Lawson criterion (J.D. Lawson): This is the condition for the discharge of energy from a thermonuclear reactor. This is usually stated as the minimum value for the product of the density of the fuel particles and the energy imprisonment time for energy breakeven. For a half-and-half mixture of tritium and deuterium at ignition temperature, nG tau is in the range 1014 and 1015 s/cm3.