News Feature: Small-scale fusion tackles energy, space applications

Oops. A not-so-minor clarification / correction. The PNAS article I linked to was not specifically about Helion Energy. It was a more general article about the field-reversed configuration (FRC) for dense plasma confinement, as explored by a group led by Samuel Cohen at the Princeton Plasma Physics Laboratory. The article does go on to talk about Helion Energy. Helion is working to commercialize a fusion reactor using the same principles of FRC plasmas studied by Cohen's group. Here's a paragraph I should have included:

If and when Cohen does reach his fusion energy milestone, he will likely have company. His device is just one of a family of small, alternative reactor projects designed to exploit a phenomenon known as the field-reversed configuration (FRC): a dense mass of ionized plasma that holds itself together something like a smoke ring and that could allow researchers to achieve fusion conditions with comparatively little effort. Among the members of this family are some of the best-known fusion upstarts: firms such as TAE Technologies (formerly TriAlpha Energy) in Foothill Ranch, California, and Helion Energy in Redmond, Washington.

Cohen's group is apparently more focused on use of D-3He fusion for high performance interplanetary spacecraft, not for large-scale terrestrial power. They're not planning to produce 3He.

And speaking of production of 3He, I should have read the FAQs on Helion's web site before I posted. There's another way to produce 3He besides neutron activation of 6Li. At the plasma conditions required for D-3He fusion, there will also be a degree D-D fusion. D-D fusion events produce, with equal probability, either a tritium nucleus + high energy proton, or a 3He nucleus + high energy neutron. If plasma temperature and density are sustained for any appreciable length of time, the tritium and 3He products of D-D fusion events will be consumed in subsequent D-T or D-3He events. But if the plasma is expanded and cooled very quickly, some of the residue of D-D fusion will remain. That's partly how Helion is aiming to produce helium-3 fuel. I'm sure neutron activation of 6Li will still be part of it, since that's the most effective way to capture the high energy neutron radiation produced by half of the D-D fusion events.