High-beta plasma effects in a low-pressure helicon plasma
High-beta plasma effects in a low-pressure helicon plasma
复制标题
低压螺旋等离子体中的高β等离子体效应
DOI：
10.1063/1.2802080
复制
发表时间：
2007
影响因子：
2.2
通讯作者：
R. Boswell
中科院分区：
文献类型：
--
作者：
C. Corr;R. Boswell
在这项工作中，高β等离子体的影响进行了研究，在一个低压螺旋等离子体源连接到一个大体积的扩散室。当在900 W的输入功率和30 G的磁场以上操作时，沿着扩散室的轴观察到由于Ar II辐射而产生的明亮蓝光的窄柱。在这种蓝色模式下，扩散室中的等离子体密度在轴向非常均匀;然而，径向分布却不是这样，这表明可能会感应出大的反磁电流。通过测量脉冲放电模式下磁场Bz和等离子体动压的时间演化，研究了等离子体的抗磁行为。据发现，虽然电子压力可以超过磁场压力的2倍，从等离子体内部的磁场的完全驱逐没有观察到。事实上，在我们使用磁化离子的操作条件下，观察到的最大抗磁性为2%。据观察，磁场显示最强的变化在等离子体中心，这对应于在等离子体动力学压力的最大值。这些结果表明，磁场扩散到等离子体足够快，在很长的时间尺度上，只有轻微的扰动的磁场被观察到。© 2007美国物理学会。DOI：10.1063/1.2802080
In this work, high-beta plasma effects are investigated in a low-pressure helicon plasma source attached to a large volume diffusion chamber. When operating above an input power of 900 W and a magnetic field of 30 G a narrow column of bright blue light due to Ar II radiation is observed along the axis of the diffusion chamber. With this blue mode, the plasma density is axially very uniform in the diffusion chamber; however, the radial profiles are not, suggesting that a large diamagnetic current might be induced. The diamagnetic behavior of the plasma has been investigated by measuring the temporal evolution of the magnetic field Bz and the plasma kinetic pressure when operating in a pulsed discharge mode. It is found that although the electron pressure can exceed the magnetic field pressure by a factor of 2, a complete expulsion of the magnetic field from the plasma interior is not observed. In fact, under our operating conditions with magnetized ions, the maximum diamagnetism observed is 2%. It is observed that the magnetic field displays the strongest change at the plasma centre, which corresponds to the maximum in the plasma kinetic pressure. These results suggest that the magnetic field diffuses into the plasma sufficiently quickly that on a long time scale only a slight perturbation of the magnetic field is ever observed. © 2007 American Institute of Physics. DOI: 10.1063/1.2802080