Stimulated scattering of relativistically strong radiation from an underdense plasma at high-frequency harmonics

The theory of stimulated scattering of relativistically strong, arbitrarily polarized laser radiation from an underdense plasma is developed. It is shown that, in addition to the scattering at the near-carrier frequency, the scattering at the odd and even high-frequency harmonics can occur in a wide range of angles. The growth rates of the instability associated with the harmonic generation are obtained as functions of the scattering angle. It is shown that, at certain directions, the growth rates for higher harmonics can exceed the growth rate for the fundamental harmonic.