Improvement in Performance of Non-equilibrium Disk MHD Generator by means of Radio-Frequency Plasma Control

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，需要针对不同工况对发电机入口等离子体特性进行控制和优化。从这个角度来看，本研究的目标是通过射频等离子体控制（rf预电离）来改善发生器的性能并扩大可接受的工作条件范围。首先进行了射频预电离温度下的发电实验，射频预电离提高了输出功率。此外，这种增加超过了提供的射频功率，并且在低进口停滞温度下更明显地观察到，在这种温度下，只有由于自激电动势引起的焦耳加热才不会产生等离子体。从而验证了射频预电离扩大了滞止温度的可接受范围。此外，还进行了He/Cs工质的大范围种子组分和负载阻力发电实验。结果表明，射频预电离不仅在低种子分数条件下，而且在最佳种子分数和高种子分数条件下，都能提高输出功率。在低负载电阻导致较少焦耳加热的情况下，验证了输出功率的增加。通过二次和三次数值模拟研究了等离子体在射频电磁场作用下的行为和发生器的性能。通过本文的研究，“利用射频等离子体控制提高非平衡盘式MHD发电机的性能”得到了成功的演示，取得了丰硕的成果，必将为非平衡等离子体MHD发电的研究与开发做出贡献。

In order to realize the high performance non-equilibrium disk MHD generator working under the wide range operating conditions, the plasma properties at the generator inlet should be controlled and optimized in response to the various operating conditions. From this viewpoint, the objectives of the present research are to improve the generator performance and expand the acceptable range of operating conditions by means of the radio-frequency plasma control (rf pre-ionization).First of all, the power generation experiments with the rf pre-ionization temperatures, the output power was increased by the rf pre-ionization. Moreover, this increase exceeded the supplied rf power, and was more markedly observed for the low inlet stagnation temperature where no plasma was produced only by the Joule heating attributed to a self-excited electromotive force. Thus, it was verified that the acceptable range of the stagnation temperature was expanded by the rf pre-ionization.Furthermore, the power generation experiments with He/Cs working fluid were conducted for the wide range of seed fractions and load resistances. It was confirmed that the output power was increased not only at the low seed fraction but also at the optimal or high seed fractions by the rf pre-ionization. The increase in the output power was verified for low load resistances leading less Joule heating. The plasma behavior and the generator performance under applying rf electromagnetic field were also examined with two-and three-numerical simulations.As a result of the present research, "Improvement in Performance of Non-equilibrium Disk MHD Generator by means of Radio-Frequency Plasma Control" was successfully demonstrated, and the fruitful results obtained here surely contribute to the advancement in the research and development of the non-equilibrium plasma MHD electrical power generation.