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Articles 1  30 of 439
FullText Articles in Physics
WaveOptics Investigation Of Turbulence Thermal Blooming Interaction: Ii. Using TimeDependent Simulations, Mark F. Spencer
WaveOptics Investigation Of Turbulence Thermal Blooming Interaction: Ii. Using TimeDependent Simulations, Mark F. Spencer
Faculty Publications
Part II of this twopart paper uses waveoptics simulations to look at the Monte Carlo averages associated with turbulence and timedependent thermal blooming (TDTB). The goal is to investigate turbulence thermal blooming interaction (TTBI). At wavelengths near 1 μm, TTBI increases the amount of constructive and destructive interference (i.e., scintillation) that results from highpower laser beam propagation through distributedvolume atmospheric aberrations. As a result, we use the sphericalwave Rytov number, the number of windclearing periods, and the distortion number to gauge the strength of the simulated turbulence and TDTB. These parameters simply greatly given propagation paths with constant atmospheric ...
WaveOptics Investigation Of Turbulence Thermal Blooming Interaction: I. Using SteadyState Simulations, Mark F. Spencer
WaveOptics Investigation Of Turbulence Thermal Blooming Interaction: I. Using SteadyState Simulations, Mark F. Spencer
Faculty Publications
Part I of this twopart paper uses waveoptics simulations to look at the Monte Carlo averages associated with turbulence and steadystate thermal blooming (SSTB). The goal is to investigate turbulence thermal blooming interaction (TTBI). At wavelengths near 1 μm, TTBI increases the amount of constructive and destructive interference (i.e., scintillation) that results from highpower laser beam propagation through distributedvolume atmospheric aberrations. As a result, we use the sphericalwave Rytov number and the distortion number to gauge the strength of the simulated turbulence and SSTB. These parameters simplify greatly given propagation paths with constant atmospheric conditions. In addition, we use ...
Implications Of FourDimensional Weather Cubes For Improved CloudFree LineOfSight Assessments Of FreeSpace Optical Communications Link Performance, Steven T. Fiorino, Santasri BosePillai, Jaclyn Schmidt, Brannon Elmore, Kevin J. Keefer
Implications Of FourDimensional Weather Cubes For Improved CloudFree LineOfSight Assessments Of FreeSpace Optical Communications Link Performance, Steven T. Fiorino, Santasri BosePillai, Jaclyn Schmidt, Brannon Elmore, Kevin J. Keefer
Faculty Publications
We advance the benefits of previously reported fourdimensional (4D) weather cubes toward the creation of highfidelity cloudfree lineofsight (CFLOS) beam propagation for realistic assessment of autotracked/dynamically routed freespace optical (FSO) communication datalink concepts. The weather cubes accrue parameterization of optical effects and custom atmospheric resolution through implementation of numerical weather prediction data in the Laser Environmental Effects Definition and Reference atmospheric characterization and radiative transfer code. 4D weather cube analyses have recently been expanded to accurately assess system performance (probabilistic climatologies and performance forecasts) at any wavelength/frequency or spectral band in the absence of field tests and employment ...
Turbulence Profiling Using Pupil Plane Wavefront Data Derived Fried Parameter Values For A Dynamically Ranged Rayleigh Beacon, Steven M. Zuraski, Elizabeth Beecher, Jack E. Mccrae, Steven T. Fiorino
Turbulence Profiling Using Pupil Plane Wavefront Data Derived Fried Parameter Values For A Dynamically Ranged Rayleigh Beacon, Steven M. Zuraski, Elizabeth Beecher, Jack E. Mccrae, Steven T. Fiorino
Faculty Publications
Longrange optical imaging applications are typically hindered by atmospheric turbulence. The effect of turbulence on an imaging system can manifest itself as an image blur effect usually quantified by the phase distortions present in the system. The blurring effect can be understood on the basis of the measured strength of atmospheric optical turbulence along the propagation path and its impacts on phase perturbation statistics within the imaging system. One method for obtaining these measurements is by the use of a dynamically ranged Rayleigh beacon system that exploits strategically varied beacon ranges along the propagation path, effectively obtaining estimates of the ...
