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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Cooling Design and Thermal Analysis for Thermal Shields of a Cryocooler-Cooled Superconducting ECR Ion Source MARS-D Magnet

Here, a demonstrative NbTi based Mixed Axial and Radial field System (MARS-D) is being developed for a next-Generation Electron Cyclotron Resonance Ion Source (ECRIS) at Lawrence Berkeley National Laboratory (LBL), which employs a novel closed-loop coil design scheme that more efficiently utilizes conductor fields and extend the application of NbTi for high frequency (up to 45 GHz) ECR operation. The NbTi MARS-D magnet consists of a single hexagonally shaped closed-loop coil and a set of auxiliary solenoids. A cryostat for cooling the MARS-D magnet is under design at LBL. The MARS-D magnet working around 4.2 K will be bath-cooled in liquid helium using multiple two-stage cryocoolers. An intermediate temperature thermal radiation shield is adopted to reduce the heat leakage imposed on 4.2 K coil cold mass from room temperature. The thermal shield is conduction-cooled by the first-stage cold heads of four two-stage cryocoolers and the cold head of a single-stage cryocooler shared with nine binary leads. The temperature in the area of the shield that warm ends of HTS leads are mounted on is expected no higher than 60 K, which is limited by maximum allowable working temperature of HTS leads. The paper presents thermal analysis on the thermal radiation shield including heat loads and effects of eddy current induced during quench on its material selection.

ECRIS↗
DOE OSTI2025

Operational Experience of the NML Cryogenic Plant at the FAST Test Facility

The NML cryogenic plant cools two individually cryostated superconducting radio frequency (SRF) capture cavities and one prototype ILC cryomodule with eight SRF cavities. This complex accelerates electrons at 150 MeV for the Integrable Optics Test Accelerator (IOTA) ring, located at the Fermilab Accelerator Science and Technology (FAST) facility. The cryogenic plant is composed of two nitrogen precooled Tevatron satellite refrigerators, two Mycom 2016C compressors, a cryogenic distribution system, a Frick purifier compressor, two charcoal bed adsorber purifiers, and a liquid ring vacuum pump with a roots booster. The SRF cavities are immersed in a 2.0 K liquid helium bath, shielded with a 5 K gaseous helium shield and a liquid nitrogen cooled thermal shield. Since 2019, this R&D accelerator complex has gone through four science runs with an average duration of 12 months. Operational experience for each run, availability metrics, performance data and common outages are presented in this paper.

Wallace, Timothy [Fermilab] (ORCID:000900051589302↗
DOE OSTI2025

Compact cryomodule for mobile stand-alone superconducting industrial accelerators

Superconducting RF (SRF) accelerators have the potential to be more profitable in comparison with normally conducting accelerators, as long they can be made compact, achieve operational simplicity, autonomy, trans- portability, satisfactory energy efficiency, as well as have reasonable costs. The development of SRF technologies such as Nb 3 Sn coating, conductively-cooled resonators, and high-capacity liquid-helium-free cryocoolers made SRF accelerators mobile and energetically and economically efficient at a beam power of tens of kW. One of the key elements of such an accelerator is the cryomodule, which must have minimal thermal losses to enable operation from low power cryoheads and enable conductive cooling of SRF resonator. In this research we present the design and test results of a compact cryomodule for an industrial stand-alone SRF linear accelerator proto- type, based on 650 MHz elliptical resonators, being developed at Fermi National Accelerator Laboratory.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Effect of Cathode Cooling in Three-Dimensional Simulations of an Atmospheric Pressure Glow Discharge

The Atmospheric Pressure Glow Discharge (APGD) is a relatively simple and versatile plasma source used in a wide range of applications. Active cooling of the cathode can effectively mitigate instabilities, leading to glow-to-arc transitions. This study investigates the effect of varying the degree of cathode cooling in APGD with a planar cathode in helium. The plasma flow model incorporates mass conservation, chemical species transport, momentum conservation, conservation of thermal energy of heavy species and of electrons, and electrostatics. The model is applied to time-dependent simulations through a three-dimensional computational domain describing the whole discharge, without geometric symmetry or steady-state assumptions. Simulations of an experimentally characterized APGD explore the effects of electric current and cathode cooling—ranging from thermally insulated to extreme convective cooling. Results show the formation of an annular region with high electric field over the cathode surface under conditions of high current and low cooling.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Experimental Results for an Inverter Integrated with A High-Speed Surface Permanent Magnet External Rotor Motor

