In recent, high intensity laser pulse interaction with solid density matter has been studied in several laboratory and facilities. Multi-MeV proton and ion beams from plasma produced by this interaction is one important application research area of HEDP. In this thesis, the basic theory of hot electron generation associated with proton acceleration will be introduced. A basic proton acceleration mechanism called TNSA will be introduced with supplemental free plasma expansion model. To investigate proton acceleration at the Texas Petawatt Facility, the experimental set up and target alignmen will be introduced in the chapter 5. While the analysis of data acquired from this experiment is still unfinished, a brief result with RCF image will be introduced in chapter 6. / text

The Rayleigh-Taylor instability (RTI) is one of the primary hydrodynamic instabilities that acts as a disputer to achieving high yield inertial confinement fusion (ICF). The potential for RTI to grow on the interior surface of ICF capsules, caused by deceleration during the implosion, further emphasises the need to better understand the seed mechanisms for RTI and possible mitigation methods for damping the instability growth. Reducing the growth of RTI during deceleration could preserve the spherical symmetry of ICF implosions and reduce the amount of mix between the solid capsule liner and fuel hot-spot. Additionally, it has been shown that magnetic fields do damp RTI growth, and the presence of a magnetic field lowers the threshold for achieving fusion and increases the yield. Understanding the seed mechanisms of the RTI, especially on the interior surface of ICF capsules, further allows for better understanding of the morphology of the RTI growth dur- ing deceleration. Classically RTI has been studied using single or multi-mode sinusoidal perturbations, which result in bubble and spike morphology. However in addition to si- nusoidal perturbations, single-feature perturbation, such as voids or divots, can seed RTI. This form of RTI is considered the thin-layer RTI, where the perturbation's wavelength is longer than the dense layer's thickness. This specific RTI evolution results in a morphology consisting of a single central spike and arms that extend horizontally away from the spike and eventually fall back towards the interface. Thin-layer RTI is important to explore dur- ing deceleration due to the presence of the fill-tubes in ICF capsules causing holes in the shell. Creating experimental platforms for current laser configurations on Omega and the Na- tional Ignition Facility (NIF) is necessary to study deceleration-stage RTI experimentally and validate computational modeling. A comprehensive exploration of potential experimen- tal designs on Omega, Omega-EP, and NIF are explored to identify a platform with which deceleration-stage RTI can be studied with and without the presence of an externally applied magnetic field. Additionally, the design of a novel experimental platform for Omega-EP to study thin-layer RTI during deceleration with and without an externally applied magnetic field is presented, along with data collected during the first experiments performed utilizing the platform. Lastly, a first of it's kind RTI platform for NIF is fielded and the results are presented, including an exploration of the possible impacts high-intensity-laser generated hot-electrons can have on experimental targets. The results of these experimental platforms are used to benchmark computational models, and demonstrate the potential for magnetized RTI to be studied comprehensively in future experiments. / Doctor of Philosophy / The potential of controlled sustained nuclear fusions as a viable energy source has rapidly become a reality in recent years. Monumental progress has been made in the pursuit of con- trolled fusion, including the repeated achievement of fusion ignition at the National Ignition Facility (NIF), meaning there was successful production of more energy from the fusion reac- tion than laser energy used to trigger the reaction. However, in order for fusion to become a truly viable energy source improvements in capsule design and the mitigation of disruptions, like hydrodynamic instabilities, must be explored to produce higher energy yields. The Rayleigh-Taylor instability (RTI) is one of the most detrimental hydrodynamic insta- bilities in inertial confinement fusion (ICF). RTI occurs when a lighter fluid, like the fuel used in fusion reactions, supports a heavier fluid, the ICF capsule itself, under the influence of gravity. An ICF capsule is imploded, induced by the driving mechanism, such as a laser, but once the driver stops the capsule will begin to decelerate. During this deceleration stage, the interior surface of the ICF capsule in susceptible to RTI growth causing the cold capsule material to mix with the hot fusion fuel. This mixing reduces the fuel's ability to reach the necessary temperatures and densities need to achieve ignition and produce high energy yields. As a result, it is crucial to better understand the defects that cause RTI to grow and explore methods that could damp the RTI growth and preserve the integrity of the implosion and fusion fuel. The work presented here focuses on exploring both the seed mechanisms for RTI and miti- gation strategies. Specifically, using an externally applied magnetic field has been shown to damp RTI growth and in know to lower the threshold of the conditions needed to achieve ignition. A study of possible experimental setups at both the Omega laser and NIF is ex- plored in order to identify a design with which the damping effects of an externally applied magnetic field on deceleration-stage RTI can be studied experimentally. From this design study platforms for the Omega-EP and NIF were conceptualized and ultimately fielded. The results from these novel experiments are presented, along with an exploration of pos- sible effects on RTI unexpected preheating of the experimental targets. Additionally, an exploration of the seed mechanisms of RTI is presented with a look at the classic sinusoidal perturbation as well as using a divot to seeded thin-layer RTI, which evolves with a spike and arm morphology rather than the classical bubble and spike. The experimental results from Omega-EP using a divot as the perturbation are presented. Novel results of varying RTI platforms and their potential for further development provide crucial insight into the possible presence of deceleration-stage RTI in ICF capsules and can be iterated on in the future to further explore RTI evolution and damping methods.

