The parameter dependence of transition between electrostatic instabilities is studied using gyrokinetic simulation based on a real discharge of steady-state scenario in the Experimental Advanced Superconducting Tokama...The parameter dependence of transition between electrostatic instabilities is studied using gyrokinetic simulation based on a real discharge of steady-state scenario in the Experimental Advanced Superconducting Tokamak.The scan of radial locations shows that trapped electron mode(TEM)dominates around the core while the ion temperature gradient mode(ITG)simultaneously dominates outside.The maximum growth rate of TEM appears aroundρ=0.24,where the maximum electron temperature gradient R/LTelocates,ρis the normalized poloidal flux.Effects of the parameters on the transition between TEM and ITG instability are studied atρ=0.24.It is found that TEM dominates in the scanning with individually changing R/LTe from 2.50 to 25.02 or the density gradient R/L_(n)from 1.38 to 13.76.Meanwhile,the electron-ion temperature ratio T_(e)/T_(i)is found to destabilize TEM,the effect of Teis more sensitive than that of T_(i).The dominant instability diagrams in the(R/L_(Te),R/L_(Ti))plane at different T_(e)/T_(i)and R/Lnare numerically obtained,which clearly show the parameter range of the dominant TEM or dominant ITG instability region.It is found that the dominant TEM region becomes narrower in the plane by decreasing R/L_(n)when T_(e)/T_(i)>0.5.展开更多
The interaction between a magnetized ion and two monochromatic shear Alfvtn waves propagating obliquely to an ambient magnetic field is investigated both analytically and numerically. According to the Hamiltonian of t...The interaction between a magnetized ion and two monochromatic shear Alfvtn waves propagating obliquely to an ambient magnetic field is investigated both analytically and numerically. According to the Hamiltonian of this system, the invariant of motion at the lowest order and the half-island widths at the corresponding resonances are obtained analytically using the Lie transformation method. It is shown that these theoretical results agree with the numerical ones from the Poincare surface of section. The regular motions from the invariant and the transition to stochasticity due to resonance overlapping are demonstrated. Compared to the case of a single wave, there may be a lower stochastic threshold in the multiple-wave problem.展开更多
基于全超导托卡马克(experimental and advanced superconducting tokamak, EAST)中以电子加热为主的放电试验,使用GTC(Gyrokinetic Toroidal Code)代码进行线性回旋动理学模拟,研究等离子体参数对捕获电子模(trapped electron mode, T...基于全超导托卡马克(experimental and advanced superconducting tokamak, EAST)中以电子加热为主的放电试验,使用GTC(Gyrokinetic Toroidal Code)代码进行线性回旋动理学模拟,研究等离子体参数对捕获电子模(trapped electron mode, TEM)线性增长率(γ)的影响。结果表明,γ随电子与离子温度比( T e / T i )和归一化电子温度梯度( R / L T e )的增大而增大,但随着归一化密度梯度( R / L n )的增加而降低。安全因子( q )和磁剪切( s ∧)对TEM线性增长率的影响与归一化半径范围内(ρ<0.4) s ∧值的大小有关。当 s ∧>0.3时,γ随着 q 的增大而增大,随着 s ∧的增大而减小,与简化模型的理论分析一致。然而,当 s ∧<0.3时出现了相反的结果,即γ随 q 的增大而减小,随着 s ∧的增大而增大,其原因可能是较小的 s ∧无法抑制TEM湍流。展开更多
In this work,the anomalous transport driven by the ion temperature gradient instability is investigated in an anisotropic deuterium-tritium(D-T)plasma.The anisotropic factorα,defined as the ratio of perpendicular tem...In this work,the anomalous transport driven by the ion temperature gradient instability is investigated in an anisotropic deuterium-tritium(D-T)plasma.The anisotropic factorα,defined as the ratio of perpendicular temperature to parallel temperature,is introduced to describe the temperature anisotropy in the equilibrium distribution function.The linear dispersion relation in local kinetic limit is derived,and then numerically evaluated to study the dependence of mode frequency on the anisotropic factorαof D and the fraction of T particleεTby choosing three sets of typical parameters,denoted as the cyclone base case,ITER and CFETR cases.Based on the linear results,the mixing length model approximation is adopted to analyze the quasi-linear particle and energy fluxes for D and T.It is found that choosing smallαand largeεTis beneficial for the confinement of particle and energy for D and T.This work may be helpful for the estimation of turbulent transport level in the ITER and CFETR devices.展开更多
