In the edge of an $L$-mode tokamak plasma, particle transport and ion energy transport are shown to follow a strong microturbulence (SMT) scaling, whereas in the plasma core the transport is shown to follow quasilinear turbulence scaling. The dependence of diffusivity on potential fluctuation amplitude is linear in the SMT regime, and quadratic in the quasilinear regime. The transition to strong microturbulence results from larger $E\times B$ drift velocities in the edge compared to the plasma core. At these larger velocities, ions traverse the spatially correlated range faster than the stochastic evolution of the electric potential. Hence, these particles do not experience a time-stochastic field as required by the quasilinear approximation. Instead, scattering of particles in the SMT regime is caused by spatial stochasticity. In contrast, electron energy transport remains quasilinear due to decorrelations caused by collisions and fast parallel motion. Improved understanding of transport beyond quasilinear theory opens the path to more accurate modeling of transport in the tokamak plasma edge.

中文翻译：

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托卡马克边缘中拟线性理论的分解

在一个边缘$L$模式托卡马克等离子体、粒子输运和离子能量输运显示出遵循强微湍流（SMT）标度，而在等离子体核心中，输运显示出遵循准线性湍流标度。扩散率对电势波动幅度的依赖性在 SMT 区域中是线性的，在拟线性区域中是二次的。向强微湍流的转变是由于较大的$乙\times 乙$与等离子体核心相比，边缘的漂移速度。在这些较大的速度下，离子穿过空间相关范围的速度比电势的随机演化更快。因此，这些粒子不会经历拟线性近似所需的时间随机场。相反，SMT 区域中的粒子散射是由空间随机性引起的。相反，由于碰撞和快速平行运动引起的去相关，电子能量传输保持准线性。改进对准线性理论之外的输运的理解，为更准确地模拟托卡马克等离子体边缘的输运开辟了道路。