Measurements Of Optical Turbulence Over 149Km Path, Jack E. Mccrae, Santasri BosePillai, Steven T. Fiorino, Aaron J. Archibald, Joel Meoak, Brannon Elmore, Thomas Kesler, Christopher A. Rice
Measurements Of Optical Turbulence Over 149Km Path, Jack E. Mccrae, Santasri BosePillai, Steven T. Fiorino, Aaron J. Archibald, Joel Meoak, Brannon Elmore, Thomas Kesler, Christopher A. Rice
Faculty Publications
An experiment was conducted to study turbulence along a 149km path between the Mauna Loa and Haleakala mountain tops using digital cameras and lightemitting diode (LED) beacons. Much of the path is over the ocean, and a large portion of the path is 3 km above sea level. On the Mauna Loa side, six LED beacons were placed in a roughly linear array with pair spacings from 7 to 62 m. From the Haleakala side, a pair of cameras separated by 83.8 cm observed these beacons. Turbulence along the path induces tilts on the wavefronts, which results in displacements ...
SinglePulse, KerrEffect Mueller Matrix Lidar Polarimeter, Keyser, Christian K., Richard K. Martin, Helena LopezAviles, Khanh Nguyen, Arielle M. Adams, Demetrios Christodoulides
SinglePulse, KerrEffect Mueller Matrix Lidar Polarimeter, Keyser, Christian K., Richard K. Martin, Helena LopezAviles, Khanh Nguyen, Arielle M. Adams, Demetrios Christodoulides
Faculty Publications
We present a novel light detection and ranging (LiDAR) polarimeter that enables measurement of 12 of 16 sample Mueller matrix elements in a single, 10 ns pulse. The new polarization state generator (PSG) leverages Kerr phase modulation in a birefringent optical fiber, creating a probe pulse characterized by temporally varying polarization. Theoretical expressions for the Polarization State Generator (PSG) Stokes vector are derived for birefringent walkoff and no walkoff and incorporated into a timedependent polarimeter signal model employing multiple polarization state analyzers (PSA). Polarimeter modeling compares the Kerr effect and electrooptic phase modulator–based PSG using a single Polarization State ...
OneDimensional MultiFrame Blind Deconvolution Using Astronomical Data For Spatially Separable Objects, Marc R. Brown
OneDimensional MultiFrame Blind Deconvolution Using Astronomical Data For Spatially Separable Objects, Marc R. Brown
Theses and Dissertations
Blind deconvolution is used to complete missions to detect adversary assets in space and to defend the nation's assets. A new algorithm was developed to perform blind deconvolution for objects that are spatially separable using multiple frames of data. This new onedimensional approach uses the expectationmaximization algorithm to blindly deconvolve spatially separable objects. This object separation reduces the size of the object matrix from an NxN matrix to two singular vectors of length N. With limited knowledge of the object and point spread function the onedimensional algorithm successfully deconvolved the objects in both simulated and laboratory data.
Synthesizing General Electromagnetic Partially Coherent Sources From Random, Correlated Complex Screens, Milo W. Hyde Iv
Synthesizing General Electromagnetic Partially Coherent Sources From Random, Correlated Complex Screens, Milo W. Hyde Iv
Faculty Publications
We present a method to generate any genuine electromagnetic partially coherent source (PCS) from correlated, stochastic complex screens. The method described here can be directly implemented on existing spatiallightmodulatorbased vector beam generators and can be used in any application which utilizes electromagnetic PCSs. Our method is based on the genuine crossspectral density matrix criterion. Applying that criterion, we show that stochastic vector field realizations (corresponding to a desired electromagnetic PCS) can be generated by passing correlated Gaussian random numbers through “filters” with spacevariant transfer functions. We include stepbystep instructions on how to generate the electromagnetic PCS field realizations. As an ...
Laser Shock Peening Pressure Impulse Determination Via Empirical DataMatching With Optimization Software, Colin C. Engebretsen
Laser Shock Peening Pressure Impulse Determination Via Empirical DataMatching With Optimization Software, Colin C. Engebretsen
Theses and Dissertations
Laser shock peening (LSP) is a form of work hardening by means of laser induced pressure impulse. LSP imparts compressive residual stresses which can improve fatigue life of metallic alloys for structural use. The finite element modeling (FEM) of LSP is typically done by applying an assumed pressure impulse, as useful experimental measurement of this pressure impulse has not been adequately accomplished. This shortfall in the field is a current limitation to the accuracy of FE modeling, and was addressed in the current work. A novel method was tested to determine the pressure impulse shape in time and space by ...
