Calculations of a Fill Hole/Tube in an Ignition Capsule

Filling an ignition capsule through a drilled hole in the ablator is the current approach to fielding an ignition capsule. But it adds an initial defect to the capsule which might grow large enough to affect or even prevent ignition. We present here calculations of the effects of fill tubes and holes for the 1.4 MJ 300 eV BeCu NIF capsule. The code used is the 3D AMR code written by Los Alamos and SAIC, "RAGE". Several fill tube/hole sizes were tried. Most calculations were made in a planar 2D geometry, providing reliable information on the first part of the implosion before convergence effects become important. A 5 (mu)m diameter hole generates a 25 by 30 m jet when the main shock breaks out into the DT gas. The mass involved in the jet is insignificant, less than 1/1000 of the hot spot mass. There is no large difference between the jets formed by a plug and a fill tube, before they break out into DT gas. High resolution spherical calculations are still in progress to understand the end of the implosion. Experiments are planned as a support to this study.