Study of the insulating wall used in MHD generator channel

An enhanced peg wall has been developed as a result of many years' study on the insulating inside wall usable for long duration in the open cycle MHD generator channel installed at the Electrotechnical Laboratory. The enhanced peg wall is superior to ordinary peg wall and other types of insulating walls in electric and thermal characteristics. The structure of the cooling pass for the wall segments is taken into consideration so as to hold out high heat flux density. The surface of the wall segments is coated with alumina ceramics for the purpose of improving their electric characteristics and protecting them against corrosion. As the result of preliminary experiments it has been confirmed that the enhanced peg wall holds out continual high heat flux density of about 1kW/cm2 and has high breakdown voltage of about 500 V between adjacent wall segments. Generating experiments were performed with a long duration MHD generator ETL-MARK III and a large-scale MHD generator ETL MARK V. Results of the experiments indicate that the enhanced peg wall is usable as the inside wall of MHD generator channel for about 500 hours, and suggest that it is capable of holding out the estimated strength of the electric field inside commercial MHD generator channels. (auth.)