Nonlinear gyrokinetic turbulence simulations of E × B shear quenching of transport
Nonlinear gyrokinetic turbulence simulations of E × B shear quenching of transport
复制标题
输运 E × B 剪切淬火的非线性回旋湍流模拟
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
J. Candy
中科院分区：
文献类型：
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作者：
J. Kinsey;R. Waltz;J. Candy
在考虑动能电子和不考虑动能电子的非线性回转运动湍流模拟中，研究了E×B速度剪切的影响。在静电通量管模拟中，E×B剪切稳定化的影响可以用一个简单的猝灭规则来很好地模拟，其中湍流扩散率标度为1−αEγE/γmax，其中γE是E×B剪切速率，γmax是没有E×B剪切的最大线性增长率，αE是乘数。猝灭规则最初是从绝热电子离子温度梯度模拟中推导出来的，其中发现αE≈1。本文的结果表明，在动能电子存在的情况下，该猝灭规则也适用于向离子回旋射线尺度下的长波输运。在没有平行速度剪切的情况下，电子和离子的输运在γE/γmax≈2(αE≈1/2)附近猝灭。当模拟中考虑了平行速度剪切的失稳效应时，由于开尔文-亥姆霍兹驱动增加γmax的速度比γE增加的速度快，所以输运可能不会被任何水平的E×B剪切完全熄灭。同时考虑了附加陷阱电子驱动的ITG湍流和电子定向和曲率驱动的陷阱电子模湍流。在考虑和不考虑动能电子的情况下，研究了E×B速度剪切对非线性陀螺运动湍流的影响。在静电通量管模拟中，E×B剪切稳定化的影响可以用一个简单的猝灭规则来很好地模拟，其中湍流扩散率标度为1−αEγE/γmax，其中γE是E×B剪切速率，γmax是没有E×B剪切的最大线性增长率，αE是乘数。猝灭规则最初是从绝热电子离子温度梯度模拟中推导出来的，其中发现αE≈1。本文的结果表明，在动能电子存在的情况下，该猝灭规则也适用于向下到离子回旋半径尺度的长波输运。在没有平行速度剪切的情况下，电子和离子的输运在γE/γmax≈2(αE≈1/2)附近猝灭。当模拟中考虑平行速度剪切的失稳效应时，输运可能不会被任何一种方法完全熄灭，这与纯环形旋转一致。
The effects of E×B velocity shear have been investigated in nonliner gyrokinetic turbulence simulations with and without kinetic electrons. The impact of E×B shear stabilization in electrostatic flux-tube simulations is well modeled by a simple quench rule with the turbulent diffusivity scaling like 1−αEγE∕γmax, where γE is the E×B shear rate, γmax is maximum linear growth rate without E×B shear, and αE is a multiplier. The quench rule was originally deduced from adiabatic electron ion temperature gradient (ITG) simulations where it was found that αE≈1. The results presented in this paper show that the quench rule also applies in the presence of kinetic electrons for long-wavelength transport down to the ion gyroradius scale. Without parallel velocity shear, the electron and ion transport is quenched near γE∕γmax≈2 (αE≈1∕2). When the destabilizing effect of parallel velocity shear is included in the simulations, consistent with purely toroidal rotation, the transport may not be completely quenched by any level of E×B shear because the Kelvin–Helmholtz drive increases γmax faster than γE increases. Both ITG turbulence with added trapped electron drive and electron-directed and curvature-driven trapped electron mode turbulence are considered.The effects of E×B velocity shear have been investigated in nonliner gyrokinetic turbulence simulations with and without kinetic electrons. The impact of E×B shear stabilization in electrostatic flux-tube simulations is well modeled by a simple quench rule with the turbulent diffusivity scaling like 1−αEγE∕γmax, where γE is the E×B shear rate, γmax is maximum linear growth rate without E×B shear, and αE is a multiplier. The quench rule was originally deduced from adiabatic electron ion temperature gradient (ITG) simulations where it was found that αE≈1. The results presented in this paper show that the quench rule also applies in the presence of kinetic electrons for long-wavelength transport down to the ion gyroradius scale. Without parallel velocity shear, the electron and ion transport is quenched near γE∕γmax≈2 (αE≈1∕2). When the destabilizing effect of parallel velocity shear is included in the simulations, consistent with purely toroidal rotation, the transport may not be completely quenched by any ...