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

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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.