About chance and uncertainty in fusion reactions

[marcuac]

Hello everyone,

I was wondering how big of a role does chance have in fusion reactions, specifically for pB11 with inertial confinement, and this forum seemed like a good place to ask.

If we consider a linear accelerator where protons are being fired at a solid pure B11 crystal target, assuming that every proton hits the target with just the right amount of energy, what are the odds of reaction for each proton? What measures could be taken to increase the odds of fusion, and is there a fundamental theoretical limit, a residual degree of uncertainty that cannot be removed no matter what?

Thank you.

[delt0r]

Long story short… It can’t work.

There are 3 different collisions you care about with beam matter interaction. The first is collision with electrons. The second is collision with B11. The 3rd is fusion events. The probability of these events and how much energy goes where is fairly easy to measure. So we don’t even need to make assumptions about our models. It turns out we are most likely to hit electrons and give them lots of energy which results in heat and xrays. Second is to bounce of the B11 nucleus. Even with perfect energy matching, you still have a fairly low probability of fusion. In fact the probability of a fusion event is so low you can’t get net energy out.

Its just the way the universe is wired. Over all the probability even in favorable conditions is really really low compared to all the other loss mechanisms. This is why fusion is hard. Its also why the sun is stable for billions of years……

[Lerner]

Experiments like the ones you describe are exactly how we know the reaction cross sections and reaction rates–the chance that a proton of energy x will cause a fusion reaction. Nuclear physics is not at the point these rates can be calculated–they are measured. The maximum probability occurs at energy of around 600 keV. But at much lower energies, which FF-1 has already obtained, we can release enough energy to heat the plasmoid up to 600 keV or even hotter.

[Author]

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