DENDRITIC MELTING IN MODULATED LASER-BEAM

The effect of laser beam chopping on the side-branch structure and oth er characteristics of <<liquid dendrites>> produced under laser meltin g inside the NaCl volume have been experimentally studied. At chopping frequencies smaller than that of intrinsic branching two branch syste ms are observed: one with coarser period forced externally and the oth er of a smaller period, which is closer to the intrinsic one. Against all expectations, the latter turned out to depend on external frequenc y too, the dependence being sublinear. The reason may be the non-stati onary dendrite motion caused by strong modulation. of superheating.