The Facility for Rare Isotope Beams (FRIB) is a high-power heavy ion accelerator facility at Michigan State University that completed in 2022. Its driver linac is designed to accelerate all stable ions to energies above 200 MeV/u with beam power of up to 400 kW. Currently, FRIB is operating between 10 to 20 kW, delivering multiple primary beam species. The beam dump absorbs approximately 75% of the primary beam power. The existing beam dump head can accommodate up to 20 kW operation, with a planned transition to an optimized mini-channel beam dump design with capability up to 30 kW and beyond. Presented here is an overview of the mini-channel beam dump head design optimization and supporting analysis.

The SiC acts as the primary barrier against the release of fission products in the TRISO-type fuel. For the present generation, SMR technology A highly explored area for optimizing commercial nuclear fuel efficiency is managing the Kr/Xe fission gas budget, as these gases act as time limiters due to thermal fission gas swelling or nucleating high swelling behaviour (HSB) structures' expansion. In this study, we investigate irradiation stability of SiC(TiO2) Al2O3 composit. Alumina is recognized for its role in enhancing adhesion under high-temperature conditions, while TiO₂ functions as a binding agent within the matrix. The sample (Al₂O₃)x(TiO₂)ySiCz, where the concentration x=y=0-10,z=1-x+y was prepared by the additive method using pure powders pressed into pellets, followed by dual-step sintering for 10 and 14 hours at 1000°C and 1400°C, respectively. The samples were irradiated with a 800 keV Ar⁺ beam at doses ranging from 1e15 to 1e17 atoms/cm². The crystal structure, morphology, and physical properties were studied in pre- and post-irradiation conditions using characterization techniques such as RBS, FESEM, XRD, TEM, and nano-indentation.

Cocktail beams, composed of multiple ion species with tailored energy and composition, have emerged as a transformative tool for simulating the synergistic irradiation effects experienced by structural materials in advanced nuclear reactors. This study demonstrates the development of cocktail ion beams at the Low Energy high-intensity heavy ion Accelerator Facility (LEAF), leveraging a fourth-generation superconducting ECR ion source (FECR) and energy modulation systems to generate high-intensity, low-energy-spread beams. Key innovations include a drift tube linac (DTL) and rebunchers, enabling precise energy tuning to align ion penetration depths. To validate the radiation-induced damage characteristics of mixed-ion beams, irradiation responses of monocrystalline copper were systematically compared across different irradiation modalities. The analysis reveals that simultaneous cocktail beam exposure induces markedly distinct microstructural evolution compared to sequential irradiation (e.g., Fe→He or He→Fe) and single-ion (e.g., Fe or He) irradiation protocols under equivalent displacement damage conditions.

The FRIB, a leading experimental nuclear physics facility, produces high-intensity beams of proton- and neutron-rich nuclei. FRIB provides high-yield, high-purity rare isotope beams via primary beams interactions with a graphite target. After the target, the unreacted primary beam should be absorbed by a beam dump. To support operations at 20 kW, an intermediate beam dump system, called the minichannel beam dump (MCBD), has been developed and implemented. This system features a static structure oriented at a 6° angle, reducing power density by 10 times. The MCBD is fabricated as a bimetal using an Al-Cu alloy, with a high-thermal-conductivity copper absorber for enhanced heat dissipation and 2 mm × 7 mm aluminum cooling channels that prevent copper oxidation and significantly improve cooling efficiency. The thermal performance of the MCBD was validated through experimental testing using a 17 keV e-beam at the Applied Research Laboratory, showing measured temperatures matching ANSYS simulation within 10% uncertainty. These results indicate that the MCBD can reliably support FRIB operations at 20 kW or higher, ensuring effective heat dissipation under high-power conditions.

The Facility for Rare Isotope Beams (FRIB) at Michigan State University is a high-power heavy-ion accelerator, completed in 2022. Its driver linac is designed to accelerate all stable ions to energies exceeding 200 MeV/u, with a maximum beam power of 400 kW. Currently, FRIB operates at beam powers between 10 and 20 kW, delivering multiple primary beam species. Approximately 75% of the primary beam power is absorbed by the beam dump. The existing mini-channel beam dump (MCBD) absorber is designed to handle up to 20 kW, with plans for an optimized beam dump capable of supporting 30 kW and beyond. This paper presents the design-by-analysis procedures outlined in ASME Boiler and Pressure Vessel Code that have been applied to the MCBD design.

