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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

High Radiation Resistance in the Binary W‐Ta System Through Small V Additions: A New Paradigm for Nuclear Fusion Materials

Abstract Refractory High‐Entropy Alloys (RHEAs) are promising candidates for structural materials in nuclear fusion reactors, where W‐based alloys are currently leading. Fusion materials must withstand extreme conditions, including i) severe radiation damage from energetic neutrons, ii) embrittlement due to H and He ion implantation, and iii) exposure to high temperatures and thermal gradients. Recent RHEAs, such as WTaCrV and WTaCrVHf, have shown superior radiation tolerance and microstructural stability compared to pure W, but their multi‐element compositions complicate bulk fabrication and limit practical use. In this study, it is demonstrated that reducing alloying elements in RHEAs is feasible without compromising radiation tolerance. Herein, two Highly Concentrated Refractory Alloys (HCRAs) − W 53 Ta 44 V 3 and W 53 Ta 42 V 5 (at.%) − were synthesized and investigated. We found that small V additions significantly influence the radiation response of the binary W–Ta system. Experimental results, supported by ab‐initio Monte Carlo simulations and machine‐learning‐driven molecular dynamics, reveal that minor variations in V content enhance Ta–V chemical short‐range order (CSRO), improving radiation resistance in the W 53 Ta 42 V 5 HCRA. By focusing on reducing chemical complexity and the number of alloying elements, the conventional high‐entropy alloy paradigm is challenged, suggesting a new approach to designing simplified multi‐component alloys with refractory properties for thermonuclear fusion applications.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Mysteries of Nuclear Fusion: How can we build a star on Earth? [Slides]

This presentation given at the Women's Physics Summer Camp focuses on nuclear fusion as an alternative to fossil fuels, renewable energy sources and nuclear fission energy. The presentation explains plasma physics and how it might be used to generate power. Current attempts and potential applications are outlined. An appeal is made for people trained in mathematics, physics, chemistry, engineering, computer science to solve these problems. If technical problems can be overcome, fusion technology will play a part in a clean, prosperous Earth and expand humanity’s reach to the stars.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Introduction to Special Issue on the Early History of Nuclear Fusion

This introductory paper to the special issue of Fusion Science and Technology commemorates early research on fusion conducted at Los Alamos (the singular entity denoted Los Alamos Laboratory/Los Alamos Scientific Laboratory/Los Alamos National Laboratory at different times is designated “Los Alamos” in this paper) in support of the eventual H-bomb program. We survey the historical origins of the thermonuclear program, what was known of fusion reactions at the outbreak of the war, and the remarkable breakthroughs involving particularly the prospect of deuterium-tritium (DT) reactions conducted during the war, and we summarize the papers in this volume. Much of the nuclear fusion technical history presented herein has not been previously reported. Papers describe aspects of fusion science during these days, on shock hydrodynamics and on electron-radiation coupling, and on nuclear physics including the discoveries of resonances in both the DT cross section and in the lithium tritium-breeding cross section. Three papers follow our colleague Mark Paris’s finding Arthur Ruhlig’s 1938 paper on the first observation of DT fusion: one on how it influenced subsequent Manhattan Project research, another on a modern calculation of that historic experiment, and a third that has repeated the experiment using modern experimental capabilities. Other papers discuss how the first H-bomb test, Ivy Mike, led to the discovery of the new elements einsteinium and fermium and how the DT fusion processes played a key role in our universe’s development after the Big Bang. We also present a paper that analyzes the pioneering Cambridge University 1934 experiment by Marcus Oliphant, Paul Harteck, and Ernest Rutherford where deuterium-deuterium fusion was first observed and that describes how Ernest Lawrence missed identifying fusion in 1933. Finally, we present a summary of early concepts for controlled fusion energy that grew out of wartime discussions at Los Alamos. The papers show how J. Robert Oppenheimer played a leading technical role in the early developments of the H-bomb, before his later opposition—our first paper in this issue addresses the U.S. Department of Energy’s 2022 vacation of the earlier 1954 decision to revoke his security clearance.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2021

Edge and scrape-off layer modeling for a Fusion Nuclear Science Facility with tungsten walls; a summary report for 2019-21

This report summarizes model development and simulations for the edge/scrape-off layer (SOL) region of a Fusion Nuclear Science Facility (FNSF) as part of the DOE Fusion Energy Systems Studies project. An overview of the FNSF device is given in Ref. 1. Our earlier related modeling of FNSF in the 2015-16 timeframe is reported in Ref. 2, and similar work on the ARIES ACT-1 tokamak device is described in Ref. 3. During 2017-18, we contributed to the analysis of a liquid lithium wall for FNSF [4].

