MSimon wrote:A 100 MW fusion plant will produce about .5 Kg of He a day. More than enough to meet the plant's needs if losses can be kept low.
So graphene may help, make the cotainer with it:
How Ultrathin 'Graphene' Carbon Sheets Keep Everything Inside
One of the most impressive properties is its mechanical strength, which is surprising since it is so thin.
Both experiments in the lab and simulations carried out in a computer have now shown that graphene sheets can sustain high pressure and act as ideal containers. Physicists in the theory group of Francois Peeters at the University of Antwerp in Belgium have performed studies of how graphene sheets can hold gases within a tiny balloon structure. If any atom could escape from a nanoscopic bag it would be helium. As one of the noble gases, helium is chemically inert and might be able to wiggle past any atomically-thin enclosure. But, according to Antwerp researcher Ortwin Leenaerts, helium is unable to escape.
An experiment at Cornell in the laboratory of Harold Craighead, with a sheet of graphene stretched across a tiny bottle holding gas, has shown that indeed the gas, even high-pressure gas, is kept in. (This work was published in the journal Nano Letters).