Three-dimensional coulomb ordering of a highly space-charge-dominated ion beam in a storage ring

Yuri, Yosuke

A molecular dynamics simulation study has been performed to investigate the three-dimensional (3D) Coulomb-ordered state established in highly space-charge-dominated ion beams circulating in a storage ring. Actual parameters of the cooler storage ring "S-LSR" in Kyoto University are taken into account in the simulation. 40-keV Mg ion beams of different line densities are strongly cooled down to the space-charge-dominated region with a 3D cooling method using horizontally-displaced Gaussian lasers and resonant coupling under several focusing conditions. It has been found that 3D ordered states in the laser-cooled beams can be attained depending on cooling conditions such as the laser irradiation position. We have revealed various unique characteristics of the ordered beams such as the rotational motion of the ions in the beam cross-section, and demonstrated that they are different from those of a crystalline beam, whose emittance is theoretically zero.