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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Multiphysics Simulation of the Thermal Response of a Nanofibrous Target in a High-Intensity Beam

Nanofibrous structures are of high interest to the fields of engineering and materials science, and investigation of their properties as well as discovery of novel applications for them both constitute lively areas of research. A very promising application of nanofiber mats lies in the field of accelerator technology: beam targets made from nanofiber mats offer a solution to the problem of advancing the "intensity frontier"–-the limit on the beam intensities that can be realized in fixed target experiments and neutrino production facilities. However, testing has shown that the survivability of these nanofiber targets depends strongly on their manufacturing parameters, such as the packing density of fibers. In this work, we will use multiphysics simulations to perform a thermal study on how nanofiber targets react to high intensity beams, so that the dependency of the targets’ lifetime on their construction parameters can be better understood.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Metric Type in the Target-matrix Mesh Optimization Paradigm

The Target Matrix Optimization Paradigm (TMOP) is a method for improving the accuracy, efficiency, and robustness of numerical solutions to partial differential equations by improving the geometric quality of the computational mesh, primarily through node movement. TMOP has been successfully applied to a number applications even though the paradigm was not fully understood at the time. With this work, TMOP can be seen to be a tightly woven fabric of interconnecting ideas and concepts that provides a powerful approach to mesh optimization. The central unifying concepts in TMOP are the concept of a Target Matrix and the concept of Metric Type. Target matrices are motivated by the desire to make mesh quality improvement application-specific and, when needed, solution-adaptive. Metric type plays an essential role because it provides, through the use of typed metrics, the bridge between application-specific quality and target construction. It is shown that there are eight theoretical metric types, including the shape and shape+size types used informally in the past. It is shown further that there exist well-posed metrics corresponding to six of the eight metric types. A well-posed metric is a metric that is typed and convex, polyconvex, or invex, and further, it is a metric that simplifies target construction.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Plasma Guns for Magnetized Fuel Targets for PJMIF

In plasma jet driven magneto-inertial fusion (PJMIF) an array of discrete supersonic plasma jets is used to form a spherically imploding plasma liner, which then compresses a magnetized plasma target to fusion conditions. With funding from ARPA-E’s ALPHA program and from Strong Atomics LLC, HyperJet Fusion Corp and HyperV Technologies Corp. previously developed the plasma guns required for an experimental demonstration of the plasma liner formation part of the concept. A 36-gun demonstration of an imploding spherical plasma liner is currently underway on the PLX facility at Los Alamos National Laboratory. This present project addresses the next step required for a complete PJMIF concept, i.e. developing the magnetized plasma target. We proposed to form the target by stagnating a number of magnetized plasma jets in the center of the target chamber. This is accomplished by adding a bias field coil to the plasma liner gun to form a magnetized plasma jet. This experimental development took place at HyperJet in a geometry replicating the bias field environment that will be seen on a PLX port so the results are directly transferrable to the PLX experiment. The objective of this effort was the technical development and characterization of a new magnetized plasma jet using a high-performance, high momentum flux, contoured-gap coaxial plasma gun appropriate for use on the next stage of the PLX experiment. Electromagnetic modeling of the coil indicated the coil was best placed around the aluminum tubes of the gun transmission line, rather than around the chamber port as originally proposed. This maximized field strength in the breech and yielded much better flux linkage between gun electrodes. A 30-turn coil was ultimately implemented, allowing long pulses that could diffuse through the metal walls on the timescale of interest. \machtwo modeling predicted that less capacitance in the main PFN could potentially improve plasma jet velocities due to better matching of the current to the smaller plasma mass and the existing electrode contour designed to suppress blowby. This proved true, as testing showed markedly improved performance when the original 600uF bank was reduced to 400uF. A number of diagnostics were built and/or upgraded in order to characterize the plasma jets, inluding laser interferomtery for density, photodiodes for velocity, Bdot probes for magnetic field measurements, a Triple probe for temperature measurements, and spectroscopy for impurity content. A plasma gun with the 30-turn magnet coil installed, a 70% reduction in gas valve plenum volume, and a 33% reduction in main PFN capacitance produced a dense, high velocity, well magnetized plasma jet. We met or exceeded virtually all of the plasma jet parameter goals. Peak velocity of 135 km/s exceeded the 100 km/s goal by 35%, while the peak density of over 1.0x10 15 cm -3 was 3.3 times the goal of >3.0x10 14 cm -3 . Shot-to-shot repeatability is excellent, with a jitter of less than 300ns observed on the arrival fronts of the photodiode signals from one shot to the next. Average plasma jet lengths of 33cm (at 120km/s) were slightly longer than the 20cm goal, but jets as short as 11.8cm were observed at 135km/s. Mass is much higher than the targeted goal, averaging 106ug per shot compared to 20ug. The magnetic field is still a bit lower than desired, with a maximum to date of ~811G, compared to the goal of 1000G. Average values, though, were typically in the 300-450G range, when measured further downstream after some expected in flight decay. Temperature measurements are still a work in progress. Increasing the B field and completing temperature measurements will be continued on into the ongoing BETHE project.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Assembly of MiniFuel Targets for Irradiation of TRISO Fuel Compacts in the High Flux Isotope Reactor

