# What kind of energy is released in a nuclear fusion reaction?

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• freddie_mclair
freddie_mclair
Hi, I have a fundamental (and maybe silly question) but I couldn't find a proper answer anywhere yet:

For example, for a nuclear fusion reaction of Tritium (T) and Deuterium (D), we get an alpha particle (##\alpha##) a neutron (n) and energy release due to the mass difference ##\Delta m=m_D+m_T-m_n-m_{\alpha}##, which means that: ##D + T \rightarrow \alpha + n + \mbox{ 17.6 MeV}## where ##\mbox{ 17.6 MeV}= \Delta m c^2 ##. These 17.6MeV get split by the neutron (14.1MeV) and the alpha particle (3.5MeV).

Now, my question is: what does it mean, to release energy? What kind of energy is this?
Thanks!

dextercioby
AFAIK, kinetic energy of the products and gamma rays.

I agree with the kinetic energy of the products, but where are the gamma rays? What I understand is that the 17.6MeV are just split into the kinetic energy of the neutron by ##KE_n=\Delta m c^2 \frac{m_{\alpha}}{m_{\alpha}+m_n} ## and the rest to the alpha particle ##KE_{\alpha} = \Delta m c^2 - T_n ##.

freddie_mclair said:
but where are the gamma rays
You posited a reaction without them.

You posited a reaction without them.
what would be the correct formulation then? and what amount of radiation would that be in terms of energy?

I can't tell you what reaction you are thinking of. Just that A+B → C+D and A+B → C+D+γ are not the same process.

For this specific reaction I mentioned it is just Deuterium + Tritium, there are no gamma rays, just an alpha particle and a neutron. But in several places it is indicated that, apart from the reaction products, there is also an energy release, like for example here.

freddie_mclair said:
here are no gamma rays
freddie_mclair said:
but where are the gamma rays?

Do you see why people are confused?

No, why? I asked Hill where are the gamma rays in the reaction I described.

The reaction without gamma rays is the most common outcome, all the released energy becomes kinetic energy of the reaction products:
##D + T \rightarrow \alpha + n##

This is possible, too:
##D + T \rightarrow \alpha + n + \gamma##
Here the photon energy is variable and the rest will be kinetic energy of the alpha and n.

Astronuc, dextercioby and fresh_42
freddie_mclair said:
For this specific reaction I mentioned it is just Deuterium + Tritium, there are no gamma rays, just an alpha particle and a neutron. But in several places it is indicated that, apart from the reaction products, there is also an energy release, like for example here.
That's not a sufficiently detailed source for discussion. In this reaction, most of the energy is kinetic energy of the neutron. Hyperphysics has a little more detail:

http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/fusion.html

Lord Jestocost
Thanks mfb, and PeroK.
To conclude: energy release in this specific fusion reaction can be totally kinetic (shared the n and ) or kinetic + EM radiation.

The deuterium tritium reaction produces an alpha particle and a neutron. The energy of the reaction becomes the kinetic energy of the products. Gamma rays do not seem to be produced.

sharmast said:
Gamma rays do not seem to be produced.
It's possible, as discussed, it's just rare. It even has a 16.75 MeV photon line corresponding to He-5 decaying to its ground state before emitting a neutron.

When neutrons are emitted, nuclei of the surrounding material could capture a neutron and emit gamma rays. So even though the reaction itself may not emit gammas, you will get gamma rays "in real life" from any reaction with neutrons as a product.

## What kind of energy is released in a nuclear fusion reaction?

In a nuclear fusion reaction, the primary form of energy released is in the form of kinetic energy of the resultant particles. This energy is subsequently converted into heat and other forms of energy.

## How does the energy released in fusion compare to that in fission?

The energy released in a single nuclear fusion reaction is generally greater than that released in a single nuclear fission reaction. Fusion reactions release energy on the order of millions of electron volts (MeV), while fission reactions release energy on the order of hundreds of MeV.

## What are the by-products of the energy released in nuclear fusion?

The by-products of nuclear fusion typically include light nuclei, such as helium, and subatomic particles like neutrons. The kinetic energy of these by-products is what constitutes the energy released in the reaction.

## What role do electromagnetic waves play in the energy released by nuclear fusion?

Electromagnetic waves, particularly in the form of gamma rays, can be a significant component of the energy released in nuclear fusion. These high-energy photons are produced during the reaction and contribute to the overall energy output.

## Can the energy from nuclear fusion be harnessed for practical use?

Yes, the energy from nuclear fusion can theoretically be harnessed for practical use, such as in electricity generation. However, achieving controlled and sustained nuclear fusion for practical energy production remains a significant scientific and engineering challenge.

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