Determining Bulk Aerosol Absorption From Off Axis Backscattering Using Rayleigh Beacon Laser Pulses, Julie C. Grossnickle
Determining Bulk Aerosol Absorption From Off Axis Backscattering Using Rayleigh Beacon Laser Pulses, Julie C. Grossnickle
Theses and Dissertations
Aerosol absorption and scattering can play a key role in degrading high energy laser performance in the form of thermal blooming and beam attenuation. Aerosol absorption properties are not completely understood, and thus affect how we are able to quantify expected high energy laser weapon performance. The Air Force Institute of Technology Center for Directed Energy (AFIT CDE) developed both Laser Environmental Effects Definition and Reference (LEEDR) and the High Energy Laser EndtoEnd Operational Simulation (HELEEOS) code to characterize atmospheric radiative transfer effects and evaluate expected directed energy weapon system performance. These packages enable modeling of total irradiance at given ...
Solving Combinatorial Optimization Problems Using The Quantum Approximation Optimization Algorithm, Nicholas J. Guerrero
Solving Combinatorial Optimization Problems Using The Quantum Approximation Optimization Algorithm, Nicholas J. Guerrero
Theses and Dissertations
The Quantum Approximation Optimization Algorithm (QAOA) is one of the most promising applications for noisy intermediatescale quantum machines due to the low number of qubits required as well as the relatively low gate count. Much work has been done on QAOA regarding algorithm implementation and development; less has been done checking how these algorithms actually perform on a real quantum computer. Using the IBM Q Network, several instances of combinatorial optimization problems (the max cut problem and dominating set problem) were implemented into QAOA and analyzed. It was found that only the smallest toy max cut algorithms performed adequately: those ...
Measurement Of The ^{160}Gd(P,N)^{160}Tb Excitation Function From 4 18 Mev, Using A Stacked Foil Technique, Ryan K. Chapman
Measurement Of The 160Gd(P,N)160Tb Excitation Function From 4 18 Mev, Using A Stacked Foil Technique, Ryan K. Chapman
Theses and Dissertations
A stack of thin Gd, Ti, and Cu foils were irradiated with an 18 MeV proton beam at LawrenceBerkeley National Laboratory's 88Inch Cyclotron to investigate the ^{160}Gd(p,n)^{160}Tb nuclear reaction for nuclear forensics applications. This experiment will improve knowledge of ^{160}Tb production rates, allowing ^{160}Tb to be efficiently created in a foil stack consisting of other proton induced isotopes for forensics applications. A set of 15 measured cross sections between 418 MeV for ^{160}Gd(p,n)^{160}Tb were obtained using a stacked foil technique. The foil stack consisted of one stainless ...
Rapid Analysis Of Plutonium Surrogate Material Via HandHeld LaserInduced Breakdown Spectroscopy, Ashwin P. Rao
Rapid Analysis Of Plutonium Surrogate Material Via HandHeld LaserInduced Breakdown Spectroscopy, Ashwin P. Rao
Theses and Dissertations
This work investigated the capability of a portable LIBS device to detect and quantify dopants in plutonium surrogate alloys, specifically gallium, which is a common stabilizer used in plutonium alloys. The SciAps Z500ER was utilized to collect spectral data from ceriumgallium alloys of varying gallium concentrations. Calibration models were built to process spectra from the CeGa alloys and calculate gallium concentration from spectral emission intensities. Univariate and multivariate analysis techniques were used to determine limits of detection of different emission line ratios. Spatial mapping measurements were conducted to determine the device's ability to detect variations in gallium concentration on ...
Comparison Of The Accuracy Of RayleighRice Polarization Factors To Improve Microfacet Brdf Models, Rachael L. Wolfgang
Comparison Of The Accuracy Of RayleighRice Polarization Factors To Improve Microfacet Brdf Models, Rachael L. Wolfgang
Theses and Dissertations
Microfacet BRDF models assume that a surface has many small microfacets making up the roughness of the surface. Despite their computational simplicity in applications in remote sensing and scene generation, microfacet models lack the physical accuracy of wave optics models. In a previous work, Butler proposed to replace the Fresnel reflectance term of microfacet models with the RayleighRice polarization factor, Q, to create a more accurate model. This work examines the novel model that combines microfacet and wave optics terms for its accuracy in the pp and ss polarized cases individually. The model is fitted to the polarized data in ...
