Why Does He3 Fusion Create He4 + 2 Protons?

In summary, He3 fusion creates He4 and 2 protons instead of Beryllium due to conservation of momentum and energy. Creating a single particle from two equal-energy He3 nuclei would violate these laws, and even if the nuclei had different energies, the resulting Li6 would be at rest in the center of mass frame, violating the principle that a stable particle cannot decay by endowing it with lots of energy.
  • #1
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Curious, why does He3 fusion (3He + 3He → 4He+ 2p) create He4 + 2 protons instead of Beryllium? (or any other arbitrary rearrangement of the protons & neutrons)
 
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You shouldn't just look at the number of protons, but also the number of neutrons.
(3, 2)He + (3, 2)He
would have to give (6, 4)Be, which does not appear to be an existing isotope (or may be so unstable that it immediately decays to He(4, 2) + 2 p(1, 1)).
 
  • #3
CompuChip said:
You shouldn't just look at the number of protons, but also the number of neutrons.
(3, 2)He + (3, 2)He
would have to give (6, 4)Be, which does not appear to be an existing isotope (or may be so unstable that it immediately decays to He(4, 2) + 2 p(1, 1)).

so is the stability of the isotope the sole determinant? (6,3)Li is stable, so is there some reason you would not get (3, 2)He + (3, 2)He = (6,3)Li+ (0,1) H ? which superficially seems more stable than a combination with 2 free protons
 
  • #4
If you create a single particle, you won't conserve momentum and energy. Suppose two nuclei of He3 of equal energy collide head on. Then conservation of momentum demands that the resulting Li6 be at rest. So where does the excess binding energy go?

If the He3 were not of equal energy, we transpose the problem into the center of mass frame. The Li6 must be at rest in the CoM frame of the heliums.

It's an offshoot of the "a stable particle can't decay by endowing it with lots of energy" problem. In some reference frame the stable particle is at rest.
 
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1. Why is He3 fusion important in understanding nuclear reactions?

He3 fusion is important because it is one of the main reactions that occurs in stars, including our own sun. Understanding this reaction can help us better understand the processes that power the universe.

2. How does He3 fusion create He4 and 2 protons?

In He3 fusion, two He3 nuclei combine to create a He4 nucleus and two protons. This process releases a large amount of energy in the form of gamma rays.

3. What is the significance of He3 fusion in energy production?

He3 fusion has the potential to be a source of clean and sustainable energy. It produces significantly less radioactive waste compared to other nuclear reactions, making it a promising candidate for future energy production.

4. What conditions are required for He3 fusion to occur?

He3 fusion requires extremely high temperatures and pressures, similar to those found in the core of stars. In addition, a strong source of energy, such as a laser or particle accelerator, is needed to initiate the fusion reaction.

5. Why is He3 fusion not currently used as a source of energy?

Despite its potential, He3 fusion is not currently used as a source of energy because the technology needed to sustain a controlled fusion reaction is still being developed. Additionally, the supply of He3 is limited and difficult to obtain, making it an expensive and impractical option for energy production at this time.

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