Filamentation is a complex process that gives rise to many nonlinear interactions. However, the fundamentals of filament formation and propagation can be explained in terms of two dominant mechanisms: Kerr self-focusing and plasma defocusing. The first to occur, self-focusing, is responsible for an increase in irradiance through beam collapse. This process requires sufficient initial peak power, on the order of gigawatts for near infrared beams in air. Plasma defocusing then arrests the collapse process once the irradiance reaches the ionization threshold of the medium. These two processes balance each other in an extended plasma channel known as a filament. A beam's collapse behavior is strongly influenced by the initial beam conditions, especially in applications that require power scaling to terawatt levels where the Kerr effect is more pronounced. Therefore, understanding and controlling the collapse process is essential in this regime. For this reason, an exploration of the wavefront evolution of filamenting beams is of great interest and the topic of this thesis, which has three parts. First, it reviews the filamentation process and describes characteristics of filaments. Next, experimental measurements of the wavefronts of filamenting beams are given in two separate regimes. The first regime is the Kerr self-focusing that takes place before beam collapse is arrested. This data is then contrasted with wavefront measurements within a filament after collapse has occurred.
| Identifer | oai:union.ndltd.org:ucf.edu/oai:stars.library.ucf.edu:etd-6639 |
| Date | 01 January 2017 |
| Creators | Thul, Daniel |
| Publisher | University of Central Florida |
| Source Sets | University of Central Florida |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Electronic Theses and Dissertations |
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