[en] The fusion power multiplication factor including the beam-plasma reaction (TCT effect), Q, has been evaluated with a simple plasma model, in which the radial profiles of the plasma temperature and density are taken to be typical forms observed in the recent experiments. The parameters to be varied in this model are n-bar_e, τ_E, beam power and energy, rf power, and impurity contents which affect the reduction of fueling density. For the typical application, we have investigated the operation window to attain a larger Q value for JT-60 hydrogen plasma which is converted to the equivalent deuterium-tritium plasma. When the TCT effect by 100 keV deuterium beam are considered, the minimum nτT = 2.7 x 10²³ (sec · eV · m^-3) is necessary to achieve the break-even condition of JT-60. The Troyon β-limit is a crucial parameter in the break-even condition for a Ip = 2 MA discharge if τ_E < 0.55 sec for 100 keV beam. The minimum nτT required to attain the break-even condition is lowered by enhancement of the beam-plasma reaction, by forming the peaked density and temperature profile, and by reducing the impurity contents. When the TCT effect by 200 keV deuterium beam are considered, the minimum nτT can be lowered to 2.0 x 10²³ (sec · eV · m^-3). (author)