Calculator Inputs
The page stays single-column overall, while the input grid shifts to three, two, or one column depending on screen size.
Example Data Table
| Reaction | Mass Defect (u) | Q-Value (MeV) | Energy per Reaction (J) |
|---|---|---|---|
| Deuterium + Tritium → Helium-4 + Neutron | 0.01888289 | 17.589301 | 2.818117e-12 |
| Deuterium + Deuterium → Helium-3 + Neutron | 0.00350932 | 3.268909 | 5.237369e-13 |
| Deuterium + Deuterium → Tritium + Proton | 0.00432924 | 4.032663 | 6.461039e-13 |
| Deuterium + Helium-3 → Helium-4 + Proton | 0.01970281 | 18.353055 | 2.940484e-12 |
| Proton + Boron-11 → 3 Helium-4 | 0.00932044 | 8.681931 | 1.390999e-12 |
Values are based on atomic mass differences and are suitable for estimation and educational use.
Formula Used
This method follows the standard mass-energy relation used in nuclear physics. The main idea is simple: when product masses are slightly lower than reactant masses, the missing mass appears as released energy.
For practical systems, only part of that fusion energy becomes usable electricity or delivered heat, so the calculator includes an efficiency factor for engineering estimates.
How to Use This Calculator
- Select a preset fusion reaction or choose the custom option.
- If using custom mode, enter total reactant and product masses in atomic mass units.
- Enter the reaction rate and the duration of operation.
- Optionally enter a direct reaction count if you already know it.
- Set the efficiency to estimate usable output instead of theoretical output alone.
- Add fuel mass to estimate usable energy per gram.
- Press the calculate button.
- Review the result section shown above the form and download CSV or PDF if needed.
Why This Calculator Is Useful
Fusion discussions often mix per-reaction energy, reactor-scale power, and fuel-scale energy density. This tool separates those layers clearly. It lets you compare classic fusion reactions, explore custom mass data, estimate useful recovered energy, and convert results into engineering-friendly units such as joules, megajoules, kilowatt-hours, and watts.
FAQs
1. What is fusion energy per reaction?
It is the energy released by one single fusion event. The value usually comes from the mass defect between reactants and products and is commonly reported as a Q-value in MeV.
2. Why does mass defect matter?
Mass defect is the tiny difference between starting and ending mass totals. In nuclear reactions, that missing mass becomes energy according to mass-energy equivalence, making it the core of any fusion energy estimate.
3. Why is D-T fusion often used as a reference?
Deuterium-tritium fusion has a relatively large energy release and a comparatively achievable reaction cross section. That combination makes it the most common benchmark in current fusion engineering discussions.
4. Is the calculator showing theoretical or usable energy?
It shows both. First it calculates theoretical fusion output from the Q-value. Then it applies your efficiency setting to estimate usable delivered energy and average power.
5. What if I already know total reaction count?
Enter that value in the optional reaction count field. When present, the calculator uses it directly and ignores reaction rate multiplied by duration.
6. Can I use custom reaction masses?
Yes. Choose the custom reaction preset and enter your own reactant and product mass totals in atomic mass units. The calculator then computes the Q-value from those entries.
7. Why include fuel mass in grams?
Fuel mass lets you express usable output as energy density. That makes it easier to compare fuels, evaluate storage implications, and translate reaction-scale physics into system-scale engineering terms.
8. Does a higher Q-value always mean a better reactor fuel?
Not always. Q-value matters, but ignition conditions, neutron production, confinement difficulty, fuel availability, materials damage, and conversion method also affect overall reactor practicality.