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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 OSTI2026

Lyapunov-Based Iterative Learning of the Region of Attraction for Autonomous Systems

This presentation introduces a novel algorithm for estimating the region of attraction of equilibrium points for nonlinear discrete-time autonomous systems. The method iteratively expands an initial estimate of the region of attraction by constructing unions of sublevel sets of learned functions parametrized as neural networks. Unlike conventional techniques that rely on a single global Lyapunov function, the proposed approach provides a collection of local Lyapunov-like functions, enabling richer representations and potentially larger region of attraction estimates. These functions are trained using sampled state-space data, and their Lipschitz continuity ensures that desirable properties extend beyond the training samples. The devised strategy is tested via numerical simulations, demonstrating the effectiveness of the proposed approach.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2026

Splat Quenching as a High Throughput Rapid Solidification Testing Method for Developing Additive Manufacturing Alloys

Splat quenching as a high throughput rapid solidification screening tool is evaluated. Samples were made using known alloys (SS316, IN625, Ti-5553) to evaluate and establish the microstructures for a variety of alloy systems as well as the predicted cooling rates. The samples are inductively heated and levitated prior to being struck between two platens that produce a high contact pressure and a thin sample resulting in cooling rates on the order of 10 6 to 10 7 K/s. Process parameters were evaluated with analytical models in addition to numerical simulations to provide an effect of process variables such as substrate material, melt superheat, and platen velocity on the resulting solidification. The splat thickness was found to be controlled by platen velocity, melt superheat, as well as the feedstock volume. The sample thickness is the key controlling factor for varying the average cooling rate experienced by the splat quenched sample. The splat quenching techniques can reach regions of rapid solidification space that meet and exceed laser and electron beam techniques across the sample. In conclusion, the results of the study provide a useful foundation in understanding the splat quenching technique and its potential as a low effort tool to explore rapid solidification effects on alloys.

Alloy Design↗
DOE OSTI2022

Micro-Environmental Control System (Final Report)

This project developed an innovative micro-environmental control system (µX) that enables office buildings to reduce energy used for heating and cooling by 15% or more. The µX is a compact, quiet, and ergonomic device that is designed to be installed under an office workstation; it is designed to maintain occupant comfort when room thermostat setpoints are incremented by 4°F or more (warmer in the summer and cooler in the winter) to save energy. When ambient room temperatures are outside of the usual comfort range, the µX maintains occupant comfort by delivering personalized cooling or heating locally to each office worker. The µX provides personalized cooling using a micro vapor compression system that includes a new high-performance micro-scroll compressor and a novel thermal storage unit. The vapor compression system operates at night to freeze a phase-change material (PCM). During the workday, the cooling stored in the PCM is released as a cool breeze of air to make occupants more comfortable. The micro-scroll compressor was developed specifically for this application; it is smaller than any of its type, minimizing the amount of power needed. In heating mode, the µX maintains occupant comfort using a foot heating mat with an infrared reflective box. The µX R&D project was conducted by Syracuse University in collaboration with United Technologies Research Center, Air Innovations, Bush Technical, and Cornell University. Over the course of the initial three-year project, the team developed and evaluated four versions of the unit, advancing the concept to Technology Readiness Level 6. The capabilities of individual proof-of-concept prototypes were verified in tests that were conducted with: 1) units in psychrometric chambers, 2) an instrumented manikin in a laboratory, and 3) human subjects in laboratories that simulate office environments. The tests verified that the µX prototypes met or exceeded all performance targets required to enable office buildings to reduce energy used for heating and cooling by 15% or more by maintaining occupant comfort when thermostat setpoints are incremented by 4°F or more.

25 ENERGY STORAGE↗
DOE OSTI2018

Redox Control for Processing of High-Bi HLW (VSL-18R4400-1, Rev. 0)

This report provides results from tests designed to determine the redox conditions associated with bismuth reduction and the potential for molten bismuth metal formation in a high-Bi HLW glass melt, its role in Inconel metal corrosion, and to identify feed reductant and oxidant contents to avoid issues during melter feed processing. This was accomplished through crucible scale tests and with DM10 melter system tests using simulated high bismuth HLW and a glass composition that performed well during crucible scale and DM100 melter testing.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Analysis of impact toughness scatter in simulated coarse-grained HAZ of E550 grade offshore engineering steel from the aspect of crystallographic structure

