More Helion Energy news....

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Giorgio
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Re: More Helion Energy news....

Post by Giorgio »

Skipjack wrote:
Mon Feb 22, 2021 10:11 pm
2. That divertor has a molybdenum-coated wall.
3. They have issues with high velocity plasmas causing arcing and erosion on that molybdemium coated wall.
I am actually surprised that they are still experimenting with molybdenum coated divertors, this is stuff from 1980's and 1990's.
There is already plenty of literature (especially from Alcator C-MOD Tokamak) that has shown that molybdenum coating of tiles suffer from much higher erosion rates from sputtering due to its inferior melting and evaporation temperatures in respect to Tungsten coated tiles.

I am really scratching my head now trying to understand why they are still pursuing that road.....
A society of dogmas is a dead society.

Skipjack
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Re: More Helion Energy news....

Post by Skipjack »

Giorgio wrote:
Tue Feb 23, 2021 9:38 am
Skipjack wrote:
Mon Feb 22, 2021 10:11 pm
2. That divertor has a molybdenum-coated wall.
3. They have issues with high velocity plasmas causing arcing and erosion on that molybdemium coated wall.
I am actually surprised that they are still experimenting with molybdenum coated divertors, this is stuff from 1980's and 1990's.
There is already plenty of literature (especially from Alcator C-MOD Tokamak) that has shown that molybdenum coating of tiles suffer from much higher erosion rates from sputtering due to its inferior melting and evaporation temperatures in respect to Tungsten coated tiles.

I am really scratching my head now trying to understand why they are still pursuing that road.....
My guess:
Their reactor design is very different. So the reason and requirements for the divertor might be as well. Molybdenum is much cheaper than Tungsten. So they might have tried that one first to see if they could get away with it instead of Tungsten. I might be wrong, though.

Skipjack
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Re: More Helion Energy news....

Post by Skipjack »

Small update on the divertor material choices: Their linear reactor design indeed has the advantage that concentrated heat loads on the divertor are a lot more benign when compared to a Tok (I guessed that earlier, but I know for sure now). It is also used for a different purpose than in a Tokamak. I think I can say that much.
Because of all that, they think that they can get away with Molybdenum which does still have some other advantages over Tungsten aside from cost. E.g. while Tungsten does have the best MW/m2, it also has nasty activation products and that is the main reason why they are trying to avoid using it.

Also note that (and that is currently just my own speculation here), their pulsed design makes a few things easier for them. E.g. some small scale abrasion on the divertor is likely not a big deal because (to my understanding) that won't introduce impurities to the plasma and (unlike in a steady state reactor design) they can extract potential contaminants between shots. But again that is currently just speculation on my side.

Giorgio
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Re: More Helion Energy news....

Post by Giorgio »

Indeed if the thermal load is greatly inferior to its melting point, than molybdenum has the inherent advantages over tungsten that it does not form aggressive impurities as you said.
But considering that the diverters will work also as FRC Energy recovery, partial magnetic energy recovery and direct fusion energy to electricity recovery, I am very curious to see how much the heat load will be in the end.

Skipjack wrote:
Sat Mar 27, 2021 7:37 pm
Also note that (and that is currently just my own speculation here), their pulsed design makes a few things easier for them.
I believe you are totally correct here. The last i saw from their presentation they was planning a 2 Hz frequency for the commercial reactor. This would give them enough time to evacuate the diverters chambers from previous plasma shot, including related impurities.
A society of dogmas is a dead society.

Skipjack
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Re: More Helion Energy news....

Post by Skipjack »

The divertor is not used for energy recovery in Helion's design it has an entirely different purpose.

Giorgio
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Re: More Helion Energy news....

Post by Giorgio »

Skipjack wrote:
Mon Mar 29, 2021 4:00 am
The divertor is not used for energy recovery in Helion's design it has an entirely different purpose.
According the arpa-e papers I saw from them, diverters was playing an important role in the energy recovery balance, harvesting about 50% of the "net" energy of each single pulse.

If they changed this point it also mean that the whole machine must have undergone deep changes.
That's interesting.
A society of dogmas is a dead society.

Skipjack
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Re: More Helion Energy news....

Post by Skipjack »

Giorgio wrote:
Mon Mar 29, 2021 7:46 am
Skipjack wrote:
Mon Mar 29, 2021 4:00 am
The divertor is not used for energy recovery in Helion's design it has an entirely different purpose.
According the arpa-e papers I saw from them, diverters was playing an important role in the energy recovery balance, harvesting about 50% of the "net" energy of each single pulse.

If they changed this point it also mean that the whole machine must have undergone deep changes.
That's interesting.
Which ARPA-E papers are those?
IIRC, Helion was "selling" a D+T version to ARPA-E since that was considered the more "conservative" choice. So maybe the difference regarding the divertor is from that?
Another reason might be that they have further developed their direct energy conversion system and are now more confident that it can capture more of the energy and convert it to electricity.

Giorgio
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Re: More Helion Energy news....

Post by Giorgio »

Skipjack wrote:
Mon Mar 29, 2021 8:50 am
Which ARPA-E papers are those?
IIRC, Helion was "selling" a D+T version to ARPA-E since that was considered the more "conservative" choice. So maybe the difference regarding the divertor is from that?
Could be, but the ARPA-E papers numbers ares more coherent for a D-D route.
They published several papers as this one: https://arpa-e.energy.gov/sites/default ... SLOUGH.pdf
At page 4 you can find the energy input/output balance of each section of the machine involved in supplying/collecting the energy and the relevant amount during each step of one fusion cycle.

Based on my understanding of their fusion process I doubt that they could make a self sustain reactor from a pure D-T cycle, but I could be wrong.
A society of dogmas is a dead society.

