Electromagnetic theory of turbulent acceleration of parallel flow and momentum conservation

Peng, Shuitao; Wang, Lu

doi:10.1063/1.4974040

Cited by 7 publications

(19 citation statements)

References 27 publications

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“…Then, we extended our theory to electromagnetic ITG turbulence and found the importance of electromagnetic effects on intrinsic parallel rotation drive [15]. Finally, we demonstrated that the conserved quantity corresponding to axisymmetry is the total canonical momentum or total momentum carried by both particles and electromagnetic fields, and the presence of turbulent acceleration does not imply its confliction with momentum conservation [16].…”

Section: Introductionmentioning

confidence: 76%

“…Through equations (14) and 15, we can obtain the same mean field equation of the parallel flow velocity (i.e., equation 11) regardless of the sequence of taking flux average and decoupling the parallel flow from parallel momentum density [16]. Therefore, the presence of the turbulent acceleration does not result from regrouping terms as one may wonder.…”

Section: Turbulent Acceleration and Momentum Conservationmentioning

confidence: 98%

“…These two gyrocenter momentum conservation equations mentioned above (i.e., equations (16) and (18)) are equivalent. We can see that the conserved quantity can be either the total gyrocenter parallel canonical momentum carried by both species or the total gyrocenter parallel momentum including the ion gyrocenter kinematic momentum and the electromagnetic fields momentum, but not the ion parallel kinematic momentum or the ion parallel flow velocity.…”

Section: Turbulent Acceleration and Momentum Conservationmentioning

confidence: 99%

“…We can see that the conserved quantity can be either the total gyrocenter parallel canonical momentum carried by both species or the total gyrocenter parallel momentum including the ion gyrocenter kinematic momentum and the electromagnetic fields momentum, but not the ion parallel kinematic momentum or the ion parallel flow velocity. Hence, the turbulent acceleration-the local source or sink of the mean ion parallel flow does not imply that the momentum conservations is broken [16].…”

Section: Turbulent Acceleration and Momentum Conservationmentioning

confidence: 99%

“…we can obtain the gyrocenter momentum conservation equation after some algebra[16] canonical parallel momentum of one species including the ordinary gyrocenter kinematic momentum and the gyrocenter magnetic vector momentum. The ordinary kinematic momentum carried by electrons was neglected because of small electron mass as compared to ion mass …”

mentioning

confidence: 99%

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Gyrokinetic theory of turbulent acceleration and momentum conservation in tokamak plasmas

Wang

Peng

Diamond

2018

Plasma Sci. Technol.

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Understanding the generation of intrinsic rotation in tokamak plasmas is crucial for future fusion reactors such as ITER. We proposed a new mechanism named turbulent acceleration for the origin of the intrinsic parallel rotation based on gyrokinetic theory. The turbulent acceleration acts as a local source or sink of parallel rotation, i.e., volume force, which is different from the divergence of residual stress, i.e., surface force. However, the order of magnitude of turbulent acceleration can be comparable to that of the divergence of residual stress for electrostatic ion temperature gradient (ITG) turbulence. A possible theoretical explanation for the experimental observation of electron cyclotron heating induced decrease of co-current rotation was also proposed via comparison between the turbulent acceleration driven by ITG turbulence and that driven by collisionless trapped electron mode turbulence. We also extended this theory to electromagnetic ITG turbulence and investigated the electromagnetic effects on intrinsic parallel rotation drive. Finally, we demonstrated that the presence of turbulent acceleration does not conflict with momentum conservation.

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Section: Introductionmentioning

confidence: 76%

Section: Turbulent Acceleration and Momentum Conservationmentioning

confidence: 98%

Section: Turbulent Acceleration and Momentum Conservationmentioning

confidence: 99%

Section: Turbulent Acceleration and Momentum Conservationmentioning

confidence: 99%

mentioning

confidence: 99%

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Gyrokinetic theory of turbulent acceleration and momentum conservation in tokamak plasmas

Wang

Peng

Diamond

2018

Plasma Sci. Technol.

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Intrinsic parallel rotation drive by electromagnetic ion temperature gradient turbulence

2016

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The quasilinear intrinsic parallel flow drive including parallel residual stress, kinetic stress, cross Maxwell stress and parallel turbulent acceleration by electromagnetic ion temperature gradient (ITG) turbulence is calculated analytically using electromagnetic gyrokinetic theory. Both the kinetic stress and cross Maxwell stress also enter the mean parallel flow velocity equation via their divergence, as for the usual residual stress. The turbulent acceleration driven by ion pressure gradient along the total magnetic field (including equilibrium magnetic field and fluctuating radial magnetic field) cannot be written as a divergence of stress, and so should be treated as a local source/sink. All these terms can provide intrinsic parallel rotation drive.Electromagnetic effects reduce the non-resonant electrostatic stress force and even reverse it, but enhance the resonant stress force. Both the non-resonant and resonant turbulent acceleration terms are also enhanced by electromagnetic effects. The possible implications of our results for experimental observations are discussed.

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Overview of the recent experimental research on the J-TEXT tokamak

et al. 2019

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Recent J-TEXT research has highlighted the significance of the role that non-axisymmetric magnetic perturbations, so called three-dimensional (3D) magnetic perturbation (MP) fields, play in a fundamentally 2D concept, i.e. tokamaks. This paper presents the J-TEXT results achieved over the last two years, especially on the impacts of 3D MP fields on magnetohydrodynamic instabilities, plasma disruptions and plasma turbulence transport. On J-TEXT, the resonant MP (RMP) system, capable of providing either a static or a high frequency (up to 8 kHz) rotating RMP field, has been upgraded by adding a new set of 12 in-vessel saddle coils. The shattered pellet injection system was built in J-TEXT in the spring of 2018. The new capabilities advance J-TEXT to be at the forefront of international magnetic fusion facilities, allowing flexible study of 3D effects and disruption mitigation in a tokamak. The fast rotating RMP field has been successfully applied for avoidance of mode locking and the prevention of plasma disruption. A new control strategy, which applies pulsed RMP to the tearing mode only during the accelerating phase region, was proved by nonlinear numerical modelling to be efficient in accelerating mode rotation and even completely suppresses the mode. Remarkably, the rotating tearing mode was completely suppressed by the electrode biasing. The impacts of 3D magnetic topology on the turbulence has been investigated on J-TEXT. It is found that the fluctuations of electron density, electron temperature and plasma potential can be significantly modulated by the island structure, and a larger fluctuation level appears at the X-point of islands. The suppression of runaway electrons during disruptions is essential to the operation of ITER, and it has been reached by utilizing the 3D magnetic perturbations on J-TEXT. This may provide an alternative mechanism of runaway suppression for large-scale tokamaks and ITER.

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Electromagnetic theory of turbulent acceleration of parallel flow and momentum conservation

Cited by 7 publications

References 27 publications

Gyrokinetic theory of turbulent acceleration and momentum conservation in tokamak plasmas

Gyrokinetic theory of turbulent acceleration and momentum conservation in tokamak plasmas

Intrinsic parallel rotation drive by electromagnetic ion temperature gradient turbulence

Overview of the recent experimental research on the J-TEXT tokamak

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