 Even using these isotopes, the Coulomb barrier is large enough that the nuclei must be given great amounts of energy before they will fuse.Although there are a number of ways to do this, the simplest is to heat the gas mixture, which, according to the Maxwell–Boltzmann distribution, will result in a small number of particles with the required energy even when the gas as a whole is relatively "cool" compared to the Coulomb barrier energy.In the case of the D-T mixture, rapid fusion will occur when the gas is heated to about 100 million degrees.