EVOLUTION OF THE WAVE-NUMBER RANGE DURING THE DEVELOPMENT OF THE DRIFT INSTABILITY

The dispersion relation of the drift waves is studied in the presence of a fluctuating electric field consisting of a superposition of small -amplitude, linear, independent drift waves. It is shown that a stabil ization effect appears due to the perturbation of particle trajectorie s, consisting in the partial destruction of the small clumps. A transi ent process during the increase of the drift instability is revealed. It leads to a stabilization of waves with the largest wavenumbers, bef ore reaching the final nonlinear stage.