• P A Naik

      Articles written in Pramana – Journal of Physics

    • Effect of lateral energy transport on ablation pressure scaling in laser irradiated planar foil targets

      L J Dhareshwar P A Naik S Sharma H C Pant

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      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 (Ia) was slower (PIa0.4) for a smaller laser focal spot (30 µm) as compared to the scaling (PIa0.7) 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.

    • Enhancement of ablation smoothing in laser-irradiated, highZ coated, thin foil targets

      L J Dhareshwar P A Naik H C Pant

      More Details Abstract Fulltext PDF

      An enhanced spatial smoothing of ablative motion of thin plastic foil targets coated with high atomic number ablators such as gold or aluminium, irradiated by a spatially modulated Nd: glass laser beam was observed. Optical shadowgraphy coupled with double foil technique was used to observe the laser-irradiated foil motion. Laser irradiance used for the experiments was in the range of 1011–1013 watts/cm2. A 60–80% enhancement in the smoothing was observed for a laser beam modulation (width 75–150 µm) at the target surface.

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