To intercept unwanted charge states from stripped beams with higher power densities, an advanced charge selector is currently under development at the Facility for Rare Isotope Beams (FRIB). This upgraded charge selector is designed to intercept beam spots that have a power of up to 5 kW and an rms size as small as 0.7 mm × 1.25 mm. To enhance heat dissipation and mitigate thermal stress, rotating graphite wheels are employed as the beam-intercepting medium. An essential aspect of this design is the development of a robust vacuum system to ensure reliable and efficient operation while minimize beam losses in downstream sections. The high graphite temperature, maintained over 1000 °C for radiation damage annealing, raised concerns about gas load. To aid the vacuum system design, vacuum simulations were carried out using a Monte Carlo-based simulation code, MolFlow. The sublimation of graphite, outgassing from the vacuum chamber’s inner wall and the effect of pumping speed on vacuum performance are considered. The results demonstrate that the proposed vacuum system can maintain a pressure under $1×10^{-7}$ mbar, ensuring adequate vacuum conditions for beam operations.

The RF beam sweeper is a crucial component for radioactive ion beam production, which enhances the purity of in-flight produced rare isotope beams by introducing a time-of-flight separation. The current sweeper operates at ATLAS’s subharmonic frequency of 6 MHz using 1-meter-long electrode plates and a maximum deflecting voltage of 55 kV, which is sufficient for the separation of certain beams. However, the new capabilities, enabled by the recently commissioned in-flight radioactive beam separator RAISOR demand higher voltages and higher frequency operation. To address these needs, we are developing an advanced RF sweeper capable of switching between 6 MHz and 12 MHz, depending on the beam, with a maximum deflecting voltage of 150 kV. The design is based on a resonant circuit with electrode plates and an adjustable coil, along with a sliding contact switch for frequency switching. This talk presents the sweeper design and fabrication progress.

- Laboratories such as Oak Ridge, Fermilab, and Jefferson Laboratory have been developing plasma cleaning techniques for superconducting radio-frequency (SRF) cavities. These techniques show promise as an in-situ method of mitigating degradation in cavity performance via removal of surface hydrocarbon contamination. Plasma cleaning studies for SRF cavities in the driver linac at the Facility for Rare Isotope Beams (FRIB) began in 2020.  Both neon-oxygen and argon-oxygen plasmas have been found to be effective in improving FRIB accelerating cavities. The ignition threshold RF electric field can be predicted for a diffusion-dominated plasma using the solution to the diffusion equation for a given cavity shape; a numerical solution is needed for realistic cavity shapes.  Predictions for several cavity shapes will be presented and compared to available plasma ignition threshold measurements.

In general, accelerator facilities are controlled by a huge number of parameters. The RIKEN RI Beam Factory (RIBF), a heavy-ion accelerator complex consisting of several cyclotrons and Linacs, is controlled or influenced by more than 600 parameters, including environmental factors. To optimize these parameters more efficiently and accurately, we are attempting to implement Bayesian optimization (BO). Given the importance of space charge effects and beam loading, it is desirable to adjust parameters at high beam intensity, making it crucial to develop an optimization system capable of handling high-intensity heavy ion beams. We have been working on developing indices suitable for high-intensity beams and exploring methods for optimization while maintaining operational safety. So far we developed a technique that enables the simultaneous measurement of beam transmission and spot shape on the target by tracking charge-converted particles after passing through the target. Additionally, we are investigating the use of line BO with a safety function to ensure safe beam optimization. Currently, we are preparing for simulations and tests using beam line.

We have developed a browser-based user interface for AI-ML applications at Argonne’s ATLAS ion linac facility. The new interface is named the “ATLAS AI-ML Dashboard”, it is based on the web application package, Dash, and customized to easily include any ATLAS beamline and select from several beam tuning options and optimization algorithms. The interface is being introduced to the operators and their feedback will be used to further improve its capabilities. Among the features that are being added is the extraction of the initial beam parameters, from pepper-pots and quad scans, to use as input for the optimization procedure. In addition to presenting the main features of the ATLAS AI-ML interface, we will also present the first online experience of the operators.

