Abstract
The general method of Nozawa-Steiner for analysis of the power balance in fusion reactors is applied to the case of the magnetic-mirror “Pure DD” fusion reactor. In order to achieve the overall plant efficiency η =30%, we need the plasma of the Lawson number nτ =1016cm-3. sec, in case of the efficiency of the direct converter ηd =0.7, that of the thermal converter η t=0.4, that of the neutral beam injector η =0.7, that of absorption η a = 1 and the ion temperature Ti=200KeV.