Direct energy converters - Efficiency and cost estimates for two electrostatic concepts

Abstract

This study is concerned with two specific types of electrostatic direct energy converters for direct recovery of a large fraction of the plasma ion energy from magnetic-mirror-type fusion reactors. Simplified equations are presented for each of the important loss mechanisms in both single-stage direct converters and multistage venetian blind-type direct converters. These equations can be used to estimate the efficiency and electric power output of the direct converter subsystem. Scaling relations for the cost of each major component in the direct converter subsystem are also given; these include the vacuum tank, direct converter (DC) modules, the DC power conditioning equipment, cryogenic vacuum pumping system, and the thermal bottoming plant. Examples of cost-effectiveness studies for two specific reference direct converter designs are presented in terms of the specific capital costs (i.e., the capital cost per unit of electric power produced) for the direct converter subsubsystem. These examples show that relaxation of the requirement for small charge exchange losses can significantly reduce the specific capital costs of the direct converter subsystem.