Data inaccuracies make training an accurate Beam Quadrupole Moment at BPM (BPMQ) model challenging. Similarly, reconstructing Courant-Snyder (CS) parameters from BPMQ predictions is difficult due to BPMQ model limitations. Increasing the number of BPMQ predictions helps mitigate overfitting in CS inference caused by inaccurate BPMQ predictions. We present Bayesian Active Learning (BAL) to acquire measurements strategically, improving CS parameter inference despite model limitations.

High reliability is a major challenge of high-current linear accelerators. This is particularly problematic for Accelerator Driven Systems(ADS) such as the China initiative Accelerator Driven System(CiADS). In order to achieve rapid beam recovery, it is necessary to adjust and compensate the cavities adjacent to the failed cavity. In this study, we employ the Proximal Policy Optimization (PPO) algorithm, a reinforcement learning technique, to train a compensation model within a simulated environment of the CiADS superconducting HWR010 section. Compared to previous methods utilizing genetic algorithms, the reinforcement learning approach demonstrates superior performance in delivering more stable and consistent results.

The Facility for Rare Isotope Beams has begun operations for scientific users since May 2022. To reduce beam loss in the driver linac, we plan to operate two multi-gap bunchers (MGBs) at a higher accelerating voltage. This paper presents progress and lessons learned from the early-stage operations of the MGBs, as well as a summary of the phased high-power conditioning, which progressed from an RF power of 18 kW to 26.5 kW, and then to 30 kW. Both MGBs were successfully conditioned during maintenance periods. After approximately 100 hours of conditioning, MGB1 operated without any trips in the last 12 hours, and MGB2 experienced only three trips during the same period.

Beam instabilities and resonances affect the transverse dynamics in particle accelerators and, when encountered, can trigger emittance growth and beam loss. Resonance lines originate from nonlinear elements and effects in the lattice,and impose strict constraints on the choice of working points and narrow the available tune space. Circular modes—intrinsically coupled, flat-round eigenmodes—provide an alternative beam motion and dynamics. In this study we derive the third-order sextupole resonance conditions in the coupled (normal-mode) parametrization and show that, with circular-mode lattice design and beam operation, most of these resonance lines are naturally suppressed thanks to the mode’s inherent flatness.

Inductive ovens are integral to electron cyclotron resonance (ECR) ion sources, facilitating the generation of high-intensity solid ion beams. At the Facility for Rare Isotope Beams (FRIB), specialized inductive High Temperature Oven (HTO) has been developed to ensure the reliable production of solid ion beams for the High-Power ECR (HPECR) ion source. These HTOs have successfully supported the operation of various solid ion beams, including Silicon, Nickel, and Uranium. In alignment with the FRIB beam power ramp-up objectives, future requirements include increased beam currents and prolonged operational durations for heavier species. To optimize HTO performance in response to these evolving demands, a series of design improvements have been implemented, drawing on insights from previous operational experience. These improvements are intended to enhance both operational stability and beam consistency. The detailed improved design, Ansys® simulation results, and testing results will be presented and discussed.

An upgrade of the magnetic field profile of the Texas A&M 14.5 GHz electron cyclotron resonance ion source (ECRIS) is in progress, guided by well-established magnetic-field scaling rules for ECRIS. On the injection end, a new lower-carbon steel plug with a modified design has already been installed to increase the axial magnetic field at the injection end of the plasma chamber. Now, detailed calculations, using the permanent-magnet code PANDIRA, have been performed to optimize the radial magnetic field of the hexapole. A new aluminum plasma chamber will soon be constructed with more reliable cooling. Finally, six new NdFeB permanent-magnet bars will be installed in the new chamber before the final replacement of the old plasma-chamber-hexapole assembly. Together, these modifications are expected to significantly improve the performance of the ion source by achieving better plasma confinement and by enhancing beam stability, eventually leading to an increase in high-charge-state ion production.