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1998

A Spherical Torus Nuclear Fusion Reactor Space Propulsion Vehicle Concept for Fast Interplanetary Travel

A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Initial requirements were for a human mission to Saturn with a greater than 5% payload mass fraction and a one way trip time of less than one year. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 235 days, with an initial mass in low Earth orbit of 2,941 mt. Engineering conceptual design, analysis, and assessment was performed on all ma or systems including payload, central truss, nuclear reactor (including divertor and fuel injector), power conversion (including turbine, compressor, alternator, radiator, recuperator, and conditioning), magnetic nozzle, neutral beam injector, tankage, start/re-start reactor and battery, refrigeration, communications, reaction control, and in-space operations. Detailed assessment was done on reactor operations, including plasma characteristics, power balance, power utilization, and component design.

Williams, Craig H.↗
DOE OSTI2022

Steady state thermo-mechanics and material property definition framework for analyzing DCLL blanket in the fusion nuclear science facility

In this work, a thermo-mechanics model that relies on creating the material property definition framework (MPDF) and multiphysics coupling of the heat transfer and the solid mechanics modules is developed to determine the structural integrity of the recently designed dual cooled lead lithium (DCLL) inboard blanket (IB) for the Fusion Nuclear Science Facility under steady state loads. The MPDF is called to supply fusion relevant neutron irradiation and temperature induced changes in material properties during multiphysics finite element runs, and PbLi temperature profiles are used to approximate Magnetohydrodynamics effect and the nuclear volumetric heating on the PbLi. Neutron irradiation and temperature induced reduction of the yield and ultimate strengths of F82H steel at the first wall (FW) are quantified for one year. A blanket in an assembly with gaps between blanket sectors and another blanket in an assembly with no gaps between blanket sectors, both exposed to radiation damage that lasted for one year are analyzed. Analysis using the elastic ITER structural design criteria for in-vessel components (ITER SDC-IC) design rules and a linear isotropic-hardening-type elastoplastic material model are used where most appropriate. The IB blanket with gaps between blanket sectors will withstand the steady state combined thermal and coolant loads for one year operational period but will fail if no gaps are allowed between blanket sectors. It is recommended that a gap of about 7.62 mm should be provided between IB blanket sectors during assembly which would close up during service, stop neutron streaming, reduce stresses and reduce bending of the FW into the scrape-off layer.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Analysis and design of fast flow liquid Li divertor for fusion nuclear science facility (FNSF) using coupled plasma boundary and LM MHD/heat transfer codes *

The SOLPS-ITER code is utilized to analyze the boundary plasma associated with a fast-flow lithium (Li) divertor configuration in the fusion nuclear science facility (FNSF) tokamak and identify operational regimes with acceptable divertor and core conditions. Plasma transport from the SOLPS-ITER code has been coupled with a liquid metal (LM) MHD/heat transfer code to model a Li open-surface divertor design and assess its impact on the scrape-off-layer (SOL) and core plasma performance. Simulations with only Neon (Ne) impurity seeding have been conducted to evaluate its impact on meeting FNSF design demands for the divertor and upstream plasma parameters. Simulation results indicate that Ne seeding significantly mitigates divertor heat flux but potentially reduces both upstream electron and main ion density due to fuel dilution. The combined application of Ne seeding and deuterium (D 2 ) puffing is required to satisfy the FNSF design requirements on upstream density ($n^{OMP}_{e,sep}$~1× 10 20 m -3 ) and divertor energy flux ($q^{Odiv}_{\bot,max}$<10 MW m -2 ). D 2 puffing plays a role in counteracting upstream density drops and augmenting energy and momentum losses through atomic and molecular processes. The inlet Li flow velocity is systematically varied across a wide range to identify acceptable flows and corresponding LM surface temperatures. This comprehensive analysis identifies the acceptable Li flow parameters, LM surface temperature, and emitted Li fluxes necessary to meet the major design constraints. The emitted Li fluxes exhibit minimal impact on the main plasma at surface temperatures up to approximately ~525 °C, corresponding emitted Li fluxes of up to φ Li ~2X10 23 atoms s -1 . Uncertainties in the Li emission processes from the surface are also investigated, primarily influencing Li loss in the lower surface temperature range (<525 °C), with simulation results indicating a minor impact on the divertor and upstream plasma. Conversely, evaporation predominantly drives the Li loss processes at higher surface temperature ranges (>525 °C), contaminating both the divertor and upstream plasma.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Stability optimization of energetic particle driven modes in nuclear fusion devices: the FAR3d gyro-fluid code

