The Coulomb barrier, named after physicist Charles-Augustin de Coulomb (1736—1806), is the energy barrier due to electrostatic interaction that two nuclei need to overcome so they can get close enough to undergo nuclear fusion. This energy barrier is given by the electrostatic potential energy: Portrait of Coulomb Charles Augustin Coulomb (June 14, 1736 – August 23, 1806) was a French physicist. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ...

where

k is the Coulomb's constant = 8.9876×10⁹ N m² C⁻²;

ε₀ is the permittivity of space;

q₁, q₂ are the charges of the interacting particles;

r is the interaction radius.

A positive value of U is due to a repulsive force, so interacting particles get at higher energy levels when they get closer. A negative potential energy indicates a bound state (due to an attractive force). The coulomb (symbol: C) is the SI unit of electric charge. ... The permittivity of a medium is an intensive physical quantity that describes how an electric field affects and is affected by the medium. ...

Coulomb's barrier increases with the atomic numbers (i.e. the number of protons) of the colliding nuclei: The atomic number (Z) is a term used in chemistry and physics to represent the number of protons found in the nucleus of an atom. ...

where e is the elementary charge, 1.602 176 53×10⁻¹⁹ C, and Z_i the corresponding atomic numbers. The elementary charge (symbol e or sometimes q) is the electric charge carried by a single proton, or equivalently, the negative of the electric charge carried by a single electron. ...

To overcome this barrier nuclei have to collide at high velocities, so their kinetic energies drive them close enough for the strong interaction to take place and bind them together. The strong interaction or strong force is today understood to represent the interactions between quarks and gluons as detailed by the theory of quantum chromodynamics. ...

According to the kinetic theory of gases, the temperature of a gas is just a measure of the average velocity of the particles in that gas. For normal gases, the Maxwell-Boltzmann distribution gives the fraction of particles moving at a given velocity as a function of gas temperature, and thus the fraction of particles moving at velocities high enough to overcome the Coulomb's barrier can be derived. The Maxwell-Boltzmann distribution is a probability distribution with applications in physics and chemistry. ...

In practice, temperatures needed to overcome Coulomb's barrier turn out to be smaller than expected due to quantum-mechanical tunneling, as established by Gamow. The consideration of barrier-penetration through tunneling and the speed distribution gives rise to a limited range of conditions where the fusion can take place, known as the Gamow window. Quantum tunneling is the quantum-mechanical effect of transitioning through a classically-forbidden energy state. ...