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For pre-Sedov phase supernova remnants, where the stellar ejecta are expanding into a uniform interstellar medium or a presupernova wind, the interaction region between the ejecta and surrounding medium is Rayleigh-Taylor unstable. This instability produces turbulent amplification of magnetic field and corresponding enhanced synchrotron emission. We have created synthetic images of such remnants in order to investigate the spatial morphology of their synchrotron emission. We assume that the energy density of the amplified magnetic field is proportional to the turbulent energy density. The flow field was calculated using a two-dimensional numerical hydrodynamics code and then converted to a function of radius only by taking an angle-average of the physical quantities. Also included in the model is the compression and evolution of ambient field and the shock acceleration of electrons. The postshock energy density of the electrons is assumed to be proportional to the postshock pressure of the thermal gas. For the case of a uniform ambient magnetic field, a simple characterization of the dependence of the acceleration efficiency on the angle between the shock normal and the external field has been incorporated. We have generated images for various angles between the line of sight and the external field and for various time steps. This model exhibits both a double shell structure and bipolarity. In the case of a presupernova wind, we have assumed that the external magnetic field is everywhere tangential to the shock and depends only on radius. A time series of images has also been created for this model, showing the evolution of a double shell structure. In both instances the relative brightness of the two shells varies with time and may provide observational constraints on the importance of amplification of magnetic field in SNR radio emission.