Skipjack
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Re: More Helion Energy news....

Post by Skipjack »

Giorgio wrote:
Mon Mar 29, 2021 9:39 am
They published several papers as this one: https://arpa-e.energy.gov/sites/default ... SLOUGH.pdf
Yeah, I remember that paper (and several others). That was most certainly the D+T design, not the D+He3 design. It even says Tritium breeding in the graphic to the right (3rd paragraph) on the last page.
The "comp" is the power they expect to extract from the lithium blanket in the central compression (burn) chamber, where most of the "action" happens. The divertors at the end would get the rest, when the plasma expands again, driven apart by the fusion reaction. Again that is the D+T design, not the D+He3 design.

Giorgio
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Re: More Helion Energy news....

Post by Giorgio »

Skipjack wrote:
Mon Mar 29, 2021 10:04 am
Giorgio wrote:
Mon Mar 29, 2021 9:39 am
They published several papers as this one: https://arpa-e.energy.gov/sites/default ... SLOUGH.pdf
Yeah, I remember that paper (and several others). That was most certainly the D+T design, not the D+He3 design. It even says Tritium breeding in the graphic to the right (3rd paragraph) on the last page.
Yes, I noticed the tritium breeding mention on the last page but I did not give it the interpretation of being the fuel of the reaction but just the Tritium breeding part of their patent.
The numbers on page 5 are more coherent with D-D reaction, but I would not put my hands on fire for being D-D or D-T as we lack too many data to be sure about one or the other.
Anyhow (as I wrote you on the other thread), the technology for the D-D reaction chain must be mastered if they want to have a self sustaining reaction cycle as they designed in their patent.
A society of dogmas is a dead society.

Skipjack
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Re: More Helion Energy news....

Post by Skipjack »

Giorgio wrote:
Mon Mar 29, 2021 10:25 am
Yes, I noticed the tritium breeding mention on the last page but I did not give it the interpretation of being the fuel of the reaction but just the Tritium breeding part of their patent.
The numbers on page 5 are more coherent with D-D reaction, but I would not put my hands on fire for being D-D or D-T as we lack too many data to be sure about one or the other.
Anyhow (as I wrote you on the other thread), the technology for the D-D reaction chain must be mastered if they want to have a self sustaining reaction cycle as they designed in their patent.
You just have to trust me on that being for the D+T reactor ;)
That said, it would make sense to have a lithium blanket to breed extra Tritium from the D+D neutrons. That would allow them to add more He3 to the fuel mix (once it has decayed to He3), increasing the ratio of He3 to D and that in turn would lower the chance of a D+T side- reaction even more.

Giorgio
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Re: More Helion Energy news....

Post by Giorgio »

Skipjack wrote:
Mon Mar 29, 2021 10:34 am
You just have to trust me on that being for the D+T reactor ;)
That said, it would make sense to have a lithium blanket to breed extra Tritium from the D+D neutrons. That would allow them to add more He3 to the fuel mix (once it has decayed to He3), increasing the ratio of He3 to D and that in turn would lower the chance of a D+T side- reaction even more.
No problem on trusting you on that, I guess you have your own sources :wink:
A lithium blanket would make sense (they also mentioned it in their patent), but adding too much 3He to the fuel mix could have a deleterious effect on the fusion efficiency.
Of course that is unless the machine reaches a technological level where they can actually control the fusion process in such fine details.
A society of dogmas is a dead society.

Skipjack
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Re: More Helion Energy news....

Post by Skipjack »

Giorgio wrote:
Mon Mar 29, 2021 11:04 am
Skipjack wrote:
Mon Mar 29, 2021 10:34 am
You just have to trust me on that being for the D+T reactor ;)
That said, it would make sense to have a lithium blanket to breed extra Tritium from the D+D neutrons. That would allow them to add more He3 to the fuel mix (once it has decayed to He3), increasing the ratio of He3 to D and that in turn would lower the chance of a D+T side- reaction even more.
No problem on trusting you on that, I guess you have your own sources :wink:
A lithium blanket would make sense (they also mentioned it in their patent), but adding too much 3He to the fuel mix could have a deleterious effect on the fusion efficiency.
Of course that is unless the machine reaches a technological level where they can actually control the fusion process in such fine details.
I found a version of their second patent that has the drawings and tables included (yay!).
That one is a lot more clear on the various fuel ratios, etc and what can be achieved with them:
https://patentscope.wipo.int/search/en/ ... ESCRIPTION

I believe that some of the reactor parameters have changed since this patent was filed. E.g. the B field seems to be a lot higher in the plans they had for Venti and FEP (though FEP as presented to ARPA-E was for D+T ). I wonder whether the temperature was reduced in return.
Also, look at the numbers for energy from neutrons! 6% if Tritium is removed and 4% if they use a Lithium blanket. I would assume that most of those neutrons are from D+D, even though the D+T neutrons would produce 5 times more energy. Either way, interesting.

Giorgio
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Re: More Helion Energy news....

Post by Giorgio »

Skipjack wrote:
Mon Mar 29, 2021 8:39 pm
I found a version of their second patent that has the drawings and tables included (yay!).
That one is a lot more clear on the various fuel ratios, etc and what can be achieved with them:
https://patentscope.wipo.int/search/en/ ... ESCRIPTION
This patent should be the equivalent of the 2017 US patent (which is the one I was referring to).
https://patents.google.com/patent/US20170011811A1

There is lot of potential hidden hints inside, so it is indeed worth reading.
A society of dogmas is a dead society.

Skipjack
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Re: More Helion Energy news....

Post by Skipjack »

Yeah, but the google version is missing the charts.

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