Experimental investigation of a large-scale paste-cooled MHD channel

The results are given of experimental investigations of the continuous-electrode channel of a pulsed Faraday MHD generator of the Pamir type [1–4]. In the channel, the most heat-stressed inlet section is paste-cooled. The channel may be readily disassembled, which enables one to exchange the structures of both electrode and insulating walls during the runs with a view to investigating the effect of the structure on the power performance. The runs are performed with a solid-fuel plasma generator (with the pressure and temperature in the combustor of $\sim4.5$ MPa and $3750$ K) in different modes, namely, with applied electric field in order to determine the electrical conductivity of the working medium and the effect of the injection of decomposition products on the electrical conductivity, and in modes with induced field (independent excitation and self-excitation with reaching the extreme operating mode such as short-circuiting) in order to compare the power performance of the channel for different techniques of injection and removal of the cooling agent decomposition products. A sublimating pastelike cooling agent on the basis of ammonium oxalate is used. It is demonstrated that the injection of the products of decomposition of cooling agent on the insulating walls has no effect on the power performance of the channel. The experiments have revealed a high resistance and desired insulating properties of paste-cooled structures under conditions of repeated operation, as well as the agreement in the power performance between paste-cooled and uncooled channels. The obtained results point to the possibility of developing paste-cooled channels of pulsed MHD generators.