Zernike Piston Statistics In Turbulent MultiAperture Optical Systems, Joshua J. Garretson
Zernike Piston Statistics In Turbulent MultiAperture Optical Systems, Joshua J. Garretson
Theses and Dissertations
There is currently a lack of research into how the atmosphere effects Zernike piston. This Zernike piston is a coefficient related to the average phase delay of a wave. Usually Zernike piston can be ignored over a single aperture because it is merely a delay added to the entire wavefront. For multiaperture interferometers though piston cannot be ignored. The statistics of Zernike piston could supplement and improve atmospheric monitoring, adaptive optics, stellar interferometers, and fringe tracking. This research will focus on developing a statistical model for Zernike piston introduced by atmospheric turbulence.
The Design Of A Continuous Wave Molecular Nitrogen Stimulated Raman Laser In The Visible Spectrum, Timothy J. Bate
The Design Of A Continuous Wave Molecular Nitrogen Stimulated Raman Laser In The Visible Spectrum, Timothy J. Bate
Theses and Dissertations
Hollowcore photonic crystal fibers (HCPCFs) shows promise as a hybrid laser with higher nonlinear process limits and small beam size over long gain lengths. This work focuses on the design of a CW molecular nitrogen (N_{2}) stimulated Raman laser. N_{2} offers Raman gains scaling up to 900 amg, scaling higher than H_{2}. The cavity experiment showed the need to include Rayleigh scattering in the high pressure required for N_{2} Raman lasing. Even at relatively low pressure ssuch as 1,500 psi, high conversion percentages should be found if the fiber length is chosen based on the ...
Validation Of Hts Optical Turbulence Profiling Via Sonic Anemometry, Alexander S. Boeckenstedt
Validation Of Hts Optical Turbulence Profiling Via Sonic Anemometry, Alexander S. Boeckenstedt
Theses and Dissertations
Previous turbulence measurements along a nearground, 500 m, horizontal path using two heliumneon laser beacons and Hartmann Turbulence Sensor (HTS) yielded profiles of C^{2}_{n} by measuring local aberrated wavefront tilts. The HTS C^{2}_{n} estimates were consistent with integrated turbulence values collected along the same path by a BLS900 scintillometer. Further validation of the HTS profiling method is necessary to produce accurate optical turbulence profiles for wavefront correction and to eventually gain an improved understanding of turbulence in the lower atmosphere and its variation as a function of altitude. In order to add confidence to the HTS ...
Laser Induced Thermal Degradation Of Carbon FiberCarbon Nanotube Hybrid Laminates, Joshua A. Key
Laser Induced Thermal Degradation Of Carbon FiberCarbon Nanotube Hybrid Laminates, Joshua A. Key
Theses and Dissertations
Recent advancements in fiber laser technology have increased interest in target material interactions and the development of thermal protection layers for tactical laser defense. A significant material of interest is carbon fiber reinforced polymers due to their increased use in aircraft construction. In this work, the thermal response of carbon fibercarbon nanotube (CNT) hybrid composites exposed to average irradiances of 0.876.8 W/cm^{2} were observed using a FLIR sc6900 thermal camera. The camera had a pixel resolution of 640x512 which resulted in a spatial resolution of 0.394x0.383 mm/pixel for the front and 0.463x0 ...
Conduction Mapping For Quality Control Of Laser Powder Bed Fusion Additive Manufacturing, Chance M. Baxter
Conduction Mapping For Quality Control Of Laser Powder Bed Fusion Additive Manufacturing, Chance M. Baxter
Theses and Dissertations
A process was developed to identify potential defects in previous layers of Selective Laser Melting (SLM) Powder Bed Fusion (PBF) 3D printed metal parts using a midIR thermal camera to track infrared 3.84 m band emission over time as the part cooled to ambient temperature. Efforts focused on identifying anomalies in thermal conduction. To simplify the approach and reduce the need for significant computation, no attempts were made to calibrate measured intensity, extract surface temperature, apply machine learning, or compare measured cooldown behavior to computer model predictions. Raw intensity cooldown curves were fit to a simplified functional form designed ...