To support the development of Kairos Power’s fluoride-salt-cooled high-temperature reactor, irradiation testing of tristructural isotropic (TRISO) fuel compacts was performed at the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) to collect experimental data on TRISO fuel during high particle-power operation and validate fuel performance models. Fuel compacts containing enriched uranium oxycarbide (UCO), natural UCO (NUCO), or uranium dioxide (UO 2 ) TRISO particles were fabricated at ORNL and inserted into MiniFuel targets for HFIR irradiation. Five MiniFuel targets were successfully assembled, welded, tested, and delivered to HFIR, along with their quality assurance documentation. The targets were inserted into HFIR’s inner vertical experiment facility within the permanent beryllium reflector. Each target contains six fuel compacts and will be irradiated in HFIR for four cycles, with target temperatures of 500, 700, and 900°C. This report summarizes the experiment design, test matrix, and fabrication. This work was performed under the Nuclear Science User Facility program.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Radiobiology, Omics and Microdosimetry of Systemic and Targeted Radiotherapeutics Workshop

The Radiobiology, Omics and Microdosimetry of Systemic and Targeted Radiotherapeutics Workshop fostered engagement across disciplines on critical topics that impact the development of targeted radionuclide therapies, bringing together scientific and medical professionals actively involved in radiotherapeutic design, optimization testing, patient treatment, and clinical trials along with basic science researchers, whose novel techniques have the potential to further our understanding of targeted radionuclide therapy. Discussion of the applications of radiotherapeutics to pediatric and adult, brain, prostate and blood cancers, and metastatic disease allowed scientific research to be presented in the context of real-world medical applications and provided an important backdrop to the basic research performed in computers, laboratories, and animal facilities. The workshop format, presentations, and panel discussions were designed to consider a holistic approach to the development of systemic and targeted radiotherapies, integrating radiobiology and microdosimetry, biological assessments on the microscale, and physiologically relevant models of tumor and tissue microenvironments. Important needs highlighted in the workshop include better models to assess the biological effects of radionuclide therapy, novel strategies to target radiotherapeutics to disease sites with high specificity, and new dosimetry techniques that address the importance of tumor microenvironments.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

KIPT ADS Target Cooling Analyses by MCNP/Fluent

This report presents multi-physics analyses of the target cooling system of the accelerator driven system (ADS) of the Kharkiv Institute of Physics and Technology (KIPT) using MCNP and Fluent computer programs. MCNP has been used to transport electrons, gammas, and neutrons, and to calculate the energy deposition in the target using a mesh-tally. The mesh-tally data have been imported in Fluent by a C subroutine that has been compiled and linked to Fluent as a user defined function. The KIPT ADS is in operation and Fluent used the CAD model from the manufacturing process of the target. The Fluent results for the reference case match very well the literature results obtained by STAR-CCM+ during the design phase. Other cases that differ from the reference one have been analyzed; in these cases, it is assumed a malfunction of the electron accelerator control or the primary water coolant pump. The target cooling system operates normally for all the analyzed cases except when the inlet water mass flow rate is decreased. If the water coolant mass flow decreases to 25%, the water maximum temperature exceeds the boiling point. However, the transient analysis showed that the target cooling system can operate for 180 seconds when the inlet water mass flow rate is decreased down by 50%.

