  Dusty plasma crystals have traditionally been observed and studied in radio
frequency (RF) discharge plasmas and their formation in a DC glow discharge
plasma remains experimentally challenging. We report the first ever observation
of a stable dusty plasma Coulomb crystal in the cathode sheath region of a DC
glow discharge plasma. The observations are made in the DPEx device where
crystals of mono-disperse Melamine Formaldehyde grains are produced in the
background of an Argon plasma. The crystalline nature of the structure is
confirmed through a host of measurements that includes the radial pair
correlation function, Voronoi diagram, Delaunay Triangulation, the structural
order parameter, the dust temperature and the Coulomb coupling parameter. The
special features of the DPEx device that permit such a crystal formation are
delineated and some principal physical features of the crystal discussed.
