Heavy ion storage ring without linear dispersion

Abstract

A possible method to realize a dispersion-free storage ring is described. The simultaneous use of a magnetic field B and an electric field E in bending regions, where the two fields are set perpendicular to each other, enables us to control the effect of momentum dispersion. When the relation 1 1= 2 0 E ÿv 0 B is satisfied for a beam with the velocity v 0 , the linear dispersion can be completely eliminated all around the ring. It is shown that the acceleration and deceleration induced by the electrostatic deflector counteracts the heating mechanism due to the shearing force from dipole magnets. The dispersion-free system is thus beneficial to producing ultracold beams. It looks probable that the technique will allow one to achieve three-dimensional crystalline beams. At ICR Kyoto University, an ion cooler storage ring S-LSR oriented for various beam physics purposes is now under construction. The application of the present idea to S-LSR is discussed and the actual design of the dispersionless bend is given.

Resonance coupling induced enhancement of indirect transverse cooling in a laser-cooled ion beam

“…It has been concluded that a beam phase transition to 1D string or 2D zigzag is feasible by the conventional Doppler cooling technique, provided that a sufficiently powerful laser is employed together with the SBRC technique. The production of a 3D crystalline beam further requires the so-called tapered cooling [12,30] or a combination of dispersionfree bending elements [31] and a coupling cavity [10,32], in order to avoid shear heating.…”

Electrostatic deflectors and dispersion suppressors: Their formulation and application to a storage ring

“…This condition is completely the same as the dispersion-free condition shown in Ref. [14]. When the dispersion-free condition qV 0 = 2 0 2 0 E 0 1 is imposed, the equations of motion become…”

“…We reported the beam dynamics in a dispersion-free storage ring S-LSR constructed with the cylindrical dispersion suppressor of the field index 1 [14]. The result is that S-LSR cannot operate satisfying the maintenance condition for crystalline beam due to the strong radial focusing of the cylindrical dispersion suppressor.…”

“…It has been suggested that a storage ring constructed by a bending element simultaneously using electric field and magnetic field can eliminate the shear [11]. This element also can eliminate the linear dispersion of the beam [12,13], together with the shear [14]. Therefore such deflector is called a dispersion suppressor.…”

“…In Ref. [14], the condition for crystalline beams in dispersion-free rings was investigated. It was found that the formation condition is satisfied in any dispersion-free storage ring, in principle.…”