High-speed optical studies of the driving plasma in laser acceleration of flyer plates

摘要

High-speed optical methods have been used to study several characteristics of the high-temperature driving plasma in laser acceleration of flyers with optical fiber coupling. Flyer materials examined include pure aluminum and composite targets containing an insulating layer of Al2O3. Results from fast-gating spectroscopy show that silicon appears early in the plasma spectrum, indicating that the coupling fiber material plays an active role in flyer acceleration. Plasma emission persists longer and pressure broadening of discrete lines decays more slowly in the launch of composite flyers. Fast-gating spectroscopy has also been used in conjunction with very thin ((open quotes)trace(close quotes)) metal layers deposited in the target fabrication process to examine the depth of ablation by the driving plasma.