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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Pre-commissioning of the wide-dynamic range halo monitor to be installed in the Fermilab MI-8 line

The beam halo can contribute to beam losses in accelerators and is very difficult to measure. With an increase in beam intensity following the PIP-II upgrade at Fermilab, the beam losses are expected to be higher with some coming from beam halo. Therefore, it is important to measure the sources of beam halo to minimize the beam losses. A modified Halo Monitor developed by J-PARC will be installed in Fermilab MI-8 transfer line to measure the beam halo. In this paper, an update on the beam profile monitor fabrication is covered. The updates include the location selection for the Halo Monitor in the MI-8 transfer line, shielding options for instrumentation, initial testing of equipment, and ray tracing simulations for the Offner optics and the targets used in the monitor.

Babacan, Betiay [IIT, Chicago; Fermilab]↗
DOE OSTI2016

Consideration of neutral beam prompt loss in the design of a tokamak helicon antenna

Neutral beam prompt losses (injected neutrals that ionize such that their first poloidal transit intersects with the wall) can put appreciable power on the outer wall of tokamaks, and this power may damage the wall or other internal components. These prompt losses are simulated including a protruding helicon antenna installation in the DIII-D tokamak and it is determined that 160 kW of power will impact the antenna during the injection of a particular neutral beam. Protective graphite tiles are designed in response to this modeling and the wall shape of the installed antenna is precisely measured to improve the accuracy of these calculations. Initial experiments con rm that the antenna component temperature increases according to the amount of neutral beam energy injected into the plasma. Incorporating neutral beam prompt loss considerations into the design of this in-vessel component serves to ensure that adequate protection or cooling is provided.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Characterization of beam ion loss in high poloidal beta regime on EAST

A critical issue for achieving the integrated operation of steady-state long-pulse high-confinement (H-mode) plasmas on experimental advanced superconducting tokamak (EAST) is to improve beam ion population confinement during neutral beam injection (NBI). To study the characterization of beam ion loss and improve beam ion confinement, the steady-state long pulse scenario discharges were conducted on EAST (β p $\geqslant$ 2.0, β N $\geqslant$ 1.7, q 95 $\geqslant$ 6.7 and H 98y2 $\geqslant$ 1.1) with NBI heating. Based on neutron yield, the beam voltage and line-averaged electron density were adjusted from 50 kV to 60 kV and 4.4 × 10 19 m –3 to 5.0 × 10 19 m –3 , respectively. The results show that the dominant mechanisms of beam ion loss are shine-through loss, prompt loss, and stochastic ripple loss. The shine-through loss fraction is determined by initial velocity, flight time and entire beam path. The change in prompt loss fraction is caused by the change in the deposition of beam ions. The change in stochastic ripple loss fraction is caused by the change in the initial fraction of trapped-confined ions. Detailed physics shows that the prompt loss fraction during counter-Ip injections (~45%) is far larger than during co-Ip injections (~5%) due to the finite orbit width. The lost ions are mainly deposited on the lower divertor or below the midplane since the direction of magnetic drift is vertical down. The orbit types of prompt loss during counter-Ip injections are mainly trapped-lost and ctr-passing lost. To minimize the prompt loss fraction during counter-Ip injections, a reversed Ip configuration (rev-Ip) discharge #94758 was conducted. The result suggests that the beam ion wall load fraction during counter-Ip tangential injection (~3%) is far lower than that in normal Ip configuration (nor-Ip) discharge #94820. It is also found that the confinement of beam ion population in the counter-Ip injection #94758 was greatly improved when compared to #94820. Finally, this study can provide unique support for the improvement of beam ion population confinement and for the performance evaluation of the NBI system on EAST and future tokamaks.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Post-DTL Beam Delivery

