Speaker
Description
Since May 2022, the Facility for Rare Isotope Beams (FRIB) has been delivering various heavy ions ranging from oxygen to uranium on target with energy up to 300 MeV/u for user operation. The primary beam power has been steadily raised from 1 to 10 kW with a successful demonstration of multi-charge simultaneous acceleration after a stripper. Over the next five years, an incremental ramp-up to the ultimate design beam power of 400 kW is planned. It is more challenging to operate high-power heavy-ion facilities than those of electron and proton due to higher power deposition density and higher radiation damage, as well as the necessity for the frequent switches of beam species. Both carbon foil and liquid lithium film strippers are currently used to boost ion charge states around 20 MeV/u. Although multi-charge states are selected for further acceleration simultaneously, for some ions, up to 10 kW undesired charge states will dissipate on the charge state selector. Regulation of low-level RF is being developed to stabilize beam energy due to the instability of lithium film. Beam collimators in the front-end and stripper area have been implemented. Adding more refined collimation along the linac to reduce uncontrolled losses is being investigated. Besides the traditional beam loss monitors, halo monitor rings and thermal sensors at both cryogenic and room temperatures are used to detect low beam losses. We will share our operational experience and discuss the challenges of beam power ramp-up.
Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0023633, the State of Michigan, and Michigan State University.
