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At least 739 records · Page 41

All sources NASA NTRS DOE OSTI

DOE OSTI2023

Enhancement of chiral edge currents in ($d$+1)-dimensional atomic Mott-band hybrid insulators

We consider the effect of a local interatomic repulsion on synthetic heterostructures where a discrete synthetic dimension is created by Raman processes on top of SU(N) S U ( N ) -symmetric two-dimensional lattice systems. At a filling of one fermion per site, increasing the interaction strength, the system is driven towards a Mott state which is adiabatically connected to a band insulator. The chiral currents associated with the synthetic magnetic field increase all the way to the Mott transition, where they reach the maximum value, and they remain finite in the whole insulating state. The transition towards the Mott-band insulator is associated with the opening of a gap within the low-energy quasiparticle peak, while a mean-field picture is recovered deep in the insulating state.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2019

Physics-Based Probabilistic Model of the Effects of Ionizing Radiation on Polymeric Insulators of Electric Cables used in Nuclear Power Plants

This report describes the results of a 3-year project aimed at developing a probabilistic predictive model of degradation of insulation of cables installed in nuclear power plants where heat and radiation are two major environmental stressors. The developed models have been developed based on exploring fundamental physical and chemical processes involved and validated by experimental data from open literature and data collected from experiments conducted as part of this study. The report comprises of two parts: Volume I and Volume II. In Volume I, degradation of three most widely-used insulation materials, cross-linked polyethylene (XLPE or PEX), ethylene propylene rubber (EPR), and silicone rubber (SIR) are discussed. Based on the identified degradation mechanisms and kinetics of the cable insulation, physics-based models have been proposed to quantitatively define and predict the degree of the degradation for functional failures of concern. Various sets of experimental data from the literature were used to help understand the phenomenon involved and to validate the models developed. Further validations were performed with data collected from experiments conducted as part of the research project. Methods and results of the experimental work are detailed in Volume II. These experimental results were found to be consistent with data reported in the literature and support the proposed models. The models developed here can probabilistically predict the lifetime of the cable insulation used in nuclear power plants.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2019

Retrofit of Blown Attic Insulation in Existing HUD-Code Manufactured Homes: Needs Assessment Report

This needs assessment was conducted by the Washington State University (WSU) Energy Program and Building Science Corporation (BSC), with support from the U.S. Department of Energy's (DOE) Building Technologies Office. The primary goal of this research was to identify moisture durability, energy savings, and savings-to-investment ratio (SIR) research needs related to the retrofit of attic insulation in the DOE Weatherization Assistance Program (WAP). Specifically, manufactured homes that comply with building codes established by the U.S. Department of Housing and Urban Development (HUD) built after 1976 and sited in colder climates. This project assessed current practice of WAP insulation and/or roof venting solutions that improve attic insulation energy savings and durability. WSU and BSC conducted outreach to stakeholders via email, phone, one-on-one interviews, and group meetings designed to inquire about relevant issues that they may have observed. Needs assessment feedback was provided from stakeholders involved with attic insulation retrofits in existing HUD-code manufactured housing in the colder climates of the United States. The list of more than 50 stakeholders who provided input into this needs assessment is provided in Appendix A.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2019

Retrofit of Blown Attic Insulation in Existing HUD-Code Manufactured Homes: Needs Assessment Report

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2019

Energy Saving by Insulating a Cooking Pot

Sandia National Laboratories is one of the most technologically advanced and resourceful national laboratories in the United States. Their mission is to use science and technology, innovative research, and global engagement to counter threats, reduce dangers, and respond to disasters. To achieve this mission, Sandia is divided into ten divisions that are overlooked by Dr. Stephen Younger, the Laboratories Director. Amongst the ten divisions, the internship will take place in Division 8000, which is Integrated Security Solutions. Inside this division, the internship will be a Structural and Thermal Analysis R&D. Apart from being strictly focused on security, the division performs research for small companies that do not count with the resources to perform it themselves. During the summer internship, one of these cases is being attended. A small company invented an insulating cover that is supposed to be placed over the top of a cooking pot lid. They claim that the insulating cover helps in the saving of energy. As an intern and researcher, the task is to determine how much energy is effectively saved by placing the insulating cover over the cooking pot. To achieve the goal, mathematical analyses, experiments and simulations will be done. Then, if appropriate, a better design will be made to increase the energy saved by the insulating cover. For the mathematical analysis, the thermal resistance method was used, resulting in energy saved at a rate of 14.2795 W. After the mathematical analysis was done, a test plan was developed and presented to the supervisor for approval. After some recommendations, the test plan will be modified accordingly.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2022

Nondestructive Evaluation of Rexolite Insulators for the Purpose of Monitoring the Structural Health of Particle Accelerator

