A document discusses an innovation designed to effectively monitor dielectric charging in spacecraft components to measure the potential for discharge in order to prevent damage from internal electrostatic discharge (IESD). High-energy electrons penetrate the structural materials and shielding of a spacecraft and then stop inside dielectrics and keep accumulating. Those deposited charges generate an electric field. If the electric field becomes higher than the breakdown threshold (≈2 × 105 V/cm), discharge occurs.
This monitor measures potentials as a function of dielectric depth. Differentiation of potential with respect to the depth yields electric field. Direct measurement of the depth profile of the potential in a dielectric makes real-time electronic field evaluation possible without simulations.
The IESDM has been designed to emulate a multi-layer circuit board, to insert very thin metallic layers between the dielectric layers. The conductors serve as diagnostic monitoring locations to measure the deposited electron-charge and the charge dynamics. Measurement of the time-dependent potential of the metal layers provides information on the amount of charge deposited in the dielectrics and the movement of that charge with time (dynamics).
This work was done by Wousik Kim, Dan M. Goebel, Insoo Jun, and Henry B. Garrett of Caltech for NASA’s Jet Propulsion Laboratory. NPO-47347
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Internal Electrostatic Discharge Monitor — IESDM
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Overview
The document outlines the development and objectives of the Internal Electrostatic Discharge Monitor (IESDM) by NASA's Jet Propulsion Laboratory (JPL). The IESDM is designed to measure the depth profile of potential in dielectrics caused by space radiation, which is critical for understanding and mitigating internal electrostatic discharge (IESD) in spacecraft. IESD is responsible for approximately 60% of reported spacecraft anomalies, making it essential to develop effective monitoring and mitigation strategies.
The IESDM emulates a multi-layer circuit board, incorporating very thin metallic layers (~0.2μm) between dielectric layers. These metallic conductors serve as diagnostic locations to monitor electron charge deposition and dynamics. Two prototypes were fabricated: a thick metal version (8.9 μm) that disturbed electron dynamics and a thin metal version (250 nm) that did not. Initial tests on the thick metal prototype demonstrated the monitor's ability to detect charge deposition and discharge events, although further testing is needed to fully understand the discharge conditions.
The document highlights the significance of the IESDM for NASA and JPL, emphasizing its potential to provide real-time data on the radiation environment and dielectric charging in spacecraft components. This information can inform future spacecraft designs and mission modifications, particularly for missions in extreme environments like those around Jupiter and Saturn.
Future plans for the IESDM include integrating the monitor with a Plug-and-Play sensor interface unit, collecting more data under various test conditions, and calibrating a new "hockey-puck" IESD monitor. The project aims to reduce the overly conservative designs and shielding techniques currently employed due to insufficient understanding of IESD processes, ultimately allowing for more efficient spacecraft designs that do not compromise mission success or survivability.
In summary, the IESDM project represents a significant advancement in monitoring and understanding electrostatic discharge in space environments, with the potential to enhance the reliability and longevity of future spacecraft missions. The insights gained from this research will contribute to better design practices and risk management in aerospace engineering.
