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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Efficacy and Safety of Augmenting the Preclose Technique with a Collagen-Based Closure Device for Percutaneous Endovascular Aneurysm Repair

PurposeTo report our experience of selectively augmenting the preclose technique for percutaneous endovascular aneurysm repair (p-EVAR) with an Angio-Seal device as a haemostatic adjunct in cases of significant bleeding after tensioning the sutures of the suture-mediated closure devices.Materials and MethodsProspectively collected data for p-EVAR patients at our institute were analysed. Outcomes included technical success and access site complications. A logistic regression model was used to analyse the effects of sheath size, CFA features and stent graft type on primary failure of the preclose technique necessitating augmentation and also on the development of complications.Resultsp-EVAR was attempted via 122 CFA access sites with a median sheath size of 18-French (range 12- to 28-French). Primary success of the preclose technique was 75.4 % (92/122). Angio-Seal augmentation was utilised as an adjunct to the preclose technique in 20.5 % (25/122). The overall p-EVAR success rate was 95.1 % (116/122). There was a statistically significant relationship (p = 0.0093) between depth of CFA and primary failure of preclose technique. CFA diameter, calcification, type of stent graft and sheath size did not have significant effects on primary preclose technique failure. Overall 4.9 % (6/122) required surgical conversion but otherwise there were no major complications.ConclusionAugmentation with an Angio-Seal device is a safe and effective adjunct to increase the success rate of the preclose technique in p-EVAR.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Cath Lab Robotics: Paradigm Change in Interventional Cardiology?

Purpose of Review: To review the contemporary evidence for robotic-assisted percutaneous coronary and vascular interventions, discussing its current capabilities, limitations, and potential future applications. Recent Findings: Robotic-assisted cardiovascular interventions significantly reduce radiation exposure and orthopedic strains for interventionalists, while maintaining high rates of device and clinical success. The PRECISE and CORA-PCI studies demonstrated the safety and efficacy of robotic-assisted percutaneous coronary intervention (PCI) in increasingly complex coronary lesions. The RAPID study demonstrated similar findings in peripheral vascular interventions (PVI). Subsequent studies have demonstrated the safety and efficacy of second-generation devices, with automations mimicking manual PCI techniques. While innovations such as telestenting continue to bring excitement to the field, major limitations remain—particularly the lack of randomized trials comparing robotic-assisted PCI with manual PCI. Summary: Robotic technology has successfully been applied to multiple cardiovascular procedures. There are limited data to evaluate outcomes with robotic-assisted PCI and other robotic-assisted cardiovascular procedures, but existing data show some promise of improving the precision of PCI while decreasing occupational hazards associated with radiation exposure.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

Safety perceptions of solid-state lithium metal batteries

Safety concerns hamper the wide application of lithium-ion batteries (LIBs) in the fields of electric vehicles and stationary energy storage. As the blame of the battery thermal runway was widely cast on the flowable, volatile, and flammable nature of liquid organic electrolytes, solid-state lithium batteries with solid and nonflammable electrolytes are highly praised for potentially better safety characteristics. Furthermore, solid-state lithium metal batteries (SS-LMBs) may become an ultimate solution for safe, high-energy density batteries. Whether SS-LMBs are safe enough to meet emerging demands remains unclear, as recent publications have presented serious safety concerns at both the material and device levels. In conclusion, this review summarizes recent investigations into SS-LMB safety, and systematic analysis and discussion are provided in this discussion of the safety concerns of SS-LMBs.

