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Full-Text Articles in Physical Sciences and Mathematics
Measuring And Modeling The Conductivity Of Highly Insulating Materials, David King
Measuring And Modeling The Conductivity Of Highly Insulating Materials, David King
Physics Capstone Projects
Satellites and other spacecraft must be able to withstand hazardous conditions in order to be viable in their expected operating environments. One specific hazard that occurs due to incident radiation is spacecraft charging. Insulating materials, frequently used in spacecraft and other electrical equipment, while very good at preventing charge flow, also store charge very well. This can create problems; specifically, “if the charge decay time exceeds the orbital period, not all charge will be dissipated before orbital conditions act again to further charge the satellite. As the insulator accumulates charge, the electric field will rise until the insulator breaks down” …
Defect-Driven Dynamic Model Of Electrostatic Discharge And Endurance Time Measurements Of Polymeric Spacecraft Materials, Charles Sim, Alec Sim, Jr Dennison, Matthew Stormo
Defect-Driven Dynamic Model Of Electrostatic Discharge And Endurance Time Measurements Of Polymeric Spacecraft Materials, Charles Sim, Alec Sim, Jr Dennison, Matthew Stormo
Posters
Charge buildup on insulating materials in the space environment can produce long exposure to electric fields, which can lead to Electrostatic Discharge (ESD). Charge buildup is the leading cause of spacecraft failure due to space environment interactions. ESD can be thought of as the point at which the buildup of charge in localized defects, found in polymeric insulating materials, leads to a catastrophic change in electrical conductivity, which can cause the materials to structurally breakdown. Defects produced by radiation, or prolonged exposure to electric fields, significantly alter the endurance time, the time it takes to produce enough defects to generate …
Defect-Driven Dynamic Model Of Electrostatic Discharge And Endurance Time Measurements Of Polymeric Spacecraft Materials, Alec Sim, John R. Dennison, Matthew Stormo
Defect-Driven Dynamic Model Of Electrostatic Discharge And Endurance Time Measurements Of Polymeric Spacecraft Materials, Alec Sim, John R. Dennison, Matthew Stormo
All Physics Faculty Presentations
Charge buildup on insulating materials in the space environment can produce long exposure to electric fields, which can lead to Electrostatic Discharge (ESD). Charge buildup is the leading cause of spacecraft failure due to space environment interactions. ESD can be thought of as the point at which the buildup of charge in localized defects, found in polymeric insulating materials, leads to a catastrophic change in electrical conductivity, which can cause the materials to structurally breakdown. Defects produced by radiation, or prolonged exposure to electric fields, significantly alter the endurance time, the time it takes to produce enough defects to generate …
Electron-Induced Electron Yields Of Uncharged Insulating Materials, Ryan Carl Hoffmann
Electron-Induced Electron Yields Of Uncharged Insulating Materials, Ryan Carl Hoffmann
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Presented here are electron-induced electron yield measurements from high-resistivity, high-yield materials to support a model for the yield of uncharged insulators. These measurements are made using a low-fluence, pulsed electron beam and charge neutralization to minimize charge accumulation. They show charging induced changes in the total yield, as much as 75%, even for incident electron fluences of <3 fC/mm2, when compared to an uncharged yield. The evolution of the yield as charge accumulates in the material is described in terms of electron recapture, based on the extended Chung and Everhart model of the electron emission spectrum and the dual dynamic …
The Effects Of Surface Modification On Spacecraft Charging Parameters, Amberly Evans, John R. Dennison
The Effects Of Surface Modification On Spacecraft Charging Parameters, Amberly Evans, John R. Dennison
All Physics Faculty Publications
Charging of materials by incident radiation is affected by both environmental and physical conditions. Modifying a material’s physical surface will change its reflection, transmission and absorption of the incident radiation which are integrally related to the accumulation of charge and energy deposition in the material. An optical analysis of the effect of surface modification on spacecraft charging parameters on prototypical Kapton HN and Cu samples is presented. Samples were roughened with abrasive compounds ranging from 0.5 to 10 μm in size, comparable to the range of incident wavelengths. They were also contaminated with thin layers of DC 704 diffusion pump …
Engineering Tool For Temperature, Electric Field And Dose Rate Dependence Of High Resistivity Spacecraft Materials, John R. Dennison, Alec Sim, Jerilyn Brunson, Steven Hart, Jodie Gillespie, Justin Dekany, Charles Sim, Dan Arnfield
Engineering Tool For Temperature, Electric Field And Dose Rate Dependence Of High Resistivity Spacecraft Materials, John R. Dennison, Alec Sim, Jerilyn Brunson, Steven Hart, Jodie Gillespie, Justin Dekany, Charles Sim, Dan Arnfield
All Physics Faculty Publications
An engineering tool has been developed to predict the equilibrium conductivity of common spacecraft insulating materials as a function of electric field, temperature, and adsorbed dose rate based on parameterized, analytic functions derived from physics-based theories. The USU Resistivity Calculator Engineering Tool calculates the total conductivity as the sum of three independent conductivity mechanisms: a thermally activated hopping conductivity, a variable range hopping conductivity, and a radiation induced conductivity using a total of nine independent fitting parameters determined from fits to an extensive data set taken by the Utah State University Materials Physics Group. It also provides a fit for …
