Physical Sciences and Mathematics Commons^™

High Altitude Dependence Of Ionizing Radiation From Cosmic Rays, Zack Gibson, Akihiro Nagata, Midori Morikawa, Takuyuki Sakai, Takahiro Shimizu, Yuta Takahashi, Shusuke Okita, Raul Ramirez, Alexandra Hughlett, Toshihiro Kameda, Jr Dennison

Posters

The flux of ionizing radiation from cosmic background sources has been measured as a function of altitude using a compact Geiger counter aboard a high altitude balloon. The payload was developed by researchers from University of Tsukuba and flown under the auspices of the Utah State Get-Away-Special (GAS) team. Dose rate, temperature, pressure, humidity, altitude and position data were acquired during a ~4 hour flight up to an altitude of 32 km in August 2016. The altitude reached by this balloon was more than 5 times the height of that reached by Victor Hess’ experiment in 1912, which later won …

Plasma Deflection Test Setup For E-Sail Propulsion Concept, Allen Andersen, Jason Vaughn, Todd Schneider, Ken Wright

Presentations

The Electronic Sail or E-Sail is a novel propulsion concept based on momentum exchange between fast solar wind protons and the plasma sheath of long positively charged conductors comprising the E-Sail. The effective sail area increases with decreasing plasma density allowing an E-Sail craft to continue to accelerate at predicted ranges well beyond the capabilities of existing electronic or chemical propulsion spacecraft. While negatively charged conductors in plasmas have been extensively studied and flown, the interaction between plasma and a positively charged conductor is not well studied. We present a plasma deflection test method using a differential ion flux probe …

Space Environment Effects Of Ionizing Radiation On Seed Germination And Growth, Alex Souvall, Takuyuki Sakai, Takahiro Shimizu, Yuta Takahashi, Midori Morikawa, Shusuke Okita, Akihiro Nagata, Toshihiro Kameda, Shaunda Wenger, Jr Dennison

Presentations

An initial limited set of tests of germination rate and seed growth in a controlled environment have identified statistically significant differences between control samples and seed flown in a Russian LEO research flight. Most significantly, average seed germination of space borne seeds was 2 days less than the 6 days for the control seeds. Modification of the seed coat leading to enhanced rate of water uptake, as a result of radiation from the space environment or abrasion due to launch vibrations, is hypothesized to cause early germination. High school students will conduct growth tests on seeds exposed to simulated space …

Relaxation Of Radiation Effects On The Optical Transmission Of Polymers, Alexandra Hughlett, Tyler Kippen, J. R. Dennison

Posters

Changes in optical transmission of polymers over time were studied to determine the factors contributing to relaxation of defect states induced by intense radiation doses. Samples of low density polyethylene (LDPE), polyether ether ketone (PEEK), polypropylene (PP), and polyimide (PI) received doses up to 500 MGy from an 8 MeV electron accelerator. These doses were intended to simulate long-term exposure of common spacecraft materials in geosynchronous orbit. Features and absorption edges in ~250 nm to 1000 nm UV to IR transmission spectra can be related to energies associated with various defects previously observed in these highly disordered materials. Recent work …

Temperature Dependence Of Electrostatic Breakdown In Highly Disordered Polymers, Tyler Kippen

Senior Theses and Projects

No abstract provided.

Temperature Dependency Of Electrostatic Breakdown In Ldpe And Peek, Tyler Kippen, Allen Andersen, Jr Dennison

Posters

Electrostatic breakdown is a leading cause of many of the anomalies and failures attributed to spacecraft interactions with the space environment. It is therefore critical to understand how the electrostatic field strength varies due to changing environmental conditions, including temperature and radiation dose. Standard step-up to electrostatic discharge (ESD) tests were performed on two polymers, low density polyethylene (LDPE) and polyetheretherketone (PEEK). Tests were done at room temperature and at other temperatures ranging from ~130 K to ~350 K. Preliminary analysis found that samples tested at a higher temperature had lower average breakdown field strength and a narrower distribution of …

Dependence Of Electrostatic Field Strength On Voltage Ramp Rate For Spacecraft Materials, Krysta Moser, Allen Andersen, Jr Dennison

Posters

No abstract provided.

