Theory on Spiral Structure Formation in Magnetized Plasmas

磁化等离子体中螺旋结构形成理论

基本信息

批准号：
12680481
负责人：
KONO Mitsuo
金额：
$ 2.43万
依托单位：
CHUO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

We studied the processes of plasma density hole formation observed in a rotating plasma and obtained corresponding stationary solution. On the contrary to typhoon for which centrifugal force and pressure are balanced with each other, the observed hole has similar structure to the Burgers vortex. The stationary solution has been derived based on this observation. Then the viscosity obtained from the parameters for which the theoretical stationary solution fits the observed hole is larger by order of 10^6 than the viscosity estimated from collisional processes. However the rotation is stemed from E x B drift which is determined by the potential. Thus a phenomenological approach for which the potential profile observed in the experiments is used gives not only the density profile but also the velocity fields and vorticity which coincide with the observations. Interesting things are that the velocity fields agree the Burgers vortex field in the vicinity of the rotation axis and vanish at the far distance from the vortex axis although the Burgers vortex field diverges at infinity. This shows the plasma hole belongs to the same class of self-organization in magnetized plasma as the spiral structure.In the same experimenta device a tripole vortex is also observed. This tripole vortex rotates in an opposite direction to E x B rotation. This rotation is identified with the drift induced by the momentum transfer due to charge exchange between ions and neutral particles. A stationary tripole vortex solution has been obtained and parameters are shown to be chosen so that the solution shows the best fit with the observed tripole vortex. However we have not checked the stability of the stationary tripole vortex solution.

我们研究了旋转等离子体中观察到的等离子体密度空穴形成过程，并得到了相应的静止解。与离心力和压力相互平衡的台风相反，观测到的孔具有与伯格涡类似的结构。平稳解是根据这一观察得出的。然后，从理论固定解拟合观察孔的参数获得的粘度比从碰撞过程估计的粘度大 10^6 数量级。然而，旋转源于由电势决定的 E x B 漂移。因此，使用实验中观察到的势分布的唯象方法不仅给出了密度分布，而且还给出了与观察结果一致的速度场和涡度。有趣的是，速度场在旋转轴附近与伯格涡流场一致，并且在距涡流轴较远的地方消失，尽管伯格涡流场在无穷远处发散。这表明等离子体孔与螺旋结构属于磁化等离子体中的同一类自组织。在同一实验装置中还观察到三极涡旋。该三极涡旋以与 E x B 旋转相反的方向旋转。这种旋转被认为是由于离子和中性粒子之间的电荷交换而引起的动量转移引起的漂移。已经获得了固定三极涡旋解，并且显示了要选择的参数，以便该解显示出与观察到的三极涡旋的最佳拟合。然而我们还没有检查静止三极涡旋解的稳定性。