Highlights: • Crystallographic structure evolution in CGHAZ caused by variation of prior austenite grain size was analyzed quantitatively. • Variant selection rules changed from CP (close-packed plane) to Bain grouping with decreasing of prior austenite grain size. • A possible correlation between impact toughness scatter and crystallographic structure was established. - Abstract: This study aims at providing a new insights into the impact toughness scatter from the aspect of crystallographic structure. It demonstrated that the large impact toughness scatter associated much to the microstructure diversity. The crystallographic structure with evident scatter will display obvious discrepancy. In this work, three groups of samples simulated coarse-grained heat affected zone (CGHAZ) of an offshore engineering steel were obtained at different cooling rates. The Charpy test results showed that the toughness decreases dramatically with the decrease of cooling rate. However, the largest scatter in impact toughness occurred in the sample with medium cooling rate (15 °C/s), which was attributed to the heterogeneity in crystallographic structures. The visualization of crystallographic features showed that the prior austenite grain size has a significant effect on bainitic variant selection, which governed the effective grain size and crack propagation mechanism. CP (close-packed plane) grouping of variants is more likely to take place in large austenite grain, indicating that the size of CP region is larger than Bain zone, and the crack is short and flexural. On the contrary, in smaller austenite grain, Bain grouping of variants that always forms low angle grain boundary and favors crack propagation dominates the transformation, and it will promote the crack to propagate through the entire Bain zone and then yield large long crack. However, these two cases can co-exist in the same sample at medium cooling rate, indicating that the cleavage fracture is controlled by the effective grain size (Bain-zone size) and the scatter in impact toughness is associated much to the proportion and relative location between fine and coarse Bain zones.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Assessment of the Electrical Substation-Grid Testbed with Inside/Outside Devices and Distributed Ledger Technology

The electrical substation-grid testbed was created to integrate the GOOSE and/or DNP (Distributed Network Protocol) messages with time synchronized sources and Distributed Ledger Technology (DLT). The objective was to study the impact of faults and cyber-events at an electrical substation with inside (protective relays) and outside (power meters) substation devices. The electrical substation-grid testbed was based on the design of a 34.5/ 12.47 kV electrical substation (sectionalized bus configuration) with two power transformers, connected to radial power lines and load feeders. The electrical substation-grid testbed was installed at 252 lab space (Advanced Power System Protection), Grid Research Integration and Deployment Center (GRID-C), Oak Ridge National Laboratory. This testbed was created for Task 5, DarkNet project. The electrical substation-grid testbed was created to simulate fault and/or cyber events that could potentially result in damage to the electrical infrastructure. In addition, tests were run that are usually not allowed to be performed in an operational electrical power grid, because these test scenarios could trip breakers and/or generate fault situations that could potentially damage equipment. The number of tests performed in the electrical substation-grid testbed were executed in a better way than in a real electrical substation and/or power grid, because multiple tests could be run in a short period of time, and complex permits, and safety/ schedule restrictions like in a real electrical substation environment were not needed. The electrical substation-grid testbed was created using real measurement, communication, and protection devices that are used by electrical utilities, to have same conditions that we could observe in a real power grid or electrical substation. The electrical substation-grid testbed was based on using a real time simulator and expansion box with amplifiers that were wired to electrical substation-grid devices. This hardware-in-the-loop (HIL) was provided by protective relays, power meters, ethernet switches, remote terminal units, synchronized timing network clock, DLT devices, workstations, and servers. This report includes the design, installation, and assessment of the electrical substation-grid testbed that was similar to an operational electrical substation, integrating the power system protection, communication, and control systems. The results for the electrical substation-grid testbed were based on:• verifying the analog signals for protective relays and power meters, • observing the synchronized time source frame at devices, • authenticating the GOOSE (IEC 61850) and DNP messages from power meters and protective relays, and • verifying the trip conditions of protective relays at fault tests with the power system fault event detection, using DLT devices. For future work, the electrical substation-grid testbed with protective relays and power meters, using DLT and synchronized time source from DarkNet, will be used to study the impact of cyber-events at inside and outside substation devices. Advanced algorithms for detecting cyber-events produced by non-desired protective relay settings will be studied, to improve the detection and reliability of protection, control, and communication systems at power grids.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2022

