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Frank Jenko - One of the best experts on this subject based on the ideXlab platform.
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critical gradient formula for toroidal Electron Temperature gradient modes
Physics of Plasmas, 2001Co-Authors: Frank Jenko, William Dorland, G W HammettAbstract:Under certain conditions, the Electron heat transport induced by Electron Temperature gradient (ETG) streamers is sufficiently large and sensitive with respect to the normalized Electron Temperature gradient to represent a possible cause for Electron Temperature profile consistency (“stiffness”). Here, linear gyrokinetic simulations of toroidal ETG modes in tokamak core and edge plasmas are presented. An algebraic formula for the threshold of the linear instability is derived from the numerical solutions of the linear gyrokinetic equations which recovers previous analytical results in the appropriate limits.
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Electron Temperature gradient turbulence.
Physical Review Letters, 2000Co-Authors: William Dorland, Frank Jenko, M T Kotschenreuther, B. N. RogersAbstract:The first toroidal, gyrokinetic, electromagnetic simulations of small scale plasma turbulence are presented. The turbulence considered is driven by gradients in the Electron Temperature. It is found that Electron Temperature gradient (ETG) turbulence can induce experimentally relevant thermal losses in magnetic confinement fusion devices. For typical tokamak parameters, the transport is essentially electrostatic in character. The simulation results are qualitatively consistent with a model that balances linear and secondary mode growth rates. Significant streamer-dominated transport at long wavelengths occurs because the secondary modes that produce saturation become weak in the ETG limit.
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Electron Temperature gradient driven turbulence
Physics of Plasmas, 2000Co-Authors: Frank Jenko, William Dorland, M T Kotschenreuther, B. N. RogersAbstract:Collisionless Electron-Temperature-gradient-driven (ETG) turbulence in toroidal geometry is studied via nonlinear numerical simulations. To this aim, two massively parallel, fully gyrokinetic Vlasov codes are used, both including electromagnetic effects. Somewhat surprisingly, and unlike in the analogous case of ion-Temperature-gradient-driven (ITG) turbulence, we find that the turbulent Electron heat flux is significantly underpredicted by simple mixing length estimates in a certain parameter regime (ŝ∼1, low α). This observation is directly linked to the presence of radially highly elongated vortices (“streamers”) which lead to very effective cross-field transport. The simulations therefore indicate that ETG turbulence is likely to be relevant to magnetic confinement fusion experiments.
B. N. Rogers - One of the best experts on this subject based on the ideXlab platform.
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Electron Temperature gradient turbulence.
Physical Review Letters, 2000Co-Authors: William Dorland, Frank Jenko, M T Kotschenreuther, B. N. RogersAbstract:The first toroidal, gyrokinetic, electromagnetic simulations of small scale plasma turbulence are presented. The turbulence considered is driven by gradients in the Electron Temperature. It is found that Electron Temperature gradient (ETG) turbulence can induce experimentally relevant thermal losses in magnetic confinement fusion devices. For typical tokamak parameters, the transport is essentially electrostatic in character. The simulation results are qualitatively consistent with a model that balances linear and secondary mode growth rates. Significant streamer-dominated transport at long wavelengths occurs because the secondary modes that produce saturation become weak in the ETG limit.
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Electron Temperature gradient driven turbulence
Physics of Plasmas, 2000Co-Authors: Frank Jenko, William Dorland, M T Kotschenreuther, B. N. RogersAbstract:Collisionless Electron-Temperature-gradient-driven (ETG) turbulence in toroidal geometry is studied via nonlinear numerical simulations. To this aim, two massively parallel, fully gyrokinetic Vlasov codes are used, both including electromagnetic effects. Somewhat surprisingly, and unlike in the analogous case of ion-Temperature-gradient-driven (ITG) turbulence, we find that the turbulent Electron heat flux is significantly underpredicted by simple mixing length estimates in a certain parameter regime (ŝ∼1, low α). This observation is directly linked to the presence of radially highly elongated vortices (“streamers”) which lead to very effective cross-field transport. The simulations therefore indicate that ETG turbulence is likely to be relevant to magnetic confinement fusion experiments.
William Dorland - One of the best experts on this subject based on the ideXlab platform.
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critical gradient formula for toroidal Electron Temperature gradient modes
Physics of Plasmas, 2001Co-Authors: Frank Jenko, William Dorland, G W HammettAbstract:Under certain conditions, the Electron heat transport induced by Electron Temperature gradient (ETG) streamers is sufficiently large and sensitive with respect to the normalized Electron Temperature gradient to represent a possible cause for Electron Temperature profile consistency (“stiffness”). Here, linear gyrokinetic simulations of toroidal ETG modes in tokamak core and edge plasmas are presented. An algebraic formula for the threshold of the linear instability is derived from the numerical solutions of the linear gyrokinetic equations which recovers previous analytical results in the appropriate limits.
