Fusion Science and Technology / Volume 63 / Number 2 / March/April 2013 / Pages 136-141
Technical Paper / Selected papers from 20th Target Fabrication Meeting, May 20-24, 2012, Santa Fe, NM, Guest Editor: Robert C. Cook
The atomic layer deposition technique generates very thin Al2O3 films to control the hydrogen diffusion half-life of glow discharge polymer (GDP) inertial confinement fusion shells. The films generated by this process have an easily controlled thickness and are pinhole free. As a result, they can be used to set the hydrogen diffusion half-life of a GDP shell to the required value of hours, from an uncoated value of minutes. Such diffusivity control is much harder to achieve with the currently used sputtered Al coating, which also renders the shell opaque, causing difficulties with ice-layer characterization. The [approximately]10-nm oxide is also less intrusive to target performance than an [approximately]100-nm (and highly nonuniform) metal coating such that it can be safely ignored by the target designer.