The first observation of the strongly coupled quasi-2D dust coulomb clusters in a novel cylindrical rf plasma trap is demonstrated. The system has the advantages of directly tracking the precise motion of each particle in a 2D plane and operating at room temperature. The particle number N in the cluster can be controlled and changed from a few to a few hundreds. Their structures and motions are mainly determined by the competition between the central confining force and mutual Coulomb repulsions. The generic behaviors of the packing rules and the collective excitations under the shell structures at small N, and the transition to the triangular lattice structure surrounded by one to two circular shells at large N are investigated and compared with our molecular dynamic simulations with more ideal models. Other interesting dynamical behavior such as the slow rotation of the whole cluster under the moderate axial magnetic field is also introduced.
