The height of the barrier depends on the charges and
radii of the two interacting nuclei It can be shown, for example, that
the barrier height for two protons is ~ 400 keV, and is higher for nuclei
with higher charges We can estimate the temperature at which two
protons in a proton gas would (averagely) have enough energy to
overcome the coulomb barrier:
(3/2)k T = K ≃  400 keV, which gives T ~ 3 × 109 K When fusion is achieved by raising the temperature of the system so
that particles have enough kinetic energy to overcome the coulomb
repulsive behaviour, it is called thermonuclear fusion