Coaxial plasma accelerators have been the subject of experimental and theoretical analysis since the 1950s. Theories have evolved that predict subsets of the measured data. This work separates coaxial plasma accelerator research into two broad categories classified by the ratio of accelerator discharge current to input gas flow rate. Devices that operate with this ratio above a particular threshold are called "starved" and the acceleration process is termed "“deflagration". Devices that operate below the threshold are called “over-fed" and the plasma undergoes a compressive energy conversion process termed "detonation". Over-fed (detonation) plasma accelerators add energy to the plasma through plasma heating and compression. The plasma exhaust velocity is limited to the magneto-sonic velocity which is nearly identical to the plasma Alfven velocity. Measured energy conversion efficiencies for detonation plasma accelerators have been typically less than 10%. Starved (deflagration) plasma accelerators add energy to the plasma by increasing the plasma kinetic energy. Thus, the plasma exhaust velocities measured in the deflagration accelerator exceed the plasma Alfven velocity by two orders of magnitude. Measured energy conversion efficiencies for the deflagration mode exceed 40%. Two additional sub-categories have been defined. The first is based on the number of acceleration stages. A single stage device processes neutral gas into the accelerated plasma. Multi-stage devices first ionize the neutral gas and then accelerate it to the final velocity. Finally, plasma accelerators with coaxial electrodes are classified by the interval in which the electrical energy is transformed into plasma energy. A new theory was developed to explain the deflagration plasma accelerator operation by examining the failures of previous magneto-hydro-dynamic based theories. The new theoretical treatment was used to develop a computer simulation of the deflagration plasma accelerator process. The theory and model were tested against experimental data for single and dual stage deflagration accelerator devices. With successful correlation achieved between the theory, computer model and experimental measurements, changes were made to the original accelerator, guided by modeling results. The new deflagration plasma accelerator was tested and the results closely matched the predictions for all key accelerator performance parameters. / Ph. D.

Digitized by Kansas Correctional Industries

La thèse porte sur le développement d'une décharge à barrière diélectrique de surface pour la dépollution de l'air. Il s'agit d'une thématique tout à fait d'actualité. En effet l'application des réglementations sur la qualité de l'air nécessite de nouvelles technologies. Parmi elles, la dépollution par plasma froid est un candidat on ne peut plus prometteur. Dans un tel contexte, il est nécessaire de savoir approcher le problème sous différents aspects: Le premier est bien sûr de comprendre la physique fondamentale de ce type de plasma. Cela requiert une démarche expérimentale adaptée aux échelles du phénomène. Ces décharges sont constituées de filaments de petites dimensions (quelques centaines de micromètres de diamètre, quelques centimètres de long) se propageant extrêmement vite, avec une durée de vie très courte (quelques dizaines de nanosecondes). Ces caractéristiques en font des objets difficiles à étudier. Les résultats ont montré des phénomènes d'autodéclenchement des filaments de plasma. Ce comportement tout à fait original est expliqué par l'effet mémoire de la surface diélectrique, qui peut retenir les charges sur des temps très longs (plusieurs minutes). Ces charges peuvent alors être photodésorbées et déclencher le départ de plusieurs streamers en un temps très court (40 ns). L'organisation et la propagation des filaments ont été étudiées par imagerie iCCD avec une résolution temporelle raffinée à la nanoseconde. Le deuxième aspect est d'identifier les qualités du système qui peuvent être exploitées du point de vue procédé: efficacité chimique, coût énergétique, géométrie du dispositif. L'identification de ces points a permis de déposer un brevet sur le système. Par la suite, un travail d'étude de marché a été réalisé grâce à l'encadrement d'étudiants de l'ISTIA (Institut des Sciences et Techniques de l'Ingénieur d'Angers) pour leur stage de M2.

The effects of an 11-week jogging program on the plasma lipid fractions and clotting time of 19 late adolescent males (18 to 19 years) were investigated. Total lipids, triglycerides, total and free cholesterol, phospholipids, non-esterified fatty acids, and clotting time of plasma were determined. Statistical analysis was applied to the change in each parameter. Dietary patterns prior to and following the fitness program were examined. The mean concentrations of total lipids, total and free cholesterol, and phospholipids were lower than those reported for young men; plasma clotting times were longer. The mean plasma triglycerides and non-esterified fatty acids were comparable to those observed in adults. Individual values of the plasma lipid fractions were within the ranges reported in the literature. Consistent relationships could not be found between dietary intake, changes in weight, or any of the lipid parameters. Significant changes in triglycerides, total and free cholesterol, and non-esterified fatty acids were not apparent as a result of exercise. There was a significant decrease in phospholipids; total lipids and clotting time increased significantly following the fitness program. / Graduation date: 1970

