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Full-Text Articles in Physical Sciences and Mathematics
Threshold Extension Of Gallium Arsenide/Aluminum Gallium Arsenide Terahertz Detectors And Switching In Heterostructures, Mohamed Buhary Rinzan
Threshold Extension Of Gallium Arsenide/Aluminum Gallium Arsenide Terahertz Detectors And Switching In Heterostructures, Mohamed Buhary Rinzan
Physics and Astronomy Dissertations
In this work, homojunction interfacial workfunction internal photoemission (HIWIP) detectors based on GaAs, and heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors based mainly on the Gallium Arsenide/Aluminum Gallium Arsenide material system are presented. Design principles of HIWIP and HEIWIP detectors, such as free carrier absorption, photocarrier generation, photoemission, and responsivity, are discussed in detail. Results of p-type HIWIPs based on GaAs material are presented. Homojunction detectors based on p-type GaAs were found to limit their operating wavelength range. This is mainly due to band depletion arising through carrier transitions from the heavy/light hole bands to the split off band. Designing …
Reproducibility Distinguishability And Correlation Of Fireball And Shockwave Dynamics In Explosive Munitions Detonations, Bryan J. Steward
Reproducibility Distinguishability And Correlation Of Fireball And Shockwave Dynamics In Explosive Munitions Detonations, Bryan J. Steward
Theses and Dissertations
The classification of battlespace detonations, specifically the determination of munitions type and size using temporal and spectral features of infrared emissions, is a particularly challenging problem. The intense infrared radiation produced by the detonation of high explosives is largely unstudied. Furthermore, the time-varying fireball imagery and spectra are driven by many factors including the type, size and age of the chemical explosive, method of detonation, interaction with the environment, and the casing used to enclose the explosive. To distinguish between conventional military munitions and improvised or enhanced explosives, the current study investigates fireball expansion dynamics using high speed, multi-band imagery. …
Passive Ranging Using Atmospheric Oxygen Absorption Spectra, Michael R. Hawks
Passive Ranging Using Atmospheric Oxygen Absorption Spectra, Michael R. Hawks
Theses and Dissertations
The depth of absorption bands in observed spectra of distant, bright sources can be used to estimate range to the source. A novel approach is presented and demonstrated using observations of the oxygen absorption band near 762 nm. Range is estimated by comparing observed values of band-average absorption against curves derived from either historical data or model predictions. Curves are based on fitting a random band model to the data, which reduces average range error by 67% compared to the Beer's Law model used in previous work. A new modification to existing band models for long, inhomogeneous paths is presented …