Rexolite is a cross-linked polystyrene plastic with stable electrical properties into the gigahertz frequency range. The ability to withstand high voltage makes Rexolite one of the most used materials as insulators for particle accelerators. Although, Rexolite’s poor outgassing performance relative to traditional vacuum materials such as stainless steel or aluminum deems the necessity to treat Rexolite prior to its use as insulators. Insulators are mandatory for an accelerator system because a uniform electric field is required to ensure the alignment of the accelerated particles. Furthermore, to operate properly, a particle accelerator is required to maintain a high vacuum or even an ultrahigh vacuum. Although, because outgassing is the major contributor to the gas load of a vacuum system, Rexolite insulators with uncontrolled outgassing characteristics can severely damage the particle accelerator. Disassembly and reassembly of a complex system like a particle accelerator is also time consuming.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Automation of debris removal and resurfacing of insulators in terawatt pulsed power systems using state of the art laser technology

The increasing complexity and scale of pulsed power systems necessitate effective maintenance strategies to ensure optimal performance and safety. This report investigates the automation of debris removal and resurfacing of insulators in terawatt pulsed power systems using advanced laser cleaning technologies. The motivation for this research stems from the limitations of current manual cleaning methods, which are labor-intensive and pose health risks due to hazardous materials. The study addresses the problem of surface flashover, a significant issue affecting insulator performance, by evaluating two innovative cleaning techniques: Pulsed Laser Cleaning (PLC) and Flash Lamp Annealing (FLA). Experimental results demonstrate that PLC effectively restores the dielectric strength of Rexolite insulators, while FLA shows limited success. The findings highlight the potential for automated cleaning solutions to enhance safety and efficiency in insulator maintenance, paving the way for future advancements in pulsed power technology.

42 ENGINEERING↗

DOE OSTI2021

Designing the Insulation System for Motors in Electrified Aircraft: Optimization, Partial Discharge Issues and Use of Advanced Materials

Designing the insulation system for motors to be used in electrical aircraft requires efforts for maximizing specific power, but, in parallel, particular attention to achieve high reliability. As a major harm for organic insulation systems is partial discharges, design must be able to infer their likelihood during any operation stage and handle their potential inception. This paper proposes a new approach to carry out optimized or conservative insulation system designs which can provide the specified life at the chosen failure probability as well as look at the option of possibly reducing the risk of partial discharges to zero, at any altitude. Examples of designing turn, phase to ground and phase-to-phase insulation systems are reported, with cases where the design can be optimized and other cases where the optimized design does not pass IEC testing standard. Therefore, the limits for design feasibility as a function of the required level of safety and reliability are discussed, showing that the presence of partial discharges cannot be always avoided even through conservative design criteria. Therefore, the use of advanced, corona-resistant materials must be considered, in order to reach a higher, sometimes redundant, level of reliability.

Ramin, Robin (ORCID:0000000211455006)↗

NASA NTRS1972

Alternator insulation evaluation tests

Tests were conducted to predict the remaining electrical insulation life of a 60 KW homopolar inductor alternator following completion of NASA turbo-alternator endurance tests for SNAP-8 space electrical power systems application. The insulation quality was established for two alternators following completion of these tests. A step-temperature aging test procedure was developed for insulation life prediction and applied to one of the two alternators. Armature winding insulation life of over 80,000 hours for an average winding temperature of 248 degrees C was predicted using the developed procedure.

Penn, W. B.↗

NASA NTRS1972

Status of reusable surface insulation thermal protection system technology programs

The development of three low-density rigidized insulation materials for the shuttle TPS application is reported. These materials consist of one high purity silica system and two systems based on mullite, an aluminum silicate. Both systems consist of fibers joined together with appropriate binders to obtain a rigidized insulation composite. Both material systems require the application of a glassy coating to provide a wear resistant, high emittance surface and to prevent the absorption of water by the fiber matrix. The technology program has addressed the development of water impervious coatings, methods of assembling the materials in design concepts while minimizing the thermal stress in the insulation, achieving compatibility between the RSI material and the structural system, and test evaluations to demonstrate the feasibility of the surface insulation concept.

Greenshields, D. H.↗

NASA NTRS1972

Development of advanced materials composites for use as insulations for LH2 tanks

A study of internal insulation materials and fabrication processes for space shuttle LH2 tanks is reported. Emphasis was placed on an insulation system capable of reentry and multiple reuse in the Shuttle environment. Results are given on the optimization and manufacturing process scale-up of a 3D fiberreinforced foam insulation, BX-251-3D, derived from the Saturn S-4B internal insulation. It is shown that BX-251-3D can be satisfactorily installed in large-scale tanks under conditions that will permit a significant cost saving over the existing S-4B technology.

Lemons, C. R.↗

NASA NTRS1972

Development of techniques and instrumentation for the nondestructive evaluation of multi-layer insulation

The development of techniques and instrumentation suitable for the nondestructive evaluation of purged multilayer insulation prior to and after a shuttle orbiter flight is discussed. These techniques are desirable because of the possibility that corrosion, compression, or tearing of the insulation will degrade the performance of the insulation during subsequent flights. A second objective was the application of the developed technology to the evaluation of other insulation types. Three nondestructive evaluation techniques, electromagnetic, thermal, and acoustic were selected for evaluation. The results of evaluation of each technique are described.

