Finite Larmor radius effects on the coupled trapped electron and ion temperature gradient modes

Abstract Gyro-average is a crucial operation to capture the essential finite Larmor radius effect (FLR) in gyrokinetic simulation. In order to simulate strongly shaped plasmas, an innovative multi-point average method based on non-orthogonal coordinates has been developed to improve the accuracy of the original multi-point average method in gyrokinetic particle simulation. This new gyro-average method has been implemented in the gyrokinetic toroidal code (GTC). Benchmarks have been carried out to prove the accuracy of this new method. In the limit of concircular tokamak, ion temperature gradient (ITG) instability is accurately recovered for this new method and consistency is achieved. The new gyro-average method is also used to solve the gyrokinetic Poisson equation, and its correctness has been confirmed in the long wavelength limit for realistic shaped plasmas. The improved GTC code with the new gyro-average method has been used to investigate the ITG instability with EAST magnetic geometry. The simulation results show that the correction induced by this new method in the linear growth rate is more significant for short wavelength modes where the finite Larmor radius (FLR) effect becomes important. Due to its simplicity and accuracy, this new gyro-average method can find broader applications in simulating the shaped plasmas in realistic tokamaks.

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Collisionless trapped electron and ion temperature gradient modes in an advanced tokamak equilibrium

Physics of Plasmas ◽

10.1063/1.3076209 ◽

2009 ◽

Vol 16 (2) ◽

pp. 022503 ◽

Cited By ~ 2

Author(s):

M. Ansar Mahmood ◽

T. Rafiq ◽

M. Persson ◽

J. Weiland

Keyword(s):

Temperature Gradient ◽

Ion Temperature ◽

Ion Temperature Gradient ◽

Trapped Electron

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Linear interaction and relative role of the ion temperature gradient and trapped electron modes in the reactor-relevant finite beta plasma condition

Physics of Plasmas ◽

10.1063/1.4990071 ◽

2017 ◽

Vol 24 (7) ◽

pp. 072501 ◽

Cited By ~ 8

Author(s):

J. Y. Kim ◽

H. S. Han

Keyword(s):

Temperature Gradient ◽

Relative Role ◽

Ion Temperature ◽

Plasma Condition ◽

Ion Temperature Gradient ◽

Linear Interaction ◽

Trapped Electron

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Temperature ratio dependence of ion temperature gradient and trapped electron mode instability thresholds

Physics of Plasmas ◽

10.1063/1.2906223 ◽

2008 ◽

Vol 15 (4) ◽

pp. 042310 ◽

Cited By ~ 27

Author(s):

Alessandro Casati ◽

C. Bourdelle ◽

X. Garbet ◽

F. Imbeaux

Keyword(s):

Temperature Gradient ◽

Ion Temperature ◽

Temperature Ratio ◽

Mode Instability ◽

Ion Temperature Gradient ◽

Ratio Dependence ◽

Electron Mode ◽

Trapped Electron

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Enstrophy non-conservation and the forward cascade of energy in two-dimensional electrostatic magnetized plasma turbulence

Journal of Plasma Physics ◽

10.1017/s0022377820000872 ◽

2020 ◽

Vol 86 (4) ◽

Author(s):

G. G. Plunk

Keyword(s):

Temperature Gradient ◽

Plasma Turbulence ◽

Magnetized Plasma ◽

Larmor Radius ◽

Ion Temperature ◽

Fluid System ◽

Ion Temperature Gradient ◽

Zonal Flows ◽

Electron Temperature Gradient ◽

Enstrophy Cascade

A fluid system is derived to describe electrostatic magnetized plasma turbulence at scales somewhat larger than the Larmor radius of a given species. It is related to the Hasegawa–Mima equation, but does not conserve enstrophy, and, as a result, exhibits a forward cascade of energy, to small scales. The inertial-range energy spectrum is argued to be shallower than a $-11/3$ power law, as compared to the $-5$ law of the Hasegawa–Mima enstrophy cascade. This property, confirmed here by direct numerical simulations of the fluid system, may help explain the fluctuation spectrum observed in gyrokinetic simulations of streamer-dominated electron-temperature-gradient driven turbulence (Plunk et al., Phys. Rev. Lett., vol. 122, 2019, 035002), and also possibly some cases of ion-temperature-gradient driven turbulence where zonal flows are suppressed (Plunk et al., Phys. Rev. Lett., vol. 118, 2017, 105002).

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