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Title: Optimisation of the output characteristics of a pulsed carbondioxide laser for processing of materials
Author: Khahra, Jagdeep Singh
ISNI:       0000 0001 3597 9739
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 1976
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The work presented is part of a programme for the development of a high mean power pulsed carbon dioxide-nitrogen laser for machining and welding applications in materials used in engineering construction. The system seeks to overcome the power intensity limitations inherent in continuous wave operation which restricts performance, particularly in the case of metals. Herein, the discharge characteristics and the form of the output pulse are studied with the purpose of maximising the efficiency of the laser and optimising the energy coupled with the workpiece. The work is divided into four distinct sections: in the first, a short review is given of the elementary processes occurring in the laser which depend upon the structure of the carbon dioxide and nitrogen molecules present. Mechanisms of excitation are identified and the influence of the electron energy distribution on efficiency is considered using an analytical model. In the second section a suitable geometry for the electrodes is suggested and the optimisation of various physical parameters in order to obtain a uniform, stable glow discharge is considered. Experimental work on gas discharges is reported which relates the ratio of discharge voltage to pressure (which directly affects the vibrational excitation of gases) to the operating current, voltage, gas composition, etc. In the third section a theoretical model is developed relating the characteristics of the input and output for various gas mixture compositions. This theoretical model is based on the four level laser system first developed by Moore, et al ( Ref. [1] ,Chapter III) and subsequently used by various investigators. The fourth section describes the experimental work carried out to relate the input/output characteristics of the laser system, and to make possible a comparison between the experimental and theoretical results. The results are discussed and conclusions regarding the input/output characteristics are made in this section.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available