FRIB, East Lansing, Michigan, USA
The FRIB driver linac accelerates CW beams of all stable ions up to uranium to the energy of 200 MeV/u with the beam power of 400 kW. We plan to start staged beam commissioning in December 2017 in parallel with ongoing installation activities. This allows early recognition of technical issues, which is essential for smooth commissioning and early completion of commissioning goals. As the interlaced nature of commissioning and installation poses both scheduling challenges and special safety issues, it is essential to develop a commissioning plan with focused consideration of each. In this paper, we present a commissioning plan with emphasis on its characteristic features.
FRIB, East Lansing, Michigan, USA
The Facility for Rare Isotope Beams driver linac provides CW beams of all the stable ions (from protons to uranium) with a beam power of 400 kW and a minimum beam energy of 200 MeV/u in order to produce a wide variety of rare isotopes, mainly for nuclear physics study. The low beam emittances, both transverse and longitudinal, are key performance requirements, together with beam stability. These are required for efficiently separating one isotope from another, the reason for choosing this linac configuration. Multi-charge states (five charge states for the uranium case) are accelerated for maximizing the beam current, while keeping the low emittances. The efficient acceleration of high beam currents from 0.5 MeV/u through the superconducting linac is, needless to say, one of the biggest challenges. The beam power is more than 200 times higher than existing similar SC heavy ion linac. In particular, the SC cavities are difficult to protect from heavy ion beam damage, which can be 30 times larger locally than a proton beam with the same beam power. Other challenges peculiar to the FRIB linac will be presented, together with the solutions.
FRIB, East Lansing, Michigan, USA
FRIB is a $730M heavy ion accelerator project and a very large scale machine for many nuclear physics users. The civil construction started on March 17th 2014. The SRF system design and development have completed. The machine is to be in early completion end of 2019. FRIB accelerates ion species up to 238U with energies of no less than 200MeV/u and provides a beam power up to 400kW. Four SRF cavity families are used from β=0.041, 0.085 (QWRs) to 0.29 and 0.53 (HWRs). 8T superconducting solenoids are installed in the cryomodules for space effective strong beam focusing. The biggest challenges are in accelerating the high-power heavy ion beams from the very low energy to medium energy and the stable operation for large user community. The SRF cryomodule design addressed three critical issues: high performance, stable operation and easy maintainability, which chose several unique technical strategies, e.g.2K operation, bottom up cryomodule assembly, local magnetic shielding and so on. This talk will include high performance cavity R&D, local magnetic shielding, flux trapping by solenoid fringe field, and bottom up cryomodule assembly.
