Transition from Bohm to classical diffusion due to edge rotation of a cylindrical plasma
Transition from Bohm to classical diffusion due to edge rotation of a cylindrical plasma
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由于圆柱形等离子体的边缘旋转，从玻姆到经典扩散的转变
DOI：
10.1063/1.2722302
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发表时间：
2007
影响因子：
2.2
通讯作者：
Roger H. Taylor
中科院分区：
文献类型：
--
作者：
J. Maggs;T. Carter;Roger H. Taylor
大型线性等离子体装置的等离子体柱的外部区域通过使真空室壁的一部分相对于阴极（Er<0）偏置正，以受控的方式旋转。施加偏置电压时产生的观察到的交叉场电流的大小和时间依赖性与离子中性碰撞产生的离子电流一致。等离子体柱外部区域的流速超过了局部声速。在不旋转的等离子体柱中，跨场径向粒子输运以玻姆扩散速率进行。高于阈值偏置电压的旋转减少了从玻姆速率到经典速率的场间输运，导致径向密度曲线更陡峭。粒子输运的减少是全局的，而不是孤立于流动剪切区域。线性等离子体柱中从非旋转等离子体边缘到旋转等离子体边缘的转变类似于在Er<0时在托卡马克中观察到的低约束模式到高约束模式的转变。
The outer region of the plasma column of a large, linear plasma device is rotated in a controlled fashion by biasing a section of the vacuum chamber wall positive with respect to the cathode (Er<0). The magnitude and temporal dependence of the observed cross-field current, produced when the bias voltage is applied, is consistent with ion current arising from ion-neutral collisions. Flow speeds in the outer regions of the plasma column exceed the local sound speed. In the nonrotating plasma column, cross-field, radial particle transport proceeds at the Bohm diffusion rate. Rotation, above a threshold bias voltage, reduces cross-field transport from Bohm to classical rates, leading to steeper radial density profiles. Reduction of particle transport is global and not isolated to the region of flow shear. The transition from the nonrotating to the rotating plasma edge in the linear plasma column is similar to the low confinement to high confinement mode transition observed in tokamaks when Er<0.