Relation between a plasma confinement improvement due to internal transport barrier formation and the effects of sheared flows on the suppression of turbulent vortices

反常的粒子和能量跨场输运是核聚变磁等离子体约束中最关键的问题之一，也是磁化等离子体物理中最关键的问题之一。最近的实验表明，在具有不同磁场拓扑(如托卡马克、星角器和反射镜)的磁约束系统中，低频(LF)湍流和与之相关的反常跨场等离子体输运呈现出相当常见的特征，包括高约束(H)模跃迁和内部输运势垒(ITB)的形成。势垒位于强剪切E_r×B等离子体旋转层内。这个高涡度层预计将通过等离子体加热来形成和保持，这将产生一个具有部分电子损失的层，将初始的高斯径向势分布修改为具有驼峰结构的非单调分布。在ITB层，T_i和T_e的局域梯度也有望得到增强，类似于托卡马克和恒星装置中的ITB。因此，在势垒层中，有效离子和电子的热扩散系数被预期减小。在ITB层中观察到的低频湍流的减少，以及位于该层两侧的湍流结构的部分去耦合被证明。最近，我们得到了各种控制方法的想法，尽管意外事件干扰了他们的报告。这些新方法将在未来得到推广。这种外控输运势垒的形成对于包括ITER等离子体在内的聚变等离子体的升级具有重要意义，因为它可以主动控制内部输运势垒的形成。

Anomalous particle and energy cross-field transport is one of the most critical issues in magnetic plasma confinement for fusion, as well as in the physics of magnetized plasmas in general. In magnetic confinement systems with different magnetic-field topologies (e. g., tokamaks, stellarators, and mirrors), recent experiment shave shown that low-frequency (LF) turbulence and the associated anomalous cross-field plasma transport exhibit rather common features including high-confinement (H) mode transition sand internal transport-barrier (ITB) formation.The controlled formation of an internal transport barrier is investigated. The barrier is localized within a layer of a strongly sheared E_r×B plasma rotation. This high-vorticity layer is anticipated to be formed and maintained by plasma heating, which generates a layer with a partial loss of electrons that modifies the initial Gaussian radial potential profile into a non-monotonic one with a hump structure. The local gradients of T_I and T_e are also expected to be enhanced in the ITB layer, similarly to those of the ITB in tokamaks and stellarators. Reductions in the effective ion and electron thermal diffusivities are thus anticipated in the barrier layer A reduction of the observed low-frequency turbulence in the ITB layer and a partial decoupling of the turbulent structures localized on either side of the layer are demonstrated. Recently, we have obtained the ideas of various controlled methods, although unexpected matters disturbed their reports. These new methods will be extended in future.Such externally controlled transport barrier formation is of great importance for the fusion plasma upgrade including ITER plasmas in terms of the active control of the internal transport barrier formation.