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At least 1,783 records · Page 99
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DOE OSTI2021

Increasing the Dose Rate on the DARHT-II Accelerator

Recent studies have shown a strong correlation between spot size on target and the dose. At higher doses, the spot size is larger. At very low doses (< 75 R @ 1m per pulse) all four spots are small and essentially the same with 50%MTFs of 1.0-1.2 mm. For higher dose pulse formats, the first two pulses, P1 and P2 remain small (< 1.2 mm 50%MTF) and relatively independent of dose. The later pulses, P3 and P4, become larger as the dose increases. Longer pulse lengths are required to achieve higher doses. There are simulations that suggest space charge neutralization and current neutralization could be introducing dynamic changes in the spot size over the pulse. This implies that increasing the dose rate will allow for reduced pulse lengths and spot size for the same dose.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Recent Improvements in the Beam Capture at Fermilab Booster for High Intensity Operation

The Fermilab Booster uses multi-turn beam injection with all its cavities phased such that beam sees a net zero RF voltage even when each station is at the same maxi-mum voltage. During beam capture the RF voltage is increased slowly by using its paraphase system. At the end of the capture the feedback is turned on for beam acceleration. It is vital for present operations as well as during the PIP-II era that both the HLRF and LLRF systems provide the proper intended phase and RF voltage to preserve the longitudinal emittance from injection to extraction. In this paper, we describe the original architecture of the cavity phase distribution, our recent beam-based RF phase measurements, observed significant deviation in the relative phases between cavities and correction effort. Results from the improved capture for high intensity beam are also presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Simulation study of high-current 7 Li 3+ beam acceleration with laser ion source and RFQ linac using direct plasma injection

Accelerator-based neutron sources (ABNS) utilizing the 7 Li(p,n) 7 Be reaction in inverse kinematics offer strong forward-directed neutron emission, making them attractive for compact and clean neutron source with low background neutrons and unwanted radiation. However, practical use of such systems requires lithium ion beam currents that exceed the capability of conventional ion accelerators by two orders of magnitude. In this study, we numerically designed and evaluated a high-current acceleration system based on a direct plasma injection scheme (DPIS), combining a laser ion source (LIS) and a radio-frequency quadrupole (RFQ) linac. The ion extraction optics and RFQ entrance were optimized using IGUN, OPERA, and GPT, demonstrating that over 1.2 A-class beam current can be injected into the RFQ. The RFQ structure was designed under realistic engineering constraints including surface field strength (Kilpatrick factor) and RF power. GPT simulations showed that a 370 mA 7 Li 3+ beam can be successfully accelerated within a ±10 % energy spread. To validate downstream compatibility, we also designed a simplified medium-energy beam transport (MEBT) section and an interdigital H-type (IH) linac, confirming successful acceleration of a 320 mA beam to the total energy of 14 MeV. These results support the feasibility of the DPIS and RFQ approach as a promising solution for compact neutron sources and other high-intensity ion beam applications.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Status of the PIP-II Cryoplant

The Proton Improvement Plan-II (PIP-II) is an essential upgrade to the Fermilab accelerator complex featuring a new 800-MeV Superconducting Radio-Frequency (SRF) linear accelerator (Linac). The Linac contains 23 SRF cryomodules with the SRF cavities operating at 2 K, a high temperature thermal shield at 40 K and low temperature intercepts at 4.5 K. The PIP-II cryoplant will provide the necessary cooling for the cryomodules and the cryogenic distribution system interconnecting cryoplant and cryomodules. This paper describes the evolution of the PIP-II cryoplant conceptual design and specifications, including the expected heat loads, required cooling features and the integrated design. The cryoplant capacity margin analysis and fast cool-down mode will also be discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Progress of PIP-II Activities at IJCLab

