Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp

The original publication is available at http://www.sajs.co.za/A dielectric barrier discharge excited neutral argon (Ar I) excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV) emission at 126 nm and near infrared (NIR) lines at 750.4 nm and 811.5 nm have been investigated. These three lines were chosen as they represent emissions resulting from deexcitation of excimer states that emit energetic photons with an energy of 9.8 eV. We observed that the intensity of the VUV Ar2* excimer emission at 126 nm increased with increasing gas pressure, but decreased with increasing excitation pulse frequency and pulse width. In contrast, the intensities of the NIR lines decreased with increasing gas pressure and increased with increasing pulse frequency and pulse width. We have demonstrated that energetic VUV photons of 9.8 eV can be efficiently generated in a dielectric barrier discharge in Ar

Geospatial Analysis of the Aquiferous Potential Zones in the Crystalline Basement of Bulawayo Metropolitan Area, Zimbabwe

64th International Astronautical Congress, Beijing, China.,Efforts have been made to review the literatures on groundwater exploitation and the constraints to effective and sustainable management of groundwater in Bulawayo Metropolitan, Zimbabwe. However, the attempts are hindered by the underlain crystalline basement aquifers which are complex in nature and highly heterogeneous in yield. Therefore this study seeks to demarcate the potential aquiferous zones in Bulawayo Metropolitan for groundwater development using satellite data and geological inference. Remote Sensing and Geographical Information Systems (GIS) are useful in the recognition and delineation of aquiferous zones for potential groundwater in crystalline basement aquifers. LANDSAT ETM+ image, SRTM data, aeromagnetic data and other ancillary data sets were utilized to extract information on the groundwater storing controlling features of this study area. GIS modeling using the index overlay method was used to produce the groundwater potential map. The study revealed that the regional lineaments correlate with faults, fracture zones, and lithological contrasts along fold belts in the crystalline basement rocks, while the main direction of faulting and jointing is north-north-west to north, with several faults oriented to the north-north-east parallel to the Zimbabwe Great Dyke. The areas close to lineaments are the highest zone of increased porosity and permeability, which in turn have a greater chance of accumulating groundwater. The results have shown massive spatial variability of ground water potential ranging from very good to poor. The variability closely followed variations in the structures, geology, topography/slope, drainage density and land use/land cover in the project area. This exploratory work needs to be validated by the use of high-resolution terrain data and satellite imagery, along with quantitative analysis, which should be done using geophysical and hydrogeological surveys

Fault-plane solutions of the Deka Fault zone and mid-zambezi Valley

An analysis of twenty-one fault-plane solutions from the Deka Fault zone and the mid-Zambezi Valley shows normal (dip-slip) faulting with a strike-slip component. The fault planes strike in a south-westerly direction in conformity with the north-easterly geologically observed striking lineaments. The T axes of the fauIt planes obtained are nearly horizontal with their domains in the north-west and south-east quadrants of the focal sphere. One composite focal mechanism solution for the seismically active area just to the west-north-west of the Kariba dam is constructed. The overall results are correlated with the known tectonics of the area. The stress regime obtained in this study is predominantly influenced by a north-west-south-east tensional stress field that is orthogonal to the orographic strike direction of the main geological structures

Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp

The original publication is available at http://www.sajs.co.za/A dielectric barrier discharge excited neutral argon (Ar I) excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV) emission at 126 nm and near infrared (NIR) lines at 750.4 nm and 811.5 nm have been investigated. These three lines were chosen as they represent emissions resulting from deexcitation of excimer states that emit energetic photons with an energy of 9.8 eV. We observed that the intensity of the VUV Ar2* excimer emission at 126 nm increased with increasing gas pressure, but decreased with increasing excitation pulse frequency and pulse width. In contrast, the intensities of the NIR lines decreased with increasing gas pressure and increased with increasing pulse frequency and pulse width. We have demonstrated that energetic VUV photons of 9.8 eV can be efficiently generated in a dielectric barrier discharge in Ar