Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas
Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas
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Alcator C-Mod 欧姆 L 模式等离子体中的非局部热传输、旋转反转和上/下杂质密度不对称
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发表时间：
2013
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通讯作者：
S. M. Wolfe
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作者：
John E. Rice;C. Gao;M. Reinke;Patrick H Diamond;N. Howard;H. J. Sun;I. Cziegler;A. Hubbard;Y. Podpaly;W. Rowan;J. L. Terry;M. Chilenski;L. Delgado;P. Ennever;D. Ernst;Martin Greenwald;J. Hughes;Y. Ma;E. Marmar;M. Porkolab;Anne White;S. M. Wolfe
Alcator C-Mod欧姆L模式等离子体中的几个看似无关的效应被证明是紧密相连的：非局部热传输，核心环形旋转反转，能量约束饱和和上/下杂质密度不对称。这些现象都在碰撞性的临界值处突然转变。在线性欧姆限制区的低密度下，碰撞性ν*<$0.35（在q = 3/2表面内部评估），热输运表现出非局域行为，核心环形旋转是定向的并流，边缘杂质密度分布是上下对称的，并且在kθ高达15 cm−1（kθρs <$1）的核心密度波动中存在湍流特征。在高密度/高碰撞度和饱和欧姆约束条件下，电子热输运为扩散性质，芯旋转为逆流方向，边缘杂质浓度分布为上下不对称，不存在高kθ湍流特征。旋转反转停滞点（就在q = 3/2表面的内部）与非局部电子温度分布反转半径一致。所有这些观察表明，在一个模型中，在低碰撞性和离子温度梯度模式的优势，在高碰撞性的捕获电子模式的流行可能的统一。
Several seemingly unrelated effects in Alcator C-Mod ohmic L-mode plasmas are shown to be closely connected: non-local heat transport, core toroidal rotation reversals, energy confinement saturation and up/down impurity density asymmetries. These phenomena all abruptly transform at a critical value of the collisionality. At low densities in the linear ohmic confinement regime, with collisionality ν* ⩽ 0.35 (evaluated inside of the q = 3/2 surface), heat transport exhibits non-local behaviour, core toroidal rotation is directed co-current, edge impurity density profiles are up/down symmetric and a turbulent feature in core density fluctuations with kθ up to 15 cm−1 (kθρs ∼ 1) is present. At high density/collisionality with saturated ohmic confinement, electron thermal transport is diffusive, core rotation is in the counter-current direction, edge impurity density profiles are up/down asymmetric and the high kθ turbulent feature is absent. The rotation reversal stagnation point (just inside of the q = 3/2 surface) coincides with the non-local electron temperature profile inversion radius. All of these observations suggest a possible unification in a model with trapped electron mode prevalence at low collisionality and ion temperature gradient mode domination at high collisionality.