[en] The dynamics of intense Langmuir waves in current-carrying plasma is studied both analytically and numerically. Starting with the widely used Zakharov equations adapted to these systems, specific features of the problem are pointed out. The role of resonant particles is analyzed. Using a one-dimensional macroparticle numerical code, nonlinear regimes of modified-decay and modulational instabilities are modelled. An efficient cooperation of essentially ponderomotive and electron-ion drift effects is demonstrated. It appears that the heating of a current-carrying plasma can be activated by releasing the inductively stored energy, due to the enhanced conversion of energy associated with the electron drift motion. The underlying physics is discussed and its relationship to the solar flare theory is suggested. (author). 6 figs., 1 tab., 30 refs