Double emulsion generation in the mass production of inertial confinement fusion targets using T-junctions

This work demonstrates a new device for the continuous controlled production of double emulsions for the manufacturing of inertial confinement fusion targets. This device can be integrated into a microfluidic approach to produce targets which should increase the yield and quality of the targets and at a lower cost. The device is a double T-Junction, which has been scaled, optimized and built to produce oil-in-water-in-oil double emulsions from diameters of roughly 4 mm or less. A T-Junction is an intersection of two channels at a right angle where fluid emerges and is broken off to form droplets. A systematic study presented here has shown that a single T-Junction has four modes of operation: squeezing, dripping, transition and streaming. The droplet size may be controlled by controlling the fluid flow rate through the channels; the droplet increases with increasing dispersed flow and decreasing continuous flow. The device was utilized to produce hundreds of ∼ 2.5 mm diameter resorcinol formaldehyde double emulsions with better than 2 percent reproducibility in diameter. The device was used to produce 2.0 mm shells with an average wall thickness of 510 microns.