This work presents the prototyping and testing of a high-speed outer rotor surface permanent magnet motor. The motor employs non-heavy rare-earth permanent magnets and operates at a rated speed of 6,666 rpm. In-slot ceramic heat exchangers are used to cool the windings. The external rotor configuration provides substantial space within the stator bore, which is used for power electronics integration. This integration introduces several design and thermal management challenges that are discussed in the paper. The machine has been prototyped and tested under various operating conditions, and both simulation and experimental results are presented.

Rallabandi, Vandana [ORNL] (ORCID:0000000236241901↗
DOE OSTI2025

Risk Assessment of EIC Central Detector (ePIC) Solenoid Magnet (MARCO)

As part of the BNL-JLab-CEA Electron Ion Collider (EIC) collaboration, the design of a 2 T, 2.8 m bore diameter, 3.8 m long conduction cooled superconducting detector magnet design is completed. Such magnet will be employed at the interaction region of ePIC for physics experiment. The magnet is a passive shielded solenoidal magnet system consisting of 3 coils wound with specially designed conductor using NbTi Rutherford type cable in copper stabilized channel. This paper describes the risk analysis as the part of Failure Modes and Effects Analysis (FMEA) that was carried out as a team to identify their various failure modes and risks associated with the magnets system. In conclusion, this FMEA is intended to become the content of the designed document as an integral part of the engineering assessment and the statement of work for the potential vendors towards design and built.

Ghoshal, Probir K. [Thomas Jefferson National Acce↗
DOE OSTI2025

The "Fake" Supernova Neutrinos of SBND: Using Muons Decaying at Rest to Study the Charged Current MeV-Scale $V_e$-Ar Cross Section

In a Type-II core collapse supernova, 99% of the total amount of energy is released in the form of neutrinos. However, the nearest supernova explosion in the last few hundred years was in 1987, over thirty years ago. It was also the first from which particle detectors around the world managed to detect the neutrino flux, yielding important information about their properties and the explosion mechanism. Neutrinos are the most weakly interacting subatomic fundamental particles known to date, and they act as a cooling mechanism for the star. Out of the six neutrino flavours currently known, the majority exiting the explosion are electron neutrinos, ve. Neutrino experiments using liquid argon (LAr) as their detector medium are unique at probing this specific channel. In the meantime, however, until the next explosion, we can still practise for the big event. With the Short Baseline Near Detector (SBND) experiment at Fermilab, we can study how electron neutrinos of the same energy coming from the Booster Neutrino Beam (BNB) interact in LAr, and measure the cross section. As BNB measurements are mostly tailored to higher energy neutrinos, I will present an overview of how SBND is aiming to select the low-energy neutrino candidates from muons Decaying At Rest (DAR) in the absorber and target within the BNB beam pipe. This is not a straightforward feat, encompassing special difficulties that include beam and flux systematic uncertainty simulation, system trigger needs and particular reconstruction efforts, and so I will present how each challenge is being addressed in SBND. This will be a novel measurement in the neutrino particle physics community, and will prove fundamental for the next generation of supernova neutrino detectors.

