The different orbital modes that appear from the misalignment of the laser beams in the <i>xy</i> plane of a low-density magneto-optical trap are studied. Using the circular motion approximation, one can obtain a qualitative description of the phenomenon and can calculate the ring radii, the atom’s velocity in the ring, and the trap parameters in which the rings appear. A careful analysis of some theories previously employed in researching this topic shows that they have extrapolation problems that led to unreasonable conclusions. In particular, we compare the results of the circular motion approximation itself with those obtained from a direct numerical integration of the atomic trajectory. Within this approximation the influence of the increase in the number of trapped atoms over the ring is also investigated, and we observe an instability in a ring-shaped structure when the interaction between the atoms is included.
© 2000 Optical Society of America
(020.0020) Atomic and molecular physics : Atomic and molecular physics
(020.7010) Atomic and molecular physics : Laser trapping
(140.0140) Lasers and laser optics : Lasers and laser optics
(140.7010) Lasers and laser optics : Laser trapping
D. Felinto and S. S. Vianna, "Orbital modes in low-density magneto-optical traps," J. Opt. Soc. Am. B 17, 681-689 (2000)