Thermodynamics of microplasma initiation in liquids

Summary form only given. It has been shown that microplasmas, ranging from 3-20 μm in diameter, can be generated in electrolyte and dielectric liquids. The application of short duration pulses, ranging in energy from milijoules to joules, to submerged electrodes releases energy in the form of shockwaves, light emission and chemistry. The energy dissipation occurs in a highly localized and non-uniform manner and the state of the fluid can vary rapidly both spatially and temporally around the electrode. Concerns about bubble formation during discharge initiation may be a moot issue as in theory the localized state may even pass through super critical states during this breakdown process. To understand such plasma initiation within a liquid the thermodynamic state and process should be understood. The nature of this breakdown process can be compared to underwater explosions and this is used as a point reference throughout this analysis. Voltage-current characteristics, Schlieren and Shadowgraphs techniques are employed to trace state transitions and to obtain a better understanding of the process. Optical emission spectroscopy is also used to identify species. Production of plasma in liquid can provide both nonthermal and thermal mechanisms for chemically modifying water, oil and other liquids. It is hypothesized that the thermodynamic state and plasma state can be controlled by modifying rise time and duration of the pulses. Determining such methods of controlling the state can lead to better control over the chemistry taking place.