FRIB, East Lansing, USA
NSCL, East Lansing, Michigan, USA
The linear accelerator in the Facility for Rare Isotope Beams (FRIB) will use Electron Cyclotron Resonance (ECR) sources. ECR sources can generate a high-brightness DC beam with high charge states. However, the ECR sources produce numerous species that must be collimated to one or two target species with minimal degradation to beam quality. The first stage of this collimation is accomplished in a tight 90 degree dipole bend with a wide aperture and slanted pole faces to provide additional focusing. We report on simulations for the high-rigidity U ion operation using linked 2D xy-slice runs in the straight section upstream of the bend and steady-state 3D simulations in the dipole bend comparing simulations with both ideal (sector) and full 3D field maps of the dipole magnet. Issues associated with placing a 3D dipole field with fringe on a bent simulation coordinate system are addressed. Placement of the dipole bend is optimized consistent with the 3D field and is found to closely correspond to the ideal field center. Minimal problems are found (small centroid shift and distribution distortions) due to 3D space-charge effects in the species separation within the bend when using simple fractional neutralization factors.
NSCL, East Lansing, Michigan, USA
FRIB, East Lansing, USA
Self-consistent simulation studies of the FRIB low energy beam transport (LEBT) system are conducted with the PIC code Warp. Transport of the many-species DC ion beam emerging from an Electron Cyclotron Resonance (ECR) ion source is examined in a realistic lattice through the Charge Selection System (CSS) which employs two 90-degree bends, two quadrupole triplets, and slits to collimate non-target species. Simulation tools developed will support commissioning activities on the FRIB front end which begins early operations in 2017. Efficient transverse (xy) slice simulation models using 3D lattice fields are employed within a scripted framework that is readily adaptable to analyze many ion cases and levels of model detail. Effects from large canonical angular momentum (magnetized beam emerging from ECR), thermal spread, nonlinear focusing, and electron neutralization are examined for impact on collimated beam quality.
ANL, Argonne, USA
Soreq NRC, Yavne, Israel
The motivations and the concept for the multi-user upgrade of the ATLAS facility at Argonne were presented at recent conferences. With the near completion of the integration of the CARIBU-EBIS for more pure and efficient charge breeding of radioactive beams, more effort is being devoted to study the design options for a potential ATLAS mutli-user upgrade. The proposed upgrade will take advantage of the pulsed nature of the EBIS beams and the cw nature of ATLAS, in order to simultaneously accelerate beams with very close charge-to-mass ratios. In addition to enhancing the nuclear physics program, beam extraction at different points along the linac will open up the opportunity for other possible applications. Different beam injection and extraction schemes are being studied and will be presented.
IMP/CAS, Lanzhou, People's Republic of China
