  We proposed a dynamic mitigation method for plasma instabilities based on a
phase control to mitigate plasma instabilities and to smooth plasma
non-uniformities [e.g. Phys. Plasmas, 19(2012)024503]. In plasmas, perturbation
phase would be unknown in general, and instability growth rate is discussed.
However, if the perturbation is introduced by, for example, an illumination
non-uniformity of an input energy driver beam, the perturbation phase would be
defined by the driver illumination non-uniformity itself. When the driver axis
is controlled by its axis oscillation or wobbling motion, the perturbation
phase would be known and controlled. By the superimposition of the growing
phase-controlled perturbations, the overall plasma instability growth is
mitigated. The dynamic mitigation method is effective to mitigate growths of
various plasma instabilities. At the same time, it was found that the phase of
the growing perturbations mitigated would be still defined by the initial
imprint. In this paper, the initial imprint effect is focused on the dynamic
mitigation mechanism in plasmas. The results in this paper demonstrate that the
initial imprint effect is reduced by a pulse shaping of the oscillating or
wobbling perturbation.
