Raman scattering instability of an intense laser pulse in a plasma channel
proceeds differently than in a homogeneous plasma: The growth rate is reduc
ed and the scaling with the laser intensity modified. These differences, si
gnificant even for shallow plasma channels, arise because of the radial she
ar of the plasma frequency and the existence of the weakly damped hybrid (e
lectrostatic/electromagnetic) modes of the radially inhomogeneous plasma. T
he interplay of these two effects produces double-peaked spectra for the di
rect forward scattering in a channel. (C) 2001 American Institute of Physic
s. [DOI: 10.1063/1.11331566].