Fabrication and characterization of millimeter-sized glass shells for inertial confinement fusion targets

• Millimeter-sized glass shells for ICF targets have been fabricated.
• The larger the glass shell diameters, the lower the quality and yields of glass shells.
• Higher fraction of helium gas in furnace gas favors improving shell diameters and quality.
• Increasing temperature and refining zone length benefits shell's quality and yields.

To fabricate target quality millimeter-sized glass shells for inertial confinement fusion (ICF) fuel micro-containers by sol–gel technology, the effects of gel particle properties and processing parameters on the diameter, quality and yield of resulting glass shells were investigated by simulation and experiments. The results show that the initial compositions and sizes of the gel particles, the blowing agents, the pressures and compositions of furnace atmosphere, the refining temperatures and the lengths of refining zone are the key parameters to obtain target quality millimeter-sized glass shells. Increasing the gel particle sizes and/or lowering the furnace atmosphere pressures, the resulting glass shell diameters increase rapidly but the sphericity, wall uniformity and surface finish decrease notably. Displacing argon gas with helium gas in the furnace atmosphere can significantly improve the glass shell diameters, quality and yields; however, keeping appropriate fraction of argon gas in the furnace atmosphere can reduce the fragmentation of the gel particles and the ripples and collapse on the shell walls. The quality and yields of the resulting glass shells can also be improved by increasing the temperatures and lengths of the refining zone.