Voltage Violation Prediction in Unobservable Distribution Systems

Recently, distributed energy resources (DERs) such as photovoltaic (PV) systems have garnered significant attention due to their economic and environmental benefits. However, DERs can also pose new technical challenges to distribution system operation including under/over voltage issues. In this regard, voltage violation prediction (VVP) becomes an essential component of system operation as it enables proactive control strategies. Unfortunately, classical voltage monitoring techniques assume full availability of state measurements across all nodes in the system. In real-world scenarios, distribution systems are limited with few measurement devices, rendering the system unobservable. Therefore, this paper proposes a new Bayesian matrix completion (BMC) based VVP technique that accurately predicts the probability of nodal voltage violations in unobservable (and unbalanced) distribution systems. The proposed approach is tested via simulations on the IEEE 37 test system. Results show that the proposed method offers over 90% violation prediction accuracy with as low as 50% fraction of available data.

Abujubbeh, Mohammad↗
DOE OSTI2026

Laboratory tests of laser control of electron beams for future colliders

Laser-driven Compton backscattering (CBS) has been proposed as method for controlling the intensity of colliding bunches in the FCC-ee so as to avoid the flip-flop instability caused by intensity asymmetry in colliding bunches. Laser-based collimation has also been proposed as an indestructible collimator for high-intensity electron beams. We have initiated a laboratory-based test program of these concepts with the E344 experiment at FACET-II. In this paper, we describe simulations of laser–beam interactions at FACET-II and the relevant scaling for FCC-ee. We also describe the experimental setup and diagnostics that will be used to make the measurements at FACET-II.

accelerator physics↗
DOE OSTI2026

Feedback, physics, and forecasts: The emerging paradigm of machine learning-driven battery research

Machine learning (ML) is reshaping how we understand, predict, and optimize electrochemical systems. In batteries, ML accelerates discovery across chemistry, design, and operation by transforming massive experimental and simulated datasets into predictive, interpretable models. This review consolidates a decade of progress in ML-driven battery innovation, from early-cycle feature extraction to operando image analysis and physics-informed modeling. We categorize approaches by data domain and physical fidelity, emphasizing interpretable ML for diagnostics, reinforcement learning for control, and multi-objective optimization for lifetime extension strategies. Additionally, we demonstrate how integrated models accelerate discovery, reduce testing time, and guide sustainable design. Economic analyses furthermore illustrate how these advances can lower cost per cycle and improve circularity. Together, these developments chart a path toward self-optimizing, sustainable battery technologies.

artificial intelligence↗
DOE OSTI2015

Evaluation of Variable Refrigerant Flow Systems Performance and the Enhanced Control Algorithm on Oak Ridge National Laboratory's Flexible Research Platform

A research project “Evaluation of Variable Refrigerant Flow (VRF) Systems Performance and the Enhanced Control Algorithm on Oak Ridge National Laboratory’s (ORNL’s) Flexible Research Platform” was performed to (1) install and validate the performance of Samsung VRF systems compared with the baseline rooftop unit (RTU) variable-air-volume (VAV) system and (2) evaluate the enhanced control algorithm for the VRF system on the two-story flexible research platform (FRP) in Oak Ridge, Tennessee. Based on the VRF system designed by Samsung and ORNL, the system was installed from February 18 through April 15, 2014. The final commissioning and system optimization were completed on June 2, 2014, and the initial test for system operation was started the following day, June 3, 2014. In addition, the enhanced control algorithm was implemented and updated on June 18. After a series of additional commissioning actions, the energy performance data from the RTU and the VRF system were monitored from July 7, 2014, through February 28, 2015. Data monitoring and analysis were performed for the cooling season and heating season separately, and the calibrated simulation model was developed and used to estimate the energy performance of the RTU and VRF systems. This final report includes discussion of the design and installation of the VRF system, the data monitoring and analysis plan, the cooling season and heating season data analysis, and the building energy modeling study