Ensuring that the beam delivered from the upgraded Front-End (FE) meets the Key Performance Parameters (KPPs) at each user facility is critical to the success of the LANSCE Accelerator Modernization Project (LAMP). For a high-intensity, multi-user facility like LANSCE, compliance with beam loss and radiation thresholds is as important as the charge delivered to each target. While early LAMPF/LANSCE operations relied on iterative tuning to minimize losses from beam halo and tail particles, the new FE may introduce different beam distributions and loss modes—making predictive modeling essential. To manage this, the F2E (Front-End to End) effort is developing detailed particle-tracking models that reflect realistic beamline conditions, including halo formation and expected diagnostic readings. These "snapshot" simulations aim to benchmark live machine performance at a given moment. This will help quantify how beam quality from the new FE will propagate downstream through the facility. Only by validating these models can we confidently assess and mitigate the potential impacts of the LAMP FE on beam delivery. Post-DTL, the beam splits to serve five major user facilities. Historically, low-energy beam transport has been modeled using TRACE, and higher-energy sections with TRANSPORT. These have now been unified into MAD-X format and validated with codes such as Elegant, pyOrbit, XSuite, Impact-Z, and HPSim. The primary focus now is on accurate modeling of full particle distributions (including beam halo) as they traverse the accelerator and beamlines to each experimental station. All models are at various stages of validation with empirical data.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

A Gap Clearing Kicker for Main Injector

Fermilab Main Injector has been operating at high Beam Power levels since 2008 when multi-batch slip stacking became operational. In order to maintain and increase the beam power levels the localized beam loss due to beam left over in the injection kicker gap during slip stacking needs to be addressed. A set of gap clearing kickers that kick any beam left in the injection gap to the beam abort have been built. The kickers were installed in the summer of 2009 and became operational in November of 2010. The kicker performance and its effect on the beam losses will be described.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Measuring Optical Component Radiation Damage

Scintillator based detectors are used to monitor beam losses in the Fermilab accelerator complex. These detectors are approximately 500 times faster than traditional ionization chamber loss monitors and can see beam losses 20 nanoseconds apart. These fast loss monitors are used in areas of the accelerator known to be sources of heavy beam loss and as such, are exposed to high doses of radiation. Over time, radiation exposure reduces the ability of optical components to transmit light by darkening the material. The most dramatic effects are seen in the optical cement and light guide materials comprising the detector. We explore this darkening effect by measuring the transmittance spectra of the detector materials for varying irradiation exposures. Presented here, are the optical transmittance spectra for a variety of radiation exposures and optical materials. The data has revealed an epoxy which withstands exposure far better than traditional optical cements.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Experimental investigation of beam-ion losses induced by magnetic perturbations using the light ion beam probe technique in the ASDEX Upgrade tokamak

The impact of externally applied magnetic perturbations (MPs) on fast-ion losses has been investigated by means of the light ion beam probe (LIBP) technique in the ASDEX Upgrade tokamak. The LIBP technique allows to experimentally infer the fast-ion orbit displacement induced by MPs via first-orbit losses using scintillator based fast-ion loss detector (FILD) measurements. The fast-ion orbit displacement against different applied MP spectra has been studied. These shots were conducted in ELM mitigated H-mode plasmas. A rigid rotation of the MP coils was applied with a frequency of 1 Hz, with an n = 2 configuration and changing the differential phase between the upper and lower set of coils (ΔΦ ul ) on a shot-to-shot basis. Beam sources Q7 (tangential) and Q8 (radial) were used to probe different fast-ion orbits with FILD1. The measured fast-ion orbit displacement ranges from 3 to 20 mm approximately, and no qualitative difference is observed between ions from beam sources Q7 and Q8. The minimum is found for a ΔΦ ul ~ 50°, which is shifted with respect to the minimum of the plasma boundary displacement, found at ΔΦ ul ~ 0°. A first attempt to validate the orbit following code ASCOT—including the plasma response calculated with the MARS-F code—against these experimental measurements is performed. Finally, while the dependence of the first-orbit fast-ion displacement with ΔΦ ul does not match the experimental measurements, these simulations do capture other features such as the order of magnitude of the orbit displacement and the importance of the toroidal spectrum of the applied perturbation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Local Radiation Shielding Design Methodology

