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Title: Plasmas in liquids and their use for biomedical application
Author: Schaper, Lucas Fiete
ISNI:       0000 0004 2722 7731
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2011
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Plasma formation in liquids has due to the tremendous application potential been a fast developing topic in the past two decades. Here a study on sub-kV plasma formation in conducting liquids is presented. In this environment the temporal evolution from initiation of power input into the liquid can be separated into different phases. First of all, an Ohmic heating phase leads to vapour formation in the electrode proximity. This will be investigated experimentally as well as with a computer model. The present experimental studies demonstrate not only the complexity of this multi parameter system but also reveal the influence of specific parameters, such as conductivity and applied voltage. Those results have lead to incorporation and refinement of the model. Consecutively the advanced model enabled further understanding of the system and effects involved effects, e.g. superheating of the liquid before evaporation. When formed the vapour regime leads to isolation of the electrode from the liquid. Since electrode surface properties play an important role on discharge formation study of these lead to detection and information on salt as a surface contaminant after evaporation. For plasma formation those small salt crystals play a crucial role in discharge formation processes. After generation of a low density vapour environment formation of a plasma is observed within it. Regimes with stochastic discharge appearance as well as continuous discharges have been observed and ultimately lead to characterisation of the discharge type as well as determination of the electron density. Pronounced differences for positive and negative polarity are also highlighted. The rich chemistry with its reactive species in the liquid phase is then used for investigation of cancer cell treatment efficiency and compared with conventional x-ray treatment and there are indications of higher efficiency, in particular relating to range effects.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available