A new charge selector is currently under development at FRIB to intercept unwanted charge states of higher-power 17 - 20 MeV/u stripped heavy ion beams. The charge selector is located in the first bending segment of the FRIB linac, where high dispersion separates charge states to allow for their selection. The design concept is based on rotating graphite cylinders that act as an intermediate heat transfer medium, efficiently absorbing beam power and radiating it to a water-cooled heat exchanger. The power in the beam spot of up to 5 kW and the rms spot width as small as 0.7 mm present significant design challenges. Beyond thermal stress, the proposed design addresses the effects of radiation damage and implantation of the intercepted ions. The challenges of the engineering design associated with high temperatures, thermal expansion, rotation and linear actuation feedthrough into vacuum, as well as radiation shielding and remote handling, will be discussed. A comprehensive exploration of these challenges aims to contribute to the broader field of beam interception technology.

Charge stripping is inherent for high power ion accelerators such as the FRIB LINAC. However, at high power, strippers require motion to prolong the operational life of the stripping media, or by flowing a liquid Lithium film. The charge stripping process introduces energy losses that vary with the actual Lithium film thickness, which can result in observable beam losses along the tuned beamline at high on-target beam power, above ~100 kW, if not adequately mitigated. BPM phase feedback is used in real-time to compensate for these effects, controlling upstream RF cavities in order to maintain a constant beam energy and phase post-stripper, which significantly reduces beam energy fluctuations.

The folded Linear Accelerator (linac) at the Facility for Rare Isotope Beams (FRIB) presents many challenges to effectively utilizing beam loss monitors (BLMs) for machine protection. Dozens of ion chambers and neutron detectors are installed at various locations in the linac tunnel to monitor radiation from beam losses. Each device must be configured with thresholds to meet machine protection requirements for an array of beam destinations, ion species, beam energies, beam power, and response times. This presents an extremely large configuration space with numerous use-cases and beam modes to account for. We present a largely automated tool to effectively manage BLM thresholds that requires minimal input from operators.

The Facility for Rare Isotopes Beams started operation nearly two years ago and ramped up beam power by a factor of 10 from 1 kW to 10 kW. The main contributions to the beam losses are due to the beam halo generated in the ion source and low energy beam transport, the effect of the stripper, and multiple charge state acceleration. The linac tuning procedure includes setting both RF cavity fields, phases, and beam optical devices based on pre-calculated values followed by Courant-Snyder parameters matching based on profile measurements in several linac sections. The simultaneous acceleration of multiple charge states of heavy ion beams is routinely used to minimize the beam power deposition on the charge selector slits after the stripper and provide higher power on the target for the heaviest ions with limited intensity from the ion source. Recently, we added acceleration of dual charge state beams, which is a significant challenge due to the absence of the central charge state but highly desirable for light ions (Z<50) to reduce controlled beam losses on the charge selector. The optics at the Beam Delivery System are optimized to simultaneously focus all charge states into the required phase space on the target. The transverse and longitudinal envelop mapping is applied for each charge state to confirm low-loss linac tuning. The uncontrolled beam losses for any ion species from neon to platinum at the entire linac are well below 1e-4.