Kobayashi M, Tanaka K, Ida K, Hayashi Y, Takemura Y, Kinoshita T
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu 509-5292, Japan.
National Institute for Fusion Science, SOKENDAI, The Graduate University for Advanced Studies, Toki, Gifu 509-5292, Japan.
Phys Rev Lett. 2022 Mar 25;128(12):125001. doi: 10.1103/PhysRevLett.128.125001.
Turbulence spreading into the edge stochastic magnetic layer induced by magnetic fluctuation is observed at the sharp boundary region in the large helical device. The density fluctuation excited at the sharp boundary region with a large pressure gradient does not propagate into the boundary region due to the blocking of turbulence spreading by the large second derivative of the pressure gradient. Once the magnetic fluctuation appears at the boundary, the density fluctuation begins to penetrate the edge stochastic layer and the second derivative of the pressure gradient also decreases. The increase of density fluctuation in this layer results in the broadening and reduction of the peak divertor heat load. It is demonstrated that magnetic fluctuation plays a key role in controlling the turbulence spreading at the boundary of plasma which contributes to the reduction of divertor heat load.
在大型螺旋装置的尖锐边界区域观察到由磁涨落引起的湍流扩散到边缘随机磁层中。在具有大压力梯度的尖锐边界区域激发的密度涨落由于压力梯度的大二阶导数对湍流扩散的阻挡而不会传播到边界区域。一旦磁涨落在边界处出现，密度涨落就开始穿透边缘随机层，并且压力梯度的二阶导数也会减小。该层中密度涨落的增加导致偏滤器峰值热负荷变宽和降低。结果表明，磁涨落在控制等离子体边界处的湍流扩散中起着关键作用，这有助于降低偏滤器热负荷。
