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Dissertation Defense

Spacecraft Charge Neutralization During Active Electron Emission

Grant Miars
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Abstract:

Active electron emission in space is a powerful scientific tool that often proves problematic due to the spacecraft charging it induces. Indeed, effective spacecraft neutralization during electron emission in low density space plasmas has yet to be achieved. A charge control technique was recently identified which promises to deliver this critical capability. The technique is termed the ion emission model and uses ion emission from the surface of a dense, quasi-neutral contactor plasma. This ion emission is shown to balance electron emission from the spacecraft without inducing significant spacecraft charging.

This dissertation focuses on Earth-based plasma experiments which validate the ion emission model. These experiments are divided into four experimental campaigns which examine: 1) the initial “spacecraft” potential and plasma response to simulated electron beam emission, 2) the steady state plasma response to simulated electron beam emission, 3) whether the measured ion emission current matches the ion emission model prediction and 4) how the peak spacecraft potential scales with electron emission current, emitted plasma current, and plasma ion mass. The results from these experiments support the ion emission model and add to the physical understanding of ion emission as it may occur in low density space plasmas.

Chair: Professor Brian E. Gilchrist

Remote Access: https://umich.bluejeans.com/395359786