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Electron Temperature gradient turbulence.
Physical Review Letters, 2000Co-Authors: William Dorland, Frank Jenko, M T Kotschenreuther, B. N. RogersAbstract:The first toroidal, gyrokinetic, electromagnetic simulations of small scale plasma turbulence are presented. The turbulence considered is driven by gradients in the Electron Temperature. It is found that Electron Temperature gradient (ETG) turbulence can induce experimentally relevant thermal losses in magnetic confinement fusion devices. For typical tokamak parameters, the transport is essentially electrostatic in character. The simulation results are qualitatively consistent with a model that balances linear and secondary mode growth rates. Significant streamer-dominated transport at long wavelengths occurs because the secondary modes that produce saturation become weak in the ETG limit.
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Electron Temperature gradient driven turbulence
Physics of Plasmas, 2000Co-Authors: Frank Jenko, William Dorland, M T Kotschenreuther, B. N. RogersAbstract:Collisionless Electron-Temperature-gradient-driven (ETG) turbulence in toroidal geometry is studied via nonlinear numerical simulations. To this aim, two massively parallel, fully gyrokinetic Vlasov codes are used, both including electromagnetic effects. Somewhat surprisingly, and unlike in the analogous case of ion-Temperature-gradient-driven (ITG) turbulence, we find that the turbulent Electron heat flux is significantly underpredicted by simple mixing length estimates in a certain parameter regime (ŝ∼1, low α). This observation is directly linked to the presence of radially highly elongated vortices (“streamers”) which lead to very effective cross-field transport. The simulations therefore indicate that ETG turbulence is likely to be relevant to magnetic confinement fusion experiments.
S. Benkadda - One of the best experts on this subject based on the ideXlab platform.
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Electromagnetic Electron Temperature gradient driven instability in toroidal plasmas
Physics of Plasmas, 2017Co-Authors: J. Zielinski, A. I. Smolyakov, P. Beyer, S. BenkaddaAbstract:The fluid theory of a new type of Electron Temperature gradient instability is proposed. This mode is closely related to the short wavelength Alfven mode in the regime k(perpendicular to)(2)rho(2)(i) > 1. Contrary to standard Electron Temperature gradient modes, which are mostly electrostatic, the considered mode is fundamentally electromagnetic and does not exist in the electrostatic limit. The mechanism of instability relies on gradients in both the Electron Temperature and magnetic field. It is suggested that this instability may be a destabilizing mechanism for collisionless microtearing modes, which are observed in a number of gyrokinetic simulations.
M T Kotschenreuther - One of the best experts on this subject based on the ideXlab platform.
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Electron Temperature gradient turbulence.
Physical Review Letters, 2000Co-Authors: William Dorland, Frank Jenko, M T Kotschenreuther, B. N. RogersAbstract:The first toroidal, gyrokinetic, electromagnetic simulations of small scale plasma turbulence are presented. The turbulence considered is driven by gradients in the Electron Temperature. It is found that Electron Temperature gradient (ETG) turbulence can induce experimentally relevant thermal losses in magnetic confinement fusion devices. For typical tokamak parameters, the transport is essentially electrostatic in character. The simulation results are qualitatively consistent with a model that balances linear and secondary mode growth rates. Significant streamer-dominated transport at long wavelengths occurs because the secondary modes that produce saturation become weak in the ETG limit.
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Electron Temperature gradient driven turbulence
Physics of Plasmas, 2000Co-Authors: Frank Jenko, William Dorland, M T Kotschenreuther, B. N. RogersAbstract:Collisionless Electron-Temperature-gradient-driven (ETG) turbulence in toroidal geometry is studied via nonlinear numerical simulations. To this aim, two massively parallel, fully gyrokinetic Vlasov codes are used, both including electromagnetic effects. Somewhat surprisingly, and unlike in the analogous case of ion-Temperature-gradient-driven (ITG) turbulence, we find that the turbulent Electron heat flux is significantly underpredicted by simple mixing length estimates in a certain parameter regime (ŝ∼1, low α). This observation is directly linked to the presence of radially highly elongated vortices (“streamers”) which lead to very effective cross-field transport. The simulations therefore indicate that ETG turbulence is likely to be relevant to magnetic confinement fusion experiments.