Higher Tier Only: Why Fusion Is Difficult to Achieve on Earth
Part of Nuclear Fission & Fusion — GCSE Physics
This higher tier covers Higher Tier Only: Why Fusion Is Difficult to Achieve on Earth within Nuclear Fission & Fusion for GCSE Physics. Revise Nuclear Fission & Fusion in Atomic Structure for GCSE Physics with 13 exam-style questions and 25 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 15 of 18 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
Topic position
Section 15 of 18
Practice
13 questions
Recall
25 flashcards
🎓 Higher Tier Only: Why Fusion Is Difficult to Achieve on Earth
For fusion to occur, nuclei must be brought within ~1 fm (femtometre = 10⁻¹⁵ m) of each other so the strong nuclear force can overcome electrostatic repulsion. This requires kinetic energies equivalent to temperatures above 10⁸ K.
At these temperatures, atoms are fully ionised — all electrons have been stripped away. The result is a plasma (superheated ionised gas). No material container can hold plasma at 100 million°C without melting. Solutions being tested:
- Tokamak (ITER, JET): Strong magnetic fields contain the plasma in a donut-shaped vessel
- Inertial confinement (NIF, USA): Laser beams compress a tiny pellet of deuterium-tritium very rapidly
The major challenge is achieving "net energy gain" — the fusion must release more energy than was put in to heat and confine the plasma. As of 2024, NIF has achieved this briefly; a commercial reactor is still decades away.