Optimal nutritional management of growing pigs is constrained by lack of quantitative information on the response of animals between 30 and 110 kg live weight to dietary energy content. Under 'ideal' conditions modern genotypes appear to adjust feed intake to maintain a constant DE intake over a much wider range of dietary energy concentrations than previously thought (Mullan et al, 1998). However, under commercial pen conditions, voluntary feed intake is lower, pigs respond in terms of both growth rate and feed conversion to dietary DE density considerably above the levels currently thought to maximise biological and economic responses. The present study was designed to provide information on the response of growing pigs to dietary energy content under ideal and commercial housing conditions for two growth periods 30-60kg liveweight and 60-100kg liveweight. The results of the pigs kept under individual (ideal) housed conditions were consistent with the literature in that they adjusted their voluntary feed intake with digestible energy density to maintain a constant energy intake. The results of the pigs kept in groups (commercial) housing conditions tended to increase their daily energy intake as the energy density of the feed increased. This increase in energy intake improved the growth rate of the pigs and increased the fat deposition of those pigs. Economic analysis of the experiments involving pigs in groups indicates that formulating diets to a least cost per megajoule of digestible energy is not the most profitable point to set the digestible energy density. Modelling programs need to be used to determine where the least cost per unit of growth of the pig occurs. This is the most economical digestible energy density to formulate too. This will have major impact on the cost of production of piggery operations as the cost of energy is the single most important parameter in the cost of producing a pig.

Torrefaction has become a topic of interest in recent times not only because farmers could increase their income due to more farming activities for biomass feedstock demands but also it promotes opportunities for green job creation, provides alternative fuel source for coal fired plants, and contributes to greenhouse gas emission mitigation. Hence, this thesis explored the torrefaction behaviour of both herbaceous (switchgrass, miscanthus, wheat straw) and short rotation (willow) agricultural energy crops in terms of hydrophobicity, grindability and energy density. The lignocellulosic compositions of raw and treated switchgrass and bulk density of raw and treated miscanthus were also determined. Hence, the outcomes of these experimental investigations facilitated the development of a torrefaction definition. The research also studied the heat transfer mechanisms of torrefaction and developed mathematical models to simulate the heat generation profile due to the internal and spontaneous combustion of a cylindrically-shaped poplar wood. COMSOL modeling software was used to analyze and simulate the heat generation profiles that were closely similar to those from the experiments; hence led to a development of a correction factor to scale treatment inputs. / Thesis / OMAFRA HQP

