Control of Plasma at the Inlet of Disk MHD Generator by a Radio-Frequency Electromagnetic Field

为了使非平衡盘式MHD发电机在大范围工况下实现高性能工作，需要根据工况的变化对发电机入口等离子体特性进行控制和优化。从这个角度出发，本研究的目的是阐明射频电磁场对圆盘MHD发生器入口等离子体产生和控制的有用性。为此，研制了一种新型圆盘MHD发电机。在圆盘MHD发电机中，射频感应线圈嵌入在一边的圆盘壁上，另一边安装了电力提取所需的阳极。在无播种、无流动、无磁场的条件下，在圆盘MHD发电机中尝试了射频电磁场产生等离子体。实验结果表明，在较宽的气体压力条件下，在方位方向上产生了均匀的非平衡惰性气体等离子体。作为下一步，磁盘MHD发电机安装在激波管设施。实验证实，在高温、高压、高速流动和磁场的作用下，射频电磁场沿感应线圈可以实现在方位方向上相当均匀的非平衡等离子体。此外，在无射频电磁场的发电实验中，证实了采用非对称电极结构的圆盘型MHD发电机的性能与传统MHD发电机相当。在本研究的基础上提出的后续研究是针对射频电磁场对圆盘MHD发电机性能的改善。

In order to realize the high performance non-equilibrium disk MHD generator working under wide range operating conditions, the plasma properties at the generator inlet should be controlled and optimized in response to the change in the operating condition. From this viewpoint, the aim of the present research is to clarify the usefulness of a radio-frequency electromagnetic field for the plasma production and control at the inlet of the disk MHD generator.For the present research, a new disk MHD generator was manufactured. In the disk MHD generator, radio-frequency induction coils are embedded in one side disk wall and anodes, which are needed for electric power extraction, are equipped in another side. At first, the plasma production by the radio-frequency electromagnetic field was attempted in the disk MHD generator under no seeding, no flow and no magnetic field. The experimental results showed that the nonequilibrium inert gas plasma uniform in the azimuthal direction was produced under the wide range of gas pressure condition. As the next step, the disk MHD generator was installed in the shock tube facility. It was confirmed in the experiment that the nonequilibrium plasma fairly uniform in the azimuthal direction was realized along the induction coil in the presence of high temperature, high pressure, high velocity flow and magnetic field by the radio-frequency electromagnetic field. Furthermore, in the power generation experiment without radio-frequency electromagnetic field, the performance of the present disk MHD generator with the asymmetrical electrode configuration was confirmed to be comparable to that of a conventional MHD generator.The subsequent research proposed on the basis of the present research is addressed to the improvement in the performance of disk MHD Generator by a radio-frequency electromagnetic field.