I'm not showing my math now because of the difficulty in typing it. I'm using tools at this point and I can't paste a high energy calculator app into the forum.
So, at these temperatures and pressures, fusion does happen. A spectacular amount of it. We have enough energy to be absorbed by these particles to do some amazing things.
First, they absolutely do start to fuse. We have the sun's core beat for heat and pressure. They're fusing. This makes things... WORSE.
See, when elements LIGHTER than iron fuse, such as Carbon, Hydrogen, Helium, Oxygen, Nitrogen... you know, the things in the air... they GIVE OFF MORE ENERGY.
At this point, the pressure also drops because our particle count lowered so the number of mols of stuff we have is lower. Also, their total mass is decreasing, which decreases the density, and the pressure.
But that energy makes things hotter. And the hotness is enough to overcome the drop in pressure. WE MAKE IRON. All that air very quickly becomes iron. And then...
Iron is a tipping point for fusion. Once you make iron, it doesn't give energy back. It just sits there being hot. But we still have energy left.
So we keep going. Performing fusion after iron EATS the energy. Our pressure decreases, our mol count decreases, and our temperature decreases, and our mass starts increasing again.
But not enough. We can make tiny amounts of gold with this. And then everything in it explodes at roughly 13km/s. This kills the chakra crab.
So calculate what portion of the surface area of a sphere centered on the blast your cross-section presents by using the inverse square law. And you are struck by that fraction of 8.21e8 g of vaporous radioactive heavy metal supernova traveling 13km/s and at a temperature of several hundred thousand degrees.
And that's the answer to
@OliWhail's question.