In the nuclear fusion reaction, <br> $_1^2H +_1^3H \to _2^4He+n$ <br> given that the repulsive potential energy between the two nuclei is $7.7 \times 10^{-14} J$, the temperature at which the gases must be heated to initiate the reaction is nearly [Boltzmann's constant $k = 1.38 \times 10^{-23} J/K$] :
