi; Sheng, Zhengmao Physics of Plasmas, Vol. 24, Issue 10 https://doi.org/10.1063/1.5004427	journal	October 2017
Flow helicity of wavy plasma turbulence Kosuga, Y.; Sasaki, M.; Guo, Z. B. Physics of Plasmas, Vol. 27, Issue 2 https://doi.org/10.1063/1.5121351	journal	February 2020
Recent progress in understanding electron thermal transport in NSTX Ren, Y.; Belova, E.; Gorelenkov, N. Nuclear Fusion, Vol. 57, Issue 7 https://doi.org/10.1088/1741-4326/aa4fba	journal	March 2017
NSTX/NSTX-U theory, modeling and analysis results Kaye, S. M.; Battaglia, D. J.; Baver, D. Nuclear Fusion, Vol. 59, Issue 11 https://doi.org/10.1088/1741-4326/ab023a	journal	June 2019
Initial transport and turbulence analysis and gyrokinetic simulation validation in NSTX-U L-mode plasmas Guttenfelder, W.; Kaye, S. M.; Kriete, D. M. Nuclear Fusion, Vol. 59, Issue 5 https://doi.org/10.1088/1741-4326/ab0b2c	journal	April 2019
Impurity transport driven by parallel velocity shear turbulence in hydrogen isotope plasmas Guo, Weixin; Wang, Lu; Zhuang, Ge Nuclear Fusion, Vol. 59, Issue 7 https://doi.org/10.1088/1741-4326/ab1967	journal	May 2019
Self-driven current generation in turbulent fusion plasmas Wang, W. X.; Hahm, T. S.; Startsev, E. A. Nuclear Fusion, Vol. 59, Issue 8 https://doi.org/10.1088/1741-4326/ab266d	journal	June 2019
Exploring the regime of validity of global gyrokinetic simulations with spherical tokamak plasmas Ren, Y.; Wang, W. X.; Guttenfelder, W. Nuclear Fusion, Vol. 60, Issue 2 https://doi.org/10.1088/1741-4326/ab5bf5	journal	December 2019

Similar Records

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

Journal Article · Fri Oct 30 00:00:00 UTC 2015 · Nuclear Fusion · OSTI ID:1256375

Simulation of microtearing turbulence in national spherical torus experiment

Journal Article · Tue May 15 04:00:00 UTC 2012 · Physics of Plasmas · OSTI ID:22072397

Simulation of microtearing turbulence in national spherical torus experiment

Journal Article · Fri Apr 27 00:00:00 UTC 2012 · Physics of Plasmas · OSTI ID:1564859

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Kelvin Helmholtz instability
driven
edge
geometry
instability
ion temperature gradient mode
magnetic field
modes
particle simulation
plasma transport properties
sheared flows
suppression
tokamaks
toroidal plasma confinement
toroidal plasmas

Identification of new turbulence contributions to plasma transport and confinement in spherical tokamak regime

Citation Formats

References (44)

Cited By (8)

Similar Records

Related Subjects