42 ENGINEERING↗
DOE OSTI2022

Small Punch Testing of Molybdenum-99 Targets

Northstar Medical Radioisotopes is developing an accelerator-based method to produce 99 Mo, which is a parent isotope of the commonly used 99m Tc medical isotope. The Mo targets being designed for the accelerator will be produced from enriched 100 Mo, also known as aMo . Pressed and sintered powder feedstock is used to fabricate aMo targets, producing 29 mm disk-shaped targets. The targets are subjected to 1–6 days in line of an electron beam with subsequent dissolution of the disk to retain the 99 Mo, which decays to 99m Tc at radio-pharmacies. The press and sinter method is advantageous because the inherent porosity produced by this method enables increased surface area and therefore increased flow of dissolution media, decreasing the dissolution time and reducing the need for a highly acidic media. Although porosity aids in dissolution, it reduces the mechanical strength and ductility. Targets require good mechanical integrity when subjected to the conditions in the accelerator. Therefore, Northstar is seeking methods to rapidly test disk samples after fabrication to assure mechanical performance metrics are achieved. This report details the design and testing of a small punch test (SPT) that accommodates the 29 mm disk. Initial data were used to relate the SPT data to tensile properties, such as the yield strength (YS), ultimate tensile strength (UTS), and total elongation to failure. Although the SPT has been established as a somewhat reliable method for testing metallic materials, few studies have applied the SPT to refractory materials such as Mo. Based on tensile testing performed at Oak Ridge National Laboratory on different Mo samples, correlation between the Mo tensile and SPT properties could be performed, establishing a standard calibration that could be applied to other Mo samples. To test the efficacy of the SPT with Mo, multiple different disk batches were fabricated under different conditions (e.g., pressure, lubricant) with commercially available pure Mo powder. Generally, only a UTS could be well defined because the press and sinter disks failed under brittle fracture, making it difficult to determine the YS and elongation. Compared with disks fabricated with aMo powder, the aMo samples underperformed their pure nat Mo counterparts. This report summarizes the current status of the SPT, but further evaluation is needed before it can be applied as a reliable quality assurance tool.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Assembly of MiniFuel Targets for Irradiation of U-Mo Fuel Specimens in the High Flux Isotope Reactor

To support the development of advanced low-enriched uranium for use in nuclear reactors, irradiation testing of U-Mo disk specimens was performed at the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) to collect experimental irradiation data on this type of fuel at pressurized water reactor–relevant temperatures. U-Mo is a uranium alloy that has superior dimensional stability relative to alpha-phase uranium metal and has a substantially higher uranium density compared to UO 2 . U-Mo disks specimens were fabricated at Idaho National Laboratory and inserted into MiniFuel targets for HFIR irradiation. Three MiniFuel targets were successfully assembled, welded, tested, and delivered to HFIR, along with their quality assurance documentation. The targets were inserted into HFIR’s inner vertical experiment facility within the permanent beryllium reflector. Each target contains six disk specimens and will be irradiated in HFIR for three, four, and eight cycles, with target temperatures between 250 and 500°C. This report summarizes the experiment design, test matrix, pre-characterization of specimens, and experiment assembly.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Development of a Beam Sweeping System for the Fermilab Antiproton Source Target

Intensity of the incident 120-GeV proton beam on the antiproton production target is scheduled to increase to 5x10 12 protons per pulse. To prevent damage to the target, we plan to spread the hot spot on target with a beam sweeping system, Now under development are rotating-field magnets for installation upstream and downstream of the target. These magnets will deflect the beam in a circular pattern on the target. Peak current of 7 kA and peak voltage drop of 6 kV are expected. The power supply, which is separated from the magnet by a distance of about 10 m, utilizes magnetic pulse compression by saturating inductors to drive the magnets through the long transmission lines.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Baseline Hypothetical Facility for the Production of 131 I, 99 Mo, and 133 Xe from HALEU Fission Targets

The report describes the development of a hypothetical facility to produce the pharmaceutical radioisotope 131 I at an amount of 60 curies per week via the fission of a High Assay Low Enriched Uranium (HALEU) target, along with the chemical and physical processes and equipment needed to separate the 131 I and co-produced 99 Mo and 133 Xe. The hypothetical design was carried out using a 10 MWt research reactor. The irradiation calculation determined that three HALEU targets with aluminum cladding can be used to produce 60 Ci/week of 131 I, 750 Ci/week of 99 Mo and 560 Ci/week of 133 Xe. The process selected for the baseline design uses caustic dissolution of the target material with ion exchange processes to separate and purify the iodine and molybdenum. The xenon is processed using a cryogenic carbon bed separation process. Target processing occurs in seven shielded hot cells with a total footprint of 16m 2 and waste management occurs in an eight hot cell with a 2.5 m 2 footprint. Waste generated from the processing of the three targets per week would generate less than 4 shielded drums of waste annually. These hot cells would need varying levels of shielding due to the amount of fission products being handled in the unit. Hot cell facilities also require support services including QA/QC, health physics, administrative staff, operator changing room, radiological buffer areas, and waste storage. The overall facility would require a footprint of 1050 m 2 with 20.25 m 2 of shielded hot cells.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