Digital Holography Experiments With Degraded Temporal Coherence, Douglas E. Thornton, Davin Mao, Mark F. Spencer, Christopher A. Rice, Glen P. Perram
Digital Holography Experiments With Degraded Temporal Coherence, Douglas E. Thornton, Davin Mao, Mark F. Spencer, Christopher A. Rice, Glen P. Perram
Faculty Publications
To simulate the effects of multiplelongitudinal modes and rapid fluctuations in center frequency, we use sinusoidal phase modulation and linewidth broadening, respectively. These effects allow us to degrade the temporal coherence of our masteroscillator laser, which we then use to conduct digital holography experiments. In turn, our results show that the coherence efficiency decreases quadratically with fringe visibility and that our measurements agree with our models to within 1.8% for sinusoidal phase modulation and 6.9% for linewidth broadening.
Stochastic Complex Transmittance Screens For Synthesizing General Partially Coherent Sources, Milo W. Hyde Iv
Stochastic Complex Transmittance Screens For Synthesizing General Partially Coherent Sources, Milo W. Hyde Iv
Faculty Publications
We develop a method to synthesize any partially coherent source (PCS) with a genuine crossspectral density (CSD) function using complex transmittance screens. Prior work concerning PCS synthesis with complex transmittance screens has focused on generating Schellmodel (uniformly correlated) sources. Here, using the necessary and sufficient condition for a genuine CSD function, we derive an expression, in the form of a superposition integral, that produces stochastic complex screen realizations. The sample autocorrelation of the screens is equal to the complex correlation function of the desired PCS. We validate our work by generating, in simulation, three PCSs from the literature—none has ...
Twisted SpaceFrequency And SpaceTime Partially Coherent Beams, Milo W. Hyde Iv
Twisted SpaceFrequency And SpaceTime Partially Coherent Beams, Milo W. Hyde Iv
Faculty Publications
We present partially coherent sources that are statistically twisted in the spacefrequency and spacetime domains. Beginning with the superposition rule for genuine partially coherent sources, we derive source plane expressions for the crossspectral density (CSD) and mutual coherence functions (MCFs) for twisted spacefrequency and spacetime Gaussian Schellmodel (GSM) beams. Using the Fresnel approximation to the freespace Green’s function, we then paraxially propagate the CSD and MCF to any plane z> 0. We discuss the beams’ behavior as they propagate, with particular emphasis on how the beam shape rotates or tumbles versus z. To validate our analysis, we simulate the ...
Effect Of Ar(3p^{5}4p; 2p)+M > Ar(3p^{5}4s; 1s)+M Branching Ratio On Optically Pumped Rare Gas Laser Performance, Daniel J. Emmons Ii, David E. Weeks
Effect Of Ar(3p54p; 2p)+M > Ar(3p54s; 1s)+M Branching Ratio On Optically Pumped Rare Gas Laser Performance, Daniel J. Emmons Ii, David E. Weeks
Faculty Publications
Optically pumped rare gas laser performance is analyzed as a function of the Ar(3p^{5}4p; 2p) + M → Ar(3p^{5}4s; 1s) + M branching ratios. Due to the uncertainty in the branching ratios, a sensitivity study is performed to determine the effect on output and absorbed pump laser intensities. The analysis is performed using a radio frequency dielectric barrier discharge as the source of metastable production for a variety of Argon in Helium mixtures over pressures ranging from 200 to 500 Torr. Peak output laser intensities show a factor of 7 increase as the branching ratio is increased ...
Measurement Of Electron Density And Temperature From LaserInduced Nitrogen Plasma At Elevated Pressure (1–6 Bar), Ashwin P. Rao, Mark Gragston, A Patnaik, Paul Hsu, Michael B. Shattan
Measurement Of Electron Density And Temperature From LaserInduced Nitrogen Plasma At Elevated Pressure (1–6 Bar), Ashwin P. Rao, Mark Gragston, A Patnaik, Paul Hsu, Michael B. Shattan
Faculty Publications
Laserinduced plasmas experience Stark broadening and shifts of spectral lines carrying spectral signatures of plasma properties. In this paper, we report timeresolved Stark broadening measurements of a nitrogen triplet emission line at 1–6 bar ambient pressure in a pure nitrogen cell. Electron densities are calculated using the Stark broadening for different pressure conditions, which are shown to linearly increase with pressure. Additionally, using a Boltzmann fit for the triplet, the electron temperature is calculated and shown to decrease with increasing pressure. The rate of plasma cooling is observed to increase with pressure. The reported Stark broadening based plasma diagnostics ...