25 ENERGY STORAGE↗
DOE OSTI2019

Battery Thermal Characterization

A well-designed thermal management system is critical to the life and performance of electric-drive vehicles (EDVs) hybrids (HEVs), plug-in hybrids (PHEVs), and all-electric vehicles (EVs). Temperature and temperature uniformity both significantly affect the performance, lifespan, and safety of vehicle energy storage devices. NREL conducts thermal management research and development (R&D) to optimize battery performance and extend useful life. A recognized leader in battery thermal analysis and characterization, NREL evaluates electrical and thermal performance of battery cells, modules, and packs, full energy storage systems, and the interaction of these systems with other vehicle components. The lab's performance assessments factor in the design of the thermal management system, the thermal behavior of the cell, battery lifespan, and safety of the energy storage system, as well as full integration into a vehicle. The lithium-ion (Li-ion) batteries found in most of today's electric-drive vehicles are smaller and more lightweight than previous nickel-metal hydride (NiMH) technology, but they are also more sensitive to overheating, overcharging, and extreme spikes in temperature known as thermal runaway. High temperatures diminish battery life and increase battery replacement costs, while low temperatures decrease battery power and capacity, all of which impact vehicle range, performance, and affordability. NREL's breakthrough research is focused on reducing thermal barriers to achieve more uniform temperatures. NREL uses its R&D 100 Award-winning Isothermal Battery Calorimeters, the only instruments in the world capable of such precise thermal measurements, for much of this research. Calorimeter readings are paired with thermal imaging of batteries using infrared cameras to evaluate battery temperature distribution. In addition, NREL is working with industry to develop computer-aided engineering software tools to optimize thermal management of batteries. NREL's analysis for the U.S. Advanced Battery Consortium (USABC) show that optimized thermal management can increase battery power by more than 10%. Without proper thermal management, an EDV battery can last more than 10 years in a temperate climate, like in Minnesota, but only 7 years in a hot climate, such as in Arizona. In extreme instances, battery overheating can pose safety hazards, including fires. Performance: Maintaining desired temperature ranges is critical in optimizing EDV battery storage capacity, lifespan, and performance, and eventually impacts cost and consumer acceptance. NREL's breakthrough research focuses on achieving more uniform temperatures while a vehicle is in motion and actively generating heat, as well as when it is parked and exposed to ambient temperatures over prolonged periods of time. Safety: Most energy storage systems deliver maximum performance at higher temperatures. However, this extreme heat can overload systems and create dangerous conditions. NREL evaluation helps to more effectively regulate thermal characteristics, providing greater safeguards and stronger performance. NREL has invented a device that emulates internal short circuits in batteries to better understand how to prevent future failures and related hazards.

25 ENERGY STORAGE↗
DOE OSTI2017

Investigation of instrumentation containing an embedded digital device - 257

The U.S. nuclear power industry primarily relies on mature, well-proven analog technology as the basis for most instrumentation and control (I and C) equipment employed in its nuclear power plants (NPPs). However, the market for this legacy instrumentation is very small and availability of such equipment for spare parts or replacement is increasingly limited. Frequently, modern I and C equipment contains embedded digital devices (EDDs), such as microprocessors and programmable logic devices. While the enhanced functional capabilities provided by the digital components offer improved performance, reliability, and maintainability, the corresponding complexity of sophisticated digital implementations also exacerbate concerns about an increased potential for undetected systematic faults, which can lead to common-cause failure (CCF). As part of a research project sponsored by the U.S. Department of Energy, an investigation has been conducted of commercially available instrumentation marketed for nuclear or industrial application. The objective was to identify the usage of EDDs and to determine the types of functional roles allocated to the devices. Examples of the equipment surveyed include smart sensors, sequencers for emergency diesel generators, pumps, valve actuators, motor control centers, breakers, priority logic modules, and uninterruptible power sources. Where sufficient detail was found, an evaluation was performed to ascertain the nature and role of the digital technology implemented in the instrumentation. The information gained through this investigation serves as technical input for defining a classification approach for EDDs based on the functional impact of the device. For example, the role of an EDD can involve any of the following functions: performance monitoring and diagnostics, information extraction and communication, instrument condition monitoring and protection, or execution of core instrument functions. Classifying digital devices according to their role in the operation of the instrumentation in which they are embedded can enable determination of the potential functional impact of failure of that device and contribute to determination of the potential safety significance of a CCF event disabling all instances of that device. This paper will report on the findings of the investigation of instrumentation with EDDs and indicate considerations for the emerging classification approach. The higher-level goal of this effort is to determine whether a graded approach to qualification testing may be possible based on classification. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2019

