Blob在托卡马克SOL中的传播行为研究

The propagation of blobs in the scrape-off layer of tokamak

对托卡马克等离子体刮离层(SOL)中特殊的密度相干结构blob的传播行为进行了数值研究。考虑到模型中静电势假设φ<<1与计算;结果不自洽,故对现有的blob动力学模型进行了改进。结果表明,blob在传播过程中会出现极向密度不对称的分布,并初步分析了密度不对称情况出现的原因。当初始blob强度增大时,其质心速度增加,而偏滤器靶板附近的等离子体鞘层耗散将导致其速度降低,更为重要的是这种耗散较强时将导致一种密度低于本体等离子体密度的新的相干结构,即所谓hole结构的产生。

The propagation of special coherent structures （blobs） in the tokamak scrape-off layer （SOL） is studied numerically. Considering that the hypothesis which assumes that electrostatic potentialφ 〈〈1 in existing model is not self-consistent with numerical results, thus modification i,; done to blob dynamics. Results show that the symmetry of the blob in the poloidal direction is broken and the reason for the symmetry break is discussed briefly. The blob velocity increases with its initial, relative amplitude, while decreases with the rising of plasma sheath dissipation near the divertor plate. It should be emphasized that a new type of coherent structures with density lower than the bulk plasmas referred to as holes appears in the presence of strong sheath dissipation.