A 325 MHz RF Fundamental Power Coupler (FPC) designed to operate under 20 kW CW in the high energy SC Linac of the RAON. One of the most important consideration in the FPC EM design is to reduce and eliminate a multipacting (MP) activation in both TW mode and SW mode. Prior to the MP reduction design, the MP bands of the FPC was computed with CST Particle Studio. It was confirmed that third or higher order of MP bands were activated within the operating range on the surface condition of the coupler. Therefore, designs to suppress MP are needed. To eliminate MP, a DC voltage was applied to center conductor of the FPC. Detailed the simulation modeling and computational analysis results where MP was effectively suppressed for both modes are presented.

The Facility for Rare Isotope Beams (FRIB) radio frequency quadrupole (RFQ) runs in continuous wave mode at 80.5 MHz with an input power up to 120 kW. The current tetrode amplifier had some failures and was greatly improved during commissioning and early operations. However, some potential failures may cause long repair time and compromise overall system availability. In comparison, the solid state amplifiers have shorter repair time due to the modular design and absence of high voltage. Currently FRIB is commissioning the 120 kW solid state amplifier system. It uses the same 2 kW 80.5 MHz modules as those used in FRIB linear segment 1. This allows the sharing of spares as well as reducing the effort for developing new controls and maintenance procedures. Each of the eight racks includes six amplifier modules and can output 15 kW power into a matched load. The system uses 3 dB quadrature hybrid couplers in a 3-stage corporate power combining scheme to achieve 120 kW. The paper will detail the design and commissioning of this system.

High-power proton/ion linear accelerators have important applications in both scientific research and industry. However, operation of such accelerators with megawatt-level beam power is expensive and limits the broad availability of those facilities. In this study, we propose a novel energy recovery ion linear accelerator in which the final high-energy GeV-level ion beam is reused to give its energy back to the RF fields in the accelerator. This substantially reduces the power consumption of the linear accelerator and also avoids the need for a high-power beam dump.

A ramping rate of 12 T/s is designed for the dipole magnet of BRing at HIAF. To reduce eddy current effects, a titanium alloy lined chamber with a 0.3 mm titanium alloy inner liner by 3D printing and an ultra-thin stainless steel outer wall has been adopted. To reduce the internal pressure and enhance the beam lifetime, a film of TiZrV is coated on the chamber. The ultimate vacuum of the titanium alloy-lined vacuum chamber is tested, which indicates that after coating with TiZrV, the pressure at the middle of the chamber reduced, effectively reducing the pressure in the central region. The life of the TiZrV film was studied by repeated activation and venting cycles under two conditions of N2 and air filling. With N2 filling, after 15 activation cycles, the vacuum in the middle of the chamber showed no significant change. However, with air filling, after 7 activation cycles, the vacuum in the middle degraded, indicating a decline in the pumping performance of the TiZrV film. Air exposure significantly impacts the life of the film, necessitating that TiZrV films be protected with N2 in applications and minimizing exposure time.

HIAF-BRing, the main synchrotron accelerator of the High Intensity Heavy-Ion Accelerator Facility, requires an average pressure lower than $1 × 10^{−9}$ Pa and the magnetic field increase rate of no less than 12 T/s to fulfill radioactive beam physics and high energy density physics experiments. To reduce the eddy current effect and the gap size of dipoles, a titanium alloy-lined thin-walled vacuum chamber with a wall thickness of 0.3 mm is proposed by IMP, which has been developed from the initial ceramic-lined vacuum chamber. By mechanical loading testing, when the internal stress of titanium alloy rings made by 3D selective laser melting (SLM) reaches 639 MPa, it is still within the elastic deformation range, in fact, the yield strength of the 3D printed titanium alloy material is 912 MPa. In order to reduce the pressure gradient inside the thin-walled vacuum chamber caused by the surface outgassing of the rings, TiZrV thin fflms have been deposited on the rings by planar target magnetron sputtering. Through TiZrV deposited on the rings, the pressure at the middle of the thin-walled vacuum chamber has been dropped from 1.5 × $10^{−9}$ Pa to 1.0 × $10^{−9}$ Pa.