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

Imaging LIDAR through Fog and Dust for Maritime Surveillance

This work supports Airborne Intelligence, Surveillance, and Reconnaissance (ISR) for tactical situational awareness in challenging environments with modified imaging LIDAR (light detection and ranging). LIDAR produces an irradiance-based scene with high, three-dimensional, spatial resolution; differentiating reflecting surfaces and surface textures not just for target detection, but also target recognition. LIDAR is generally prevented from working through all weather; as the traditional source wavelengths are scattered and/or absorbed by fog, clouds, and dust known as degraded visual environments (DVEs). This work identifies and quantifies improved optical wavelength regimes and polarization strategies that should open this otherwise denied operating window for LIDAR. We demonstrate modified imaging LIDAR's utility and ability to produce images in environments that have been challenging for traditional LIDAR (fog, dust) systems. We utilize a state-of-the-art Geiger mode avalanche photodiode (GMAPD) 32X32 detecting array for imaging with an integrated fast timing circuit ROIC per imaging detector pixel. This GMAPD is equivalent to 1024 radar receivers and produces a 3-D point cloud scene for each <lnsec laser interrogation pulse. Through this work, we have demonstrated Sandia's first imaging LIDAR system. We developed significant software to scan the GMAPD array, control data acquisition, and stitch an arbitrary number of images for greater lateral spatial resolution. We designed and built an optical system to evaluate performance, in the laboratory and in field tests, and relate to the performance at tactically important distances. Our use of this system is to study and characterize techniques that extend the range of useful imaging through fog for applications in a maritime environment. We quantify, with simulations, broad wavelength regimes and illuminating polarizations that have benefit in propagating through fog. In particular, we identify circular polarization over broad wavebands as a superior persisting signal technique in extending the useful range of active LIDAR in forward-scattering environments. Finally, we characterize the performance of our LIDAR system and confirm our theoretical predictions in the field and directly evaluate this system as a function of polarization in Sandia's medium-range Fog Tunnel Facility. This technology has potential impacts in improved ISR in maritime environments, but with further development could be revolutionary in tactical ISR by providing real-time three-dimensional full motion video (3D FMV) in DVEs.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Laboratory Tests of Laser Control of Electron Beams for Future Colliders

Laser-driven Compton backscattering (CBS) has been proposed as method for controlling the intensity of colliding bunches in the FCC-ee so as to avoid the flip-flop instability caused by intensity asymmetry in colliding bunches. Laser-based collimation has also been proposed as an indestructible collimator for high-intensity electron beams. We have initiated a laboratory-based test program of these concepts with the E344 experiment at FACET-II. In this paper, we describe simulations of laser-beam interactions at FACET-II and the relevant scaling for FCC-ee. We also describe the experimental setup and diagnostics that will be used to make the measurements at FACET-II.

Accelerator Physics (physics.acc-ph)↗
DOE OSTI2016

High Energy X-ray Applications for the Characterization of Metallic Uranium Alloys

Uranium-based metallic alloys are both candidates for fuels in high performance research and test reactors, as well as in fast spectrum reactors as nuclear transmutation fuels that can be utilized to burn long-lived minor actinides and fission products. Uranium-molybdenum (UMo) alloys are under development for the use in research and test reactors. Whereas, uranium-zirconium (U-Zr) alloys represent one of the types of fuels that are under consideration for use within the fast spectrum reactors. Both of these types of metallic fuels have been studied for over five decades in various types of reactors. Many of the previous studies had focused on performance-based aspects. However, recent advances in characterization tools and techniques, as well as short-term (low fluence) neutron irradiation facilities have contributed to a more in-depth understanding of nuclear fuel and material behavior following irradiation. This knowledge is crucial to the enhancement of current modeling and simulation techniques, particularly with respect to parameterization and validation. This paper focuses on the use of high energy x-rays to characterize metallic nuclear fuel. The specimens were composed of depleted uranium (DU) alloyed with either Zr or Mo, where DU-xZr (x = 10, 15, or 20 wt.%) and DU-yMo (y = 7 or 10 wt.%). The geometries of the specimens were 3 mm TEM disks that were ∼200 μm in thickness. The fuel alloys were initially prepared via an arc melting process. The samples were irradiated at the Advanced Test Reactor at Idaho National Laboratory (INL) using the hydraulic rabbit system. The hydraulic rabbit system allows for well-controlled, short term irradiations (less than one cycle), hence resulting in low fluences. The U-based alloys were irradiated to doses of 0.01 and 0.1 dpa. The irradiation temperature of the specimens ranged from 150 deg. C to 800 deg. C. Synchrotron characterization techniques can be used to provide insight into material microstructure ranging a multitude of spatial scales, from the atomic scale to the macroscale. High-energy x-rays at the National Synchrotron Light Source II (NSLS II) and the Advanced Photon Source (APS) have been utilized to understand the microstructural changes in these metallic alloys, specifically with respect to phase identification, phase fractions, chemical bonding, strain, and dislocation density through the use of diffraction and X-ray Absorption Spectroscopy (XAS). These experiments utilized a robot for specimen exchange during the diffraction measurements, allowing for remote handling of radioactive materials. This is an example of another recent advancement in characterization techniques that enables research with nuclear materials. Detailed results of the analyses of the microstructural changes are pending.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

