Originally Posted by
pasta
Exactly; in that regard it's not hugely different to conventional rocket engines using fuel to cool their nozzle. The
Wikipedia page explains it fairly well; the helium loop is also used to power turbines, which is quite elegant.
like to know where all of the helium will come from though. It’s not exactly a massively abundant element.
https://www.google.co.uk/amp/s/amp.f...amp/1116242001