Calculator
Example Data Table
| Reaction | Reactants | Products | Approx Q Value | Common Note |
|---|---|---|---|---|
| D-T | Deuterium-2 + Tritium-3 | Helium-4 + Neutron | 17.59 MeV | High yield and common study case |
| D-D branch | Deuterium-2 + Deuterium-2 | Helium-3 + Neutron | 3.27 MeV | One main deuterium branch |
| D-D branch | Deuterium-2 + Deuterium-2 | Tritium-3 + Hydrogen-1 | 4.03 MeV | Second main deuterium branch |
| D-He3 | Deuterium-2 + Helium-3 | Helium-4 + Hydrogen-1 | 18.35 MeV | Often discussed for low neutron output |
| p-B11 | Hydrogen-1 + Boron-11 | 3 Helium-4 | 8.68 MeV | Aneutronic candidate with hard conditions |
Formula Used
The calculator uses mass defect. It first adds reactant masses and product masses.
Reactant mass: Σmr = Σ(ni × mi)
Product mass: Σmp = Σ(nj × mj)
Mass defect: Δm = Σmr - Σmp
Q value: QMeV = Δm × 931.49410242
Energy per reaction: EJ = QMeV × 1.602176634 × 10-13
Total useful energy: E = EJ × N × efficiency ÷ 100
Fuel reactions: Nfuel = fuel mass ÷ reactant mass per reaction
Average power: P = useful energy ÷ time
How To Use This Calculator
- Select a reaction preset or choose custom masses.
- Enter the number of reactions for direct energy scaling.
- Enter fuel mass in grams for fuel based estimation.
- Set the expected useful efficiency percentage.
- Enter delivery time if average power is needed.
- Choose the main energy unit.
- Press the calculate button.
- Download the result as CSV or PDF when needed.
Understanding Fusion Reaction Energy
What This Calculator Measures
Fusion energy starts with mass difference. Light nuclei combine and make heavier products. The final products can weigh slightly less than the starting fuel. That missing mass becomes energy. This tool turns that mass defect into a Q value. It also scales the result for many reactions, fuel mass, and efficiency.
Why Mass Defect Matters
The mass defect is usually tiny. Yet the speed of light squared is huge. That is why a small mass change can release strong energy. A deuterium tritium reaction releases about 17.6 MeV before losses. Other fuels may release less or more energy. They may also need harder plasma conditions.
Advanced Inputs
Use a preset for common reactions. Choose custom mode for any balanced nuclear reaction. Enter each reactant mass in atomic mass units. Enter each product mass the same way. Add stoichiometric counts when more than one nucleus appears. The calculator multiplies each mass by its count before finding the mass defect.
Scaling The Result
One reaction gives energy in MeV and joules. Real work needs many reactions. Enter a reaction count for direct scaling. Enter fuel mass to estimate reactions from available reactant mass. The fuel estimate assumes ideal mixing and complete burnup. Efficiency reduces theoretical energy to useful energy.
Power And Yield
Energy is different from power. Energy tells how much work is available. Power tells how fast it is delivered. Enter a time value to estimate average power. The TNT comparison is only an energy reference. It does not describe blast behavior or reactor safety.
Best Use Cases
Students can check textbook examples. Teachers can build quick demonstrations. Researchers can compare rough fuel options before deeper modeling. Engineers can estimate order of magnitude output. The result is not a plasma simulator. It does not predict confinement, ignition, radiation loss, or engineering gain.
Good Data Practices
Use consistent atomic masses when electrons balance on both sides. Use nuclear masses when electrons do not balance. Keep enough decimal places. Small mass errors can move the final Q value. Review the reaction balance before trusting the result.
Safety Note
Fusion calculations are educational only. They do not replace shielding analysis. They do not replace fuel licensing. Seek professional reactor design review.
FAQs
What is fusion reaction energy?
It is the energy released or absorbed when light nuclei combine. The calculator finds it from the mass difference between reactants and products.
What is the Q value?
The Q value is energy per nuclear reaction. A positive Q value means energy is released. A negative value means energy must be supplied.
Can I use custom masses?
Yes. Select custom masses. Then enter reactant and product names, atomic mass units, and counts. Use reliable mass data.
Should I use atomic or nuclear masses?
Use atomic masses when electrons balance on both sides. Use nuclear masses when electron counts do not balance. Keep one standard throughout.
Why does efficiency matter?
Theoretical fusion energy is not always useful output. Efficiency adjusts energy for conversion losses, capture limits, and system performance assumptions.
Why are fuel mass and reaction count separate?
Reaction count gives direct scaling. Fuel mass estimates how many reactions could occur from available reactant mass under ideal burnup assumptions.
Does this predict reactor gain?
No. It calculates reaction energy only. It does not model plasma heating, confinement, ignition, bremsstrahlung loss, or engineering gain.
What does negative energy mean?
A negative result means products have more mass than reactants. The reaction is endothermic and needs supplied energy.