Absorption-induced stimulated scattering of second sound in a superfluidстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:A new type of wave interaction for hydrodynamics — absorption-induced
stimulated scattering — is considered. The present treatment is particular-
ized to the case of stimulated scattering of second sound in a superfluid. If
two waves — an intense pump wave and a signal wave — are propagating
in a medium, the power released in the medium, which is proportional to
the square modulus of the total field, contains an interference term at the
difference frequency of the pump and signal waves. Since the properties of
the medium depend on temperature, the temperature inhomogeneities arising
at the difference frequency cause scattering of the pump wave, resulting in a
field which is resonant for the signal wave. That field is proportional to the
absorption coefficient and the intensity of the pump wave. At low intensities
of the pump wave such scattering leads to partial compensation of the dissipa-
tion of the signal wave, and with increasing intensity of the pump wave it can
lead to amplification of the signal wave. This means that stimulated scatter-
ing can arise. Analysis of the experimental data suggests that the threshold
intensity of this stimulated scattering can be a real experimental quantity.