Transseptal Puncture: Devices, Techniques, and Considerations for Specific Interventions

Purpose of Review: Transseptal puncture is a routinely performed interventional cardiology procedure for an array of cardiac diseases. We aimed to review the current status of available devices and techniques of transseptal puncture with consideration to specific interventions. Recent Findings: Except for a few modifications, devices for transseptal puncture technique has not changed much compared to when it was first described almost 60 years ago. For difficult transseptal puncture, a few newer techniques such as radio frequency needle puncture system have been used but there is lack of robust clinical study. Advanced imaging, such as intracardiac echocardiography and transesophageal echocardiography, has been found to make transseptal puncture safer. A new transseptal approach that incorporates 3D non-fluoroscopic catheter tracking systems has shown promising results in two human studies. Summary: While various modifications in the transseptal technique tailored to the specific interventions have improved procedural safety, further improvement in existing devices focusing on distinct procedure might be needed in the future.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Crashworthiness Models for Automotive Batteries (NHTSA-ORNL 2018)

Safety is a key element of any device designed to store energy.Electrochemical batteries convert energy of chemical reactions to electrical energy. Safety considerations are especially important when applied to large automotive batteries designed for propulsion of electric vehicles (EV). The high amount of energy stored in EV battery packs translates to higher probability of fire in case of severe deformation of battery compartment due to automotive crash or impact caused by road debris. While such demand for safety has resulted in heavier protection of battery enclosure, the mechanisms leading to internal short circuit due to deformation of the battery are not well understood even on the level of a single electrochemical cell. Moreover, not all internal shorts result in thermal runaway, and thus a criterion for catastrophic failure needs to be developed.

25 ENERGY STORAGE↗
DOE OSTI2014

Radiation Mapping at JET and ITER using advanced computational acceleration techniques and tools - Paper 63

The Applied Radiation Physics group at the Culham Centre for Fusion Energy (CCFE) have developed and applied state-of-the-art radiation mapping methods and tools to enable complex shielding calculations in fusion devices during plasma operations, and associated maintenance in the device and surrounding areas. Here, we present the description and application of those tools to produce radiation maps both to support the JET safety case (the EU experimental tokamak device based at Culham) and the planned DT campaign in the next few years; and the ITER device. Radiation mapping of fusion facilities are essential for assessing radiation hardness of electronics during operations, and to define safe working dose limits to staff during routine maintenance. At CCFE the Monte Carlo radiation transport code MCNP6 is one of the codes used to perform radiation transport calculations. Due to the size and complexity of the JET and ITER devices, and their surrounding buildings, a suite of tools have been created at CCFE to reduce the computational requirements of the calculations. This paper describes three of these tools, which have been developed and applied to nuclear and radiological field mapping in fusion devices. The results presented in this paper highlight the application of three methods that have been used to improve the computational efficiency and capabilities for radiation mapping in fusion devices such as JET and ITER. These methods are Global Variance Reduction, the Surface Source Mesh routine and the Smeared Source routine. This paper demonstrates the three techniques used in combination, enabling a very computationally challenging fusion problem to become tractable (with acceptable computing effort), also enabling improved capability to allow the mapping of radiations fields during transport operations for activated materials. (authors)

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2012

Status of Global Threat Reduction Initiative's Activities Underway to Address Major Domestic Radiological Security Challenges - 12105