Kotsiopoulou, Lucy [Edinburgh U.]↗
DOE OSTI2025

Overview on Current Activities of Conduction-Cooled SRF Accelerators and their Applications

When Nb3Sn was reintroduced to the SRF community as an alternative to pure niobium, one key motivation has been to reduce the cryogenic requirements of new and existing accelerators by shifting from 2 K to 4 K operation. Meanwhile, a variety of implementations beyond research machines are being explored. The combination of Nb3Sn with conventional cryocoolers, enabling cryogen-free operation, has paved the way for the development of compact, standalone systems suitable for applications far beyond research, such as enhancing the durability of synthetics via crosslinking or sterilizing food and medical equipment, as well as environmental cleanup when it comes to decontaminating liquid and solid waste material. So, while fundamental R&D continues to refine Nb3Sn resonators, exploring improvements such as replacing the niobium substrate with copper, parallel research efforts are investigating how the increased beam power provided by SRF could expand the commercial use of electron beams. This presentation aims to deliver a comprehensive overview of ongoing research efforts to harness the benefits of SRF through Nb3Sn and conduction cooling.

Vennekate, John [Thomas Jefferson National Acceler↗
DOE OSTI2025

Photocurrent Nanoscopy of Quantum Hall Bulk

Understanding nanoscale electronic and thermal transport of two-dimensional (2D) electron systems in the quantum Hall regime, particularly in the bulk insulating state, poses considerable challenges. One of the primary difficulties arises from the presence of chiral edge channels, whose transport behavior obscures the investigation of the insulating bulk. Using near-field optical and photocurrent nanoscopy, we probe real-space variations of the optical and thermal dynamics of graphene in the quantum Hall regime without relying on complex sample or electrode geometries. Near the charge-neutrality point, we detect strong optical and photothermal signals from resonant inter-Landau-level (LL) magnetoexciton excitations between the zeroth and ± 1 st LLs, which gradually weaken with increasing doping due to Pauli blocking. Interestingly, at higher doping levels and full-integer LL fillings, photothermal signals reappear across the entire sample over an approximately 10 − μ m scale, indicating unexpectedly long cooling lengths and nonlocal photothermal heating through the insulating bulk. This observation suggests that thermal conductivity persists for the localized states even as electronic transport is suppressed—a clear violation of the Wiedemann-Franz law. Our experiments provide novel insights into nanoscale thermal and electronic transport in incompressible 2D gases, highlighting the roles of magnetoexcitons and chiral edge states in the thermo-optoelectric dynamics of the Dirac quantum Hall state. Published by the American Physical Society 2025

36 MATERIALS SCIENCE↗
DOE OSTI2025

In Situ 4D‐STEM Imaging of the Orientation of Lamellar Clusters in Polymer Crystallization

In semi‐crystalline polymeric materials, the initial stages of nucleation and the growth path of crystalline domains can determine the final performance. Here, in this work, we used four‐dimensional scanning transmission electron microscopy (4D‐STEM) imaging to analyze the changes in lamellar orientation in high‐density polyethylene (HDPE) during heating and cooling. This method allowed us to quantitatively detect the formation of lamellae clusters with different in‐plane orientations, which are not visible with traditional methods. Our analysis provided detailed insights into the orientation and size changes of crystalline domains. Additionally, this technique enabled direct observation of lattice structures in hierarchical lamellae and the growth of crystals, confirming the local variability in lamellar orientation. This innovative approach significantly improves our understanding of polymer crystallization, linking changes in morphology and lattice structures at different length scales.

4D-STEM↗
DOE OSTI2024

Difficult Measurements of Materials Systems at Cryogenic Temperatures: Cryo-EELS and Cryo-4D-STEM

Scanning/transmission electron microscopy (S/TEM) in materials science has traditionally been accomplished at room temperature due to their solid state in this temperature range and relative insensitivity to radiolysis damage. Cooling to cryogenic temperatures tended to introduce instabilities such as vibration and drift and can lead to the buildup of carbon contamination or ice reducing contrast. The need to expand TEM experimental techniques into new fields such as quantum and battery materials led to new efforts to reduce these instabilities while achieving temperatures at or well below liquid nitrogen (77 K). Further, developments in detector and spectrometer technology brought new capabilities for high resolution electron energy loss spectroscopy (EELS) and scanning nanodiffraction (4D-STEM). These experimental modalities can require even tighter controls of drift, vibration, and exposure time. Here this presentation will discuss accomplishing difficult experiments at cryogenic temperatures in honor of the late Dr. Lena Kourkoutis who inspired and led many such experiments.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Hydrogen Analysis by Gas Chromatography–Mass Spectrometry

