I understand the author poses this as a rhetorical question, but obviously the answer is more complicated than “just use 100% helium”. It’s much more likely tha

I understand the author poses this as a rhetorical question, but obviously the answer is more complicated than “just use 100% helium”. It’s much more likely that someone has already done the cost and risk analysis and determined that 8.5% hydrogen is worth the trouble. Sorry it’s not the answer [the author] is looking for.