[en] A theory of tapered laser cooling for fast circulating ion beams in a storage ring is constructed. The authors describe the fundamentals of this new cooling scheme, emphasizing that it might be the most promising way to beam crystallization. The cooling rates are analytically evaluated to study the ideal operating condition. They discuss the physical implication of the tapering factor of cooling laser, and show how to determine its optimum value. Molecular dynamics method is employed to demonstrate the validity of the present theory

[en] The recent progress of the theoretical study of crystalline beams is reviewed. Stress is placed on the dynamical difference between Coulomb ordering in an ion trap and relativistic crystalline beams in a storage ring. The stability conditions of an ordered structure are addressed and their physical background is explained with the language of beam dynamics. Approximate equations and formulae are given to provide useful information of crystalline states

[en] We study parametric resonances in arbitrary periodic lattices, incorporating the effect of space-charge self-fields. The linearized Vlasov approach is employed to provide an analytic description of resonant beam instability. Neglecting the momentum dispersion and image charges, we obtain an eigenvalue equation that determines the frequencies of collective modes in a one-dimensional waterbag beam. Approximate formulae for the resonance stopbands, growth rates, etc. are given. The theoretical predictions are compared with multi-particle simulation results. The effect of error fields is also analytically explored in the present paper

[en] A possible experimental approach is proposed to investigate halo formation in charged particle beams. It is based on a compact one-component plasma trap devise using either a radio-frequency quadrupole or a solenoidal magnetic field for particle confinement. In principle, the system can reproduce actual situations in high-intensity beam transport channels and, thus, enables one to perform systematic experimental study of space-charge-dominated beams and halo properties. We describe an example setup of the system where it is possible to explore the dependence of halo extent on mismatch factor as well as on tune depression, the effect of multipole perturbations, transverse-longitudinal coupling effects in bunched beams with various aspect ratios, emittance growth due to intra-particle collisions, etc

[en] We study parametric resonances in circular accelerators, incorporating the effect of space-charge self-fields. A general Hamiltonian formalism is constructed for this purpose. The particle-in-cell simulation technique is employed to systematically explore the role of space-charge forces on resonant instabilities in two-dimensional beams. It is shown that momentum dispersion peculiar to rings can be an additional source of resonances

[en] Space charge effects of 1D waterbag-type beams under constant linear focusing force is studied. A self-consistent stationary distribution is obtained in the form of power series, and the linearized Vlasov analysis is applied to investigate the stability of beam plasma oscillation modes. (author)

[en] Synchrobetatron resonances in alternating phase focused (APF) linacs are studied with the equations of motion obtained by the stepping field approximation method. It is shown that symmetric phase alternation patterns cause the lowest order resonance which is the most undesirable. The width of the unstable region corresponding to this resonance is evaluated approximately. (author)

[en] New equations of motion for alternating phase focused (APF) linacs with axisymmetric accelerating field are devised. The equations can apply to any type of APF accelerating structure such as the asymmetric APF, the modified APF and so on. Formulas to evaluate the transverse acceptance and the longitudinal phase capture region are derived from the equations of motion. The propriety of the theoretically obtained results were confirmed by simulation study. The limiting current in a single channel APF and other practical problems of linac design are also discussed in this paper. (orig.)

[en] New equations of motion for alternating phase focussed (APF) structures are proposed. Formulas to evaluate the acceptances and current limits, which can be applied to any type of APF structures, are derived from the equations of motion. Coupled motion in an APF is also discussed in this paper. (author)

[en] In recent papers [Okamoto, Hiroshima University Preprint HUBP-01/98 (1998); Okamoto and Tanaka, Nucl. Instr. Meth. A 437 (1999) 178], we proposed a novel experimental approach to investigate various collective effects in space-charge-dominated beams. It was demonstrated that either a radio-frequency quadrupole trap or a solenoidal trap could reproduce non-linear processes equivalent to those in a beam transport channel. In the present work, we study the former trap configuration in more detail, specifying a typical parameter range for beam-physics applications. A three-dimensional Maxwell-equation solver is employed to show the basic characteristics of the plasma confinement field. After deriving several useful formulae, we discuss possible trap experiments that greatly deepen our current understandings of collective beam instabilities including coherent resonances, halo formation, etc