Predictive Formula For Electron Penetration Depth Of Diverse Materials Over Large Energy Ranges, Anne C. Starley, Gregory Wilson, Lisa Phillipps, Jr Dennison

Posters

No abstract provided.

Cubesat Space Environments Effects Studied In The Space Survivability Test Chamber, Jr Dennison, Gregory Wilson, Alex Souvall, Ben Russon, Katie Gamaunt

Posters

CubeSats are particularly susceptible to environmental-induced modifications, which can lead to deleterious or catastrophic consequences. This is increasingly important as small satellites—with minimal shielding due to reduced mass and size constraints and reliance on more compact and sensitive electronics—have longer mission lifetimes and make more diverse, complex and sensitive measurements. The current push to expand deployment of CubeSats beyond LEO, into even more demanding environments where modest relief due to shielding by the Earth’s magnetosphere is absent (such as polar or GEO orbits), can further exacerbate these problems.

Testing of small satellites is therefore critical to avoid such problems. A …

Instrumentation Enhancements For Electron Yield Measurements Of Extremely Low-Conductivity High-Yield Dielectrics, Justin Christensen, Gregory Wilson, Jr Dennison

Conference Proceedings

Electron yield, a material dependent property which describes how it will charge under incident electron irradiation of a given energy, is defined as the number of electrons emitted from a material per incident electron. While very important for spacecraft charging modelling, the measurement of electron yield for insulating materials is very challenging because insulators quickly charge up under electron irradiation, thereby modifying the yield measurements.

Improved techniques have been implemented to reduce charging with each yield measurement, as well as to neutralize acquired charge between measurements. The goal is to determine the “intrinsic yield” (yield of uncharged insulator). New analysis …

Instrumentation Enhancements For Electron Yield Measurements Of Extremely Low-Conductivity High-Yield Dielectrics, Justin Christensen, Gregory Wilson, Jr Dennison

Presentations

Electron yield, a material dependent property which describes how it will charge under incident electron irradiation of a given energy, is defined as the number of electrons emitted from a material per incident electron. While very important for spacecraft charging modelling, the measurement of electron yield for insulating materials is very challenging because insulators quickly charge up under electron irradiation, thereby modifying the yield measurements.

Improved techniques have been implemented to reduce charging with each yield measurement, as well as to neutralize acquired charge between measurements. The goal is to determine the “intrinsic yield” (yield of uncharged insulator). New analysis …

Uv Degradation Effects: Terrestrial Versus Space Environment, Katie Gamaunt, Krysta Moser, Alex Souvall, Jr Dennison

Posters

The decrease in visible and ultraviolet transmission spectra of polymeric and glass spacecraft materials has been measured to determine the extent of degradation due to high energy UV radiation similar to the solar spectrum (both above and below the stratosphere). This project looked at the effects that the atmosphere has in regards to blocking UV radiation and thus, slowing down the UV degradation process. Materials such as quartz, borosilicate glass, sodium glasses, polyethylene, polyimide, and polyethylene terephthalate polymers were exposed to radiation from a focused high intensity deuterium lamp source, which generates radiation in the UVA and UVB spectrum. Duplicates …

Dependence Of Electrostatic Field Strength On Voltage Ramp Rate For Spacecraft Materials, Krysta Moser, Allen Andersen, Jr Dennison

Conference Proceedings

This work investigated the dependence of electrostatic field strength for spacecraft materials on voltage ramp rate, by applying an increasing electrostatic field until electrostatic breakdown occurred.

Tests on the polymeric material Kapton ETM found that at ramp rates two or three orders of magnitude lower than the maximum recommended rate, FESD was lower than at rapid rates by a factor or two or more this suggests that tabulated values of FESD which have been used by the spacecraft charging community can substantially overestimate FESD in common slowly evolving spacecraft situations. Similar measurements on other polymeric materials have been performed to …

Absolute Electron Emission Calibration: Round Eobin Tests Of Au And Graphite, Jr Dennison, Justin Christensen, Justin Dekany, Clint Thomson, Neal Nickles, Robert E. Davies, Mohamed Belhaj, Kazuhiro Toyoda, Kazutaka Kawasaki, Isabel Montero, Maria E. Dávil, Leandro Olano, Luis Galán

