  Pinned solitons are a special class of nonlinear solutions created by a
supersonically moving object in a fluid. They move with the same velocity as
the moving object and thereby remain pinned to the object. A well known
hydrodynamical phenomenon, they have been shown to exist in numerical
simulation studies but to date have not been observed experimentally in a
plasma. In this paper we report the first experimental excitation of pinned
solitons in a dusty (complex) plasma flowing over a charged obstacle. The
experiments are performed in a {\Pi} shaped Dusty Plasma Experimental (DPEx)
device in which a dusty plasma is created in the background of a DC glow
discharge Ar plasma using micron sized kaolin dust particles. A biased copper
wire creates a potential structure that acts as a stationary charged object
over which the dust fluid is made to flow at a highly supersonic speed. Under
appropriate conditions nonlinear stationary structures are observed in the
laboratory frame that correspond to pinned structures moving with the speed of
the obstacle in the frame of the moving fluid. A systematic study is made of
the propagation characteristics of these solitons by carefully tuning the flow
velocity of the dust fluid by changing the height of the potential structure.
It is found that the nature of the pinned solitons changes from a single humped
one to a multi-humped one and their amplitudes increase with an increase of the
flow velocity of the dust fluid. The experimental findings are then
qualitatively compared with the numerical solutions of a model forced Korteweg
de Vries (fKdV) equation.
