Design and performance of radioisotope space power systems based on OSC multitube AMTEC converter designs

This paper extends the analytical procedure described in another paper in these proceedings to analyze a variety of compact and light-weight OSC-designed radioisotope-heated space power generators. Those generators employed general purpose heat source (GPHS) modules and a converter containing sixteen AMTEC cells of OSC's revised five-tube design with enhanced cell wall reflectivity described in a companion paper in these proceedings. OSC found that the performance of the generator is primarily a function of the thermal insulation between the outside of the generator's 16 cells and the inside of its wall. After examining a variety of insulation options, it was found that the generator's performance is optimized by employing a hybrid insulation system, in which the space between the cells is filled with fibrous Min-K insulation, and the generator walls are lined with tapered (i.e., graded-length) multifoil insulation. The OSC design results in a very compact generator, with eight AMTEC cells on each end of the heat source stack.