In this dissertation, we investigate the n=0 Geodesic Acoustic Modes (GAM) in the framework of both magneto-hydrodynamics and kinetics. In MHD, the purpose is to understand the numerical results out of the CASTOR code (1). Effects of energetic particle are ignored. The leading perturbation is the density perturbation, which leads to a local GAM. The coupling of density perturbation to the magnetic perturbation, which is treated to be smaller, leads to global a GAM. We recover the numerical results from the CASTOR code and obtain and analytical solution to the radial eigen-mode equation though asymptotic matching. To understand recent experimental results on DIII-D (2) a kinetic theory is constructed in which magnetic perturbations are neglected and energetic ions are treated on the same footing as the thermal species based on drift kinetics. Not only do the energetic particles destabilize the local GAM induced by thermal species, but they are also crucial to establish the global GAM due to their large orbit shifts. Polarization of thermal ions is included. A mechanism for fast GAM excitation through NBI is proposed, based on our local kinetic GAM theory when there exists a loss boundary in pitch angle. / text

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The transport of solar energetic particles (SEPs) in the inner heliosphere is a very important issue which can affect our daily life. For example, large SEP events can lead to the failure of power grids, interrupt communications, and may participate in global climate change. The SEPS also can harm humans in space and destroy the instruments on board spacecraft. Studying the transport of SEPs also helps us understand remote regions of space which are not visible to us because there are not enough photons in those places.The interplanetary magnetic field is the medium in which solar energetic particles travel. The Parker Model of the solar wind and its successor, the Weber and Davis model, have been the dominant models of the solar wind and the interplanetary magnetic field since 1960s. In this thesis, I have reviewed these models and applied an important correction to the Weber and Davis model. Various solar wind models and their limitations are presented. Different models can affect the calculation of magnetic field direction at 1~AU by as much as about 30\%.Analysis of the onset of SEP events could be used to infer the release time of solar energetic particles and to differentiate between models of particle acceleration near the Sun. It is demonstrated that because of the nature of the stochastic heliospheric magnetic field, the path length measured along the lineof force can be shorter than that of the nominal Parker spiral. These results help to explain recent observations.A two dimensional model and a fully three dimensional numerical model for the transport of SEPs has been developed based on Parker's transport equation for the first time. ``Reservoir'' phenomenon, which means the inner heliosphere works like a reservoir for SEPs during large SEP events, and multi-spacecraft observation of peak intensities are explained by this numerical model.

The utilization of energetic strained molecules may be one way to mitigate carbon emissions or better and more economical fuel blends. To investigate candidate molecules, limonene and dicyclopentadiene, both theoretical and experimental procedures were implemented here. Computational quantum chemistry methods were employed to determine the thermodynamic properties and kinetic parameters for the hydrogen-abstraction reactions of limonene by a hydrogen atom. Geometry optimization and energy calculation was conducted for all stable species and transition states using Gaussian 09. The rate constants of the H-abstraction reactions were calculated using conventional transition state theory, as implemented in ChemRate software. The obtained values were fitted over the temperature range of 298 – 2000 K to obtain the modified Arrhenius parameters. Increasing the anti-knock quality of gasoline fuels can enable higher efficiency in spark ignition engines. This study explores blending the anti-knock quality of dicyclopentadiene (DCPD, a by-product of ethylene production from naphtha cracking), with various gasoline fuels. The blends were tested in an ignition quality tester (IQT) and a modified cooperative fuel research (CFR) engine operating under homogenous charge compression ignition (HCCI) and knock limited spark advance (KLSA) conditions. Ethanol is widely used as a gasoline blending component in many markets, due to current fuel regulations. The test results of DCPD-gasoline blends were compared to those of ethanol-gasoline blends. Furthermore, the anti-knock properties of dicyclopentadiene (DCPD) as an additive to primary reference fuels (PRF) and toluene primary reference fuels (TPRF) have been investigated. The research octane number (RON) and motor octane number (MON) were measured using cooperative fuels research (CFR) engine for four different fuel blends. Moreover, the ignition delay times of these mixtures were measured in a high-pressure shock tube at 40 bar and stoichiometric mixtures over a temperature range of [700-1200 K]. Ignition delay measurements were also conducted using rapid compression machine (RCM) at stoichiometric conditions and 20 bar. An ignition quality tester (IQT) compared ignition delay times of iso-octane and DCPD. Furthermore, a chemical kinetic auto-ignition model was designed to simulate the IDT experiments.

