Effects of a Void Beneath a Kapton Heater Patch in a Vacuum

The vacuum of space can lead to some interesting heater problems. In many space applications, heater patches consisting of Inconel elements joined together with Teflon sandwiched together between two Kapton layers are bonded to a structure (substrate) to provide thermal control. A void between the heater patch and the substrate can lead to a hot spot due to the loss of conduction path from the heater to the substrate. When the heater is in a vacuum with a void beneath it, heat is transferred to the substrate by radiation and fin effects through the heater and then to the substrate. The localized hot spot can cause heater layers to separate and further reduce the conduction pathway from the affected area and eventually burnout the heater. A large enough void combined with high heater heat fluxes and substrate temperatures can induce heater failures. For this paper the sensitivity of peak temperature with respect to heat flux (power density), substrate temperature, void size, and void location is considered.