Since 2018, IJCLab is involved in PIP-II project on the design and development of accelerator components for the SSR2 (Single Spoke Resonator type 2) section of the superconducting linac. First pre-production components have been fabricated, surface processing and cavity qualification in vertical cryostat are on-going. IJCLab has upgraded its facilities by developing a new set-up to perform rotational BCP. The progress of all processing and testing activities for PIP-II project will be reported and, in particular, a dedicated study to qualify removal uniformity compared to static BCP will be presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Intrabeam scattering studies with large-emittance-ratio ion beams in the Relativistic Heavy Ion Collider, and implications for the Electron-Ion Collider

The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized, high-energy electron beams with hadron beams, achieving peak luminosities of up to 1.0 x 10 34 cm -2 s -1 . To reach such high luminosity, the EIC will employ flat-beam collisions at the interaction point. The design transverse emittance ratio will be about 10:1 in the Hadron Storage Ring (HSR). Thanks to stochastic cooling and precise decoupling, we successfully generated and accelerated gold ion beams with a large emittance ratio of 11:1 in the Relativistic Heavy Ion Collider (RHIC). In this article, we present results of intrabeam scattering (IBS) measurements and modeling for large-emittance gold ion beams, both without and with controlled betatron coupling. To model the IBS growth, we use the formulas developed by Lebedev and Nagaitsev.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Net energy gain in direct laser acceleration due to enhanced dephasing induced by an applied magnetic field

Even in the situation where an electron interacts with a single plane wave, the well-known dynamical adiabaticity can be broken when an applied magnetic field is present, which will act to increase the dephasing rate of the electron during the interaction. Here we demonstrate this for the case where there is a uniform static magnetic field which is oriented either parallel or perpendicular to the electric field of the incident plane wave, and perpendicular to the direction of its propagation. The described energy gain phenomenon has direct relevance to laser-plasma interactions that involve external magnetic fields generated by laser-driven capacitor coils.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Progress of the laser ion source upgrade (LION2) for RHIC and NSRL program at Brookhaven National Laboratory

At Brookhaven National Laboratory (BNL), the LION2 ion source is being constructed to replace an existing laser ion ablation ion source (LIS) at the EBIS facility, which provides heavy ion beams of multiple ion species for the operation of NASA Space Radiation Laboratory (NSRL) and Relativistic Heavy Ion Collider (RHIC). The LION1 ion source currently provides singly charged ions of Li, B, C, O, Al, Si, Ca, Ti, Fe, Cu, Zr, Nb, Ag, Tb, Ta, W, Au, Bi, and Th with a rapid-species-change capability. An electron beam ion source, Extended-EBIS captures, confines, and ionizes the ions to high charge state, suitable for injection and acceleration by an RFQ accelerator. Typically, single pulses of the LIS ion species for NSRL are changed sequentially during Galactic Cosmic Ray experiments, while multiple pulses of a given ion beam are provided quasi-simultaneously for RHIC. LION2 will have the same capability of the rapid-species-change with improved beam performance and reliability. LION2 is being constructed in a remote assembly location and is expected to finish in December 2023. The removal of LION1 and installation of LION2 is planned during the December 2023 or summer 2024 shutdown.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

First Results of the IOTA Ring Research at Fermilab

The IOTA ring at Fermilab is a unique machine exclusively dedicated to accelerator beam physics R&D. The research conducted at IOTA includes topics such as nonlinear integrable optics, suppression of coherent beam instabilities, optical stochastic cooling and quantum science experiments. In this talk we report on the first results of experiments with implementations of nonlinear integrable beam optics. The first of its kind practical realization of a two-dimensional integrable system in a strongly-focusing storage ring was demonstrated allowing among other things for stable beam circulation near or at the integer resonance. Also presented will be the highlights of the world’s first demonstration of optical stochastic beam cooling and other selected results of IOTA’s broad experimental program.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

