Structures and motions of strongly coupled quasi-2D dust coulomb clusters in plasmas: From small N to large N

The first observation of the strongly coupled quasi-2D dust coulomb cluster s 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 2 D plane and operating at room temperature. The particle number N in the clu ster can be controlled and changed from a few to a few hundreds. Their stru ctures and motions are mainly determined by the competition between the cen tral confining force and mutual Coulomb repulsions. The generic behaviors o f the packing rules and the collective excitations under the shell structur es at small N, and the transition to the triangular lattice structure surro unded by one to two circular shells at large N are investigated and compare d with our molecular dynamic simulations with more ideal models. Other inte resting dynamical behavior such as the slow rotation of the whole cluster u nder the moderate axial magnetic held is also introduced.