A preliminary engineering design of a "Venetian blind" direct energy converter for fusion reactors

This is a very preliminary engineering design of a new direct energy conversion device for use in conjunction with a mirror fusion reactor. The device described reclaims the energy lost by the reactor through leakage of charged particles. Energy selection is accomplished through the angular dependence of transmisssion through a system of ribbon grids resembling a Venetian blind. In contrast to previously described converters in which the beam of ions from the reactor is expanded in a flat fan-like expander, the beam in this device is expanded in two directions in a conical expander. Problems of grid construction, radiation damage, grid heating, and vacuum pumping are discussed. A preliminary cost estimate shows that for a power handled of 1000 MW, the cost for the direct converter is 110 Million or 110 per kW of power into the direct converter. The efficiency is estimated to be 59% for a two-state collector and 65% for a four-stage collector. Further development of the basic concept could possibly raise the efficiency to as high as 75%. Optimized designs might increase the power handled by a factor of several without significantly increasing the unit cost, thus greatly lowering the cost/kW.