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Full-Text Articles in Engineering
Modeling And Simulations Of Electrical Breakdown And Thermal Failure In Zinc Oxide And Titanium Dioxide For High-Voltage Dielectric Applications, Guogang Zhao
Electrical & Computer Engineering Theses & Dissertations
The development of transmission lines with higher energy storage capabilities is an important goal for compact pulsed power systems. In this context, ceramic dielectrics are promising candidates from the standpoint of high dielectric constants and breakdown strength. Though such materials look promising, their breakdown response characteristics have not been well studied, nor adequately understood. The electrical response of dielectrics also seems to depend on the internal structure and its granularity. For example, the breakdown strength of nano-crystalline insulators such as titania and zinc oxide have been observed to depend on the internal grain size. In general, the hold-off voltage increases …
Modeling And Simulation Of \Sub-Microsecond Electrical Breakdown In Liquids With Application To Water, Jun Qian
Electrical & Computer Engineering Theses & Dissertations
In this dissertation, the inherent physics and sub-microsecond electrical breakdown of water stressed to high voltages is analyzed, and several relevant models are constructed for quantitative analysis. A bubble-based, drift-diffusion (DD) model proposed here includes almost all the important physical process of the system, and successfully explains many important features routinely observed in sub-microsecond water electrical breakdown. Here many physical properties and response characteristics typical for high-field stressing of liquid water have been analyzed through numerical calculations. The internal temperature profile in the water system has been calculated by Finite Difference Time Domain (FDTD) method to probe possible heating and …
Electrical Breakdown In Polar Liquids, Shu Xiao
Electrical Breakdown In Polar Liquids, Shu Xiao
Electrical & Computer Engineering Theses & Dissertations
Hydrodynamic processes following the electrical breakdown in polar liquids, mainly water and propylene carbonate, are studied with electrical pulse-probe systems and optical diagnostics including shadowgraphy and Schlieren techniques. The dielectric strength of water in a repetitively pulsed power system is found to be 750 kV/cm and 650 kV/cm for pulses of 200 nanosecond and 8 microsecond duration, respectively. For energies less than 1 J, the discharge plasma decays in approximately one microsecond. The mechanical effect created by the expanding plasma is a shock wave which has an initial pressure of 1 GPa and decays within approximately 5 microseconds. The observed …