Nitrogen-rich energetic materials (EMs) are characterized by their typically high values for heat-of-formation as well as the environmental benefit associated with the production of nitrogen gas upon detonation. This makes them the most likely class of materials to replace currently used explosives such as lead azide (LA), 2,4,6-trinitrotoluene (TNT), and 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX). The sensitivity of EMs to mechanical stimuli such as impact and friction is governed primarily by the packing arrangement, as observed in the crystal structure. For this reason, crystal engineering is the most effective tool to achieve low sensitivity, high-performing EMs. In Chapter 2 the pH-dependent formation of two different dihydrazinyl tetrazine/azobistetrazolate salts was explored. These materials have high calculated detonation parameters and are expected to have large differences in sensitivity based on the different packing arrangements adopted. In Chapter 3, azobistetrazolate was substituted for a series of more thermally stable anions for the creation of a family of dihydrazinyltetrazine-based secondary explosives. The use of oxalyldihydrazide (ODH) as an energetic cation was explored in Chapter 4, where the selective formation of both singly and doubly protonated versions of ODH allowed for the creation of both 1:1 and 2:1 energetic salts.

<p> The following document is a compilation of four manuscripts which were peer-reviewed and accepted for publication in the following scientific journals: <em>Propellants, Explosives, Pyrotechniques</em>, <em>Crystal Growth & Design</em>, <em>Zeitschrift für Anorganische und Allgemeine Chemie ZAAC</em>, and <em>Energetic Materials Frontiers</em>. This work, also, includes excerpts from the author’s review of energetic materials synthesized via reactions with nitroacetonitrile published by <em>RSC Advances</em>. The research presented is the result of a four-year graduate program in the School of Materials Engineering and as part of the Purdue Energetics Research Center (PERC). </p> <p>  </p> <p><em>1,2,4-Triazine Based Energetic Materials and Improved Nitro-Compound Synthesis</em> briefly addresses the history of energetic materials, key requirements, and ways to modify materials to meet those requirements before transitioning to the research synthesis and characterization. The discussion sections address the synthesis methods of the heterocyclic 1,2,4-triazine structure and alternative routes for the formation of nitro moieties. Also discussed are the methods for chemical characterization, thermal stability, mechanical sensitivity, and the theoretical calculations used to obtain energetic performances for comparison with traditional known explosive materials.</p> <p><br></p>

