The website answers this question [1]. "Helion produces helium-3 by fusing deuterium in its plasma accelerator utilizing a patented high-efficiency closed-fuel

The website answers this question [1]. "Helion produces helium-3 by fusing deuterium in its plasma accelerator utilizing a patented high-efficiency closed-fuel cycle." Wikipedia provides a bit more detail [2]: "The helium-3 is produced by D-D side reactions and is captured and reused, eliminating supply concerns. Helion has a patent on this process." [1] https://www.helionenergy.com/faq/ https://www.helionenergy.com/faq/ [2] https://en.wikipedia.org/wiki/Helion_Energy https://en.wikipedia.org/wiki/Helion_Energy