Nuclear Fusion Question

  • #1
Hi everyone! I was wondering if it is possible for a proton (H+) to fuse with an atom of potassium (K39 or K41) to create (Ca40+ or Ca42+)?
And if so what types of forces would need to be overcome to make this possible?

Thanks in advance for any help and sorry if this is a stupid question!:sorry:
 

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  • #2
stevendaryl
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I don't know the answer, but I believe that Just about any kind of reaction that preserves the baryon number (number of protons + neutrons) is in principle possible. Whether it's feasible in a reaction depends on whether there are alternate pathways that are more likely. Hitting a nucleus with a high-energy proton could cause it to split, rather than fuse.
 
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  • #3
Thanks!
 
  • #4
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It's possible if the incoming proton has enough energy. For a rough estimate:
* consider the potential energy a proton has just before "touching" the potassium nucleus.
* consider the energy balance and calculate the minimal proton energy
Take the larger of the two values.

It's not a very likely reaction.
 
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  • #5
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Theoretically, it is possible but you would need a lot of energy due to strong electric repulsion caused by the protons inside of the core. And of course it is a stupid question.
 
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  • #6
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It's possible if the incoming proton has enough energy. For a rough estimate:
* consider the potential energy a proton has just before "touching" the potassium nucleus.
* consider the energy balance and calculate the minimal proton energy
Take the larger of the two values.

It's not a very likely reaction.
Rough but misleading approach.
p,γ reactions are extremely common and important. Just look up.
d+p=3He+γ happens all the time, and very fast. And does not compete with fission... it releases energy, while the only alternative
d+p=2p+n
loses a lot.
Now look at CNO cycle:
1)12C+p=13N+1,95 MeV
2)13C+p=14N+7,54 MeV
3)14N+p=15O+7,35 MeV
4)15N+p=16O+12,13 MeV
12C+α+4,96 MeV
5)16O+p=17F+0,60 MeV
6)17O+p=18F+5,61 MeV
14N+α+1,19 MeV
7)18O+p=19F+7,99 MeV
15N+α+3,98 MeV
8)19F+p=...
16O+α+8,11 MeV

In every step that provides a choice between p,γ and p,α, the latter prevails, because it is the strong process. However, four of the eight just do not have α option.

Do K-39 and K-41 preferentially undergo p,γ or p,α?
How common are p,γ processes to form Ca? Especially Ca-42?
Isotopes divisible by α - Ne-20, Mg-24, Si-28, S-32, Ar-36 and Ca-40, and their daughters Ca-44, Ti-48, Cr-52 and Fe-56 are common in world, because they form simply by α,γ. But they are not the only ones that exist.
What are the most common reactions that form Ca-42, and their proportions?
41K+p=42Ca?
38Ar+α=42Ca?
Any others?
 
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  • #7
Thanks for all your response! :biggrin:

How about the energy requirement (more or less than) and possibility of this reaction in comparison to the fusion of two heavier elements? Particularly, N14+K39 or Ca42+N14.

Basically what I'm wondering is, if I have the following elements:

2K39 or 41
2H+
2N14

and assuming they will all fuse together to eventually create a single heavier element like Pd,
in what order would they most likely fuse? (e.g. H & K to form Ca, then Ca & N to form Fe, and then Fe & Fe to form Pd)

*sorry for the small script, the code seems to be correct and I couldn't figure out how to fix it!o_O
 
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  • #8
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A [sup] tag was not closed, so the rest of the post was in superscript which is smaller. I fixed it.

Thermal fusion with protons starts at much lower temperatures than thermal fusion with nitrogen as the former has a smaller Coulomb barrier. You can go to heavier elements through repeated addition of protons and beta+ decays, but it's an odd path. There might be places where competing reactions will make it very difficult to proceed, one would have to look at each reaction individually.
 
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  • #9
A [sup] tag was not closed, so the rest of the post was in superscript which is smaller. I fixed it.

Thermal fusion with protons starts at much lower temperatures than thermal fusion with nitrogen as the former has a smaller Coulomb barrier. You can go to heavier elements through repeated addition of protons and beta+ decays, but it's an odd path. There might be places where competing reactions will make it very difficult to proceed, one would have to look at each reaction individually.
Thanks for fixing it!:biggrin:

So if I understand correctly, when a nuclear reaction occurs between two elements it basically occurs proton by proton, gradually producing heavier and heavier elements, rather than just merging together and creating one heavier element? Or is it a mix of both? Like it gradually gets heavier, producing heavier elements until it reaches a certain tipping point, like the Coulomb barrier, and then it gets pulled in rapidly creating a much heavier element?

Also you mentioned thermal fusion. Are there other types of fusion (like I've heard of cold fusion), and does the process occur in the same manner?
 
  • #10
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It depends on the conditions. Very heavy stars can do processes like fusing two oxygen nuclei shortly before a supernova: Oxygen burning

Note that the usual way to heavier elements goes via neutrons and beta- decays.

Cold fusion is nonsense, with the exception of muon-catalyzed fusion of hydrogen to helium. But you can fuse nuclei by accelerating them in a particle accelerator and shooting them on other nuclei. That's how the superheavy elements (105+) are produced.
 
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  • #11
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Note that the usual way to heavier elements goes via neutrons and beta- decays.
But not only. Even elements have light isotopes which clearly cannot be produced by neutron addition
For example, starting to add neutrons slowly to Fe-56:
Fe 56, 57, 58
Co 59
Ni-58 skipped 60, 61, 62
Cu 63, 65
Zn 64, 66, 67, 68
Ga 69, 71
Ge 70, 72, 73, 74
As 75
Se-74 skipped 76, 77, 78 (79 330 000 y), 80

So where do isotopes like Se-74 come from?
Cold fusion is nonsense, with the exception of muon-catalyzed fusion of hydrogen to helium. But you can fuse nuclei by accelerating them in a particle accelerator and shooting them on other nuclei. That's how the superheavy elements (105+) are produced.
The other common form of fusion is pycnonuclear fusion.
 
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  • #12
Got it. Thanks everyone for your replies, it's much appreciated and very helpful! :biggrin:
 
  • #13
Astronuc
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So where do isotopes like Se-74 come from?
Beta decay of As-74 (although As-74 is more likely to experience electron capture and transform to Ge-74), or even (n,2n) reaction with Se-75.

Note the low abundance 0.89% of the isotope.
 

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