Observation of laser-induced cellular organization of vortex filaments, spatial period doubling, and transition to chaos
| Autor: | S. Lugomer |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | Journal of Applied Physics. 83:510-517 |
| ISSN: | 1089-7550 0021-8979 |
| DOI: | 10.1063/1.366664 |
| Popis: | Laser-induced vaporization of tantalum on the nanosecond time scale, in the nonstationary regime generates the vortex filaments which show the organization of a cellular type with remarkable degree of two-dimensional order. The adjacent hexagonal cells (deformed into the rectangularlike ones) are linked by the helical pairing (double helix), thus giving rise to a chain-link-fence vortical structure. This type of vortical flow was shown to originate from the spanwise perturbation characterized by the perturbation phase Delta phi. The change of Delta phi causes the change of two-dimensional lattice period, thus causing the cellular period doubling and transition to chaos. This process is accompanied with a gradual decrease of the "linking number", [script L], from 0.65 to 0, in the direction from the near-field (cellular) to the far-field (chaotic) region. Various types of vortex filament dynamics found in the far-field region, were shown to result from the change of Delta phi, as well as from the interaction of filaments with the background shear. These experiments indicate the presence of very complex dynamics in the vaporizing surface layer in laser– matter interaction. © 1998 American Institute of Physics. |
| Databáze: | OpenAIRE |
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