In the nuclear fusion reaction ${ }_1 \mathrm{H}^2+{ }_1 \mathrm{H}^3 \rightarrow{ }_2 \mathrm{He}^4+\mathrm{n}$, if the repulsive potential energy between the two nuclei is $2.07 \times 10^{-14} \mathrm{~J}$, then the temperature at which the gases must be heated to initiate the reaction is $\left(\right.$ Boltzmann constant $\left.=1.38 \times 10^{-23} \mathrm{JK}^{-1}\right)$