Effects of alpha particles on the CTEM driven zonal flow in deuterium–tritium tokamak plasmas

Sadam, Hussain Malik; Guo, Weixin; Wang, Lu

doi:10.1088/1741-4326/ac4db8

Cited by 5 publications

(2 citation statements)

References 33 publications

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“…Unless otherwise stated, we will take the following normalized parameters from the cyclone DIII-D base case as in the gyrokinetic simulations [56,57], but artificially exchange the magnitudes of electron density gradient and electron temperature gradient as in [35]. The mixing ratio of D-T ions is 1:1, ε 0 = 0.1, q = 1.4, ŝ = 0.8, R/L ne = 6.9, R/L Te = 2.2, Leα = 2, LeHe = 1, and both the temperature gradient of D-T ions and helium ash are artificially set as R/L T j = 0.1 ( j = D, T, He) to avoid ITG instability [29,35,58]. Similar artificial treatment by setting R/L T j = 0 has also been used in [51,59,60], and it has been shown that the wavenumber spectrum of the linear growth rate of both trapped electron mode (TEM) instability [61] and CTEM driven zonal flow (ZF) [51] would not been qualitatively changed by slightly increasing R/L T j .…”

Section: Effects Of α Particles On the Parametric Dependence Of Heliu...mentioning

confidence: 99%

“…α particles and/or electron cyclotron resonance heating (ECRH) mainly heat electrons, and thus one scan of T e is under fixed T i = 10 keV. The other case is raising T i and T e simultaneously under T i = T e , which is widely used for studying the effects of energetic particles on drift wave and ZF [33,58,67].…”

Section: The Effects Of Electron Parameters: T E and R/l Nementioning

confidence: 99%

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Effects of alpha particles on the transport of helium ash driven by collisionless trapped electron mode turbulence

Zhu¹,

Wang²,

Guo³

et al. 2022

Nucl. Fusion

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The effects of alpha (α) particles on the transport of helium ash driven by collisionless trapped electron mode (CTEM) turbulence are analytically studied using quasi-linear theory in tokamak deuterium (D) and tritium (T) plasmas. Under the parameters used in this work, the transport of helium ash is mainly determined by the diffusion due to very weak convection. It is found that the ratio between helium ash diffusivity and effective electron thermal conductivity (D_He/χ_eff) driven by CTEM turbulence, which is a proper normalized parameter for quantifying the efficiency of helium ash removal, is smaller than unity. This indicates the less efficient removal of helium ash through CTEM turbulence as compared with ion temperature gradient (ITG) turbulence in [Angioni, et al, 2009 Nucl. Fusion, 49 055013]. However, the efficiency of helium ash removal is increased 55% by the presence of 3% α particles with their density gradient being twice that of electrons, and this enhancement can be further strengthened by steeper profile of α particles. This is mainly because the enhancement of helium ash diffusivity by α particles is stronger than that of the effective electron thermal conductivity. Moreover, the higher fraction of T ions, higher temperature ratio between electrons and thermal ions as well as flatter electron density profile, the stronger enhancement of D_He/χ_eff, and α particles further strengthen the favorable effects of these parameters on the removal of helium ash.

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Section: Effects Of α Particles On the Parametric Dependence Of Heliu...mentioning

confidence: 99%

Section: The Effects Of Electron Parameters: T E and R/l Nementioning

confidence: 99%

Effects of alpha particles on the transport of helium ash driven by collisionless trapped electron mode turbulence

Zhu¹,

Wang²,

Guo³

et al. 2022

Nucl. Fusion

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Fast ion effects on zonal flow generation: A simple model

et al. 2023

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Fast ions' effects on turbulence-driven zonal flow generation are investigated in the context of a simple reduced model based on the Hasegawa–Mima equation. Fast ions' much higher characteristic frequency of parallel motion in comparison with the drift wave's phase velocity along the magnetic field facilitates a derivation of the reduced model equations. Nonlinear mode coupling analyses show that the threshold amplitude of drift wave required for the zonal flow modulational instability is significantly reduced, making its generation easier. This occurs as both a down-shift of the drift wave's frequency and a reduction of dispersion in the presence of the fast ions cause a decrease in the mismatch between the primary drift wave frequency and the zonal flow modulated sideband drift wave's characteristic frequency. This finding could be a common nonlinear physics mechanism behind numerous recent results on tokamak plasma confinement enhancement caused by the fast ions.

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

Ding,

Wang,

Chen

et al. 2024

Nucl. Fusion

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The J-TEXT capability is enhanced compared to two years ago with several upgrades of its diagnostics and the increase of electron cyclotron resonance heating (ECRH) power to 1 MW. With the application of electron cyclotron wave (ECW), the ECW assisted plasma startup is achieved; the tearing mode is suppressed; the toroidal injection of 300 kW ECW drives around 24 kA current; fast electrons are generated with toroidal injected ECW and the runaway current conversion efficiency increases with ECRH power. The mode coupling between 2/1 and 3/1 modes are extensively studied. The coupled 2/1 and 3/1 modes usually lead to major disruption. Their coupling can be either suppressed or avoided by external resonant magnetic perturbation (RMP) fields and hence avoids the major disruption. It is also found that the 2/1 threshold of external field is significantly reduced by a pre-excited 3/1 mode, which can be either a locked island or an external kink mode. The disruption control is studied by developing prediction methods capable of cross tokamak application and by new mitigation methods, such as the biased electrode or electromagnetic pellet injector. The high-density operation and related disruptions are studied from various aspects. Approaching the density limit, the collapse of the edge shear layer is observed and such collapse can be prevented by applying edge biasing, leading to an increased density limit. The density limit is also observed to increase, if the plasma is operated in the poloidal divertor configuration or the plasma purity is increased by increasing the pre-filled gas pressure or ECRH power during the start-up phase.

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Effects of alpha particles on the CTEM driven zonal flow in deuterium–tritium tokamak plasmas

Cited by 5 publications

References 33 publications

Effects of alpha particles on the transport of helium ash driven by collisionless trapped electron mode turbulence

Effects of alpha particles on the transport of helium ash driven by collisionless trapped electron mode turbulence

Fast ion effects on zonal flow generation: A simple model

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

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