Physics Commons^™

Pulsed Electro-Acoustic Measurements Of Charging And Relaxation In Low Density Polyethylene, Zachary Gibson

Presentations

No abstract provided.

Electron Yield Of Challenging Materials: Low Density Polyethylene And Carbon-Composite Nanodielectrics, Matthew Robertson, Jordan Lee, Jr Dennison

Presentations

The electron yield—the ratio of the number of emitted electrons to incident electrons—is a key material property that characterizes how materials will charge due to exposure to electron fluxes. The USU Materials Physics Group has developed expertise in measuring this for a wide array of conductors, semiconductors and insulators, including many challenging materials. The basic definitions associated with electron yield and how they are measured will be discussed. We will highlight many critical applications investigated at USU, particularly those associated with spacecraft charging as materials interact with space plasma environments. Electron irradiation experiments conducted to investigate the electron transport, charging, …

Electron Yield Of Challenging Materials: Low Density Polyethylene And Carbon-Composite Nanodielectrics, Matthew Robertson, Jordan Lee, Jr Dennison

Presentations

No abstract provided.

Effects Of Temperature And Radiation Dose On Radiation Induced Conductivity, Jr Dennison

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Radiation induced conductivity (RIC) is an important conduction mechanism in highly disordered insulating materials exposed to ionizing radiation. Measurements of RIC as a function of dose rate and exposure time of polymeric and glassy insulators will be presented. RIC results from excitation of carriers into conduction states by the ionizing radiation. The measurements will be discussed in terms of models for the distribution of localized disordered states. The effects of temperature and radiation damage from ionizing radiation on the density and occupation of trap states, and how this affects RIC, will also be discussed.

Effects Of Temperature And Radiation Dose On Radiation Induced Conductivity, Jr Dennison

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No abstract provided.

Hemispherical Grid Retarding Field Analyzer Redesign For Secondary Electron Emission Studies, Greg Wilson, Jr Dennison

Presentations

A redesign of the Hemispherical Grid Retarding Field Analyzer is discussed in relationship to multilayer charging models. In order to accurately extend single layer charging models to dynamic multilayer scenarios, precise measurements of electron emission as well as the net surface potential must be made. By learning from the previous design and thinking of future applications, the new instrument will greatly enhance our ability to precisely measure materials undergoing energetic electron bombardment.

Of Mice And Materials: Payoffs Of Unsgc Research Infrastructure Awards, Jr Dennison, Kent Hartley, Lisa Phillipps, Justin Dekany, Robert H. Johnson, James S. Dyer

Presentations

A versatile test facility has been designed and built to study space environments effects on small satellites and system components. Testing for potentially environmental-induced modifications of small satellites is critical to avoid possible deleterious or catastrophic effects over the duration of space mission. This is increasingly more important as small satellite programs have longer mission lifetimes, expand to more harsh environments (such as polar or geosynchronous orbits), make more diverse and sensitive measurements, minimize shielding to reduce mass, and utilize more compact and sensitive electronics (often including untested off-the-shelf components). The vacuum chamber described here is particularly well suited for …

Of Mice And Materials: Payoffs Of Unsgc Research Infrastructure Awards, Jr Dennison

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No abstract provided.

Dynamic Secondary Electron Emission In Dielectric/Conductor Mixed Coatings, Leandro Olano, Isabel Montero, María E. Dávila, Jr Dennison

Presentations

An unexpected behavior of the Secondary Emission Yield (SEY) on coatings composed by a mixture of conductor and dielectric microparticles was reported and modeled in [1]. As a follow up, we measured for a fixed primary energy the dynamic evolution of the SEY in similar samples and proposed a charging-roughness coupled model to simulate the experimental results. Two different coatings were selected: 1) TMM and Al microparticles (type 1), and 2) zeolites and gold nanoparticles (type 2). Pulsed and continuous tests were used to obtain the SEY as a function of the primary energy.

In both types of samples extremely …

A New Physical Model For Dc Partial Discharge In Polymeric Insulators, Allen Andersen, Jr Dennison

Presentations

The physics of DC partial discharge (DCPD) continues to pose a challenge to researchers. We present a new physically-motivated model of DCPD in amorphous polymers based on our dual-defect model of dielectric breakdown. The dual-defect model is an extension of standard static mean field theories, such as the Crine model, that describe avalanche breakdown of charge carriers trapped on uniformly distributed defect sites. It assumes the presence of both high-energy chemical defects and low-energy thermally-recoverable physical defects. We present our measurements of breakdown and DCPD for several common polymeric materials in the context of this model. Improved understanding of DCPD …

Model For Charge Injection With Electron Beams Into Highly Disordered Insulating Materials, Jr Dennison

Presentations

The Walden-Wintle model for charge injection and transport through highly disordered insulating materials has been extended to include charge injection with a charged particle beam. The original model is applicable to charge injection into a dielectric material from a pair of electrodes in a parallel-plate geometry. It provides a versatile approach to predict the time-dependent current at a rear grounded electrode and the incident surface voltage, as the injection current density evolves over time with the development of a space charge barrier near the injection electrode. The Walden-Wintle model has been applied to many standard cases including Fowler-Nordheim injection, Schottky …

Model For Charge Injection With Electron Beams Into Highly Disordered Insulating Materials, Jr Dennison

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No abstract provided.

Novel Physical Model For Dc Partial Discharge In Polymeric Insulators, Allen Andersen, Jr Dennison

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No abstract provided.

Satellite Survivability In A Harsh Space Environment: A Materials Perspective, Jr Dennison

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No abstract provided.

Using Quantile-Quantile Plots To Compare Experimental Apples And Oranges In Physics Labs, Allen Andersen, Jr Dennison

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No abstract provided.

Reduction Of Radiation Effects In Polymers Relaxation Of Radiation Effects On The Optical Transmission Of Polymers, Alexandra Hughlett, Tyler Kippen, Jr Dennison

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No abstract provided.

Hemispherical Grid Retarding Field Analyzer Redesign For Secondary Electron Emission Studies, Gregory Wilson

Presentations

No abstract provided.

Dynamic Secondary Electron Emission In Dielectric/Conductor Mixed Coatings, Leandro Olano, Isabel Montero, Maria E. Davila, Jr Dennison

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No abstract provided.

Satellite Survivability In Space: A Materials Perspective, Jr Dennison

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No abstract provided.