Closed cycle MHD power generation system without alkali-metal seed

In this paper, the authors examine the possibility of a closed-cycle MHD power generation system without using alkali-metal seed. Based on the important role of seed, they propose the use of xenon as the seed material. Consideration by solving the Saha equation shows that helium must be used to obtain a notable enhancement of the electron number density from xenon and a higher electron temperature of 8000-9000 K must be maintained to achieve the same electron number density level as that for the potassium seed case. Performance prediction by means of 1-dimensional numerical simulation is carried out. If the same disk generator and the same conditions as cesium seed are used, performance using He/Xe is much less than that of He/Cs. An increase of inlet electron temperature (which means a requirement of preionization and an increase of load resistance) are necessary to obtain reasonable output performance. Next, the authors design a suitable disk generator for xenon seed and a performance prediction with the designed channel is carried out. They succeed in designing a disk generator for xenon seed which can provide over 40% enthalpy extraction. In order to study plasma stability and discharge structure, a two-dimensional numerical simulation has been started and preliminary results are presented. However, how to increase initial conductivity, plasma stability and its effects on plasma parameter and efficiency are still to be studied.