Flow and Non-Equilibrium Ionization. Introduction to Papers in Section 2-C

I shall first review five papers relating to magnetohydrodynamic instabilities. I shall then, consider an experimental paper on the transition of MHD plasmas to a non-equilibrium state, one on the theory of boundary layers in two-temperature plasma, one on the theory of-the Hartmann problem, and finally one on the theory of travelling-wave accelerators. I shall begin with the papers on MHD instabilities. In order to avoid confusion I would point out straightaway that we are here considering instabilities associated with the form of the equations of time-dependent motion, and not particular effects (sometimes called ''operating instabilities'') due to the concentration of current lines near the segmented electrodes. In my opinion, these instabilities at present constitute the main problem of closed-cycle MHD conversion. We know that the conductivity of non-equilibrium plasmas is quite sufficient for conversion, and we have reason to believe that the difficulties attributed to segmented electrodes will be overcome. However, it remains to be seen whether or not the instabilities observed in some experiments will destroy the desired fluid properties