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.

[mvanwink5]

I suspect Helion’s #1 milestone is not net electric, but determining operating parameters so they know what to build for the commercial machine. Commercial machine timeline is what matters.
Why? Funding is not dependent on crossing net electric, everything Fusion is all about funding.

[Skipjack]

They have over a billion committed in funds if they meet their net electricity mile stone. So, I would say, yeah, net electric is important and they are working hard on achieving it while at the same time working on Orion.

[TallDave]

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.

of course, think about it... if the plasma contains 50MJ of energy, heating it by merely 10% means you now have 55MJ to recover... but if you push that past your ability to capture into the caps, all that energy still has to go somewhere

in Helion's system, ignition is not possible because the plasma lifetime is much shorter than the electron thermalization time... but electron heating is inefficient anyway, which as Kirtley points out is a major flaw in all igniting-reactor designs

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.

sure, but again, that's at current prices... He3 prices have fluctuated by 100x in the recent past, and future production costs could end up being a thousand times lower than today's prices

someone would just have to invest the capital to add another deep-cryo leg to the current fractional distillation extraction process in the natural gas flow and suddenly the supply would grow much faster

is that ultimately cheaper than a dedicated D-D machine? we'll see

[TallDave]

also while I agree they don't need a dedicated D-D, note that without dedicated D-D or an He3 source, they cannot run dedicated D-He3, which has consequences

would guess they are still doing D-D at the moment, probably so they can produce enough He3 for the whole D-He3 testing cycle