An empirical formula for the (D,T) reaction rate parameter <σν>

A simple analytic formula for the temperature dependence of the reaction rate <σν> of fusion processes in a Maxwellian DT plasma is given. Its accuracy is better than 2% between 10 and 100 keV and better than 10% between 2 and 10 keV as well as between 100 and 150 keV (if compared with the values calculated by Miley et al.). The simplicity of the formula makes it particularly useful also for orientative evaluations of the performance of fusion experiments and reactors, based on simple plasma models. A few examples of applications of the formula are presented. (author)