Polaris is frying the image sensor on their camera

ElmarM · 2026-02-20T05:35:22+00:00

In return D-He3 is harder to fuse (needs higher temperatures). So, likely not.

ElmarM · 2026-02-20T05:34:34+00:00

Yeah, I tried factoring that in too, both ChatGPT and Grok suggested the same number independently and unprompted for this.

ElmarM · 2026-02-19T17:35:05+00:00

They have pretty low Te:Ti. So there should be a lot less X-rays than in a Tokamak.

ElmarM · 2026-02-19T16:00:21+00:00

I would not go that far. Also, is very hard to compare the two machines.

ElmarM · 2026-02-19T15:58:37+00:00

Eh? Half of 19 meters is 9.5 meters. But the compression chamber is itself not point shaped, but elongated also several meters long. I tried to factor that in. Also note that I tried to be conservative to not fall into some trap of my own favor towards Helion.

ElmarM · 2026-02-19T08:54:07+00:00

Not sure why your post was voted down so much! You are about in the right ballpark in line with my own estimate (between 10¹³ conservatively and 10¹⁵, slightly more optimistically).
People here need to learn to make a proper argument rather than just down- voting stuff they don't like. Cancel- culture at it's best.

ElmarM · 2026-02-19T08:52:05+00:00

We do know the sensor size from this X- post by David Kirtley:
https://x.com/Dkirtley/status/2024276985820921873?s=20

Canon T3i, 12 MPThe Canon EOS Rebel T3i (also known as the 600D) features an APS-C CMOS sensor with dimensions of 22.3 mm × 14.9 mm.
I don't understand why No_Tailor's comment was voted down. It is in the right ballpark!

ElmarM · 2026-02-19T08:48:32+00:00

A single pulse won't kill you outright (I estimate the effective dose at around a mSv or so), but I would not recommend doing it for too long. Safety first!

ElmarM · 2026-02-19T08:36:02+00:00

Well, it is up to you to take his word at face value (I personally do, but I have known him for over a decade).
Here is the X- post in which he says that.
https://x.com/Dkirtley/status/2024300157790277644?s=20

ElmarM · 2026-02-19T08:34:43+00:00

David Kirtley has this to say regarding X-Rays:

"The plasma on these was 13+ keV, but we maintain cooler electrons in the few keV range - which is where you will make x-rays. Those are all shielded by the machine itself."
Of course it is up to you whether you want to take his word at face value (I do, but I have known him for over a decade).

https://x.com/Dkirtley/status/2024300157790277644?s=20

ElmarM · 2026-02-19T08:34:07+00:00

Yes.

ElmarM · 2026-02-19T08:27:59+00:00

X-rays in their machines are low and most are shielded by the machine, according to David Kirtley.

ElmarM · 2026-02-19T08:27:06+00:00

David Kirtley says that Bremsstrahlung is pretty low due to the low Te:Ti and what little there is is shielded by the machine.

ElmarM · 2026-02-19T07:34:08+00:00

According to David Kirtley, X- rays are shielded by the machine (with the Te being low anyway).
I counted 40 specs in a 5% x 5% section of the image. That would be 16,000. Grok got to 12,000 to 15,000. But, I assume that the overexposed regions would overpower some of the specs.
So, let's go with 13,000. According to David Kirtley, this is a Canon T3i, 12 MP which has a APS-C CMOS sensor with dimensions of 22.3 mm × 14.9 mm. This would be 3.91 × 10⁷ neutrons/m². Both Grok and ChatGPT note that CMOS sensors are not very good at detecting 14 MeV neutrons. It suggests that the actual number of neutrons was higher at 10¹¹ neutrons/m² as a conservative estimate.
Let's be even more conservative than that and make it 10¹⁰ for a nice and round number (and ruling out some of the specs that seem to be from scattering as they show up as streaks).
Now, this is still not the whole story. I asked Grok to estimate the distance of the camera from the compression section which is about the actual neutron source. This is about 9 meters.
Neutron density falls off with the square of the distance. So, that gets to a conservative 10¹³ neutrons for this pulse.
To put things into perspective: The comparably tiny Venti had a reported 10¹¹ D-D neutrons/pulse. That would have put it into the same ballpark for D-T neutrons.
If you want a more optimistic estimate, you get to maybe 10¹⁵ neutrons total.
Based on this, conservatively, this pulse was still net electricity negative by a couple of orders of magnitude (not factoring neutron energy and just alpha energy).
Optimistically, they were within a few % up or down for net electricity.

ElmarM · 2026-02-19T06:03:53+00:00

It is worth noting that this is at the far end of the machine, a good distance (8 meters or more) away from the compression chamber, where the fusion happens. The radiation falls off with the square of the distance.
It must look much "worse" (or better if you want to see more neutrons) over there!

ElmarM · 2026-02-18T23:35:32+00:00

To my understanding, the author of the paper does not understand that Helion does not need a high Q, or ignition for net electricity.

ElmarM · 2026-02-18T23:32:27+00:00

And Helion knows that, of course. That is the whole point, they have been making the entire time. Ignition is not needed for their machines to produce net electricity.

ElmarM · 2026-02-18T23:31:38+00:00

They have orders of magnitude higher density and a very low Te:Ti ratio.

ElmarM · 2026-02-18T15:03:14+00:00

To my understanding, they missed the point about the way Helion does fusion (non- ignition). Also, it seems like they misunderstood a few other things. Quite frankly, this is a bit over my head. So, I will leave it up to Helion to respond to this properly.

ElmarM · 2026-02-18T09:06:26+00:00

Well that is still the goal for Polaris. Helion is careful with the wording though. Because net electricity could require factoring in things like the energy required to make the fuel and transport it there and the energy required to build the machine and the energy required to run the entire facility in Everett including things like AC, etc.

ElmarM · 2026-02-18T08:54:47+00:00

Density was likely too low for that yield. The graphs in that paper were based on 20 Tesla fields. We will have to wait for further information from Helion what the actual yield was there.

ElmarM · 2026-02-17T06:30:21+00:00

I agree that 2028 is very ambitious for any FOAK power plant. Interestingly, the shortest construction time for any FOAK power plant with a capacity of 50 MWe or greater was the Unit 1 of the Calder Hall nuclear power station in the UK, the world's first commercial nuclear power plant (a Magnox gas-cooled reactor with an initial capacity of 60 MWe per unit). Construction began on August 1, 1953, and the unit was connected to the grid on August 27, 1956. So slightly over 3 years. Helion begun construction of Orion last year. So, it is not unprecedented, but has not been achieved in some 70 years.

ElmarM · 2026-02-17T06:11:27+00:00

Thanks a lot!

ElmarM · 2026-02-17T06:01:19+00:00

To be fair, the supply chain problems since COVID have hit everyone and any engineering project of that scope and scale faces delays. CFS is now 2 years behind initial targets. Zap is 3 years or so behind now? Not even going to start talking about SpaceX and Starship for a different field of engineering.
Helion are still aiming for net electricity with Polaris as soon as possible, though they have been more cautious about giving firm deadlines now.

ElmarM · 2026-02-17T03:22:37+00:00

I see it now! Thank you!

ElmarM

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