In general, other magnetron-powered systems may be designed with different spacetenna distributions and rectenna intercept levels. However, the quantities ST, , and will retain their previous values, while and will become variables. For these cases, expressions 5 through 9 become THE GENERAL COST FUNCTION The selection of a cost function to characterize our general magnetron-powered system is a choice between one which is oversimplified, and hence too inexact, and one which contains so many variables as to be unmanageable. The function that we have chosen for this study assumes that the cost of the solar array element is proportional to the d.c. power that it generates, while the costs of the two antenna elements are taken to be proportional to their areas. Thus, our cost equation contains three major terms, corresponding to the three major elements of the SPS system, plus two minor terms: In Eq. 13, the fourth term represents simply fixed costs, independent of the major elements, that are associated with construction of the system. The fifth term is the cost of raw land lying between the rectenna and a perimeter fence of minor diameter Df , forming a radiation hazard zone. In order to determine the values of the coefficients in Eq. 13, we make use of cost studies already conducted for the SPS reference systems (4). These studies have been carried out in four major categories: Design, Development, Test and Evaluation (DDT&E) This account comprises all one-time costs associated with designing, developing and testing the components and the subsystems required to make up a successful SPS system. Initial Capital Investment (ICI) This account is a compilation and summation of expenditures for the initial procurement and installation of a single SPS system, after all DDT&E costs are out of the way. Replacement Capital Investment (RCI) This category accounts for those plant and equipment expenditures made for
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