Surface Charge Effects on Secondary Electron Emission from Dielectrics.
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Large, pulsed power and high voltage systems often employ a stack of insulators to separate a vacuum section away from water or oil sections. The size of this insulator stack often drives overall costs and feasibility of these systems. An electric breakdown along the insulator surface is a primary failure mechanism and is especially impactful if it occurs while power is still being delivered downstream. This report describes a set of experimental and modeling investigations into the cause of these breakdowns, especially focusing on the much less well-understood anode-initiated breakdowns that occur during early parts of power delivery. Additionally, new diagnostics for assessing relevant material properties and behavior of insulators are described. These results describe breakdown behavior and evolution at new temporal and spatial fidelities and provide hypotheses and some answers as to how these breakdowns can occur. This new understanding of the roles of different physics phenomena guide modifications and trade-offs in generating newer insulator stack designs that are smaller and/or have higher electrical stress thresholds.
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The assessment of the future of astronautics is the task of a prophet, a profession not recognized as an established branch of science. Prophecy is an art rather than a profession and there are no established methods of procedure. Knowledge of specific developments in progress and past experience give a reasonable basis for extrapolating a few years ahead. For the more distant future, imagination, intuition, and faith are the only tools, and these are inevitably colored by the nature and environment of the prophet. He may be naturally an optimist or a pessimist. The seeker for financial support and the salesman will see the future very differently than the engineer responsible for the success of launching vehicles on difficult missions. Some of the problems of predicting future developments may be appreciated by looking backward in time by 52 years.
Radar methods of studying the earths ionosphere
Discussion of the nasa passive and active communications satellite programs