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

为了实现大范围工作的高性能非平衡盘式磁流体发电机，需要对发电机入口处的等离子体特性进行控制和优化，以响应运行条件的变化。从这一角度出发，本研究旨在阐明射频电磁场在盘式磁流体发电机入口处等离子体产生和控制中的作用。在盘式磁流体发电机中，一侧盘壁内嵌有射频感应线圈，另一侧安装有提取电能所需的阳极。首先，在圆盘式磁流变液发生器中，尝试在无种、无流、无磁场条件下，利用射频电磁场产生等离子体。实验结果表明，在较宽的气压范围内，产生了在方位向均匀分布的非平衡惰性气体等离子体。下一步，在激波管装置中安装了盘式磁流体发生器。实验证实，在高温、高压、高速气流和磁场的作用下，射频电磁场可以实现沿感应线圈方向上较均匀的非平衡等离子体。此外，在没有射频电磁场的发电实验中，证实了目前非对称电极结构的盘式磁流体发电机的性能与传统的磁流体发电机相当。在本研究的基础上，提出了利用射频电磁场改善盘式磁流体发电机性能的后续研究。

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.