  The spatial and time evolutions of superradiant scattering are studied
theoretically for a weak pump beam with different frequency components
traveling along the long axis of an elongated Bose-Einstein condensate.
Resulting from the analysis for mode competition between the different resonant
channels and the local depletion of the spatial distribution in the
superradiant Rayleigh scattering, a new method of getting a large number of
high-order forward modes by resonant frequency components of the pump beam is
provided, which is beneficial to a lager momentum transfer in atom manipulation
for the atom interferometry and atomic optics.
