Study of x-ray emissions from cold deuterium--tritium fuel inside glass targets for inertial confinement fusion

We have remotely monitored the thermodynamic phase of deuterium--tritium (DT) fuel inside glass shells used for inertial confinement fusion (ICF) research by observing the x-ray emissions from the shell. These studies are an adjunct to our beta heating experimental program. [M. T. Mruzek, D. L. Musinski, and J. S. Ankey, J. Appl. Phys. 63, 2217 (1988)]. By monitoring the production of low-energy x rays (< 18.6 keV) from the interaction of the beta decay with the shell walls, we are able to track phase changes between gas and solid. We incorporated the mature x-ray detection technology of scintillators and photomultiplier tubes onto the experimental apparatus we use to study the beta heating effect. [M. T. Mruzek, J. S. Ankey, and D. N. Decker, J. Vac. Sci. Technol. A 6, 1889 (1988)]. Restrictive space limitations were a major hardware consideration in the retrofit. We review the scientific basis for the technique, the proof of principle experiment that encouraged us to pursue it, and the final experimental configuration the x-ray probe has assumed. We suggest that a refinement of the measurement technique may provide information about the rate of DT fuel redistribution in beta heating targets