Electrostatic switched radiator for space based thermal control

Abstract

This paper describes a new thermal control device, termed an electrostatically controlled radiator (ESR) which uses electrostatic hold-down of a high emissivity composite film to control spacecraft skin temperature. The electrostatic hold-down switches the mode of heat transfer from the spacecraft skin from conduction to radiation. The effect is a large change in apparent emissivity. This device can operate effectively with moderate levels of DC voltages (i.e. 200–500 V). Application of the voltage results in the high emissivity state while removal gives the low ε state. It should be noted that the ESR device basically operates as a high quality capacitor (C∼400 nF/m2). Thus, if the control voltage is simply removed (as opposed to shorted) from the ESR film, the high emissivity state has a limited memory. In this paper, we provide experimental results of large effective emissivity changes having been achieved. Individual ESR devices have been fabricated with measured emissivity changes of approximately .74. Additionally, some ESR devices have been fabricated which achieved a maximum measured ε of .9 other samples have been produced which achieved a minimum ε of .1. Thus, with further material research and development and production process controls, it is expected that devices which can achieve a Δε of .8 can be produced.