The development of reduced models provide efficient methods that can be used to perform short term experimental data analysis or narrow down the parametric range of more sophisticated numerical approaches. Reduced models are derived by simplifying the physics description with the goal of retaining only the essential ingredients required to reproduce the phenomena under study. This is the role of the gyro-fluid code FAR3d, dedicated to analyze the linear and nonlinear stability of Alfvén Eigenmodes (AE), Energetic Particle Modes (EPM) and magnetic-hydrodynamic modes as pressure gradient driven mode (PGDM) and current driven modes (CDM) in nuclear fusion devices. Such analysis is valuable for improving the plasma heating efficiency and confinement; this can enhance the overall device performance. The present review is dedicated to a description of the most important contributions of the FAR3d code in the field of energetic particles (EP) and AE/EPM stability. FAR3d is used to model and characterize the AE/EPM activity measured in fusion devices as LHD, JET, DIII-D, EAST, TJ-II and Heliotron J. In addition, the computational efficiency of FAR3d facilitates performing massive parametric studies leading to the identification of optimization trends with respect to the AE/EPM stability. This can aid in identifying operational regimes where AE/EPM activity is avoided or minimized. This technique is applied to the analysis of optimized configurations with respect to the thermal plasma parameters, magnetic field configuration, external actuators and the effect of multiple EP populations. In addition, the AE/EPM saturation phase is analyzed, taking into account both steady-state phases and bursting activity observed in LHD and DIII-D devices. The nonlinear calculations provide: the induced EP transport, the generation of zonal structures as well as the energy transfer towards the thermal plasma and between different toroidal/helical families. Finally, FAR3d is used to forecast the AE/EPM stability in operational scenarios of future devices as ITER, CFETR, JT60SA and CFQS as well as possible approaches to optimization with respect to variations in the most important plasma parameters.

Alfv én Eigenmodes↗
DOE OSTI2022

Gamma-based nuclear fusion measurements at inertial confinement fusion facilities

Experiments performed on an inertial confinement fusion (ICF) platform offer a unique opportunity to study nuclear reactions, including reaction branches that are useful for diagnostic applications in ICF experiments as well as several that are relevant to nuclear astrophysics. In contrast to beam-accelerator experiments, experiments performed on an ICF platform occur over a short time scale and produce a plasma environment with physical parameters that are directly relevant to big bang and/or stellar nucleosynthesis. Several reactions of interest, such as D(T,γ) 5 He, H(D,γ) 3 He, H(T,γ) 4 He, and T( 3 He,γ) 6 Li produce high-energy gamma rays. S factors or branching ratios for these four reactions have recently been studied using various temporally-resolved Cherenkov detectors at the Omega laser facility. This work describes these detectors as well as the current standard technique for performing these measurements. Recent results for reactions D(T,γ) 5 He, H(D,γ) 3 He, H(T,γ) 4 He, and T( 3 He,γ) 6 Li are reviewed and compared to accelerator-based measurements. Limitations associated with implosion experiments and use of the current standard gamma detectors are discussed. A basic design for a gamma spectrometer for use at ICF facilities is briefly outlined.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Experimental, numerical and analytical evaluation of j × B -thrust for fast-liquid-metal-flow divertor systems of nuclear fusion devices

Abstract Divertor systems of fusion devices are exposed to intense heat loads from plasmas, which degrade solid plasma-facing components. Fast liquid metal (LM) flow divertors may be more advantageous for this purpose but have risk of piling due to intense magnetohydrodynamic (MHD) drag. However, severe deceleration of the flow could be countered with the injection of currents that are transverse to external magnetic fields, allowing to thrust the flow with j × B (Lorentz) forces. Given that the injection of currents as an approach to propel LM-divertor flows has remained experimentally understudied, this article focuses on the evaluation of j × B -thrust and finding its drawbacks. j × B -thrust was experimentally tested with free-surface-LM flows, a vertical magnetic field and an externally applied current. Experiments were reviewed with a theoretical model, showing agreement in the trends of theory and experiments. Full 3D-MHD-free-surface-flow simulations were also performed with FreeMHD and confirmed the sensitivity to unstable flow behavior in LM systems when applying external currents. Furthermore, excessive power requirements are expected for the implementation of j × B -thrust at the reactor scale, making these systems inefficient for commercial devices. This paper evidences that the simple operation of a LM-flow divertor with j × B -thrust, without any of the instabilities caused from reactor plasmas or parasitic currents, already presents intrinsic challenges.

