FRIB, East Lansing, Michigan, USA
Measurement of beam phase-space area via rms emittances in solenoid focusing channels with linear x-y coupling is complicated relative to transport channels with decoupled plane focusing. This stems from correlated azimuthal flow of the beam induced by the coupled focusing influencing how the thermal component of the flow should be measured. This is exacerbated when the beam has finite canonical angular momentum – as is the case for beams born in a magnetic field in ECR-type sources. In this study, simple measures of rms emittance for use in solenoid transport for beams with canonical angular momentum are motivated and overviewed. Emphasis is placed on simple to interpret emittance measures which reduce to familiar forms for decoupled plane motion. These emittances are applied in Warp PIC simulations of the near-source region of the FRIB linac front-end. In these simulations, a multi-species heavy-ion dc beam emerging from an ECR source are simulated primarily in transverse slice mode using a realistic lattice description. Emittance growth due to nonlinear applied fields, space-charge, and partial neutralization is analyzed including the influence of net canonical angular momentum.
TUO1LR01
FRIB, East Lansing, Michigan, USA
The Facility for Rare Isotope Beams (FRIB) is a new generation national user facility for nuclear science under establishment at the Michigan State University. The cw superconducting driver linac will accelerate all stable isotopes (from protons to uranium) to energies above 200 MeV/u with a beam power of up to 400 kW. To meet the output beam power requirements for ions heavier than xenon, two charge states will be selected from an ECR ion source and accelerated simultaneously in every other rf bucket through RFQ and Segment 1. After the acceleration in Segment 1 up to 20 Mev/u, a charge stripper is used to boost charge states for heavy ions and thus increase the acceleration efficiency for the rest of the linac. Multiple charge states (up to 5 depending on ions) will also be selected after stripper and further accelerated in Segment 2 and Segment 3 in the same rf bucket before delivery to a target. Beam dynamics associated with simultaneous acceleration/transport of multi-charge-state ions in the high power machine will be reported.
FRIB, East Lansing, Michigan, USA
Facility for Rare Isotope Beams (FRIB) is a high-power heavy ion accelerator facility presently under construction at Michigan State University located in Michigan. FRIB consists of a CW driver linac, experimental facility, the linac accelerates ions up to uranium with the energy of 200 MeV/u and with the beam power of 400 kW. As the assumed beam power is more than two order of magnitude higher than the existing heavy ion linac facilities, various beam dynamics challenges are assumed for the driver linac. In this paper, beam dynamic challenges for FRIB driver linac and undergoing studies to address them are reviewed, which would include those related to machine protection and collimation of halos after a stripper.