Conference Proceedings

This study presents a round robin comparison of absolute electron yields of conducting and insulating materials performed in four international laboratories. Measurements are reported for two standard elemental conducting samples with reproducible sample preparation for Au and highly oriented pyrolytic graphite (HOPG). The primary objectives of the study were to determine the consistency and uncertainties of these absolute yields measurements, and to investigate the effects of the similarities and differences of the diverse facilities. In this initial round robin study, HOPG total electron yield results were found to be more reproducible than those for Au. Surface contamination significantly affected the …

Extremely Low Secondary Electron Emission From Metal/Dielectricparticulate Coatings, Isabel Montero, L Aguilera, Leandro Olano, María E. Dávila, V. Nistor, L. Galán, Jr Dennison, Gregory Wilson

Conference Proceedings

We have studied the SEY behaviour of a particulate coating composed of a mixture of a metal (aluminum) in solid state contact with a particulate dielectric material (polyimide thermosetting resin). Surface charging, roughness, and volume fraction are utilized as the main parameters to characterize the electron emission behaviour. Apart from the important role played by surface composition in the SEY, the influence of the dielectric volume fraction has demonstrated to be critical to achieve a significant reduction of SEY. it was found that E1 of the particulate sample increased with increasing dielectric volume fraction. An extremely high first crossover energy, …

Pulsed Electroacoustic System Development For Volume Charge Distribution Measurement In Thin Dielectric Films, Lee H. Pearson, Jr Dennison, Erick W. Griffiths, Anthony C. Pearson

Conference Proceedings

This paper discusses an effort to develop advanced pulsed electroacoustic (PEA) measurement system capabilities that incorporate state-of-the-art hardware and improved signal processing and modeling to characterize embedded charge distributions in thin dielectric films. Objectives in developing this system include: (1) improved spatial resolution, while maintaining reasonable temporal resolution; (2) improved signal processing tools for increased signal/noise ratios; (3) integrated PEA modeling tools; and (4) integrated environmental controls. We emphasize system improvements required to achieve high spatial resolution for in vacuo measurements of thin dielectrics charged using electron beam injection, which are most applicable for spacecraft charging tests. PEA measurement systems …

Temporal And Spatial Correlations In Electron-Induced Arcs Of Adjacent Dielectric Islands, Justin Christensen, Jr Dennison, Justin Dekany

Conference Proceedings

This study investigated coincidence behaviour of a common form of electron-induced light emission [6]. These very short duration(

Synergistic Models Of Electron Emission And Transport Measurements Of Disordered Sio2, Jr Dennison, Jodie Corbridge Gillespie, Allen Andersen, Amberly Evans Jensen, Gregory Wilson, Justin Dekany, Alec Sim, Ryan C. Hoffmann

Conference Proceedings

An important way for the spacecraft charging community to address the expanding necessity for extensive characterization of electron emission and transport properties of materials is to expand the role of more fundamental materials physics. This includes the development of unifying theoretical models of the charge transport equations based on the creation, distribution, and occupancy of defect densities of states. Models that emphasize the synergistic relation between fitting parameters for diverse measurements can also lead to a better understanding of materials and facilitate solutions to spacecraft charging issues. As an example of this approach, we present results of many different measurements …

Perspectives On The Distributions Of Esd Breakdowns For Spacecraft Charging Applications, Allen Andersen, Krysta Moser, Jr Dennison

Posters

Electrostatic discharge (ESD) continues to pose significant risks to space missions despite decades of intense study. We emphasize here the advantages to spacecraft designers and modelers from considering the stochastic distributions of breakdown and how it can be affected by factors including spacecraft environment conditions, design geometries, material temperature, material purity, charging history, and appropriate timescales. Spacecraft charging models and spacecraft designs typically rely on tabulated values or ranges of breakdown strength, often based on cursory measurements with little or no experimental detail. Depending on the timescales and history of environmental and orbital changes or durations of specific missions, it …

Extremely Low Secondary Electron Emission From Metal/Dielectric Particulate Coatings, Isabel Montero, L Aguilera, Leandro Olano, María E. Dávila, Luis Galán, Jr Dennison, Gregory Wilson

Presentations

Research on low secondary electron emission coatings is essential for the design and manufacture of space high-power RF devices without multipactor discharge. This paper discusses some of the factors that reduce secondary electron emission for metal-dielectric surfaces. We have studied the total electron yield (TEY) behavior of a particulate coating composed of a mixture of a metal (aluminum) nanoparticulates in solid state contact with a particulate dielectric material (polyimide thermosetting resin). Surface charging, roughness, and volume fraction are utilized as the main parameters to characterize the electron emission behavior, which can effectively be determined by continuous (total dose 42.5 nC/mm …

