Influence of Specularly Reflected Light on Implosion Uniformity in Indirect-Drive Laser Fusion.
Abstract
At early stage of pellet heating, the collisional path length may be short and some of specularly reflected light, so called glint light, from the inner wall of the x-ray confining cavity shines on the capsule surface and imposes initial imprint on it. Effect of the glint light has been investigated. X-ray frame images of a gold coated solid sphere was obtained with Gekko XII. The cavity was either a decagonal cylinder or a circular one. Smooth emission images were obtained for the decagonal cavity whereas those for the circular cylinder were strongly nonuniform corresponding to respective laser spot. Ablation pressure distribution on a planer sample positioned equivalently to the fuel capsule was measured by shock wave velocities. Similar result was obtained, showing that, at the highest pressure portion, about a half of the drive pressure was due to the glint light. The experimental results fit with predictions with a simple 3-dimensional illumination code. It is predicted with this code that the glint effect is hard to be eliminated from the current irradiation geometry.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 1996
- Bibcode:
- 1996APS..DPP..2P05N