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Proceedings of the 12th International Spacecraft Charging and Technology Conference

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The conductivity of the material is a key transport parameter in spacecraft charging that determines how deposited charge will redistribute throughout the system, how rapidly charge imbalances will dissipate, and what equilibrium potential will be established under given environmental conditions. As the requirements for space missions extend to new regions of space and more stringent requirements are placed on spacecraft performance, it becomes necessary to better understand the underlying conduction mechanisms that determine the dynamic response of insulators to temperature, electric field dose rate, and sample conditioning and history. This study performed detailed measurements of the transient conductivity of representative highly disordered insulating materials using the constant voltage method and analyzed the data with dynamic models for the time, temperature, and electric field dependant conductivity. We describe substantial upgrades to an existing Constant Voltage Chamber (CVC), which improved the precision of conductivity measurements by more than an order of magnitude. A battery operated voltage source supplied a highly stable applied voltage. Data acquisition and analysis algorithms and the interfaces between electronics and the data acquisition system were optimized for higher precision and accuracy. Painstaking attention to ground loops, shielding, filtering and other associated issues greatly reduced electrical noise in the extremely low (50 MV/m), the ultimate instrument conductivity resolution can increase to ≈4•10-22 (Ω-cm)-1 corresponding to decay times of more than a decade; this is comparable to both the thermal Johnson noise of the sample resistance and the radiation induced conductivity


Paper presented at the 12th International Spacecraft Charging and Technology Conference. PDF available for download through link above.

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