Optimal nutritional management of growing pigs is constrained by lack of quantitative information on the response of animals between 30 and 110 kg live weight to dietary energy content. Under 'ideal' conditions modern genotypes appear to adjust feed intake to maintain a constant DE intake over a much wider range of dietary energy concentrations than previously thought (Mullan et al, 1998). However, under commercial pen conditions, voluntary feed intake is lower, pigs respond in terms of both growth rate and feed conversion to dietary DE density considerably above the levels currently thought to maximise biological and economic responses. The present study was designed to provide information on the response of growing pigs to dietary energy content under ideal and commercial housing conditions for two growth periods 30-60kg liveweight and 60-100kg liveweight. The results of the pigs kept under individual (ideal) housed conditions were consistent with the literature in that they adjusted their voluntary feed intake with digestible energy density to maintain a constant energy intake. The results of the pigs kept in groups (commercial) housing conditions tended to increase their daily energy intake as the energy density of the feed increased. This increase in energy intake improved the growth rate of the pigs and increased the fat deposition of those pigs. Economic analysis of the experiments involving pigs in groups indicates that formulating diets to a least cost per megajoule of digestible energy is not the most profitable point to set the digestible energy density. Modelling programs need to be used to determine where the least cost per unit of growth of the pig occurs. This is the most economical digestible energy density to formulate too. This will have major impact on the cost of production of piggery operations as the cost of energy is the single most important parameter in the cost of producing a pig.

Thesis advisor: Udayan Mohanty / Thesis advisor: Dunwei Wang / With the fast development of society, the demand for batteries has been increasing dramatically over the years. To satisfy the ever-increasing demand for high energy density, different chemistries were explored. From the first-generation lead–acid batteries to the state-of-the-art LIBs (lithium ion batteries), the energy density has been improved from 40 to over 200 Wh kg⁻¹. However, the development of LIBs has approached the upper limit. Electrode materials based on insertion chemistry generally deliver a low capacity of no more than 400 mAh/g. To break the bottleneck of current battery technologies, new chemistries are needed. Moving from the intercalation chemistry to conversion chemistry is a trend. The conversion electrode materials feature much higher capacity than the conventional intercalation-type materials, especially for the O₂ cathode and Li metal anode. The combination of these two can bring about a ten-folds of energy density increase to the current LIBs. Moreover, to satisfy the safety requirements, either using non-flammable electrolytes to reduce the safety risk of Li metal anode or switch to dendrite-free Mg anode is a good strategy toward high energy density batteries. First, to enable the conversion-type O₂ cathode, a wood-derived, free-standing porous carbon electrode was demonstrated and successfully be applied as a cathode in Li-O₂ batteries. The spontaneously formed hierarchical porous structure exhibits good performance in facilitating the mass transport and hosting the discharge products of Li₂O₂. Heteroatom (N) doping further improves the catalytic activity of the carbon cathode with lower overpotential and higher capacity. Next, to solve the irreversible Li plating/stripping and safety issues related with Li metal anode, we introduced O₂ as additives to enable Li metal anode operation in non-flammable triethyl phosphate (TEP) electrolyte. The electrochemically induced chemical reaction between O₂- derived species and TEP solvent molecules facilitated the beneficial SEI components formation and effectively suppressed the TEP decomposition. The promise of safe TEP electrolyte was also demonstrated in Li-O₂ battery and Li-LFP battery. If we think beyond Li chemistries, Mg anode with dendrite-free property can be a promising candidate to further reduce the safety concerns while remaining the high energy density advantage. Toward the end of this thesis, we developed a thin film metal–organic framework (MOF) for selective Mg²⁺ transport to solve the incompatibility issues between the anode and the cathode chemistry for Mg batteries. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Orbital-free density functional theory requires accurate approximations for the noninteracting kinetic energy as a functional of the ground-state electron den- sity. For explicit functionals in real space, it has proved difficult to supersede the quality of the gradient expansion, truncated at second order. This is partly because the gradient expansion diverges for atomic and molecular densities. In an effort to include information about higher-order terms in the gradient expansion but avoid divergences, we consider resummations for the series using Padé approximants and Meijer-G functions. To regularize terms that appear in the denominator, we consider various damping functions, which introduces parameter(s) that can be fit to atomic data. These results improve upon the second-order truncation, but do not achieve the exquisite accuracy that would be required for practical orbital-free density-functional theory calculations. / Thesis / Master of Science (MSc)

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