The RF Protection Interlock System Prototype Verification

The Radio Frequency Protection Interlock system plays vital role in the LLRF related/dependent accelerator sections Protection. It’s main role is to collect information from number different sensors and indicators around nearest cavities and cryomodule and provide instant RF signal termination in case of safety thresholds violation. This submission describes newly designed RFPI system tailored to the Proton Improvement Plan II (PIP-II) requirements. The proof of concept prototype of this system has been build. The paper includes also the CMTF environment evaluation tests results and findings as an input to the next full-scope prototype design.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Beam breakup in a solid state powered linear induction accelerator

It has been proposed to use solid-state pulsed-power modules to power the new Scorpius accelerator. Since this highcurrent accelerator would have 360 gaps (more than five times the number of cells as present radiography LIAs), it is natural to be concerned about the beam-breakup (BBU) instability. Earlier calculations of this effect used a half-scale model of the accelerator to avoid the limitation to 200 gaps in the code. We have now updated the code to accommodate the extraordinary number of gaps in this proposed LIA. The results of these early simulations are presented here. They indicate that BBU can only be suppressed to the same level as in designs powered by conventional pulsed power, if the calculated cell impedance can truly be achieved in practice. The magnetic focusing field required for this is of the same order as the field required for a conventionally powered LIA only if the transverse impedance can indeed be constrained to the values obtained in some simulations of the cell.

42 ENGINEERING↗
DOE OSTI2023

LANSCE Facility Longevity Assessment

This LANSCE Facility Longevity Assessment examined 34 total systems critical to the operation of the LANSCE accelerator complex. These systems are primarily owned, operated, and maintained by AOT Division. Based on the criteria used in this assessment, there are 12 AOT Division systems that are potential high risk as related to longterm LANSCE operations. These systems may also impact the success of LAMP. Also summarized in this report are the facility activities planned over the next decade. These include general facility maintenance and infrastructure upgrades, as well as planned electrical system upgrades. The LANSCE Facility Operations (LFO) Division is responsible for this activity scope and budget planning. Most of the planned activities are general in nature and should have little impact on accelerator operations or LAMP activities as currently envisioned. However, close coordination with between AOT, LFO, and LAMP would be prudent. A next step should be to develop an actionable plan to address the high-risk systems. Potential criteria for developing such a plan could include: (1) Evaluating the global impact of the system (operations, program, safety, etc.), (2) Ranking by impact (ranked now by risk), (3) Estimating cost to implement the corrective actions (Is there already a plan or not?), and (4) Estimating the time required for corrective actions. An alternative could include integration of the assessment data into both the Asset Management System and the Maintenance Analytics Risk Register.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

High Power Test Results For A Cylindrical-Shell SiC Higher-Order-Mode DAMPER

The next high-current Electron Ion Collider (EIC) is a new accelerator to be built at Brookhaven National Laboratory (BNL) in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). In the EIC Electron Storage Ring (ESR), there will be beam currents up to 2.5 A, which will excite massive Higher-Order-Modes (HOM) power in the 17 single-cell 591 MHz Superconducting Radio Frequency (SRF) cavities. To damp the HOM power in the ESR SRF cavities is a challenge. A room temperature cylindrical shell shape Silicon Carbide (SiC) Beamline HOM Absorber (BLA) was chosen as the baseline design, due to its broadband and high-power capability, and previous demonstrations at other accelerator facilities, albeit at much lower power. Because the EIC BLA HOM power dissipation is significantly greater than the previous applications, it is imperative to carry out high power testing to determine the maximum device performance levels achievable for thermal transport, RF breakdown, and mechanical stress, prior to finalizing the design. A SiC HOM absorber with state-of-the-art geometry size was prototyped to verify shrink-fit technique, test outgassing rate, and high power handling capability. This paper presents the HOM damper’s prototyping and test results.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Mitigation of space charge effects using electron column at IOTA ring

