Please read the paper. Levi says the tube is sintered.
Sintered alumina would have about 6% porosity. It will not contain hydrogen at high or low temperature. However, it is unclear as to whether the fuel was admitted already inside a separate hermetically sealed ampoule. If so, that could be a situation which could work. The problem there is the surface area of that ampoule is what should be used as the IR emitter surface for emissivity - and it would be at least 20 times less than the number which was used. From: Eric Walker Sorry – but this reactor is made of alumina – which is a proton conductor. Beta alumina is among the best proton conducting ceramics but you would never use any form of alumina if you wanted to retain a supply of hydrogen after startup. Please see the section "Diffusion Barrier to Oxygen and Hydrogen" from this link, shared earlier on Vortex (sorry, I forget who shared it): http://www.azom.com/article.aspx?ArticleID=3560 >From the article: The alpha-Al2O3 oxide structure, once formed, serves as a nearly perfect diffusion barrier for oxygen and hydrogen. I'm guessing the fact that alumina can be made a near perfect barrier to the diffusion of hydrogen is one of the reasons it was chosen (another is that it appears to be refractory). It would seem to be premature to assume that hydrogen quickly escapes. Eric