The NSLS-II accelerators are housed within a radiation enclosure of normal concrete (and in some places high density concrete) that has been designed to reduce the radiation generated from an assumed operational beam loss or bulk shielding current (BCS) from each accelerator. The beam loss model used to estimate the thickness of this bulk shielding, assumed a beam energy at the expected operating energy and a current loss based on reasonable assumptions for the fraction of the expected operating current. The thickness of the shield was determined to be the amount required to reduce the radiation outside the shield to a maximum dose rate of <0.5mrem/hr. for occupied areas for these normal operational losses. These assumed beam losses and the bulk shielding thicknesses required are given in reference [1]. Abnormal operating conditions generating higher than normal beam losses must also be considered, and additional engineering controls will be required depending on the magnitude of the radiation levels generated during the abnormal condition. Additional local shielding subject to configuration control may be utilized to reduce radiation levels associated with these abnormal loss conditions. Interlocked area radiation monitors are another means to prevent continued operation with higher than an acceptable level. The NSLS-II Shielding Policy requires that an engineered system be utilized to mitigate an abnormal condition producing radiation levels greater than 100 mR/h, and that two systems are required if the projected radiation levels during a fault condition are > 2000 mR/h. It is intended that shielding limits the dose rate to < 0.5 mR/h in occupied areas for normal operational losses, and the combination of administrative and engineered controls for abnormal losses will maintain radiation exposure to trained personnel working at the NSLS-II facility to as low as reasonably achievable. It is anticipated that all individual exposures will be well within the planned administrative control level of 100mrem/year. This technical note presents the method used to identify these potential high beam loss locations, evaluate the potential radiation risk these losses create outside the enclosure shield and the design process that specifies the required local radiation shielding needed to reduce this risk below the maximum dose rate of the bulk shield design, listed above. If shielding can’t be adequately provided or if other fault initiated losses could occur, then the necessary engineering controls will be indicated that will limit the energy, current or duration of the beam transport that constitute this high beam loss risk.

36 MATERIALS SCIENCE↗
DOE OSTI2012

The MICE Muon Beam on ISIS and the beam-line instrumentation of the Muon Ionization Cooling Experiment

The international Muon Ionization Cooling Experiment (MICE), which is under construction at the Rutherford Appleton Laboratory (RAL), will demonstrate the principle of ionization cooling as a technique for the reduction of the phase-space volume occupied by a muon beam. Ionization cooling channels are required for the Neutrino Factory and the Muon Collider. MICE will evaluate in detail the performance of a single lattice cell of the Feasibility Study 2 cooling channel. The MICE Muon Beam has been constructed at the ISIS synchrotron at RAL, and in MICE Step I, it has been characterized using the MICE beam-instrumentation system. In this paper, the MICE Muon Beam and beam-line instrumentation are described. The muon rate is presented as a function of the beam loss generated by the MICE target dipping into the ISIS proton beam. For a 1 V signal from the ISIS beam-loss monitors downstream of our target we obtain a 30 KHz instantaneous muon rate, with a neglible pion contamination in the beam.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Collimation Systems for the PSR

This note provides a review of collimator systems being used or considered in high-intensity proton accelerators like SNS, J-PARC, LHC, and PIP-II. These facilities use collimators to remove beam halo, restrict transverse size and momentum in the beam to constrain beam losses around collimators and minimize beam losses downstream, particularly losses arising from particles missing the design location at the stripping foil when injected into the proton storage ring. Collimators are placed either in the transport injection lines (single-pass collimators) or in the rings (multi-pass collimators). Collimators in the transport line are placed around stripping foils in H- accelerators, allowing the beamline optics to get rid of the unstripped protons into well localized absorbers. Rings and proton accelerators mostly rely on tungsten scrapers and collimators in a multi-stage configuration to clean the scattered beam particles mainly responsible for heavy losses at high energies. Placement of the collimators is carefully chosen in terms of the right phase advance to maximize the collimating efficiency, whether the collimation is intended to match an injection stripping foil or a downstream acceptance. Collimation systems are designed with the specific concerns of each facility in mind, although all of them prioritize the minimization of activation due to beam losses to enable hands-on access during maintenance periods. At LANSCE, there are no high-energy collimators, although pairs of horizontal and vertical jaws are routinely used in the LEBT to clean and control the transverse beam profile delivered downstream. This report will help in understanding, together with the beam dynamics simulations, which collimation schemes would be most effective for the PSR upgrade. For example, SNS designed off-momentum collimators to be placed in a 90° arc bend, a high-dispersion region in the beam injection line, very similar to the bend at Line D in LANSCE. This system was very effective at minimizing losses during injection into the SNS accumulator ring and is being re-designed for future operation.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