During their service lives, radioactive sealed sources are used for a wide variety of essential purposes. However, each year, thousands of radioactive sealed sources that pose a potential risk to national security, health, and safety become disused and unwanted in the United States. Due to their concentrated activity and portability, these sources could be used in radiological dispersal devices ('dirty bombs'). For more than a decade, the National Nuclear Security Administration and the U.S. Department of Energy, through the Global Threat Reduction Initiative Offsite Source Recovery Project (GTRI/OSRP), have facilitated the removal and disposition of thousands of disused/unwanted sources worldwide. However, the ability of GTRI/OSRP to continue its work is critically dependent on the ability to transport and appropriately dispose of these sources. On that front, GTRI/OSRP progress includes development of two prototype Type B transport containers and significant efforts toward certification, increased commercial disposal access for risk-significant sealed sources at commercial sites, and cooperation through the International Atomic Energy Agency to increase source repatriation. Disused sealed sources continue to pose a national security concern. The impact of a dirty bomb detonation could be costly both financially and to those exposed to the resulting radiation. However, significant progress has been made since 2008 on each of the challenges identified in the DHS Sealed Source Security Workshop. Not only will there be increased opportunity for commercial disposal of many sizes and types of sealed sources, but also stakeholders are studying front-end solutions to the problem of disused sealed sources, such as financial assurance and recycle. The lack of sealed source transport containers is also likely to be mitigated with the development and certification by NNSA of two new Type B models. Internationally, increased efforts at source repatriation will mitigate the threat posed by disused sealed sources abroad. Sealed sources provide irreplaceable benefits to those who use them or who benefit from their use; now stakeholders are rising to the challenge of ensuring that those benefits are safely and securely realized. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2014

Thermal Runaway Risk Evaluation of Li-Ion Cells Using a Pinch-Torsion Test

Internal short circuit (ISCr) can lead to failure of Li-ion cells and sometimes result in thermal runaway. Understanding the behavior of Li-ion cells in ISCr condition is thus critical to evaluate the safety of these energy storage devices. In the current work, a pinch-torsion test is developed to simulate ISCr in a controlled manner. It is demonstrated that the torsional component superimposed on compression loading can reduce the axial load required to induce ISCr with smaller short spot size. Using this pinch-torsion test, two commercial Li-ion pouch cells were tested under different state of charge (SOC). Based on the severity of the cell damage, a series of thermal runaway risk scores were used to rate the thermal stability of these cells. One of the cell types showed significantly increased hazard as the SOC increased while the other type exhibited relative uniform behavior among different SOC. Therefore this novel pinch-torsion test seems to be an attractive candidate for safety testing of Li-ion cells due to its abilities to consistently create small ISCr spots and to differentiate cell stability in a wide range of SOC.

internal short circuit↗
DOE OSTI2023

Development of polarization-sensitive optical coherence tomography imaging platform and metrics to quantify electrostimulation-induced peripheral nerve injury in vivo in a small animal model

Neuromodulation devices are rapidly evolving for the treatment of neurological diseases and conditions. Injury from implantation or long-term use without obvious functional losses is often only detectable through terminal histology. New technologies are needed that assess the peripheral nervous system (PNS) under normal and diseased or injured conditions. We aim to demonstrate an imaging and stimulation platform that can elucidate the biological mechanisms and impacts of neurostimulation in the PNS and apply it to the sciatic nerve to extract imaging metrics indicating electrical overstimulation. A sciatic nerve injury model in a 15-rat cohort was observed using a newly developed imaging and stimulation platform that can detect electrical overstimulation effects with polarization-sensitive optical coherence tomography. The sciatic nerve was electrically stimulated using a custom-developed nerve holder with embedded electrodes for 1 h, followed by a 1-h recovery period, delivered at above-threshold Shannon model k-values in experimental groups: sham control (SC, n = 5, 0.0 mA / 0 Hz), stimulation level 1 (SL1, n = 5, 3.4 mA / 50 Hz, and k = 2.57), and stimulation level 2 (SL2, n = 5, 6.8 mA / 100 Hz, and k = 3.17). The stimulation and imaging system successfully captured study data across the cohort. When compared to a SC after a 1-week recovery, the fascicle closest to the stimulation lead showed an average change of +4 % / – 309 % (SL1/SL2) in phase retardation and –79 % / – 148 % in optical attenuation relative to SC. Analysis of immunohistochemistry (IHC) shows a +1 % / – 36 % difference in myelin pixel counts and –13 % / + 29 % difference in axon pixel counts, and an overall increase in cell nuclei pixel count of +20 % / + 35 % . These metrics were consistent with IHC and hematoxylin/eosin tissue section analysis. The poststimulation changes observed in our study are manifestations of nerve injury and repair, specifically degeneration and angiogenesis. Optical imaging metrics quantify these processes and may help evaluate the safety and efficacy of neuromodulation devices.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Halide Substitution Effects on Lithium-Ion Diffusion in Protonated Antiperovskites