Nonlinear Characterizing Of A New Titanium Nitride On Aluminum Oxide Metalens, Michael A. Cumming
Nonlinear Characterizing Of A New Titanium Nitride On Aluminum Oxide Metalens, Michael A. Cumming
Theses and Dissertations
A sample metalens generated from Titanium Nitride deposited onto Aluminum Oxide was designed to focus at 10 microns with a beam centered at 800nm, and when analyzed with high intensity illumination was found to have a focal length of 9.650 ±.003µm at an intensity of 16.93[MW/cm^{2} ]. Analyzing this change by comparing it to a Fresnel Lens’ physics shows that for this lens, the effective nonlinear index of refraction is certainly greater than the nonlinear index of just Titanium Nitride itself, at −1.6239 × 10^{−15}[m^{2}/W] compared to the materials −1.3 × 10 ...
Generating Electromagnetic SchellModel Sources Using Complex Screens With Spatially Varying Auto And CrossCorrelation Functions, Milo W. Hyde Iv
Generating Electromagnetic SchellModel Sources Using Complex Screens With Spatially Varying Auto And CrossCorrelation Functions, Milo W. Hyde Iv
Faculty Publications
We present a method to generate any physically realizable electromagnetic Schellmodel source. Our technique can be directly implemented on existing vectorbeam generators that utilize spatial light modulators for coherence control, beam shaping, and relative phasing. This work significantly extends published research on the subject, where control over the partially coherent source’s crossspectral density matrix was limited. We begin by presenting the statistical optics theory necessary to derive and implement our method. We then apply our technique, both analytically and in simulation, to produce two electromagnetic Schellmodel sources from the literature. We demonstrate control over the full crossspectral density matrices ...
Numerical Simulation Of Unstable Laser Resonators With A High Gain Medium, Robert L. Lloyd
Numerical Simulation Of Unstable Laser Resonators With A High Gain Medium, Robert L. Lloyd
Theses and Dissertations
This research focused on the numeric simulation of unstable laser resonators with high gain media. In order to accomplish the research, the modes and eigenvalues for various bare cavity resonator were computed followed by modes of a resonator in the presence of gain. Using a Fourier Split Step Method in a Fox and Li iteration scheme, different laser outputs for various laser cavities with gain were computed. Various parameters defining positive branch confocal unstable resonators were chosen corresponding to four studies. The four studies focused on modifying laser cavity Fresnel number, gain medium parameters, gain cell position, and gain cell ...
Digital Holography Efficiency Experiments For Tactical Applications, Douglas E. Thornton
Digital Holography Efficiency Experiments For Tactical Applications, Douglas E. Thornton
Theses and Dissertations
Digital holography (DH) uses coherent detection and offers direct access to the complexoptical field to sense and correct image aberrations in low signaltonoise environments, which is critical for tactical applications. The performance of DH is compared to a similar, well studied deepturbulence wavefront sensor, the selfreferencing interferometer (SRI), with known efficiency losses. Wave optics simulations with deepturbulence conditions and noise were conducted and the results show that DH outperforms the SRI by 10's of dB due to DH's strong reference. Additionally, efficiency experiments were conducted to investigate DH system losses. The experimental results show that the mixing efficiency ...
On The Pulsed Laser Ablation Of Metals And Semiconductors, Todd A. Van Woerkom
On The Pulsed Laser Ablation Of Metals And Semiconductors, Todd A. Van Woerkom
Theses and Dissertations
This dissertation covers pulsed laser ablation of Al, Si, Ti, Ge, and InSb, with pulse durations from tens of picosecond to hundreds of microseconds, fluences from ones of J/cm^{2} to over 10,000 J/cm^{2}, and in ambient air and vacuum. A set of nondimensional scaling factors was created to interpret the data relative to the laser and material parameters, and it was found that pulse durations shorter than a critical timescale formed craters much larger than the thermal diffusion length, and longer pulse durations created holes much shallower than the thermal diffusion length. Low transverse order ...
Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace
Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace
Theses and Dissertations
Microscale beams of germanium ions were used to target different locations of aluminum galliumnitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs) to determine location dependent radiation effects. 1.7 MeV Ge ions were targeted at the gap between the gate and the drain to observe displacement damage effects while 47 MeV Ge ions were targeted at the gate to observe ionization damage effects. Electrical data was taken pre, during, and post irradiation. To separate transient from permanent degradation, the devices were characterized after a room temperature anneal for at least 30 days. Optical images were also analyzed pre ...