Determining Intrinsic Electron Emission Yields Of High Resistivity Ceramic Materials, Jr Dennison, Justin Christensen, Justin Dekany

Presentations

We describe and contrast methods for measuring the intrinsic—or zero-accumulated charge limit—electron emission yields of highly insulating materials with relatively large yields. The intrinsic electron yield is an essential measure of how charge will accumulate in such materials exposed to space environment fluxes and for predicting and mitigating spacecraft charging effects. There are three commonly used methods to determine the intrinsic electron yield: (i) the DC-yield method, which ratios constant incident and emission currents; (ii) the pulsed-yield method, which ratios integrated charge of short-duration, low-current pulses, thereby minimizing the amount of charge being deposited into the material during a measurement, …

Perspectives On The Distributions Of Esd Breakdowns For Spacecraft Charging Applications, Allen Andersen, Krysta Moser, Jr Dennison

Conference Proceedings

Electrostatic discharge (ESD) continues to pose significant risks to space missions despite decades of intense study. We emphasize here the advantages to spacecraft designers and modelers from considering the stochastic distributions of breakdown and how it can be affected by factors including spacecraft environment conditions, design geometries, material temperature, material purity, charging history, and appropriate timescales. Spacecraft charging models and spacecraft designs typically rely on tabulated values or ranges of breakdown strength, often based on cursory measurements with little or no experimental detail. Depending on the timescales and history of environmental and orbital changes or durations of specific missions, it …

Pea System Modeling And Signal Processing For Measurement Of Volume Charge Distributions In Thin Dielectric Films, Lee H. Pearson, Jr Dennison, Erick W. Griffiths, A C. Pearson

Conference Proceedings

This paper discusses an effort to develop advanced pulsed electroacoustic (PEA) measurement system capabilities that incorporate (1) improved signal processing tools for increased signal/noise ratios; and (2) integrated PEA modeling tools. In addition, we emphasize state-of-the-art system electronic components, integrated environmental controls, and sensor improvements required to achieve high spatial resolution while maintaining reasonable temporal resolution for both ambient and in vacuo measurements of thin dielectrics charged using electron beam injection, which are most applicable for spacecraft charging tests. PEA measurement systems provide an important tool to investigate the spatial extent and dynamic evolution of such embedded charge distributions in …

Temporal And Spatial Correlations In Electron-Induced Arcs Of Adjacent Dielectric Islands, Justin Christensen, Jr Dennison, Justin Dekany

Posters

This study investigates very short duration (<1ms) flashes caused by rapid discharge arcs from charged insulating epoxy “glue dots” to an underlying grounded substrate. There were 36 separate ~3 mm diameter hemispherical bisphenol/amine epoxy “glue dots” positioned around the conducting polymeric/carbon nanocomposite substrate edge exposed simultaneously to nearly identical electron fluxes. Most arcs are found to be random events which occur when built up charge produces an electric field large enough for electrostatic breakdown to occur. The possibility that a given arc might stimulate arcs in adjacent “glue dots” was investigated through coincidence correlation analysis. The dependence of such correlations with “glue dot” separation was also studied.

The data for this project were collected at Marshall Space Flight Center. The epoxy “glue dot” samples were mounted inside a high vacuum (<10^-4 Pa) chamber on a Black Kapton substrate attached to a large grounded metal plate, cooled with liquid nitrogen to ~120 K. An electron gun was used to bombard the sample with electrons of a known energy (12 to 40 keV) and flux density (0.3 to 5 nA/cm²), similar to what would be seen in a typical space environment. Light emitted from the samples was monitored with …

Dependence Of Electrostatic Field Strength On Voltage Ramp Rate For Spacecraft Materials, Krysta Moser, Allen Andersen, Jr Dennison

