Effect of lateral energy transport on ablation pressure scaling in laser irradiated planar foil targets
Experimental investigations on ablatively accelerated thin plastic foil targets irradiated by a 6J, 5 nsec Nd: glass laser pulse, were conducted using shadowgraphy technique. A 2 nsec, 0.53 µm probe pulse, derived from the main laser was used for recording the foil motion. It was observed that 6 µm plastic foils could be accelerated to a velocity of about 3 × 106 cm/sec for an incident laser intensity of 5 × 1013 W/cm2 and the corresponding ablation pressure was 0.4 Mbar. Ablation pressure (P) scaling against absorbed laser intensity (I a ) was slower (P ∝I a 0.4 ) for a smaller laser focal spot (30 µm) as compared to the scaling (P ∝I a 0.7 ) for a larger focal spot (500 µm). This result has been explained considering the loss due to lateral energy transport from the laser plasma interaction region.
KeywordsPlasma laser fusion ablative compression shadowgraphy lateral transport
PACS No52.25 52.50 52.70
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