Coulomb barrier
The Coulomb barrier, named after Coulomb's law, which is in turn named after physicist Charles-Augustin de Coulomb, is the energy barrier caused by electrostatic interaction that two nuclei need to overcome so they can get close enough to undergo a nuclear reaction such as nuclear fusion. == Potential energy barrier == This energy barrier is given by the electric potential energy: U coulomb = 1 4 π ε 0 q 1 q 2 r {\displaystyle U_{\text{coulomb}}={1 \over 4\pi \varepsilon _{0}}{q_{1}q_{2} \over r}} where ε0 is the permittivity of free space; q1, q2 are the charges of the interacting particles; r is the interaction radius.