Developments in Capsule Gas Fill Half-Life Determination

ICF experiments routinely make use of capsules filled with precise quantities of gaseous hydrogen and helium isotopes. These two gases in particular readily permeate out of capsules at rates dependent upon variables including shell wall thickness, composition and integrity. Therefore it is important that the fill half-life of these capsules be precisely known so that the exact fill pressure at shot time can be deduced, enabling valid experimental results.

This presentation will describe some of our efforts to determine ICF capsule gas fill half-lives. We will compare fill half-life data obtained using weighing, interferometry and mass spectrometry techniques. In addition, we will describe our use of glass shell standards to compare the aforementioned techniques.