Triggering Threshold Spacecraft Charging With Changes In Electron Emission From Materials, John R. Dennison, R. C. Hoffmann, J. Abbott
Triggering Threshold Spacecraft Charging With Changes In Electron Emission From Materials, John R. Dennison, R. C. Hoffmann, J. Abbott
All Physics Faculty Publications
Modest changes in spacecraft charging conditions can lead to abrupt changes in the spacecraft equilibrium, from small positive potentials to large negative potentials relative to the space plasma; this phenomenon is referred to as threshold charging. It is well known that temporal changes of the space plasma environment (electron plasma temperature or density) can cause threshold charging. Threshold charging can also result from by temporal changes in the juxtaposition of the spacecraft to the environment, including spacecraft orbit, orientation, and geometry. This study focuses on the effects of possible changes in electron emission properties of representative spacecraft materials. It is …
The Importance Of Accurate Computation Of Secondary Electron Emission For Modeling Spacecraft Charging, S. Clerc, John R. Dennison, C. D. Thomson
The Importance Of Accurate Computation Of Secondary Electron Emission For Modeling Spacecraft Charging, S. Clerc, John R. Dennison, C. D. Thomson
All Physics Faculty Publications
Secondary electron emission is a critical contributor to the current balance in spacecraft charging. Spacecraft charging codes use a parameterized expression for the secondary electron yield δ(Eo) as a function of incident electron energy Eo. Simple three-step physics models of the electron penetration, transport and emission from a solid are typically expressed in terms of the incident electron penetration depth at normal incidence or range R(Eo ), and the mean free path of the secondary electron, λ(E). We recall classical models for the range R(Eo): a power law expression of the form b1Eon1 …
Proposed Modifications To Engineering Design Guidelines Related To Resistivity Measurements And Spacecraft Charging, John R. Dennison, Prasanna Swaminathan, Randy Jost, Jerilyn Brunson, Nelson W. Green, A. Robb Frederickson
Proposed Modifications To Engineering Design Guidelines Related To Resistivity Measurements And Spacecraft Charging, John R. Dennison, Prasanna Swaminathan, Randy Jost, Jerilyn Brunson, Nelson W. Green, A. Robb Frederickson
All Physics Faculty Publications
A key parameter in modeling differential spacecraft charging is the resistivity of insulating materials. This parameter determines how charge will accumulate and redistribute across the spacecraft, as well as the time scale for charge transport and dissipation. Existing spacecraft charging guidelines recommend use of tests and imported resistivity data from handbooks that are based principally upon ASTM methods that are more applicable to classical ground conditions and designed for problems associated with power loss through the dielectric, than for how long charge can be stored on an insulator. These data have been found to underestimate charging effects by one to …
Measurement Of Charge Storage Decay Time And Resistivity Of Spacecraft Insulators, Prasanna V. Swaminathan
Measurement Of Charge Storage Decay Time And Resistivity Of Spacecraft Insulators, Prasanna V. Swaminathan
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Insulators used in the construction of spacecraft are irradiated with high-energy electrons in the space environment and this sometimes causes the insulators to charge to very high voltages. Such charged insulators can generate spontaneous electric partial-discharge pulses of the order of mA to tens of A. These pulses sometimes last enough time to destroy the expensive micro-circuitry present in the spacecraft. In evaluating the threat to the spacecraft due to these discharges, calculation of the resistivity becomes a critical parameter since it determines how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. So far, …
Materials Characterization At Utah State University: Facilities And Knowledgebase Of Electronic Properties Of Materials Applicable To Spacecraft Charging, John R. Dennison, C. D. Thomson, J. T. Kite, V. V. Zavyalov, Jodie Corbridge
Materials Characterization At Utah State University: Facilities And Knowledgebase Of Electronic Properties Of Materials Applicable To Spacecraft Charging, John R. Dennison, C. D. Thomson, J. T. Kite, V. V. Zavyalov, Jodie Corbridge
All Physics Faculty Publications
In an effort to improve the reliability and versatility of spacecraft charging models designed to assist spacecraft designers in accommodating and mitigating the harmful effects of charging on spacecraft, the NASA Space Environments and Effects (SEE) Program has funded development of facilities at Utah State University for the measurement of the electronic properties of both conducting and insulating spacecraft materials. We present here an overview of our instrumentation and capabilities, which are particularly well suited to study electron emission as related to spacecraft charging. These measurements include electron-induced secondary and backscattered yields, spectra, and angular resolved measurements as a function …
Spacecraft Charging Research, Eric Crapo
Spacecraft Charging Research, Eric Crapo
Senior Theses and Projects
No abstract provided.