We investigate a novel method to mitigate space charge effects of high intensity proton beams propagating in circular accelerators by means of trapping and controlling electrons generated from beam-induced residual gas ionization. This compensation method uses Coulomb repulsion force between a proton beam and electrons to mitigate self-space charge effects of the beam if it passes through a plasma column. The transverse electron-proton (e-p) instability in the plasma column is well controlled by the longitudinal magnetic field of a solenoid magnet and the bias voltages on electrodes. In this report, we will show simulation results how to control distributions of electrons and ions as well as that of the proton beam inside the column.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

A Broadband Mechanically Tuned Superconducting Cavity Design Suitable for the Fermilab Main Injector

Radio Frequency superconductivity has been a mainstay of accelerator science for decades. However, its benefits have yet to be applied to proton synchrotrons with demanding tuning requirements. For example, the Main Injector (MI), Fermilab's high-energy proton synchrotron, currently utilizes 20+ ferrite-loaded cavities for a targeted 1.2 s acceleration cycle. Harnessing the extremely high gradients associated with superconductivity, the required number of cavities could be reduced by an order of magnitude, dramatically lowering operational power requirements even with cryogenic considerations. Additionally, the current plans for the Fermilab accelerator complex evolution initiative involve almost doubling the number of cavities in MI if the same designs are to be used, further highlighting the potential benefits of superconductivity. These advantages are attractive, but to date, no tunable superconducting cavity suitable for MI has been proposed due to the incompatibility of conventional broadband tuning methods with superconductivity. Here, we present a tunable superconducting cavity concept capable of record-breaking performance. Tuning will be accomplished by using high-speed linear actuators to vary the insertion depth of metallic plungers into the cavity volume. This tuning concept is theoretically viable with currently available technology and will be fully compatible with a superconducting cavity.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

An Induction-Type Septum Magnet for the Hadron and Electron Injection of the EIC Complex

The design of the electron Ion Collider (EIC) project is under way to be built at the Brookhaven National Laboratory (BNL) with the collaboration of the Thomas Jefferson National Accelerator Facility (TJNAF). The Rapid Cycling Synchrotron (RCS) which is part of the EIC accelerator complex will accelerate the electron beam up to 18 GeV, and the beam will be injected into the Electron Storage Ring (ESR) to collide with the hadron beam circulating in the Hadron Storage Ring (HSR) which is a modified version of the Relativistic Heavy Ion Collider (RHIC). All three synchrotrons will be located in the same tunnel. This technical note provides information on the latest electromagnetic design of the induction-type septum magnet which will be employed by EIC to Inject the beam into the HSR and RCS and also extract the beam from the RCS.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Measured vs. Calculated Dose Rates During Ring Injection Dump Replacement

One of the most irradiated Spallation Neutron Source (SNS) accelerator components is the ring injection dump (RID), which is located downstream of the accumulator ring injection section. The unstripped and only partially stripped H - beam, about 5% of the full SNS beam current, is discarded in the injection into the accumulator ring and is redirected to the RID. According to the accelerator operation plan, the beam stop and the window assemblies of the existing RID are removed and replaced when they have reached their end-of-life owing to radiation exposure. This procedure, which includes multiple steps, took place during a facility maintenance period in March 2023. To support work planning and meet as low as reasonably achievable (ALARA) requirements during removal and exchange of the components, dose rates were calculated for each stage of the exchange operation. During each stage, dose rates were measured before and after work. This comparison shows that measured dose rates are within a factor of 2 of the predicted (calculated) dose rates.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Data-driven gradient optimization for field emission management in a superconducting radio-frequency linac

Field emission can cause significant problems in superconducting radio-frequency linear accelerators (linacs). When cavity gradients are pushed higher, radiation levels within the linacs may rise exponentially, causing degradation of many nearby systems. This research aims to utilize machine learning with uncertainty quantification to predict radiation levels at multiple locations throughout the linacs and ultimately optimize cavity gradients to reduce field emission-induced radiation while maintaining the total linac energy gain necessary for the experimental physics program. The optimized solutions show over 40% reductions for both neutron and gamma radiation from the standard operational settings. Published by the American Physical Society 2025

43 PARTICLE ACCELERATORS↗