Helium permeation through a lightweight flexible aerostat envelope material

The helium permeation mechanism through a thin film fabric laminated envelope material was studied for consisting of a plain fabric polyarylate fiber (vectran) for the main structural layer, a protective layer PVF film (tedlar) and a helium barrier layer polyester film (mylar). The equivalent permeability of vectran layer was calculated based on the Hagen-Poiseuille law. Then, the solution-diffusion model and the multilayer permeation model were used to predict the contribution of each layer and the layer thickness on the helium permeability of the overall envelope. The predicted helium permeation rates are then shown to compare well with experimental data.