High Power Solid Target for Positron Source at CEBAF

The progress in the development of a polarized positron injector for the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory is presented. The polarized positron beam is generated by a high current polarized electron beam (>1 mA @ 120 MeV) via bremsstrahlung radiation and e+e- pair production in the tungsten target. The simulations show that using an optimized target and positron beamline, the positron injector can provide a cw positron beam with a current larger than 50 nA and a polarization as large as 60%. Injected into the North Linac of CEBAF at an energy of 123 MeV, the positron beam can reach a maximum energy of 12 GeV to perform a rich experimental program. The results of the thermal and structural FEA analysis of the heat load in the target are presented, as well as the simulation results of radiation damage in the target. The performed and planned target material fatigue and radiation damage tests are discussed. This work is supported by the U.S. DOE, Office of Science, Office of Nuclear Physics, Contract No. DE-AC05-06OR23177 and the European Union?s Horizon 2020 research and innovation program under grant agreement No. 824093.

Ushakov, Andriy↗
DOE OSTI2024

Novel Materials for Next-Generation Accelerator Target Facilities

As beam power continues to increase in next-generation accelerator facilities, high-power target systems face crucial challenges. Components like beam windows and particle-production targets must endure significantly higher levels of particle fluence. The primary beam’s energy deposition causes rapid heating (thermal shock) and induces microstructural changes (radiation damage) within the target material. These effects ultimately deteriorate the components’ properties and lifespan. With conventional materials already stretched to their limits, we are exploring novel materials including High-Entropy Alloys and Electro spun Nanofibers that offer a fresh approach to enhancing tolerance against thermal shock and radiation damage. Following an introduction to the challenges facing high-power target systems, we will give an overview of the promising advancements we have made so far in customizing the compositions and microstructures of these pioneering materials. Our focus is on optimizing their in-beam thermomechanical and physics performance. Additionally, we will outline our ongoing plans for in-beam irradiation experiments and advanced material characterizations. The primary goal of this research is to push the frontiers of target materials, thereby enabling future multi-MW facilities that will benefit various programs in high-energy physics and beyond.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Multiphysics Simulations of Thermal Shock Testing of Nanofibrous High Power Targets

Increase of primary beam power for neutrino beam-lines leads to a reduced lifespan for production targets. The field of High Power Targetry (HPT) is generating new concepts to meet the need for robust targets. One idea being investigated by the HPT Research and Development Group at Fermilab is an electrospun nanofiber target. As part of their evaluation, samples with different densities were sent to the HiRadMat facility at CERN for thermal shock tests. The samples with the higher density, irradiated under a high intensity beam pulse, exhibit major damages at the impact site whereas those with the lower density show no apparent damages. The exact cause of this failure was unclear at the time. In this paper, we present the results of multiphysics simulations of the thermal shock experienced by the nanofiber targets that suggest the failure originates from the reduced permeability of the high density sample to airflow. The air present in the porous target expands due to heating from the beam, but is unable to flow freely in the high density sample, resulting in a larger back pressure that blows apart the mat. We close with a discussion on how to further validate this hypothesis.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Bayesian Optimization Scheme for the Design of a Nanofibrous High Power Target

High Power Targetry (HPT) R\&D is critical in the context of increasing beam intensity and energy for next generation accelerators. Many target concepts and novel materials are being developed and tested for their ability to withstand extreme beam environments; the HPT R\&D Group at Fermilab is developing an electrospun nanofiber material for this purpose. The performance of these nanofiber targets is sensitive to their construction parameters, such as the packing density of the fibers. Lowering the density improves the survival of the target, but reduces the secondary particle yield. Optimizing the lifetime and production efficiency of the target poses an interesting design problem, and in this paper we study the applicability of Bayesian optimization to its solution. We first describe how to encode the nanofiber target design problem as the optimization of an objective function, and how to evaluate that function with computer simulations. We then explain the optimization loop setup. Thereafter, we present the optimal design parameters suggested by the algorithm, and close with discussions of limitations and future refinements.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Computational study of tungsten and depleted uranium photoneutron targets for a 20 MeV electron linear accelerator