Charge Storage, Conductivity And Charge Profiles Of Insulators As Related To Spacecraft Charging, John R. Dennison, A. R. Frederickson, Prasanna Swaminathan
Charge Storage, Conductivity And Charge Profiles Of Insulators As Related To Spacecraft Charging, John R. Dennison, A. R. Frederickson, Prasanna Swaminathan
All Physics Faculty Publications
Dissipation of charges built up near the surface of insulators due to space environment interaction is central to understanding spacecraft charging. Conductivity of insulating materials is key to determine how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. To understand these processes requires knowledge of how charge is deposited within the insulator, the mechanisms for charge trapping and charge transport within the insulator, and how the profile of trapped charge affects the transport and emission of charges from insulators. One must consider generation of mobile electrons and holes, their trapping, thermal detrapping, mobility and …
Instrumentation And Measurement Of Secondary Electron Emission For Spacecraft Charging, Neal Nickles, John R. Dennison
Instrumentation And Measurement Of Secondary Electron Emission For Spacecraft Charging, Neal Nickles, John R. Dennison
All Physics Faculty Publications
Secondary electron emission is an important physical mechanism in the problem of spacecraft charging. The NASA Space Environments and Effects branch is currently revising NASA’s strategy for mitigating damage due to spacecraft charging. In an effort to substantially improve the modeling of spacecraft charging, measurements of secondary electron emission parameters are being made. The design of the apparatus needed to measure these parameters is discussed in detail. Various measurement techniques are explained and conclusions are drawn about the suitability of the final design.
Effects Of Spacecraft Potential On Secondary Electron Yields In Geosynchronous Orbit, Neal E. Nickles
Effects Of Spacecraft Potential On Secondary Electron Yields In Geosynchronous Orbit, Neal E. Nickles
All Physics Faculty Publications
Surface charging due to interactions with the earth=s plasma is a hazard for orbiting spacecraft. Secondary electron (SE) emission is an important physical process in spacecraft charging. Current spacecraft charging models do not consider the SE energy or angular distributions and their implications for estimating the return of SE to the spacecraft. Comprehensive work on the application of SE energy and angular distributions to spacecraft charging has been published [Nickles et al., 1999] and part of that work is summarized here. The application of SE energy distributions to the case of positive charging in geosynchronous orbit is discussed and shown …
Evolution Of Secondary Electron Emission Characteristics Of Spacecraft Surfaces: Importance To Spacecraft Charging, R. E. Davies, John R. Dennison
Evolution Of Secondary Electron Emission Characteristics Of Spacecraft Surfaces: Importance To Spacecraft Charging, R. E. Davies, John R. Dennison
All Physics Faculty Publications
Secondary electron emission (SEE) plays a key role in spacecraft charging [Garrett, 1981; Frooninckx and Sojka, 1992] . As a result, spacecraft charging codes require knowledge of the SEE characteristics of various materials in order to predict vehicle potentials in various orbital environments [Katz, et. al., 1986]. Because SEE is a surface phenomenon, occurring in the first few atomic layers of a material, the SEE characteristics of a given surface are extremely sensitive to changes in surface condition—e.g., the addition or removal of surface contaminants, or changes in surface morphology. That spacecraft surfaces can and generally do undergo significant evolution …
Utah State University Ground-Based Test Facility For Study Ofelectronic Properties Of Spacecraft Materials, W. Y. Chang, John R. Dennison, Neal Nickles, R. E. Davies
Utah State University Ground-Based Test Facility For Study Ofelectronic Properties Of Spacecraft Materials, W. Y. Chang, John R. Dennison, Neal Nickles, R. E. Davies
All Physics Faculty Publications
No abstract provided.
Secondary Electron Emission And Spacecraft Charging, Neal Nickles, John R. Dennison
Secondary Electron Emission And Spacecraft Charging, Neal Nickles, John R. Dennison
All Physics Faculty Publications
Spacecraft charging due to the natural plasma environment found in all orbits is known to produce many of the observed spacecraft anomalies and failures. A primary factor in adverse spacecraft charging is the secondary electron emission of differing materials on the spacecraft. Precipitating electrons and ions from the plasma to spacecraft surfaces can result in varying amounts of charge being released, depending on the secondary electron yield of the materials; this can lead to arcing between surfaces. NASA's Space and Environments Effects (SEE) program has recognized the need to improve their current materials database for modeling spacecraft charging and have …
Solar Cycle Dependence Of Spacecraft Charging In Low Earth Orbit, T. B. Frooninckx, Jan Josef Sojka
Solar Cycle Dependence Of Spacecraft Charging In Low Earth Orbit, T. B. Frooninckx, Jan Josef Sojka
All Physics Faculty Publications
Recent experimental evidence has shown that Defense Meteorological Satellite Program (DMSP) polar orbiting spacecraft at 840 km can develop electric potentials as severe as −1430 V while at high magnetic latitudes. To explore this charging region, an analysis of DMSP F6, F7, F8, and F9 satellite precipitating particle and ambient plasma measurements taken during periods of high, medium, and low solar flux is performed. One hundred eighty-four charging events ranging from −46 to −1430 V are identified, and an extreme solar cycle dependence is found as charging is most frequent and severe during solar minimum. Satellite measurements and time-dependent ionospheric …