Nonlinear inward particle flux component in trapped electron mode turbulence
Nonlinear inward particle flux component in trapped electron mode turbulence
复制标题
俘获电子模式湍流中的非线性向内粒子通量分量
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
R. Gatto
中科院分区：
文献类型：
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作者：
P. Terry;R. Gatto
被困电子湍流示出有一个显着的向内粒子通量分量与非线性偏差的密度-势的互相关从准线性值。由于密度平流的非线性混合了线性稳定的本征模与不稳定的本征模，所以互相关被改变。通过在一个完整的基上求解谱平衡方程来计算全非线性通量。小碰撞，垂直波数，和温度/密度梯度不稳定性阈值参数的有序扩展，使弱驱动制度的解析解。该解决方案量化的带状模式的作用，通过其饱和的湍流下强烈的各向异性传输。向内输送既不是扩散也不是对流，而是由温度梯度驱动，并由平坦的密度梯度增强。它略小于与增长的本征模相关的向外指向的通量，使得通量是准线性值的一小部分。
Trapped electron turbulence is shown to have a significant inward particle flux component associated with nonlinear deviations of the density-potential cross correlation from the quasilinear value. The cross correlation is altered because the density advection nonlinearity mixes a linearly stable eigenmode with the eigenmode of the instability. The full nonlinear flux is evaluated by solving spectrum balance equations in a complete basis spanning the fluctuation space. An ordered expansion for small collisionality, perpendicular wave number, and temperature/density-gradient instability threshold parameter enables an analytic solution for a weakly driven regime. The solution quantifies the role of zonal modes on transport via their saturation of the turbulence under intensely anisotropic transfer. The inward transport is neither diffusive nor convective, but is driven by temperature gradient and enhanced by flat density gradients. It is slightly smaller than the outwardly directed flux associated with the growing eigenmode, making the flux a small fraction of the quasilinear value.