MOPP042
FRIB, East Lansing, Michigan, USA
For the FRIB driver linac, two different types of fundamental power couplers will be used to provide cw rf power to four cavity types. A cold window design is being used to power the two 80.5 MHz QWR cavity types for β=0.041 and β=0.085. A warm window design is being used to power the 322 MHz HWR cavity types for β = 0.29 and β = 0.53. Topics discussed include coupler preparation & assembly methods, acceptance criteria, diagnostics and RF conditioning.
FRIB, East Lansing, Michigan, USA
NSCL, East Lansing, Michigan, USA
LBNL, Berkeley, California, USA
Project funded by Michigan State University
TUPP044
FRIB, East Lansing, Michigan, USA
Michigan State University is currently testing production cavities as part of final validation of fully dressed 80.5 MHz β=0.085 quarter wave resonators (QWR) and β=0.53 half wave resonators (HWR), which are being produced for a driver linac for the Facility for Rare Isotope Beams. This paper updates the developments for the FRIB and ReA resonators as preparations at MSU are being made for production runs.
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.
THPP047
FRIB, East Lansing, Michigan, USA
INFN/LNL, Legnaro (PD), Italy
A robust and extensive program of testing using the superconducting cavity vertical test facility at MSU has been used to validate cavities and ancillary systems for FRIB. The facility has been used to validate final designs of dressed HWR & QWR cavities with integrated tuners and LLRF control systems. In each test (QWR & HWR), the FRIB coupler is working at the full rated power at the full cavity field for long term operation integrated with the FRIB LLRF controller. The final validation of the SRF subsystems are achieved with long term stable lock with FRIB specified parameters for amplitude and phase control. Topics discussed include the dynamic loads of couplers and tuners, microphonics affects & QWR mechanical mode damping, and the model used to predict RF BW requirements for stable operation based on fundamental design parameters.