  It is shown that the dust density regimes in dusty plasma are characterized
by two complementary screening processes, (a) the low dust density regime where
the Debye screening is the dominant process and (b) the high dust density
regime where the Coulomb screening is the dominant process. The Debye regime is
characterized by a state where all dust particles carry an equal and constant
charge. The high-density regime or the Coulomb plasma regime is characterized
by (a) Coulomb screening where the dust charge depends on the spatial location
and is screened by other dust particles in the vicinity by charge reduction,
(b) quark like asymptotic freedom where dust particles, which on an average
carry minimal electric charge (q tends to 0), are asymptotically free, (c)
uniform dust charge density and plasma potential, (d) dust charge
neutralization by a uniform background of hot ions. Thus, the Coulomb plasma is
essentially a one-component plasma (OCP) with screening as opposed to electron
plasma which is OCP without screening. Molecular dynamics (MD) simulations
verify these properties. The MD simulations are performed, using a recently
developed Hamiltonian formalism, to study the dynamics of Yukawa particles
carrying variable electric charge. A hydrodynamic model for describing the
collective properties of Coulomb plasma and its characteristic acoustic mode
called the Coulomb acoustic wave is given.
