University of California, San Diego, La Jolla, California 92093, USA.
Phys Rev Lett. 2012 May 25;108(21):215002. doi: 10.1103/PhysRevLett.108.215002. Epub 2012 May 23.
Most of the work to date on plasma blobs found in the edge region of magnetic confinement devices is limited to 2D theory and simulations which ignore the variation of blob parameters along the magnetic field line. However, if the 2D convective rate of blobs is on the order of the growth rate of unstable drift waves, then drift wave turbulence can drastically alter the dynamics of blobs from that predicted by 2D theory. The density gradients in the drift plane that characterize the blob are mostly depleted during the nonlinear stage of drift waves resulting in a much more diffuse blob with a greatly reduced radial velocity. Sheath connected plasma blobs driven by effective gravity forces are considered in this Letter and it is found that the effects of resistive drift waves occur at earlier stages in the 2D motion for smaller blobs and in systems with a smaller effective gravity force. These conclusions are supported numerically by a direct comparison of 2D and 3D seeded blob simulations.
迄今为止，关于在磁约束装置边缘区域发现的等离子体团块的大部分工作都局限于二维理论和模拟，这些理论和模拟忽略了团块参数沿磁场线的变化。然而，如果二维团块的对流速率与不稳定漂移波的增长率相当，那么漂移波湍流就会极大地改变二维理论所预测的团块动力学。在漂移波的非线性阶段，漂移平面中的密度梯度特征主要被耗尽，导致团块变得更加弥散，径向速度大大降低。本文考虑了由有效重力驱动的鞘连接等离子体团块，发现对于较小的团块和有效重力较小的系统，在二维运动的早期阶段就会出现电阻漂移波的影响。这些结论通过对二维和三维种子团块模拟的直接比较得到了数值支持。
