Novel concept for a space power distribution busbar using HTS materials and passive cooling

Abstract

This paper presents the performance, defines the range of applications, and shows the feasibility of using high temperature superconducting (HTS) materials with passive heat rejection for space power transmission. A conceptual design for the busbar is presented, and mass and resistive energy losses are estimated for various missions, power levels, and current types (AC and DC). All applications display a large increase in power transmission efficiency, while mass comparisons show the passively cooled HTS busbar mass ranges from 12% of the mass of a copper busbar at geosynchronous orbit (GEO) and beyond, to 38% at a 1000 km earth orbit (LEO). The design of the HTS conductor is novel, consisting of interleaved HTS strip conductors (HTS plus substrate) separated by dielectric insulating material. Appropriate HTS materials are presently available in long length (≳100 m) with current densities (≳1000 amp/cm2) and critical temperatures (95 K) which make the passively cooled busbar feasible. An original numerical model for the conductor/radiator assembly is described which includes the effects of solar insolation, reflected and IR thermal loads from the earth, and internally generated losses in the HTS. Completely passive operation at low earth orbits (LEO) of 1000 km is enabled by a novel asymmetric design for a directional radiator that includes a unique back‐to‐back busbar configuration that does not require active pointing. The design includes copper conductor downleads employing the same passive cooling scheme.