OPERATIONAL EXPERIENCE WITH BEAM ABORT SYSTEM FOR SUPERCONDUCTING UNDULATOR QUENCH MITIGATION*

A beam abort system has been implemented in the Advanced Photon Source storage ring. The abort system works in tandem with the existing machine protection system (MPS), and its purpose is to control the beam loss location and, thereby, minimize beam loss-induced quenches at the two superconducting undulators (SCUs). The abort system consists of a dedicated horizontal kicker designed to kick out all the bunches in a few turns after being triggered by MPS. The abort system concept was developed on the basis of single- and multi-particle tracking simulations using elegant and bench measurements of the kicker pulse. Performance of the abort system—kick amplitudes and loss distributions of all bunches—was analyzed using beam position monitor (BPM) turn histories, and agrees reasonably well with the model. Beam loss locations indicated by the BPMs are consistent with the fast fiber-optic beam loss monitor (BLM) diagnostics described elsewhere [1,2]. Operational experience with the abort system, various issues that were encountered, limitations of the system, and quench statistics are described.

Harkay, Katherine C.↗
DOE OSTI2012

The First Observation of Intra Beam Stripping of Negative Hydrogen in a Superconducting Linear Accelerator

We report on an experiment in which a negative hydrogen ions beam in the Spallation Neutron Source (SNS) linear accelerator was replaced with a beam of protons with similar size and dynamics. Beam loss in the superconducting part of the SNS accelerator was at least an order of magnitude lower for the proton beam. Also beam loss has a stronger dependence on intensity with H- than with proton beams. These measurements verify a recent theoretical explanation of unexpected beam losses in the SNS superconducting linear accelerator based on an intra beam stripping mechanism for negative hydrogen ions. An identification of the new physics mechanism for beam loss is important for the design of new high current linear ion accelerators and the performance improvement of existing machines

08 HYDROGEN↗
DOE OSTI2013

Local Radiation Shielding Design Methodology

The NSLS-II accelerators are housed within a radiation enclosure of normal concrete (and in some places high density concrete) that has been designed to reduce the radiation generated from an assumed operational beam loss or bulk shielding current (BCS) from each accelerator. The beam loss model used to estimate the thickness of this bulk shielding, assumed a beam energy at the expected operating energy and a current loss based on reasonable assumptions for the fraction of the expected operating current. The thickness of the shield was determined to be the amount required to reduce the radiation outside the shield to a maximum dose rate of <0.5mrem/hr. for occupied areas for these normal operational losses. These assumed beam losses and the bulk shielding thicknesses required are given in reference. Abnormal operating conditions generating higher than normal beam losses must also be considered, and additional engineering controls will be required depending on the magnitude of the radiation levels generated during the abnormal condition. Additional local shielding subject to configuration control may be utilized to reduce radiation levels associated with these abnormal loss conditions. Interlocked area radiation monitors are another means to prevent continued operation with higher than an acceptable level. The NSLS-II Shielding Policy requires that an engineered system be utilized to mitigate an abnormal condition producing radiation levels greater than 100 mR/h, and that two systems are required if the projected radiation levels during a fault condition are > 2000 mR/h. It is intended that shielding limits the dose rate to < 0.5 mR/h in occupied areas for normal operational losses, and the combination of administrative and engineered controls for abnormal losses will maintain radiation exposure to trained personnel working at the NSLS-II facility to as low as reasonably achievable. It is anticipated that all individual exposures will be well within the planned administrative control level of 100mrem/year.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Fermilab PIP-II machine protection system digitized data noise elimination scheme and its FPGA implementation

