Thermonuclear fusion and combustion
Thermonuclear Fusion : Basic Principles, Achievements and Prospects

The energies of atomic and nuclear interactions are usually measured in electron volts (eV) and mega electron volts (MeV), whose conversion factors in joules are: 1 eV = 1.6 × 10^–19 J and 1 MeV = 1.6 × 10^–13 J. Boltzmann's entropy constant, k_B = 1.380 × 10^–23 J/K, which appears in the perfect gas equation (pressure [Pa] = k_B × density [m^–3] × temperature [K]), converts the electronvolt into a temperature: 1 eV [K] =1.6 × 10^–19/k_B = 11,604 K. Depending on usage, we will therefore use a scale in eV to measure energies and locate temperatures; so, for example, the typical temperature of a thermonuclear plasma, 10 keV, is therefore of the order of 10⁸ K.