The detection of hydrogen in complex gas mixtures is essential for many applications. Conventional approaches such as gas chromatography (GC) with thermal conductivity detection (TCD) and residual gas analyzers (RGAs) face significant limitations: TCD exhibits poor response when helium is used as a carrier gas, whereas RGAs lack chromatographic separation, preventing reliable quantification of hydrogen because of interference from other species. Traditional GC methods rely on dual-column configurations with packed or molecular-sieve porous layer open tubular (PLOT) columns to separate hydrogen from O2, N2, CO, CO2, CH4, and other hydrocarbons, increasing system complexity and limiting compatibility with mass spectrometry (MS) detection. In this work, we developed and validated a robust GC–MS method capable of directly detecting and quantifying hydrogen using electron ionization (EI) without dopants, reagent gases, or ion–molecule reaction schemes. By integrating a modified EI source and a cryogenically cooled single capillary column configuration, we achieved baseline separation of hydrogen from all major permanent gases and hydrocarbons in a refinery gas mixture using helium as the carrier gas. The method demonstrated excellent linearity, high sensitivity, and exceptional reproducibility. Adjustable sample-loop volumes and split ratios enabled optimization of peak shape and signal-to-noise performance for trace-level and percent-level hydrogen concentrations. Beyond hydrogen quantitation, the method provides simultaneous compositional profiling of other gases in a mixture in a single run, making it valuable for a wide range of tasks.

Lobodin, Vlad [ORNL]↗
DOE OSTI2024

Phase transition kinetics of superionic H2O ice phases revealed by Megahertz X-ray free-electron laser-heating experiments

Abstract H 2 O transforms to two forms of superionic (SI) ice at high pressures and temperatures, which contain highly mobile protons within a solid oxygen sublattice. Yet the stability field of both phases remains debated. Here, we present the results of an ultrafast X-ray heating study utilizing MHz pulse trains produced by the European X-ray Free Electron Laser to create high temperature states of H 2 O, which were probed using X-ray diffraction during dynamic cooling. We confirm an isostructural transition during heating in the 26-69 GPa range, consistent with the formation of SI-bcc. In contrast to prior work, SI-fcc was observed exclusively above ~50 GPa, despite evidence of melting at lower pressures. The absence of SI-fcc in lower pressure runs is attributed to short heating timescales and the pressure-temperature path induced by the pump-probe heating scheme in which H 2 O was heated above its melting temperature before the observation of quenched crystalline states, based on the earlier theoretical prediction that SI-bcc nucleates more readily from the fluid than SI-fcc. Our results may have implications for the stability of SI phases in ice-rich planets, for example during dynamic freezing, where the preferential crystallization of SI-bcc may result in distinct physical properties across mantle ice layers.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Low Temperature Dynamic Polaron Liquid in a Manganite Exhibiting Colossal Magnetoresistance

Polarons - fermionic charge carriers bearing a strong companion lattice deformation - exhibit a natural tendency for self-localization due to the recursive interaction between electrons and the lattice. While polarons are ubiquitous in insulators, how they evolve in transitions to metallic and superconducting states in quantum materials remains an open question. Here, we use resonant inelastic x-ray scattering to track the electron-lattice coupling in the colossal magneto-resistive bi-layer manganite La 1.2 Sr 1.8 Mn 2 O 7 across its metal-to-insulator transition. The response in the insulating high-temperature state features harmonic emissions of a dispersionless oxygen phonon at small energy transfer. Additionally, upon cooling into the metallic state, we observe a drastic redistribution of spectral weight from the region of these harmonic emissions to a broad high energy continuum. In concert with theoretical calculations, we show that this evolution implies a shift in electron-lattice coupling from static to dynamic lattice distortions that leads to a distinct polaronic ground state in the low temperature metallic phase - a dynamic polaron liquid.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

The self-annealing of irradiation induced defects in magnetite Fe 3 O 4 : Revealing reversible irradiation-induced disorder transformation through in situ TEM

