Nuclear Fusion Simulator

Q: If the total mass of the reactants in a fusion reaction is 4.033 u and the product mass is 4.002 u, what is the mass defect?

0.031 u Mass defect Delta m = 4.033 - 4.002 = 0.031 atomic mass units (u).

Q: Why does fusion require extreme temperatures?

To overcome the Coulomb barrier Nuclei are positively charged and strongly repel each other (electrostatic force). To bring them close enough for the Strong Nuclear Force to take over, they must have very high kinetic energy (temperature) to collide.

Animated D-D, D-T, and pp-chain fusion reactions. Shows nucleons, mass defect, energy release (MeV), and required temperature.

WHAT IS NUCLEAR FUSION?

Nuclear fusion is a reaction where two light atomic nuclei combine to form one or more heavier nuclei and subatomic particles. This process releases massive amounts of energy (according to ) because the total mass of the products is less than the mass of the reactants (the **mass defect**). Fusion powers stars and is the goal of future clean energy projects on Earth, though it requires extreme temperatures and pressures to overcome the electrostatic repulsion between nuclei.

HOW TO USE THIS VISUALIZATION

1. **Select a Cycle**: Choose between the Proton-Proton chain (Sun) or D-T (Deuterium-Tritium) fusion. 2. **Adjust Temperature**: Observe the minimum heat required to trigger the reaction. 3. **Track Energy Release**: See how mass is converted into energy as nuclei merge, releasing helium and high-energy neutrons.

CORE FORMULAS

Einstein's Mass-Energy Equivalence

Mass Defect

Q-value (Energy released)

AP EXAM CONNECTION

Unit: Unit 7: Quantum, Atomic, and Nuclear Physics (Topic 7.3)
Learning Objective: LO 7.C.4

COMMON MISCONCEPTIONS

Fusion and fission are the same (fusion is combining; fission is splitting)
Mass is lost forever (it is converted into kinetic energy and gamma radiation)

KEY TAKEAWAYS

Energy release in fusion comes from mass defect.
Binding energy per nucleon increases for light elements undergoing fusion.
The Sun primarily fuses hydrogen into helium via the p-p chain.
Fusion provides much higher energy density than chemical fuels.

PRACTICE QUESTIONS

Q1 (QUANTITATIVE): If the total mass of the reactants in a fusion reaction is 4.033 u and the product mass is 4.002 u, what is the mass defect?

Show Answer & Explanation

Answer: 0.031 u

Explanation: Mass defect atomic mass units (u).

Q2 (CONCEPTUAL): Why does fusion require extreme temperatures?

Show Answer & Explanation

Answer: To overcome the Coulomb barrier

Explanation: Nuclei are positively charged and strongly repel each other (electrostatic force). To bring them close enough for the Strong Nuclear Force to take over, they must have very high kinetic energy (temperature) to collide.