The presence of microconvective instability in optically induced gratings

In the present work, attention is paid to some significant effects (phenomena) in forced Rayleigh scattering (FRS) experiments with an applied magnetic field, ∇ T ∥ H, which have not been analyzed before. The work deals with the idea that the experimentally observed effects are caused by microconvection. The dimensionless numbers Cm and Rm, which are responsible for the onset of microconvection, are calculated from experiments as well as from the linear stability analysis in a Hele-Shaw approximation. The problem of definition of the true values of diffusion and Soret coefficients from experiments and their field dependence, which are not affected by the assumed microconvection, is solved by original data processing.