Source record↗

NASA NTRS1972

Development of advanced material composites for use as internal insulation for LH2 tanks (gas layer concept)

A program is described that was conducted to develop an internal insulation system for potential application to the liquid hydrogen tanks of a reusable booster, where the tanks would be subjected to repeated high temperatures. The design of the internal insulation is based on a unique gas layer concept, in which capillary or surface tension effects are used to maintain a stable gas layer, within a cellular core structure, between the tank wall and the contained liquid hydrogen. Specific objectives were to select materials for insulation systems that would be compatible with wall temperatures of 350 F and 650 F during reentry into the earth's atmosphere, and to fabricate and test insulation systems under conditions simulating the operating environment. A materials test program was conducted to evaluate the properties of candidate materials at elevated temperatures and at the temperature of liquid hydrogen, and to determine the compatibility of the materials with a hydrogen atmosphere at the appropriate elevated temperature. The materials that were finally selected included Kapton polyimide films, silicone adhesives, fiber glass batting, and in the case of the 350 F system, Teflon film.

Gille, J. P.↗

NASA NTRS1973

Development of an external ceramic insulation for the space shuttle orbiter. Part 2: Optimization

The basic insulation improvement study concentrated upon evaluating variables which could result in significant near-term gains in mechanical behavior and insulation effectiveness of the baseline system. The approaches undertaken included: evaluation of small diameter fibers, optimization of binder: slurry characteristics, evaluation of techniques for controlling fiber orientation, optimization of firing cycle, and the evaluation of methods for improving insulation efficiency. A detailed discussion of these basic insulation improvement studies is presented.

Tanzilli, R. A.↗

NASA NTRS1975

New insulation attachment method eliminates compatibility bondline stresses

Auger-shaped single-point fastener attaches rigid surface insulation tiles to orbiter shuttle spacecraft. Method can be used to bond wide variety of materials, including insulation, elastomers, and fibrous materials. Since insulation is attached at only one point, insulation and structure are free to form without inducing bond separation.

Schneider, W. C.↗

NASA NTRS1974

Insulation of nonlinear and random vibrations in the mining industry

The insulation of nonlinear and random vibrations is considered for some ore preparing and sorting implements: rotary crushers, resonance screens, hammer mills, etc. The appearance of subharmonic vibrations is analyzed, and the conditions for their appearance are determined. A method is given for calculating the insulation of these vibrations by means of elastic elements made of rubber. The insulation of the random vibrations produced by Symons crushers is calculated by determining the transmissability and deformation of the insulation system for a narrow band random response.

Zeveleanu, C.↗

NASA NTRS1974

High reliability sheathed, beryllia insulated, tungsten-rhenium alloy thermocouple assemblies; their fabrication and EMF stability

Tantalum sheathed, BeO insulated, W-3% Re/W-25% Re thermocouple assemblies were fabricated and their emf drift determined during 2059 hours of exposure at 2073 K in a gaseous helium environment. The sheathed thermocouple assemblies were constructed from aged thermoelements, specially heat-treated BeO insulators, and specially cleaned and etched tantalum sheaths. Their thermal emf drifts ranged from the equivalent of only -0.3 to -0.8 K drift per 1000 hours of exposure at 2073 K. No evidence of any gross chemical attack or degradation of the component materials was found. The emf drift and material behavior of some unsheathed, BeO insulated, W-3% Re/W-25% Re thermocouples at 2250 and 2400 K were also determined. Unsheathed thermocouples tested in an argon environment at 2250 K for 1100 hours and at 2400 K for 307 hours exhibited changes in thermal emf that typically ranged from the equivalent of a few degrees K to as much as +11 K. Post-test examinations of these thermocouples revealed some undesirable material degradation and interaction which included erosion of the BeO insulators and contamination of the thermoelements by tantalum from the tantalum blackbody enclosure in which the thermocouples were contained.

Burns, G. W.↗

NASA NTRS1976

Outline and comparison of the possible effects present in a metal-thin-film-insulator-semiconductor solar cell

The advantages possible with the insertion of a thin-film insulating or semi-insulating layer between a metal and a semiconductor to form the MIS photovoltaic device have been presented previously in the literature. This MIS configuration may be considered as a specific example of a more general class of photovoltaic devices: electrode-thin-film-insulator-semiconductor devices. Since the advantages of the configuration were pointed out, there has been considerable experimental interest in these photovoltaic devices. Because the previous analysis showed that the introduction of the insulator layer could produce several different but advantageous effects, this paper presents a further outline giving a comparison of these effects together with their ramifications.

Fonash, S. J.↗