  Self-assembly of structures from vertically aligned, charged dust particle
bundles within a glass box placed on the lower, powered electrode of a RF GEC
cell were produced and examined experimentally. Self-organized formation of
one-dimensional vertical chains, two-dimensional zigzag structures and
three-dimensional helical structures of triangular, quadrangular, pentagonal,
hexagonal, and heptagonal symmetries are shown to occur. System evolution is
shown to progress from a one-dimensional chain structure, through a zigzag
transition to a two-dimensional, spindle-like structure and then to various
three-dimensional, helical structures exhibiting multiple symmetries. Stable
configurations are found to be dependent upon the system confinement, (where
are the horizontal and vertical dust resonance frequencies), the total number
of particles within a bundle and the RF power. For clusters having fixed
numbers of particles, the RF power at which structural transitions occur is
repeatable and exhibits no observable hysteresis. The critical conditions for
these structural transitions as well as the basic symmetry exhibited by the
one-, two- and three-dimensional structures that subsequently develop are in
good agreement with the theoretically predicted configurations of minimum
energy determined employing molecular dynamics simulations for charged dust
particles confined in a prolate, spheroidal potential as presented
theoretically by Kamimura and Ishihara [10].