Electrical arcs are usually created with the breakdown of air, requiring an average electric field (AEF) of at least 100 kV/m in long spark gaps. This thesis explores a novel method of creating long electrical arcs using exploding wires (EWs). Arcs up to 60 m long have been produced with AEFs of just 4.5 kV/m. Extensive observations of the EW process are presented, which demonstrate that the arcs, which are a type of ‘restrike', form via the seldom-reported ‘plasma bead' restrike mechanism. Beads of plasma appear to form at sites of wire fragmentation, and can expand and coalesce into a continuous plasma column. There are strict conditions under which the plasma beads, and hence restrike channels, are produced. A restrike prediction model has been developed to provide a reliable method of producing restrike. The model was derived from the improved understanding of the restrike mechanism, and uses the wire's length and the energy supply voltage and characteristics as inputs. Capability diagrams are then constructed, which allow researchers to easily design experiments that will produce restrike. Extensive descriptions are provided of the experimental environments that were designed and constructed to facilitate long distance EW experiments. Experiments have been performed inside a high voltage laboratory, in the laboratory's outdoor compound, off the laboratory's earth grid and completely off-site. The off-site location allowed vertical experiments, suspended by a weather balloon, to be performed. This led to a theory on artificially triggered lightning, which is one of many exciting future applications that are suggested. It is also predicted that other research groups will be able to create arcs of several hundred metres long.

No description available.

No description available.

No description available.

Schizophrenia is a mental disorder affecting approximately one percent of the population worldwide. The introduction of the second generation antipsychotic drug, atypical antipsychotic, clozapine, has demonstrated 80% reduction in suicide incident. This drug showed effectiveness in the treatment of resistant schizophrenia, however, high concentrations of clozapine and N-desmethylclozapine in plasma exhibit the development of agranulocytosis, a possible lethal blood disorder. Therefore, constant therapeutic drug monitoring is important for patients who receive clozapine. High performance liquid chromatography (HPLC) is the current assay for clinical clozapine measurement. A different assay, the capillary electrophoresis (CE) was explored in this study. It was found the use of a background electrolyte (BGE) concentration of 60 mM, pH at 2.5, temperature at 22 ℃, voltage applied at 10 kV and sample injection at 23 kV for 1.5 seconds is the optimal condition for clozapine separation using a fused-silica capillary 75 μm in internal diameter (i.d.). The use of 75 μm (i.d.) fused-silica capillary not only permits a larger sample size, but also provided longer detection pathlength which increased the limit of detection for CE. One hundred and eight patients’ samples were analysed by CE and compared with HPLC results obtained from the Canterbury Health Laboratory. A linear regression line of 1.100 was obtained. Seven External Quality Control (EQC) samples were also analysed and compared to the HPLC results gained from the EQC program world wide. A linear regression line of 1.008 and 1.043 were obtained from clozapine and N-desmethylclozapine separation respectively. The developed CE method has shown to be a valid assay for clozapine and N-desmethylclozapine separation and a more cost effective method compared to HPLC.

This is a study of the plasma diffusion processes relevant to the physical nature of the Io plasma torus at Jupiter. A knowledge of the diffusion processes involved in the Io plasma torus is essential to an understanding of the spatial structure and energetics of the torus. The only published theory of Io torus plasma diffusion, centrifugally driven flux tube interchange instability, is based on turbulent plasma interchange instability. We have examined physical properties that lead us to conclude that flux tube interchange diffusion is not a valid mechanism in the plasma torus. The collisional nature of the hot torus plasma is seen through its observed EUV emissions which dominate the energy loss from the system. Further, the torus plasma parameters fall in the range of values satisfying the criteria for the use of collisional transport theory to derive a collisional diffusion coefficient. The collisional nature of the torus plasma is characterized in the long mean free path regime where classical transport theory breaks down. We study the Chapman-Enskog method of calculating the plasma diffusion coefficient from a solution of the Boltzmann equation. Simplifying approximations of a fully ionized plasma dominated by Coulomb elastic charged particle collisions are made to derive an ad hoc non-classical diffusion coefficient which results in slow differential diffusion rates for the various sulfur and oxygen ions in the plasma torus. The radial spatial structure and energetics of the plasma torus is modeled by employing the collisional diffusion coefficient in a computer model calculation of collisional ionization-diffusive equilibrium and energy branching. The computer model employs the known significant plasma reactions involving the torus sulfur and oxygen species, utilizing the most recently available atomic parameters. In view of the failure of Neutral Cloud Theory to adequately power the copious amounts of UV radiation emitted by the Io plasma torus, we employed the radial plasma model to investigate this "energy crisis." Toward this end, we investigate the application to our plasma model of a proposed heterogeneous source of energetic electrons and a proposal of inward diffusing energetic outer-magnetospheric OII and SII ions as ad hoc heat inputs to the plasma torus electrons, in order to maintain a steady state energy balance.