[en] The existence of a new instability mechanism of a current-carrying plasma which, for a sufficiently long system, may occur after saturation of the two-stream instability is shown. The instability is due to combined asymmetry and nonuniformity of the electron distribution and is manifested by the spontaneous appearance of a growing, localized Langmuir oscillation at approximately the position vsub(d) = vsub(t). A possible connection with the formation of double layers is pointed out. (Auth.)