Posters

This work investigated the dependence of electrostatic field strength for spacecraft materials on voltage ramp rate, by applying an increasing electrostatic field until electrostatic breakdown (a permanent, catastrophic failure of a dielectric material) occurs. Enhanced understanding of prolonged exposure to high static electric fields (DC aging) of insulating materials based on expanded experimental studies is of critical to understand the physics of highly disordered insulating materials, as well as for applications in spacecraft charging, high voltage DC power transmission cables and switching, thin film dielectrics, and semiconductor devices and sensors. Electrostatic discharge (ESD) and the associated material breakdown at the …

Pea System Modeling And Signal Processing For Measurements Of Volume Charge Distributions In Thin Dielectric Films, Lee H. Pearson, Jr Dennison, Erick W. Griffiths, A. C. Pearson

Posters

This paper discusses an effort to develop advanced pulsed electroacoustic (PEA) measurement system capabilities that incorporate state-of-the-art hardware and improved signal processing and modeling to characterize embedded charge distributions in thin dielectric films. Objectives in developing this system include: (1) improved spatial resolution, while maintaining reasonable temporal resolution; (2) improved signal processing tools for increased signal/noise ratios; (3) integrated PEA modeling tools; and (4) integrated environmental controls. We emphasize system improvements required to achieve high spatial resolution for in vacuo measurements of thin dielectrics charged using electron beam injection, which are most applicable for spacecraft charging tests. PEA measurement systems …

Synergistic Models Of Electron Emission And Transport Measurements Of Disordered Sio2, Jr Dennison, Jodie Corbridge Gillespie, Allen Andersen, Amberly Evans Jensen, Gregory Wilson, Justin Dekany, Alec M. Sim, Ryan Hoffmann

Posters

A critical component in the prediction and mitigation of spacecraft charging issues is an accurate model of the charging, transport and electron emission properties of a broad array of materials used in the construction of spacecraft. The increased sensitivity, longer-duration missions, and ventures into more demanding environments only serve to heighten this need. One important way for the spacecraft charging community to address this issue is to expand the role of more fundamental materials physics. This includes the development of unifying theoretical models of the charge transport equations based on the creation, distribution, and occupancy of defect densities of states. …

Effects Of Voltage Ramp Rates On Electrostatic Field Strength In Highly Disordered Insulating Materials, Krysta Moser, Allen Andersen, Jr Dennison

Posters

At high enough electrostatic fields or after long exposure times, insulators can break down, causing large current flow through the material: this breakdown is called electrostatic discharge (ESD). ESD is a permanent, catastrophic failure of a dielectric material: what was an insulator is now essentially a conductor. Previous tests done by the USU Materials Physics Group (MPG) using our ESD custom vacuum chamber have found that, for the polymeric materials biaxially oriented polypropylene (BOPP), polyimide (PI), and low density polyethylene (LDPE), the electrostatic field strength at breakdown depends on the ramp rate of voltage applied across some materials, but possibly …

Absolute Electron Emission Calibration: Round Robin Tests Of Au And Polyimide, Jr Dennison, Justin Christensen, Clint Thomson, Neal Nickles, Robert E. Davies, Mohamed Belhaj, Kazuhiro Toyoda, Arifur R. Khan, Kazutaka Kawasaki, Shunsuke Inoue, Isabel Montero, Maria E. Davila, Leandro Olano

Posters

Accurate determination of the absolute electron yields of conducting and insulating materials are essential for models of spacecraft charging and related processes involving charge accumulation and emission due to electron beams and plasmas. Apparatus using low-fluence pulsed electron beam sources and various methods to minimize charge accumulation have been developed at facilities around the world. This study presents a round robin comparison of such tests performed in CSIC at Instituto de Ciencia de Materiales de Madrid, LaSeine at Kyushu Institute of Technology, DESSE at ONEREA, and the Space Environment Effects Materials (SEEM) test facility at Utah State University. The primary …

Predictive Formula For Electron Range Over A Large Span Of Energies, Anne C. Starley, Gregory Wilson, Lisa Montierth Phillipps, Jr Dennison

Posters

An empirical model developed by the Materials Research Group that predicts the approximate electron penetration depth—or range—of some common materials has been extended to predict the range for a broad assortment of other materials. The electron range of a material is the maximum distance electrons can travel through a material, before losing all of their incident kinetic energy. The original model used the Continuous-Slow-Down-Approximation for energy deposition in a material to develop a composite analytical formula which estimated the range from 10 MeV with an uncertainty of v, which describes the effective number of valence electrons. N_V was empirically …