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Title: A study of laser-produced plasma beams
Author: McKenna, Colm Francis
Awarding Body: Queen's University of Belfast
Current Institution: Queen's University Belfast
Date of Award: 2008
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Pulsed Laser Deposition is a flexible and powerful tool for producing thin films of many materials. Optical Absorption Spectroscopy and Laser Induced Fluorescence can be used to characterise plasma plumes and jets derived from plumes to allow us to move from an empirical approach to P.ulsed Laser Deposition to a more quantitative approach. In this thesis, several aspects of such quantitative measurements are applied to titanium based plasma plumes produced using a KrF (248nm, 30ns) excimer laser system and probed using a tuneable dye laser. Using optical absorption spectroscopy we estimated the spatially resolved number density of atomic titanium in plasma plumes, produced with an average KrF laser fluence of 2.5 J/cm2 , to vary from 5 'x 1012 to 2 x 1013 cm-3 • Simultaneous laser induced fluorescence yielded an estimate of the atomic temperature of 1.7 ± 0.3 eV. The bandwidth of the pumping laser was reduced by up to 30% with an intracavity etalon in the pump laser and the LIF images produced for this and the standard case were used to calculate Ti I species temperature. The introduction of a pinhole on the main expansion axis of a plume restricts the lateral expansion and produces a 'plasma jet', generating of a more homogeneous ion source. Estimates of the temporal and spatial evolution of the relative proportion of ionic material in plasma jets were also made. A fundamental problem with the PLD process is the production of micron sized particulates during the laser ablation process. The interaction of two plasma plumes has been shown to remove particulates from the thin film. The LIF technique is used to characterise colliding plumes which are pumped by a tuneable dye laser.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available