The control of unstart of a supersonic model inlet flow is demonstrated at Mach 4.7 flow conditions using a dielectric barrier discharge (DBD) actuator. Rayleigh scattering from condensed CO2 particles is used to visualize flow features such as boundary layers and shock waves at low freestream static pressure (1kPa) and temperature (60K). Three inlet wall flow conditions - a laminar boundary layer, and a tripped turbulent boundary layer with and without plasma actuation, are tested for comparison in the measured time to unstart. The delay of the unstart process, initiated by mass addition to the supersonic flow, is demonstrated through the plasma actuation of the tripped freestream boundary layer when a single DBD actuator pair is oriented parallel to the freestream flow, generating spanwise disturbances. The effect of DBD actuation on this unstart process is limited to a region within about 3mm from the exposed electrode edge.