<div>Development of novel energetic molecules is a challenging endeavor. Successful discovery and synthesis of a novel viable energetic molecule is an even more challenging endeavor. To qualify for scale-up in production, the molecule must undergo extensive characterization at the small scale and meet criteria for sensitivity, stability, toxicity, lifetime, etc. A failure to qualify for further scale-up can result in significant wasted investment. Cocrystallization of energetic materials is a potentially attractive route to development of new energetic materials because existing molecules can be used to create new materials that have tailored properties different from either coformer. A cocrystal is a combination of two crystalline monomolecular materials that yields a material with a unique crystal structure. While cocrystallization reduces the front-end investment ordinarily required for discovery of new energetic molecules, discovery of energetic cocrystals is not trivial. A number of energetic cocrystals have been reported that display attractive properties such as high density and improved thermal stability. However, the effect of cocrystal formation on larger scale properties, particuarly detonation properties, is not well-understood. Knowledge of these properties is important for understanding the potential improvements gained from pursuing discovery of cocrystals. \\\\</div><div>A challenge with obtaining detonation properties is that most techniques typically require anywhere from hundreds of grams to several kilograms of material. For example, rate stick experiments typically have an L/D (length to diameter) ratio between 12 and 20. Even for ideal explosives, diameters used are typically at least two centimers in diameter. Such experimental configurations are poorly suited for materials in the early stages of development. \\\\</div><div>In this work, comparative detonation velocity measurements were performed for select hexanitrohexaazaisowurtzitane (CL-20) cocrystals that have been reported in the past five years along with corresponding formulations or physical mixtures of the components. The detonation velocity measurements were performed using microwave interferometry, a well-established detonation velocity diagnostic. Using precision-machined hardware and appropriate matching of booster charge to sample charge, it was shown with statistical analysis that well-resolved measurements of detonation velocity could be obtained with shot-to-shot variation in the range of 130 m/s. The detonation velocity for cyclotetramethylene tetranitramine (HMX) was obtained using this experimental technique to validate the method and estimated variation. It was demonstrated that detonation tests with good repeatability could be performed for the nearly ideal explosives considered. \\\\</div><div>The experimental technique described above was performed first for a cocrystal of 1-methyl-3,5-dinitro-1,2,4-triazole (MDNT) and CL-20. Comparative measurements were performed for the cocrystal and physical mixture at a loading density of 1.4 $\gcc$. We chose a fixed loading density in order to isolate isolate effects other than loading density. The cocrystal was observed to detonate about 500 m/s faster than the physical mixture. In comparison, thermochemical equilibrium predictions showed that the cocrystal would detonate about 230 m/s faster than the physical mixture at this density. The enthalpy of formation for this cocrystal was double that of the physical mixture and this difference resulted in the predicted difference. Similar measurements were performed for the cocrystal of cyclotetramethylene tetranitramine (HMX) and CL-20 and CL-20/hydrogen peroxide (HP) solvate at the same loading density. The HMX/CL-20 cocrystal was observed to detonate about 300 m/s faster than the physical mixture. The CL-20/HP solvate was observed to detonate about 300 m/s faster than CL-20. \\\\</div><div>Using the Kamlet scaling laws, it was determined that the differences in detonation velocity observed are attributable to differences in enthalpy of formation. That is, the energy state is different between the configurations. The enthalpy of formation for MDNT/CL-20 was measurably larger than its physical mixture. The CL-20/HP solvate was also measurable larger than that of CL-20. This result has implications for intermolecular bond and configurational energies formed in cocrystals that affects their energy content.</div><div>Fully explaining the precise reason for this, and perhaps exploiting this in future cocrystals and multimolecular systems is a challenge for modelers, theoreticians, and synthesis chemists.</div>

Electromagnetic Ion Cyclotron (EMIC) waves are believed to play an important role in the dynamics of energetic particles (both electrons and ions) trapped by the Earths magnetic field causing them to precipitate into the ionosphere via resonant interaction. In order to incorporate the EMIC-related loss processes into global magnetospheric models one needs to know solar wind and magnetospheric conditions favourable for EMIC wave excitation as well as the localization of the waves in the magnetosphere. EMIC waves are generated by anisotropic (Tperp/Tpara > 1) ion distributions. Generally, any process that leads to the formation of such distributions may be responsible for EMIC wave initiation. This thesis discusses magnetospheric compression as a new principal source of EMIC wave generation in the inner dayside magnetosphere. First, using ground-based and satellite instrumentation, it is shown that EMIC waves are often generated in the inner dayside magnetosphere during periods of enhanced solar wind dynamic pressure and associated dayside magnetospheric compression. The compression-related EMIC wave activity usually lasts for several hours while the magnetosphere remains compressed. Also, it is demonstrated that EMIC waves are generated in radially narrow (1 Re wide) region of high plasma density, just inside the plasmapause. Test particle simulations of energetic ion dynamics performed for this study confirmed that anisotropic ion distributions are generated in the compressed dayside magnetosphere, the temperature anisotropy being dependant on the strength of magnetospheric compression. It is found that in the inner magnetosphere these anisotropic particle distributions are formed due to particle drift shell-splitting in an asymmetric magnetic field. Finally, the generation of EMIC waves was studied self-consistently using a hybrid particle-in-cell code in order to determine whether the degree of anisotropy estimated from the test particle simulations is sufficient to produce EMIC waves like those detected and to explain some of the observed wave properties.