This work reports heavy ion-irradiation effects in polycrystalline Fe 3 O 4 . For this matter, Fe/Fe 3 O 4 heterostructures were irradiated in situ in a transmission electron microscopy with 1 MeV Kr ions at 50 K. Evidence of cubic to monoclinic transformation (a.k.a Verwey transition) was recorded in some magnetite grains upon cooling the sample (around 90 K); however, most of the oxide grains retain their cubic spinel structure. Irradiation effects were analyzed in the cubic phase up to a maximum dose of 38 dpa without the sign of amorphization. The extinction of first-order reflections was recorded at doses below 1 dpa, indicating the formation of a new (metastable) phase with half of the lattice parameters compared to the unirradiated Fe 3 O 4 crystal. The formation of the new crystalline phase, which also presents a high resistance to amorphization, is related to the disordering of the cation lattice and the high mobility of the cation interstitials. The metastable phase readily recovers around 225 K during the natural warming of the sample from 50 K to room temperature.

Atom irradiation effects↗
DOE OSTI2025

A Modified DBC Substrate Improving Thermal Performance for Confined Space Applications

High-power modules use substrates to house the semiconductor device and for electrical insulation. These substrates are constructed with thermally conductive dielectric material sandwiched between two metals to extract heat from semiconductor chips. Thus, the required cooling performance of a power module is linked to the substrate’s thermal performance and can vary based on the substrate technologies. Here, in this study, five substrate technologies were evaluated for space-restricted applications: direct-bonded copper (DBC), an insulated metal substrate (IMS), a thermally annealed pyrolytic graphite (TPG)-based IMS, DBC-based double-sided cooling, and direct-bonded aluminum (DBA) where the heat sink is directly attached without thermal interface materials (TIMs). The finite element (FE) analysis results suggest that the popular DBC substrate has thermal performance better than that of the other substrates for space-constrained applications. To further improve the thermal performance, a modified DBC substrate was proposed where a copper block was added between the semiconductor and the DBC substrate to achieve heat spreading underneath the chip. The modified DBC performance was then compared with the aforementioned substrates and the results showed significant thermal performance improvement. The results were verified with experimental results where the proposed substrate showed 20% more loss handling capability compared to an identical DBC substrate.

42 ENGINEERING↗
DOE OSTI2025

Spatially Enhanced Electrostatic Doping in Graphene Realized via Heterointerfacial Precipitated Metals

Forming heavily-doped regions in 2D materials, like graphene, is a steppingstone to the design of emergent devices and heterostructures. Here, a selective-area approach is presented to tune the work-function and carrier density in monolayer graphene by spatially synthesizing sub-monolayer gallium beneath the 2D-solid. The localized metallic gallium is formed via precipitation from an underlying diamond-like carbon (DLC) film that is spatially implanted with gallium-ions. By controlling the interfacial precipitation process with annealing temperature, spatially precise ambipolar tuning of the graphene work-function is achieved, and the tunning effect preserved upon cooling to ambient conditions. Consequently, charge carrier densities from ≈1.8 × 10 10 cm -2 (hole-doped) to ≈7 × 10 13 cm -2 (electron-doped) are realized, confirmed by in situ and ex situ measurements. The theoretical studies corroborated the role of gallium at the heterointerface on charge transfer and electrostatic doping of the graphene overlayer. Specifically, sub-monolayer gallium facilitates heavy n-doping in graphene. Extending this doping strategy to other implantable elements in DLC provides a new means of exploring the physics and chemistry of highly-doped 2D materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Operational Experience of the NML Cryogenic Plant at the FAST Test Facility

The New Muon Laboratory (NML) cools two individually cryostated superconducting radio frequency (SRF) capture cavities (CC) and one prototype ILC cryomodule (CM) with eight SRF cavities. This complex accelerates electrons at 150 MeV for the Integrable Optics Test Accelerator (IOTA) ring, located at the Fermilab Accelerator Science and Technology (FAST) facility. Since 2019, this R&D accelerator complex has gone through four science runs.

Wallace, T. [Fermilab]↗