Solid-state electrolytes (SSEs) for all-solid-state lithium-ion batteries are generating intense interest because these batteries can improve the safety and performance compared with devices fabricated with conventional, flammable liquid electrolytes. In these SSEs, it has been suggested that Li + ion diffusion in the grain boundaries is hindered and is a critical determinant of the overall ionic conductivity (σ). However, Li + ion diffusivities in the grain (D G ) and the grain boundary (D GB ) are difficult to determine experimentally, with few techniques capable of distinguishing the individual contributions. Here, we distinguished the D G and D GB for the protonated lithium antiperovskites (pLiAPs) SSEs: Li 2 OHCl, Li 2 OHBr, Li 2 OHF 0.1 Cl 0.9 , Li 2 OHF 0.1 Br 0.9 , and Li 2 OHCl 0.3 7Br 0.63 . The measurements were obtained directly from 7 Li pulsed-field gradient nuclear magnetic resonance (PFG-NMR) at 353 K. The 7 Li PFG-NMR echo profiles were composed of two primary components with additional secondary oscillatory components – the so-called NMR diffraction phenomenon. The length scale separating the two main components corresponds to a diffusion length of ~1.7 µm, which is thought to be the average grain size (by diameter). The short-range (≤ 1.7 µm) diffusion component associated with D G (≈10 -11 m 2 /s) varied minimally with halide substitution, while the long-range (≥ 1.7 µm) component D GB (≈10 -12 to 10 -15 m 2 /s) was highly sensitive to the substitution of halides and closely correlated with s. In addition, from the comparison of the ratio D GB /D G to D t (the Li + ion diffusion coefficient estimated from the rotational correlation time, t c ), it was determined that the contribution of D G to σ is negligible; 0.01 ~ 0.04 in the pLiAPs studied here. Finally, these insights provide fundamental understanding of the halide substitution effects on Li + ion grain versus grain boundary diffusion, and suggest that careful engineering of the grain boundaries at the microscopic level is necessary to achieve high-performance pLiAP SSEs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Charging toward improved lithium-ion polymer electrolytes: exploiting synergistic experimental and computational approaches to facilitate materials design

Ion-conducting polymer electrolytes are attractive materials for all-solid-state lithium-ion batteries (LiBs) as a result of their potential to improve performance, mitigate safety concerns, and facilitate efficient device processing. Understanding how lithium-ionic transport is influenced by the macromolecular features, such as dielectric strength, solvation site connectivity, monomer segment relaxation timescales, segregation strength, and mesophase composition, is crucial for advancing ion-conducting materials. The integration of experimental and computational efforts can provide comprehensive links between chemical and structural characteristics (e.g., ion solvation, chain mobility, morphology) and macroscopic performance properties, accelerating the adoption of next-generation polymer electrolytes. Furthermore, this perspective highlights several synergistic experimental–computational approaches that have provided unique insights into local ion and polymer interactions, chain dynamics, and thermodynamics to promote the rational design of new ion-conducting polymers. Additionally, this work concludes with several suggested areas in which methodologies can be augmented, novel properties can be realized, and polymer electrolytes can be integrated to generate more robust LiB systems.

