High Voltage Solar Array Development for Space and Thruster-Plume Plasma Environments

Abstract

High-power solar arrays are in development by the National Aeronautics and Space Administration (NASA) for near-term high-power solar electric propulsion (SEP) missions. These high-voltage (HV) solar arrays use deployable flexible blanket configurations and need to be able to operate in the plasma environment of high-power Hall thrusters operating at tens of kilowatts of power. Array voltages of 300–800 V are desired both to minimize the copper bus mass in the system and to potentially operate the SEP Hall thrusters directly at high specific impulse without an in- series power processing unit. Coupons with multiple strings of solar cells (SCs) have been tested to high positive and negative biases in a plasma environment representative of the edge of Hall thruster plumes. Proper encapsulation of the exposed metals and triple points is required to avoid excessive current collection and arc initiation. Fully encapsulated test coupons have been successfully been tested at highest anticipated thruster plume plasma densities at voltages from 600 to 1000 V, which enables both very high power arrays and direct drive configurations for SEP missions.