In Fermilab's PIP-II machine protection system, beam loss signals from various detectors are digitized at 125 MS/s. Noise from both high-frequency sources and low-frequency 60 Hz AC power equipment can contaminate the data. To suppress noise across these ranges—especially 60 Hz and its harmonics, which overlap with beam loss signal frequencies—advanced digital processing beyond standard filtering is required. Several real-time functional blocks were simulated and tested on an FPGA: (1) a dual time-constant discharging integrator filter, (2) a de-ripple baseline extraction and storage block, and (3) a fast-recovery discharging integrator. The nonlinear IIR integrator filter removes high-frequency noise and feeds into the baseline extractor. Upon detecting abrupt beam loss, it switches to a longer time constant to prevent baseline distortion. The de-ripple block calculates a valid baseline by averaging over multiple 60 Hz periods, storing results in a 4096-word FPGA RAM. This baseline is subtracted from raw data before integration by the fast-recovery block, which resets quickly after use. All blocks achieved expected performance and were successfully implemented on a low-cost FPGA.

Wu, Jinyuan [Fermilab]↗
DOE OSTI2023

ML-based Real-Time Control at the Edge: An Approach Using hls4ml

This study focuses on implementing a real-time control system for a particle accelerator facility that performs high energy physics experiments. A critical operating parameter in this facility is beam loss, which is the fraction of particles deviating from the accelerated proton beam into a cascade of secondary particles. Accelerators employ a large number of sensors to monitor beam loss. The data from these sensors is monitored by human operators who predict the relative contribution of different sub-systems to the beam loss. Using this information, they engage control interventions. In this paper, we present a controller to track this phenomenon in real-time using edge-Machine Learning (ML) and support control with low latency and high accuracy. We implemented this system on an Intel Arria 10 SoC. Optimizations at the algorithm, high-level synthesis, and interface levels to improve latency and resource usage are presented. Our design implements a neural network, which can predict the main source of beam loss (between two possible causes) at speeds up to 575 frames per second (fps) (average latency of 1.74 ms). The practical deployed system is required to operate at 320 fps, with a 3ms latency requirement, which has been met by our design successfully.

Shi, R.↗
DOE OSTI2018

Preliminary Radiological Considerations for the Design and Operation of NSLS-II Storage Ring and Booster Synchrotron

Radiological conditions for the design and operation of NSLS II Storage Ring and Booster Synchrotron have been analyzed using the presently available design parameters. The Booster Synchrotron will be housed in the same tunnel as the Storage Ring at NSLS II. Calculations of the resulting radiation fields and required shielding have been made for normal stored beam loss and loss of beam during injection at the septum/extraction magnets.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Tritium Production Estimates in EIC Cooling Water Systems

Annual tritium production in EIC cooling water has been estimated in one sextant cooling system from expected electron beam and proton beam losses in the tunnel. Beam losses and the secondary particles they produce are the only source within the RHIC Tunnel for producing radioactivity in cooling water, including tritium. The need to estimate tritium production supports decisions on whether cooling water systems are required to meet Suffolk County Article 12 requirements (e.g., double-walled piping, leak detection and containment, etc.). Results are extended to the remaining sextant cooling water systems because of the similarity in tunnel cooling water loads and system volumes.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Optimization of Superconducting Linac for Proton Improvement Plan-II (PIP-II)

PIP-II is an essential upgrade of the Fermilab complex that will enable the worlds most intense high-energy beam of neutrinos for the international Deep Underground Neutrino Experiment at LBNF and support a broad physics program at Fermilab. Ultimately, the PIP-II superconducting linac will be capable of accelerating the $H-$ CW beam to 800 MeV with an average power of 1.6 MW. To operate the linac with such high power, beam losses and beam emittance growth must be tightly controlled. In this paper, we present the results of global optimization of the Linac options towards a robust and efficient physics design for the superconducting section of the PIP-II linac. We also investigate the impact of the nonlinear field of the dipole correctors on the beam quality and derive the requirement on the field quality using statistical analysis. Finally, we assess the need to correct the quadrupole focusing produced by Half Wave, and Single Spoke accelerating cavities. We assess the feasibility of controlling the beam coupling in the machine by changing the polarity of the field of linac focusing solenoids

43 PARTICLE ACCELERATORS↗