Development of a neutron imaging diagnostic for inertial confinement fusion experiments

Pinhole imaging of the neutron production in laser-driven inertial confinem ent fusion experiments can provide important information about the performa nce of various capsule designs. This requires the development of systems ca pable of spatial resolutions on the order of 5 mum or less for source stren gths of 10(15) and greater. We have initiated a program which will lead to the achievement of such a system to be employed at the National Ignition Fa cility (NIF) facility. Calculated neutron output distributions for various capsule designs will be presented to illustrate the information which can b e gained from neutron imaging and to demonstrate the requirements for a use ful system. We will describe the lines-of-sight available at NIF for neutro n imaging and explain how these can be utilized to reach the required param eters for neutron imaging. We will describe initial development work to be carried out at the Omega facility and the path which will lead to systems t o be implemented at NIF. Beginning this year, preliminary experiments will be aimed at achieving resolutions of 30-60 mum for direct-drive capsules wi th neutron outputs of about 10(14). The main thrust of these experiments wi ll be to understand issues related to the fabrication and alignment of smal l diameter pinhole systems as well as the problems associated with signal-t o-background ratios at the image plane. Subsequent experiments at Omega wil l be described. These efforts will be aimed at achieving resolutions of abo ut 10 mum. Proposed developments for new imaging systems as well as further refinement of pinhole techniques will be presented. (C) 2001 American Inst itute of Physics.