Helion Energy to demonstrate net electricity production by 2024

[Skipjack]

There are almost zero D-T side reactions. The T is too hot and leaves the plasma quickly for the SOL and then the divertor.

By the way, I'd appreciate some clarification of the part about "lower temps and higher temperatures".

That was me being scatterbrained it should read: lower temps and higher density

[TallDave]

They are going for 20 to 30 keV because they need 2/3 of the reactions to be D-D which favors lower temps and higher density. They can scale pretty much linearly between the two. So they can balance it to get the optimal power to breeding ratio.
IIRC, the graphs were made for 20 Tesla magnetic fields.

They CAN do D-T with their design and Polaris will demonstrate that. It is a fallback in case D-He3 fails, but they don't like it at all.

well, temperature on the graph is a function of magnetic field strength (hence "adiabatic compression" in the paper's title ), but otherwise agree

guessing 20T would probably achieve something around 30KeV for D-He3, but again a lot depends on that proton production rate and the fine details of the PIC simulations

believe the post-Orion D-D/D-He3 mix is still up for debate, they may be able to achieve a better ratio with spin polarized He3... also, it might turn out to be cheaper to mine/refine He3 than dedicate a $100MM D-D machine to producing it, there are a couple recent He3 finds at around 9% iirc... otoh refining He3 currently requires deep cryo and is only done in small batches, so who knows where that cost will be in five years

[Skipjack]

guessing 20T would probably achieve something around 30KeV for D-He3, but again a lot depends on that proton production rate and the fine details of the PIC simulations

They actually do NOT want too much proton heating. Generally, they do not want to get anywhere near ignition territory. I do not fully understand the details, but that is what I heard.

it might turn out to be cheaper to mine/refine He3 than dedicate a $100MM D-D machine to producing it

No, not even close. A 50 MWe Helion machine would consume probably around 10 kg of He3 annually (probably a bit less but in that ballpark). That is some 200 million at current prices. Also, they do not need a dedicated machine for breeding. They can do a dedicated machine and those would likely be fine tuned to handle the neutrons and be the most efficient at doing D-D. But again, that is optional.