  We address an experimental observation of pattern formation in a magnetised
rf plasma. The experiments are carried out in a electrically grounded aluminium
chamber which is housed inside a rotatable superconducting magnetic coil. The
plasma is formed by applying a rf voltage in parallel plate electrodes in
push-pull mode under the background of argon gas. The time evolution of plasma
intensity shows that a homogeneous plasma breaks into several concentric radial
spatiotemoral bright and dark rings. These rings propagate radially at
considerably low pressure and a constant magnetic field. These patterns are
observed to trap small dust particles/grains in their potential. Exploiting
this property of the patterns, a novel technique to measure the electric field
associated with the patterns is described. The resulting estimates of the
corresponding field intensity are presented. At other specific discharge
parameters the plasma shows a range of special type of characteristic
structures observed in certain other chemical, mechanical and biological
systems.