This paper will present design principles, procurement strategies, installation and testing plans, and availability data from commissioning and operation of over 1500 magnet and electrostatic power supplies at the Facility of Rare Isotope Beams (FRIB). This paper introduces the types of power supplies required for the FRIB which range in size from electrostatic high voltage power supplies less than 1 Watt to 150 kW magnet power supplies. The power supplies range in complexity from simple single quadrant units to four-quadrant pulsed electrostatic high voltage units to units requiring complex auxiliary equipment. Stability requirements of these power supplies range from 10 ppm for some sensitive experimental equipment to 3000 ppm for some multipole magnets.

A 5-cell elliptical superconducting radio-frequency (SRF) cavity (644 MHz, beta = 0.65) is being developed at Michigan State University for the proposed FRIB driver linac energy upgrade (FRIB400). The cavity is not equipped with higher-order mode (HOM) couplers and the fundamental power coupler (FPC) coupling strength is relatively weak (loaded bandwidth = 32 Hz) due to CW operation, so a key challenge is to perform effective cavity plasma processing while avoiding plasma ignition in the FPC region; FPC ignition could otherwise lead to copper sputtering onto the niobium cavity surfaces or damage to the FPC ceramic window. In this study, we examined the feasibility of plasma processing by driving HOMs through the FPC. With a combination of TE111 passband modes, we were able to sustain plasma in each of the 5 cells without FPC ignition. We will present measurements of the plasma density as a function of drive mode, input RF power, drive RF frequency shift, and gas pressure, and will discuss an optimized cleaning recipe for future FRIB400 cryomodules.

The Argonne Tandem Linac Accelerator System (ATLAS) has been a National User Facility since 1985. Since the commissioning of the Californium Rare Isotope Breeder Unit (CARIBU) in 2012, it has used 2 bespoke water-cooled linear power supplies to allow for milliamp control of the isobar separator magnets, which allows for milligauss control of the magnets. During the upgrade to nuCARIBU, the aging linear power supplies were replaced with off-the-shelf (OTS) switched mode power supplies (SMPS). The benefit of the SMPS is higher efficiency and since they are air-cooled, no load on the water cooling system, while the detriment is the decrease in resolution of the current control. To overcome this limitation, a device was constructed that allows control of a sub-milliamp constant current sink, which is placed in parallel to the magnet. This arrangement allows the control system to “leak” a precise amount of current away from the magnet, effectively giving sub-milliamp control of the current going into the magnet.

A magnetic quadrupole pick-up structure is being assessed for creation and future use at The Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU). The geometric design makes use of magnetic loops that couple with the radial magnetic field of a beam, allowing for rejection of the common mode of the beam, while leaving the dipole signal as the dominant signal and enhancing the quadruple signal of the beam. Of interest is examining the response due to the multiple charge state heavy ion beams that FRIB produces and the ability to resolve the differing charge states. Presented here is the optimization of the device for the FRIB beamline.

At FRIB, a chopper in the low energy beamline is used for beam power control as well as machine protection through beam mitigation. An FPGA based monitoring system was developed to govern the chopper’s operation and ensure that it is functioning properly. This chopper monitoring system conducts checks of the incoming chopper control signal, the high voltage being applied to the chopper plates, and the current flow to and from the plates as the voltage is applied and removed. A curve fitting, or calibration, is required to convert from a digital value to a user readable physical quantity, and vice-versa for the input of acceptable threshold settings for machine protection purposes. As the chopper is functionally a capacitor, the current flow, as high voltage is applied or removed, will vary with level of HV applied and with any change in the capacitive load. This reality makes calibration of the chopper current readings difficult, and an analytical approach was adopted to overcome these difficulties and ensure satisfactory functioning of the monitoring system. This analytical process and a subsequent calibration of the chopper monitor will be discussed in detail in this paper.

The “Super Separator Spectrometer” project S3 is under technical commissioning at the GANIL facility (Caen-France). It is a new research installation designed for fundamental physics experiments with high intensity radioactive heavy ions beams produced by the SPIRAL2 linear accelerator. This spectrometer will open new horizons for nuclear physics. The S3 spectrometer is made of seven Superconducting Multipole Triplets (SMT) to guide and focalize the beam and select the particles of interest. This paper presents SMTs technology and their magnetic, electrical and cryogenic operating characteristics as well as their technical commissioning for the S3 project.