基金supported by the National MCF Energy R&D Program of China(Nos.2019YFE03060000,2019YFE03050000 and 2019YFE03020004)National Natural Science Foundation of China(Nos.12005063 and 11875131)+1 种基金Users with Excellence Program of Hefei Science Center CAS(Nos.2020HSC-UE011 and 2021HSC-UE015)Anhui Provincial Natural Science Foundation(No.2008085Jo4)。
文摘The parameter dependence of transition between electrostatic instabilities is studied using gyrokinetic simulation based on a real discharge of steady-state scenario in the Experimental Advanced Superconducting Tokamak.The scan of radial locations shows that trapped electron mode(TEM)dominates around the core while the ion temperature gradient mode(ITG)simultaneously dominates outside.The maximum growth rate of TEM appears aroundρ=0.24,where the maximum electron temperature gradient R/LTelocates,ρis the normalized poloidal flux.Effects of the parameters on the transition between TEM and ITG instability are studied atρ=0.24.It is found that TEM dominates in the scanning with individually changing R/LTe from 2.50 to 25.02 or the density gradient R/L_(n)from 1.38 to 13.76.Meanwhile,the electron-ion temperature ratio T_(e)/T_(i)is found to destabilize TEM,the effect of Teis more sensitive than that of T_(i).The dominant instability diagrams in the(R/L_(Te),R/L_(Ti))plane at different T_(e)/T_(i)and R/Lnare numerically obtained,which clearly show the parameter range of the dominant TEM or dominant ITG instability region.It is found that the dominant TEM region becomes narrower in the plane by decreasing R/L_(n)when T_(e)/T_(i)>0.5.
基金supported by National Natural Science Foundation of China under Grant Nos. 11075140, 11205060 and 11405058the National Magnetic Confinement Fusion Science Program of China under Grant Nos. 2013GB106002 and 2015GB110005
文摘The interaction between a magnetized ion and two monochromatic shear Alfvtn waves propagating obliquely to an ambient magnetic field is investigated both analytically and numerically. According to the Hamiltonian of this system, the invariant of motion at the lowest order and the half-island widths at the corresponding resonances are obtained analytically using the Lie transformation method. It is shown that these theoretical results agree with the numerical ones from the Poincare surface of section. The regular motions from the invariant and the transition to stochasticity due to resonance overlapping are demonstrated. Compared to the case of a single wave, there may be a lower stochastic threshold in the multiple-wave problem.
文摘基于全超导托卡马克(experimental and advanced superconducting tokamak, EAST)中以电子加热为主的放电试验,使用GTC(Gyrokinetic Toroidal Code)代码进行线性回旋动理学模拟,研究等离子体参数对捕获电子模(trapped electron mode, TEM)线性增长率(γ)的影响。结果表明,γ随电子与离子温度比( T e / T i )和归一化电子温度梯度( R / L T e )的增大而增大,但随着归一化密度梯度( R / L n )的增加而降低。安全因子( q )和磁剪切( s ∧)对TEM线性增长率的影响与归一化半径范围内(ρ<0.4) s ∧值的大小有关。当 s ∧>0.3时,γ随着 q 的增大而增大,随着 s ∧的增大而减小,与简化模型的理论分析一致。然而,当 s ∧<0.3时出现了相反的结果,即γ随 q 的增大而减小,随着 s ∧的增大而增大,其原因可能是较小的 s ∧无法抑制TEM湍流。
基金supported by the National MCF Energy R&D Program of China(No.2019YFE03060000)National Natural Science Foundation of China(Nos.12005063,12175228,11875131 and 11675053)。
文摘In this work,the anomalous transport driven by the ion temperature gradient instability is investigated in an anisotropic deuterium-tritium(D-T)plasma.The anisotropic factorα,defined as the ratio of perpendicular temperature to parallel temperature,is introduced to describe the temperature anisotropy in the equilibrium distribution function.The linear dispersion relation in local kinetic limit is derived,and then numerically evaluated to study the dependence of mode frequency on the anisotropic factorαof D and the fraction of T particleεTby choosing three sets of typical parameters,denoted as the cyclone base case,ITER and CFETR cases.Based on the linear results,the mixing length model approximation is adopted to analyze the quasi-linear particle and energy fluxes for D and T.It is found that choosing smallαand largeεTis beneficial for the confinement of particle and energy for D and T.This work may be helpful for the estimation of turbulent transport level in the ITER and CFETR devices.
