The Properties of Polyimide Targets

LLE Review, Volume 92 167 In 1996 LLE began a research effort to make spherical capsules from polyimide material for use in direct-drive inertial confinement fusion (ICF) experiments. Previously, ICF capsules were made exclusively from glass, polystyrene, or an amorphous carbon–hydrogen solid solution referred to as “plasma polymer” or “glow-discharge polymer.”1 Polyimide was first proposed as a potential material for a target wall in 1995 because of its appreciable strength;2 however, no viable method for making these capsules was identified. Following a fiveyear development project, a process for making polyimide capsules was developed and demonstrated, and the technology transferred to General Atomics—the ICF target fabricator— for production. As part of the project, polyimide shells with various properties relevant to ICF were developed. Those properties will be presented and compared in this article.