Magnetohydrodynamics↗
DOE OSTI2024

Inferring fusion nuclear burnwidths with low gain photomultiplier impulse response functions

When an inertial confinement fusion implosion is compressed, it maintains thermonuclear density and temperatures for a very short time scale, about 100 ps. The Gamma Reaction History diagnostic measures the time evolution of the fusion burn, but its temporal resolution is limited by the use of a photomultiplier tube (PMT) to amplify the photon signal. Multichannel plate-based PMTs have a fast (~120 ps) full-width at half-max impulse response function (IRF), but the time scale is similar to the incoming physics signal. An analysis routine is used to remove the effect of the PMT IRF and infer the incident fusion burnwidth. With the National Ignition Facility achieving ignition and creating much brighter signals, the PMTs are run at gains three orders of magnitude lower than nominal operation. Calibration at these settings shows the PMT IRFs get ~15% wider. Taking the gain-dependent IRF can affect the inferred nuclear burnwidths by up to ~15%.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Burning Plasma Science: Long Pulse-Materials and Fusion Nuclear Science (Final Project Report)

The series of International Conferences on Fusion Reactor Materials (ICFRM) has been established nearly forty years ago as the major international forum for exchanging and archiving a growing knowledge based on the development of materials for both near and long-term fusion energy systems. The critical role of materials science and engineering in overcoming the technological challenges to making fusion energy a practical reality has been an overarching theme of invited and contributed oral talks as well as the poster session presentations. ICFRM is the premier international forum connecting specialists in the area of development of materials for both near and longer-term fusion energy systems. A central theme is the sharing of new insights, cutting-edge research, and technology in materials science pertaining to the realization of fusion energy. The conference consists of daily overview plenary lectures, invited and contributed oral presentations, and a series of technical poster sessions. In addition to hosted satellite meetings, pre-conference technical tutorials, and stimulating discussions. The 19th International Conference on Fusion Reactor Materials (ICFRM-19) was held in La Jolla, California, U.S.A. during the period October 27 through November 1, 2019. We describe here the conference background, topics, structure, program, schedule and timeline, publications, venue, satellite meetings, short courses and seminars, and finally the budget and expenses.

36 MATERIALS SCIENCE↗
DOE OSTI2020

An Evaluation of the Global Effects of Tritium Emissions from Nuclear Fusion Power

We report that tritium, like all hydrogen isotopes, is difficult to confine and easily diffuses through most materials. As currently planned, fusion power plants will process and handle large quantities of deuterium and tritium as fuel, and therefore, will become sources of tritium input into the environment. Tritium releases from a worldwide distribution of tritium sources (fusion or fission) will lead to higher tritium levels overall and have global impact. This report investigates the hydrologic partitioning of yearly tritium releases assuming 1 g/yr loss per 500 MW of nuclear power generation for varying scales of power generation. On large scales, it is found that the worldwide average levels of tritium could exceed some public health goals and regulatory guidelines. Tritium concentrations at such levels may also have other impacts on the environment through increased ion-pair generation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1978

Nuclear fusion and carbon flashes on neutron stars

This paper reports on detailed calculations of the thermal evolution of the carbon-burning shells in the envelopes of accreting neutron stars for mass-accretion rates of 1 hundred-billionth to 2 billionths of a solar mass per yr and neutron-star masses of 0.56 and 1.41 solar masses. The work of Hansen and Van Horn (1975) is extended to higher densities, and a more detailed treatment of nuclear processing in the hydrogen- and helium-burning regions is included. Results of steady-state calculations are presented, and results of time-dependent computations are examined for accretion rates of 3 ten-billionths and 1 billionth of solar mass per yr. It is found that two evolutionary sequences lead to carbon flashes and that the carbon abundance at the base of the helium shell is a strong function of accretion rate. Upper limits are placed on the accretion rates at which carbon flashes will be important.

Taam, R. E.↗