Talk-Polywell.org

Skipjack wrote: ↑

Tue Mar 30, 2021 4:54 pm

Yeah, but the google version is missing the charts.

What charts are missing?

All the drawings, charts and the table. At least I can't see them. They are in the version I posted.

They are present also in the google version.
If for any reason you can't see them on the webpage click on "Download PDF" and you will get a complete PDF of the patent as it was originally submitted to the patent office.

Talking about patent, Helion tweeted today that their patent has been granted for Europe:
https://worldwide.espacenet.com/patent/ ... P3103119A2

Tweet by Helion today:
Helion just opened the 6th fusion prototype after an unprecedented 16 months of continuous vacuum and repetitive high-power fusion operations! Now upgrading to the Mark 2 divertor with advanced materials and magnetic shielding. Mark 1 divertor wall after 16 months: https://twitter.com/Helion_Energy/statu ... 1095695361

I would love to see the data of those 16 months of test run.

Who wouldn't!

Interesting small bit of information in a response from Helion:
" This picture is more deposition, rather than erosion. We'll know more soon as we get in-depth measurements with SEM (scanning electron microscope) and EDS (X-ray spectroscopy)."

https://twitter.com/Helion_Energy/statu ... 1234880514

It might not be a good news because if it is only deposition they might have 2 problems to solve, deposition on the divertors and erosion in some other part of the machine.

Giorgio wrote: ↑

Sat May 15, 2021 6:06 pm

It might not be a good news because if it is only deposition they might have 2 problems to solve, deposition on the divertors and erosion in some other part of the machine.

From what I understand, the deposition is from erosion in the unshielded part of the divertor. Basically what happens is that the fusion reaction creates a very high energy jet on axis. The divertor in this case is used not for electricity production but to slow down that jet.
They are already developing a new divertor with new materials, magnetic shielding and other means to mitigate those issues. They seem to have several options there too. So hopefully, it is not too big of a deal and can be solved relatively quickly. Personally, I think that they are in a rather good place, when they have to worry about problems like these. I think most other teams are not even close to worrying about things like divertor erosion/material deposition.

Skipjack wrote: ↑

Sat May 15, 2021 8:17 pm

From what I understand, the deposition is from erosion in the unshielded part of the divertor. Basically what happens is that the fusion reaction creates a very high energy jet on axis. The divertor in this case is used not for electricity production but to slow down that jet.

From my knowledge, the erosion and the redeposition process over the divertor itself (which allows an absence of plasma contamination), has been so far proved experimentally only for Tungsten coated divertor and only in a very limited range of plasma laminar flows.
Turbulent plasma (and transient cases) still need to be investigated for Tungsten, and no public data is available for Molybdenum for linear, transient and turbulent plasma modes.
The last 2 cases, transient and turbulent, are the most worrisome for molybdenum because it has an average of 20 times more sensibility to erosion than tungsten.

"I think most other teams are not even close to worrying about things like divertor erosion/material deposition."

Unlike Helion which continuously pulses plasmoids through the divertors every cycle to collide, TAE divertors are not in continuous use because their plasmoids after colliding form a sustained plasmoid, which is then maintained by neutral beam injection. Sustaining that plasma and heating it has been their huge job, and that was proven in Norman. So there are trade offs. The devil gets his due.

mvanwink5 wrote: ↑

Tue May 18, 2021 9:43 pm

"I think most other teams are not even close to worrying about things like divertor erosion/material deposition."

Unlike Helion which continuously pulses plasmoids through the divertors every cycle to collide, TAE divertors are not in continuous use because their plasmoids after colliding form a sustained plasmoid, which is then maintained by neutral beam injection. Sustaining that plasma and heating it has been their huge job, and that was proven in Norman. So there are trade offs. The devil gets his due.

Not sure how much it matters, but TAE's confinement times, to the best of understanding are the same as Helion's (~1ms - 3ms).

TAE's confinement time is until the neutral beam is shut off and that is a limitation of their experimental machine (takes a lot of power to run those Megawatt injectors). Confinement time is not a limitation of their process. In a TAE commercial machine the neutral beams will not shut off. Helion requires continuous plasmoid pulsing for heating, TAE uses neutral beam injection which is not pulsed (experiments are due to cost). Helion does not need to maintain their plasmoids as they make them in pulses and fire them at each other so Helion does not need neutral beams.

Helion knows their divertors have to be engineered for the heavier duty that they are subjected to so they are tackling that. It is just another trade off.

mvanwink5 wrote: ↑

Tue May 18, 2021 10:29 pm

TAE's confinement time is until the neutral beam is shut off and that is a limitation of their experimental machine (takes a lot of power to run those Megawatt injectors). Confinement time is not a limitation of their process.

No, that is plasma lifetime, not confinement time. Confinement time is how long a single particle remains trapped. Plasma lifetime is how long the FRC stays alive. It is one of the gripes I have with TAE, that they keep talking about the latter while sort of implying that it is the same as the former.
They are not. Both Helion and TAE have about the same confinement times. TAE's reactor is sort of a leaky bucket that constantly needs to have water added.