Neutron production can be realized with a high energy electron linear accelerator by using Bremsstrahlung and photoneutron converters. In this study, Monte Carlo N-Particle Code (MCNP) was used to evaluate potential photonuclear target designs for a high energy electron linear accelerator for applications such as neutron radiography and neutron resonance spectroscopy. A computational model was developed to inform a target design that would yield a high number of neutrons. It consists of a 20 MeV electron beam incident on a Bremsstrahlung target and a photonuclear target to generate neutrons. This computational model showed that a thickness of 0.75 inches for both tungsten and depleted uranium yields the most neutrons from photoneutron reactions. Saturation in the total number of generated neutrons was observed at over 0.75-inch thickness for both evaluated materials. Depleted uranium yielded approximately twice the number of neutrons overall compared to tungsten. The highest neutron surface flux for Depleted Uranium was 1.06 × 10-4 neutrons/cm2/source electron, and for Tungsten it was 5.12 × 10-5 neutrons/cm2/source electron. The optimal target design for this study’s application would consist of a 0.75 inch-thick block of depleted uranium with the length, width, and/or diameter varying dependent on application.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Production Facility Simulations for Annular LEU Targets

Eden Radioisotopes, LLC is designing a new molybdenum-99 (Mo-99) production facility based on a TRIGA-sized reactor with a core composed of low enriched uranium (LEU) targets. Reactor production is designed to exceed U.S. demand for Mo-99 using the fission processes. The nominal operational power is 1.8MW (less than 2.0MW, to satisfy the “non-power” reactor requirement) and desired irradiation scenarios include 7, 14, or 21 days of the irradiation for each target element. Safety limits for reactor operating margins are associated with such physical phenomena as fission gas release, fuel swelling, and stress cracking. As shown in the literature, one of the critical parameters defining safety margins for metallic uranium fuel is swelling. In its turn the fuel operational temperature is the main parameter impacting the swelling rate. This report documents the results of consecutive studies of reactor criticality, fission energy depositions, and cooling conditions for the target. The maximum temperature calculated for the LEU targets allows us to choose appropriate modeling approximation of the swelling. All obtained results refer to the preliminary targets and core designs provided by Eden. A criticality analysis was performed, and the results are listed mainly to cross-check Eden’s safety report and assume maximal neutron field disturbance for maximal reactivity. A brief description of the metallic uranium swelling model is provided in the Appendix.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2024

Focussing Protons from a Kilojoule Laser for Intense Beam Heating Using Proximal Target Structures

Proton beams driven by chirped pulse amplified lasers have multi-picosecond duration and can isochorically and volumetrically heat material samples, potentially providing an approach for creating samples of warm dense matter with conditions not present on Earth. Envisioned on a larger scale, they could heat fusion fuel to achieve ignition. We have shown in an experiment that a kilojoule-class, multi-picosecond short pulse laser is particularly effective for heating materials. The proton beam can be focussed via target design to achieve exceptionally high flux, important for the applications mentioned. The laser irradiated spherically curved diamond-like-carbon targets with intensity 4×10 18 W/cm 2 , producing proton beams with 3MeV slope temperature. A Cu witness foil was positioned behind the curved target, and the gap between was either empty or spanned with a structure. With a structured target, the total emission of Cu Kα fluorescence was increased 18 fold and the emission profile was consistent with a tightly focussed beam. Transverse proton radiography probed the target with ps order temporal and 10 μm spatial resolution, revealing the fast-acting focussing electric field. Complementary particle-in-cell simulations show how the structures funnel protons to the tight focus. The beam of protons and neutralizing electrons induce the bright Kα emission observed and heat the Cu to 100eV.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Temperature of a tungsten spallation target

We discuss the heat load inside a neutron spallation target made of tungsten hit by an 800 MeV proton beam. This problem is important for the Neutron Target project, where a spallation target will be surrounded by an extended graphite or beryllium cube to create a neutron target. The idea of a free-neutron target enables the measurement of neutron-induced reactions in inverse kinematics. This idea is part of the LANSCE strategy to stay a worldwide leader for neutron-induced research.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