25 ENERGY STORAGE↗
DOE OSTI2022

Investigating dry room compatibility of sulfide solid-state electrolytes for scalable manufacturing

All-solid-state batteries (ASSBs) are viewed as promising next-generation energy storage devices, due to their enhanced safety by replacing organic liquid electrolytes with non-flammable solid-state electrolytes (SSEs). The high ionic conductivity and low Young's modulus of sulfide SSEs make them suitable candidates for commercial ASSBs. Nevertheless, sulfide SSEs are generally reported to be unstable in ambient air. Moreover, instead of gloveboxes used for laboratory scale studies, large scale production of batteries is usually conducted in dry rooms. Thus, this study aims to elucidate the chemical evolution of a sulfide electrolyte, Li 6 PS 5 Cl (LPSCl), during air exposure and to evaluate its dry room compatibility. When LPSCl is exposed to ambient air, hydrolysis, hydration, and carbonate formation can occur. Moreover, hydrolysis can lead to irreversible sulfur loss and therefore LPSCl cannot be fully recovered in the subsequent heat treatment. During heat treatment, exposed LPSCl undergoes dehydration, decomposition of carbonate species, and reformation of the LPSCl phase. Lastly, LPSCl was found to exhibit good stability in a dry room environment and was subject to only minor conductivity loss due to carbonate formation. The dry room exposed LPSCl sample was tested in a LiNi 0.8 Co 0.1 Mn 0.1 O 2 |LiIn half-cell, exhibiting no significant loss of electrochemical performance compared with the pristine LPSCl, proving it to be compatible with dry room manufacturing processes.

36 MATERIALS SCIENCE↗
DOE OSTI2023

The nature and suppression strategies of interfacial reactions in all-solid-state batteries

Solid-state Li batteries are promising energy storage devices owing to their high safety and high theoretical energy density. However, the serious interfacial reaction between solid state electrolytes and cathodes deteriorates the battery performance, impeding the realization of long-term cyclability. The buried nature of the interphase layer presents a significant challenge in achieving a comprehensive understanding of the underlying interfacial reaction mechanisms. Herein, we systematically explore the interfacial reaction evolutions and interphase compositions and electronic properties between the popular oxide cathodes and sulfide solid electrolytes (SSEs). This includes analysis of the chemical and electrochemical reactions between cathodes/coatings and SSEs, as well as the electrochemical self-decomposition of SSEs by thermodynamic phase equilibrium analysis. Herein, we disclose that the driving force of the electrochemical reaction at the chemical potential of μ Li is much stronger than that of the chemical reaction, which dominates the interfacial reaction. Preventing the formation of an electronically conductive interphase is crucial in inhibiting the continuous interfacial degradation during long-term cycling, which can be achieved through the optimized combination of cathodes and SSEs, as well as the introduction of functional coatings between them. Based on these findings, the percentage of molar fraction ( f ) of electronically conductive species in the formed interphase is proposed as a key factor for indicating the interfacial stability for the first time. Furthermore, we propose a specific high-throughput screening scheme to filter the functional coating materials by comprehensively evaluating their functionality. The tiered screening identifies 48 coating materials with optimal properties. The work highlights the significant roles of rational coupling of the cathodes and SSEs, and optimizing interfacial coating materials for solid-state batteries. It opens new avenues for engineering an interphase with improved interfacial compatibility to realize long-term cyclability.

