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Extensions and simulations of numerical model for picosecond laser-material interaction in bulk sapphire

Huizingh, M. (2021) Extensions and simulations of numerical model for picosecond laser-material interaction in bulk sapphire.

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Abstract:An existing numerical model for picosecond laser-material interaction in bulk sapphire consisting of four partial differential equations is summarized, providing a description of physical behavior in relation to the mathematical description. The limitations of the model are presented, selecting three features to be improved. Firstly, the current collimated beam is modified to a focused beam, Gaussian in space and time. Secondly, boundary conditions are implemented representing interaction with the bulk material. Thirdly, convergence issues are reduced by implementing improvements in the model, mesh and solver configurations. Several simulations are presented to analyze the effects of input parameters and interaction between phenomena of the improved model. Classified in three groups: low pulse energy, heating the material, high pulse energy, generating plasma causing a complex interaction of phenomena, and higher pulse energy, showing stronger behavior and time extended study results. An addition to the model is the implementation of thermal stress. The temperature output from the simulations are used to determine material expansion and resulting stress in separate studies to predict crack formation observed during experiments. The improvements and extension of the model was successful in describing subsurface laser-sapphire interaction and stress concentrations. An improved understanding of model behaviour and the significance of each variable and phenomena was identified. Furthermore, recommendations are given to improve model accuracy. The inclusion of electromagnetic or wave optics, plasma physics for high pulse energy modelling and the implementation of accurate material parameters are the next steps leading to a comprehensive model for lasersapphire interaction.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:33 physics, 52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
Link to this item:https://purl.utwente.nl/essays/85768
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