SU-E-T-580: On the Significance of Model Based Dosimetry for Breast and Head and Neck 192Ir HDR Brachytherapy

Purpose: To assess the dosimetric and radiobiological differences between TG43-based and model-based dosimetry in the treatment planning of {sup 192}Ir HDR brachytherapy for breast and head and neck cancer. Methods: Two cohorts of 57 Accelerated Partial Breast Irradiation (APBI) and 22 head and neck (H&N) patients with oral cavity carcinoma were studied. Dosimetry for the treatment plans was performed using the TG43 algorithm of the Oncentra Brachy v4.4 treatment planning system (TPS). Corresponding Monte Carlo (MC) simulations were performed using MCNP6 with input files automatically prepared by the BrachyGuide software tool from DICOM RT plan data. TG43 and MC data were compared in terms of % dose differences, Dose Volume Histograms (DVHs) and related indices of clinical interest for the Planning Target Volume (PTV) and the Organs-At-Risk (OARs). A radiobiological analysis was also performed using the Equivalent Uniform Dose (EUD), mean survival fraction (S) and Tumor Control Probability (TCP) for the PTV, and the Normal Tissue Control Probability (N TCP) and the generalized EUD (gEUD) for the OARs. Significance testing of the observed differences performed using the Wilcoxon paired sample test. Results: Differences between TG43 and MC DVH indices, associated with the increased corresponding local % dose differences observed, were statistically significant. This is mainly attributed to their consistency however, since TG43 agrees closely with MC for the majority of DVH and radiobiological parameters in both patient cohorts. Differences varied considerably among patients only for the ipsilateral lung and ribs in the APBI cohort, with a strong correlation to target location. Conclusion: While the consistency and magnitude of differences in the majority of clinically relevant DVH indices imply that no change is needed in the treatment planning practice, individualized dosimetry improves accuracy and addresses instances of inter-patient variability observed. Research co-financed by the ESF and Greek funds through the Operational Program Education and Lifelong Learning Investing in Knowledge Society of the NSRF. Research Funding Program Aristeia. Nucletron, an Elekta company (Veenendaal, The Netherlands) is gratefully acknowledged for providing Oncentra Brachy v4.4 for research purposes.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2017

Transient Mechanical Test Development for Accident Tolerant Cladding Candidates to Simulate PCMI-like Conditions

This study investigates the transient mechanical response of accident tolerant fuel (ATF) cladding candidates to provide information on potential PCMI-induced deformation and failure of candidate cladding materials. The mechanical testing is applied t to Gen-I FeCrAl and triaxially-braided SiC fiber SiC matrix composite materials under loading conditions like the PCMI during a postulated design basis reactivity insertion accident. To achieve the specific loading conditions, a modified burst test instrument with accurate mechanical pulse control has been designed and constructed. The mechanical response of FeCrAl, SiC-SiC composite tubes were compared with the pre-hydrided zirconium alloy cladding. The specimens subjected to mechanical pulses were investigated in a strain-controlled manner deformation.