25 ENERGY STORAGE↗
DOE OSTI2026

Superionic conduction in solid polymer electrolytes – decoupling ion transport from segmental relaxation

Solvent-free, solid polymer electrolytes (SPEs) are promising candidates for next-generation, electrochemical energy storage systems due to their potential to enhance safety and performance, enable flexible device architectures, and streamline manufacturing processes. Conventional SPEs suffer from limited ionic conductivity due to the strong coupling between ion transport and (generally slow) polymer segmental relaxation. The realization of superionic conduction in SPEs, in which ions move faster than the structural relaxation of the polymers, requires a shift in design principles to promote this type of decoupled ion motion. In this perspective, we discuss how polymer architecture, ion–ion correlations, and ion–polymer interactions can unlock superionic behavior. We highlight several key design features, such as crystallinity, bulky side groups, high molecular weight, and percolating ionic aggregation, with a focus on creating low-barrier transport pathways in various polymer systems. We also demonstrate opportunities to combine polymer chemistry and data science through high-throughput and automated screening approaches to reveal how phase behavior, ion dynamics, and ionic interactions govern transport, thereby potentially enabling data-driven discovery of superionic polymer electrolyte materials.

Yang, Mengying [Univ. of Delaware, Newark, DE (Uni↗
DOE OSTI2022

Runaway electron deconfinement in SPARC and DIII-D by a passive 3D coil

The operation of a 3D coil—passively driven by the current quench (CQ) loop voltage—for the deconfinement of runaway electrons (REs) is modeled for disruption scenarios in the SPARC and DIII-D tokamaks. Nonlinear magnetohydrodynamic (MHD) modeling is carried out with the NIMROD code including time-dependent magnetic field boundary conditions to simulate the effect of the coil. Further modeling in some cases uses the ASCOT5 code to calculate advection and diffusion coefficients for REs based on the NIMROD-calculated fields, and the DREAM code to compute the runaway evolution in the presence of these transport coefficients. Compared with similar modeling in Tinguely et al (2021 Nucl. Fusion 61 124003), considerably more conservative assumptions are made with the ASCOT5 results, zeroing low levels of transport, particularly in regions in which closed flux surfaces have reformed. Of three coil geometries considered in SPARC, only the n = 1 coil is found to have sufficient resonant components to suppress the runaway current growth. Without the new conservative transport assumptions, full suppression of the RE current is maintained when the thermal quench MHD is included in the simulation or when the RE current is limited to 250kA, but when transport in closed flux regions is fully suppressed, these scenarios allow RE beams on the order of 1–2 MA to appear. Additional modeling is performed to consider the effects of the close ideal wall. In DIII-D, the CQ is modeled for both limited and diverted equilibrium shapes. In the limited shape, the onset of stochasticity is found to be insensitive to the coil current amplitude and governed largely by the evolution of the safety-factor profile. In both devices, prediction of the q-profile evolution is seen to be critical to predicting the later time effects of the coil.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Plasma performance and operational space with an RMP-ELM suppressed edge

Abstract The operational space and global performance of plasmas with edge-localized modes (ELMs) suppressed by resonant magnetic perturbations (RMPs) are surveyed by comparing AUG, DIII-D, EAST, and KSTAR stationary operating points. RMP-ELM suppression is achieved over a range of plasma currents, toroidal fields, and RMP toroidal mode numbers. Consistent operational windows in edge safety factor are found across devices, while windows in plasma shaping parameters are distinct. Accessed pedestal parameters reveal a quantitatively similar pedestal-top density limit for RMP-ELM suppression in all devices of just over 3 × 10 19 m −3 . This is surprising given the wide variance of many engineering parameters and edge collisionalities, and poses a challenge to extrapolation of the regime. Wide ranges in input power, confinement time, and stored energy are observed, with the achieved triple product found to scale like the product of current, field, and radius. Observed energy confinement scaling with engineering parameters for RMP-ELM suppressed plasmas are presented and compared with expectations from established H and L-mode scalings, including treatment of uncertainty analysis. Different scaling exponents for individual engineering parameters are found as compared to the established scalings. However, extrapolation to next-step tokamaks ITER and SPARC find overall consistency within uncertainties with the established scalings, finding no obvious performance penalty when extrapolating from the assembled multi-device RMP-ELM suppressed database. Overall this work identifies common physics for RMP-ELM suppression and highlights the need to pursue this no-ELM regime at higher magnetic field and different plasma physical size.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