Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M.S.) University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 10, 2006) Includes bibliographical references.

The multi-order response of the tuned secondary circuit of a Tesla transformer, following impulse excitation from its tuned primary circuit, is presented and analysed at the fundamental resonant frequency and at higher-order mode frequencies. A novel way of modifying the frequency response of the secondary coil is then investigated by utilising a technique normally applied to the design of a certain type of filter known as a helical filter. In general, these are used in radio and microwave frequency circuits in order to pass certain frequencies with little attenuation whilst significantly attenuating other frequencies. Design techniques, developed over several decades, modify and optimise the performance of such filters. The frequency response of the helical filter is modified by altering the geometry of the helical resonator component therein, which is typically in the form of an air-cored single-layer solenoid. A Tesla transformer whose secondary is constructed to be some form of single-layer solenoidal winding resonates at its designed frequency - its fundamental mode - but also at non-integer harmonics (higher-order anharmonic frequencies, also known as overtones). Those multi-order oscillatory voltages and currents energised in the secondary circuit have been identified and measured and research has determined the fundamental and higher-order mode frequencies and amplitudes for various experimental secondary winding configurations derived from helical filter design techniques. Applied to the Tesla transformer secondary winding, such techniques lead to a new design with a performance that is improved by the suppression of higher- order anharmonic frequencies whilst imparting little change to the fundamental response. It is anticipated that this feature will lead to Tesla transformers which exhibit enhanced spectral purity and which will be better suited to use in certain pulsed power applications than conventionally wound designs.

The plasma opening switch (POS) is used in pulsed power systems where a very fast opening and high current switch is required. Plasma is injected into the switch, which carries a large conduction current, before it opens in a process that lasts for a few nanosecond and transfers the current to a parallel-connected load at a much increased voltage and with a much shorter rise time. The conduction and opening times of the switch are dependent on plasma parameters such as the distribution, speed and species, all of which are determined by the plasma source. Most of the earlier reported work involves large dimension POSs and a correspondingly high input current (more than 100 kA) and uses carbon plasma. One main objective of the present research was to achieve a low input current (20 kA) and miniaturised POS by using hydrogen plasma rather than carbon plasma on account of its lower mass. A cable gun was selected for producing the plasma, since although this produces both hydrogen and carbon plasma these arise different times during its operation. For the present application a Tesla transformer was used in preference to a Marx generator to produce an initial high voltage pulse for the system, on the basis of its simpler design and cost effectiveness. This transformer together with an associated water PFL (pulse forming line) and pressurised switch was capable of producing a load current in excess of 20 kA with a rise time of 53 ns, which was fed through the POS to the final load. Special diagnostics arrangements were necessary to measure the fast high current and voltage pulse a in nonintrusive way. Faraday cups and a high speed camera were used to measure the plasma parameters. The overall system built (i.e. including the POS) is capable of producing a 22 kA current with a rise time of 5 ns, and of generating a power of more than 10 GW. Much of the work detailed in the thesis has already been presented in peer reviewed journals and at prestigious international conferences.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2003. / Thesis advisor(s): Robert W. Ashton, William B. Maier II. Includes bibliographical references (p. 83-84). Also available online.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: PPT; pulsed plasma thruster; Langmuir probe; plasma diagnostics; electric propulsion; electron temperature; electron density. Includes bibliographical references (p. 97-102).

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 5, 2009). Thesis advisor: Dr. Scott Kovaleski. Includes bibliographical references.

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: electric propulsion; applied magnetic fields; pulsed plasma thruster. Includes bibliographical references (p. 91-94).

A Tesla-Blumlein PFL-Bipolar pulsed power generator, has been successfully designed, manufactured and demonstrated. The compact Tesla transformer that it employs has successfully charged capacitive loads to peak voltages up to 0.6 MV with an overall energy efficiency in excess of 90%. The Tesla driven Blumlein PFL generator is capable of producing a voltage impulse approaching 0.6 MV with a rise time close to 2 ns, generating a peak electrical power of up to 10 GW for 5 ns when connected to a 30 Ω resistive load. Potentially for medical application, a bipolar former has been designed and successfully implemented as an extension to the system and to enable the generation of a sinusoid-like voltage impulse with a peak-to-peak value reaching 650 kV and having a frequency bandwidth beyond 1 GHz. This thesis describes the application of various numerical techniques used to design a successful generator, such as filamentary modelling, electrostatic and transient (PSpice) circuit analysis, and Computer Simulation Technology (CST) simulation. All the major parameters of both the Tesla transformer, the Blumlein pulse forming line and the bipolar former were determined, enabling accurate modelling of the overall unit to be performed. The wide bandwidth and ultrafast embedded sensors used to monitor the dynamic characteristics of the overall system are also presented. Experimental results obtained during this major experimental programme are compared with theoretical predictions and the way ahead towards connecting to an antenna for medical application is considered.

Nanofibres are useful in a broad range of applications in areas such as medical science, food science, materials engineering, environmental engineering, and energy and electronics due to their outstanding characteristics: their small size, high surface-to-volume ratio, high porosity, and superior mechanical performance. Recently, controlled drug delivery systems have gained significant attention, especially with respect to the use of polymer nanofibres. For these systems, the ability to control of the length of the polymer nanofibre is important because the amount of drug released depends on the length of the fibre. Electrospinning is the simplest and most cost-effective method of fabricating polymer nanofibres. In the process, a high voltage is used to create an electrified jet which will eventually become a nanofibre. The electrified jet ejects when a high voltage is applied to the electrospinning setup. On the other hand, the jet does not eject when the applied voltage is below the threshold voltage. It is therefore possible to fabricate and chop nanofibres by controlling the values of the voltages applied and a special high-voltage pulsed power supply has been developed for this purpose. In this research, an IGBT-based pulsed power supply has been designed and built to be used for non-continuous-mode electrospinning. The IGBTs are connected in series to deliver high voltage pulse voltages to an electrospinning setup. The IGBT-based pulsed power supply is capable of producing controllable square pulses with a width of a few hundred microseconds to DC and amplitudes up to 10 kV. The technique of non-continuous-mode electrospinning was tested using the pulsed power supply designed in this work. The new system was able to fabricate and chop nanofibres with PEO and alginate/PEO solutions. It was concluded that the minimum pulse width that can initiate an electrified jet is approximately 80 ms for the parameters used in this study. A longer period produces a more constant jet during the pulse-on voltage when the duty ratio is the same value. It is also highly likely that a jet is always ejected during the pulse-on voltage when the duty ratio is more than 40 %.