Cinbiz, Nedim↗
DOE OSTI2025

Holistic Microstructure Control Strategies in Photopolymerization‐Induced Phase Separation of Acrylate Systems

Open porous materials, known for their large surface area and interconnected structures, are essential in various applications, including batteries, ion exchange, catalysis, filtration, and electronic waste recycling. A critical aspect of the functionality of porous membranes is the precise control of pore size and morphology. Photopolymerization-induced phase separation (photo-PIPS) offers a convenient and versatile methods for creating porous structures. However, controlling the porous morphology remains challenging due to the complex interplay between thermodynamics, polymerization kinetics, and monomer structures, which makes it difficult to establish the relationship between processing conditions and resulting morphology in photo-PIPS. Herein, a physics-based phase-field model capable of generating and characterizing the microstructures of porous materials based on both average and localized features is developed. Using the phase-field simulations as test bed, the effects of polarity, light intensity, and curing temperature, as well as the previously unexplored roles of chain transfer agents and substrates, on the morphology of the resulting porous microstructure are investigated. Experiments are performed to verify the results predicted by the simulations. This work lays out a comprehensive guide for designing PIPS-derived porous microstructures and offers practical engineering strategies for tailoring microstructure-level topology and size of pores for application-specific needs.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Numerical Simulations in Support of a Long-Term Test of Gas Production from Hydrate Accumulations on the Alaska North Slope: Reservoir Response to Interruptions of Production (Shut-Ins)

In this work, we investigate by means of numerical simulation a planned year-long field test of depressurization-induced production from a permafrost-associated hydrate reservoir on the Alaska North Slope at the site of the recently drilled Hydrate-01 Stratigraphic Test Well. The main objective of this study is to assess quantitatively the impact of temporary interruptions (well shut-ins) on the expected fluid production performance from the B1 Sand of the stratigraphic Unit B during controlled depressurization over different time scales, as well as on other relevant aspects of the system response that have the potential to significantly affect the design of the field test. We consider eight different cases of depressurization, including (a) rapid depressurization over a 60-day period to a terminal bottomhole pressure P W of 2.8 MPa and (b) a slower depressurization rate to a final P W of 0.6 MPa at the end of the year-long production test, in addition to (c) a multi-step depressurization regime and (d) a quasi-linear continuous depressurization strategy. The results of the study indicate that shut-ins obviously reduce gas release and production during and immediately after their occurrence, but their longer-term effects are strongly dependent on the depressurization regime and on the time of observation, covering the entire range of potential outcomes. Shut-ins (a) have a universally strong negative effect when quasi-linear depressurization is involved regardless of the length of the production period, and (b) have a strong positive effect in multi-step depressurization schemes that becomes apparent earlier for large initial pressure drops, but (c) can also appear to have practically no effect for slow stepwise depressurization at the end of the year-long production test. Shut-ins lead to a rapid reformation of hydrates, even to the point of disappearance of a free gas phase in the reservoir. Rapid depressurization regimes lead to early maximum rates of hydrate dissociation and gas production, while the maximum rates occur at the end of the production test for the cases of slower depressurization. Shut-ins do not appear to have a significant impact on water production, as the cessation of production is followed by higher rates production when depressurization resumes. Similarly, (a) the fraction of produced CH 4 originating from exsolution from the water, (b) the water-to-gas ratio, and (c) the rate of replenishment of produced water by boundary inflows do not appear significantly affected by shut-ins, the effects of which seem to be temporary in the majority of the cases. The study confirmed the superiority of multi-step depressurization methods as the most effective strategies for hydrate dissociation and gas production and showed that two observation wells (located at distances of 30 and 50 m from the production well) are appropriately positioned and both able to capture the P, T, and S G behavior during the fluid production and shut-ins in any of the eight cases we investigated.

03 NATURAL GAS↗
DOE OSTI2020

Achieving 280 Gbar hot spot pressure in DT-layered CH capsule implosions at the National Ignition Facility

We are reporting on a series of indirect-drive 0.9-scale CH capsule implosions (inner radius = 840 μm) fielded in low gas-fill (0.6 mg/cm 3 ) hohlraums of 6.72 mm diameter at the National Ignition Facility. Thanks to the 11%-reduction of the capsule size at a given hohlraum diameter compared to previously tested full-scale capsules, we achieved good hot spot symmetry control near 33% cone-fraction and without the need to invoke cross beam energy transfer. As a result, we achieved a hot spot pressure of 280 ± 40 Gbar, which is the highest pressure demonstrated in layered DT implosions with CH capsules to date. Pushing this design to higher velocity resulted in a reduction of neutron yield. Highly resolved capsule simulations suggest that higher Au M-shell preheat resulted in an increase in Atwood number at the ablator–ice interface, which leads to increased fuel-ablator instability and mixing. The results reported here provide important scaling information for next-generation CH designs.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