Laboratory Experiments on Electrostatic Potential Structure concerned with Aurora Phenomenon

为了阐明地球疯狂层的动态特征，了解极光现象是非常重要的。电子加速引起的极光放电被认为是由于等离子体电位沿极光卵圆上方磁力线的斜率。在这项工作中，在实验室等离子体中沿着磁力线进行了孔状形成的测量。在加热到2300k左右的热钨板上，k原子表面电离产生无碰撞等离子体，该等离子体受到具有镜面结构的强轴向磁场的约束。等离子体流动速度V在V_o/C_s（C_s：离子声速）的大范围内变化，等离子体电位在磁力线汇聚的区域增大，这与基于电子和离子不同俯仰角的理论预测一致。然而，当等离子体前缘到达端板时，端板的影响很大，即当端板的偏置电位为正时，等离子体电位的增加急剧增强。电势剖面的三维结构显示了一个横跨磁场的大电场，类似于极光椭圆上方的电场。

It is quite important to understand aurora phenomena in order to clarify a dynamic feature of the Earth's madnetosphere. Electron acceleration inducing auroral discharge has been supposed to be due to a plasma potential slope along the magnetic field lines above the auroral ovalIn this work, measurements were performed on porenrial formation along the mahnetic field lines in a loboratory plasma. A collisionless plasma, produced by surface ionization of k atoms on a hot tungsten plate heated up to about 2300k, was confined by a strong axial magnetic field with mirror configuration. The plasma flow speed V was varied in the wide range of V_o/C_s(C_s: ion acoustic speed)The plasma potential is found to increase in the region where the magnetic field lines are converged, being consistent with theoretical prediction based on different pitch angles of electrons and ions. When the plasma front reaches the endplate, howevwe, a big effect of the end- plate is recognized, i.e., for a positive bias potential of the endplate, the plasma potential increase is drastically enhanced. Three-dimensional structure of the potential profile shows a large electric field across the magnetic field, being similar to that above the auroral oval.