STUDY OF A DISK MHD GENERATOR FOR NONEQUILIBRIUM PLASMA GENERATOR (NPG) SYSTEM

Design and performance prediction studies of a disk type magnetohydrod ynamic (MHD) generator which is applied to the non equilibrium plasma generator (NPG) system have been performed. The main objective of the present study was to find out whether a sufficiently high output perfo rmance demonstration is possible with the disk generator which is plan ned to be used for the NPG-MHD disk pulse power demonstration. A prese nt numerical simulation showed that the original constant height chann el could provide not more than 20% of enthalpy extraction because its channel shape could not sustain the working plasma in the stable regim e against ionization instability throughout the channel. We concluded that, in order to obtain much higher generator performance, a detailed design of the channel shape was necessary. Design work has also been performed based on the concept that the local electron temperature mus t be kept at 5000K, i.e. the plasma must be controlled to locate at th e center of the stable regime. With the designed channel, enthalpy ext raction of up to 40% and output power of 7.2 MW can be successfully ex pected under the thermal input of 18 MW. In addition, the designed cha nnel requires no major modification of the supersonic nozzle, the inle t swirl vanes and the configuration of the magnet system. (C) 1997 Els evier Science Ltd.