Coulomb barrier

physics

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 24, 2026

Quick Summary

The Coulomb barrier is a repulsive electrostatic force that charged particles must overcome to undergo nuclear fusion. This barrier exists because atomic nuclei are positively charged, and like charges repel each other, as described by Coulomb's law. For fusion to occur, such as in stars or potential fusion energy reactors, the particles need enough kinetic energy to get close enough for the strong nuclear force to take over and bind them together. This is why extremely high temperatures, like those found at the center of stars, are necessary for fusion reactions to happen at a significant rate.123

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

nuclear fusion
Rate and yield of fusion reactions
This repulsion is called the Coulomb barrier (see Coulomb force). It is highly unlikely that two positive nuclei will approach each other closely enough to undergo a fusion reaction unless they have sufficient energy to overcome the Coulomb barrier. As a result, the cross section for fusion reactions between charged…
Read More
This repulsion is called the Coulomb barrier (see Coulomb force). It is highly unlikely that two positive nuclei will approach each other closely enough to undergo a fusion reaction unless they have sufficient energy to overcome the Coulomb barrier. As a result, the cross section for fusion reactions between charged…
Read More