Cryogenic Insulation System for Soft Vacuum

NASA Technical Reports Server (NTRS)

Augustynowicz, S. D.; Fesmire, J. E.

1999-01-01

The development of a cryogenic insulation system for operation under soft vacuum is presented in this paper. Conventional insulation materials for cryogenic applications can be divided into three levels of thermal performance, in terms of apparent thermal conductivity [k-value in milliwatt per meter-kelvin (mW/m-K)]. System k-values below 0.1 can be achieved for multilayer insulation operating at a vacuum level below 1 x 10(exp -4) torr. For fiberglass or powder operating below 1 x 10(exp -3) torr, k-values of about 2 are obtained. For foam and other materials at ambient pressure, k-values around 30 are typical. New industry and aerospace applications require a versatile, robust, low-cost thermal insulation with performance in the intermediate range. The target for the new composite insulation system is a k-value below 4.8 mW/m-K (R-30) at a soft vacuum level (from 1 to 10 torr) and boundary temperatures of approximately 77 and 293 kelvin (K). Many combinations of radiation shields, spacers, and composite materials were tested from high vacuum to ambient pressure using cryostat boiloff methods. Significant improvement over conventional systems in the soft vacuum range was demonstrated. The new layered composite insulation system was also shown to provide key benefits for high vacuum applications as well.

Synthesis of the Multilayer Cryogenic Insulation Modelling and Measurements

NASA Astrophysics Data System (ADS)

Polinski, J.; Chorowski, M.; Choudhury, A.; Datta, T. S.

2008-03-01

A thermodynamic approach towards insulation systems in cryogenic engineering is proposed. A mathematical model of the heat transfer through multilayer insulation (MLI) has been developed and experimentally verified. The model comprises both physical and engineering parameters determining the MLI performance and enables a complex optimization of the insulation system including the choice of the insulation location in a vacuum space. The model takes into account an interstitial (interlayer) gas pressure variation with the MLI number of layers and layers density. The paper presents the discussion of MLI performance in different conditions and provides comparison of computation results with experimental reference and measured data.

Testing and numerical modeling of hypervelocity impact damaged Space Station multilayer insulation

NASA Technical Reports Server (NTRS)

Rule, William K.

1992-01-01

Results are presented of experiments measuring the degradation of the insulating capabilities of the multilayer insulation (MLI) of the Space Station Freedom, when subjected to hypervelocity impact damage. A simple numerical model was developed for use in an engineering design environment for quick assessment of thermal effect of the impact. The model was validated using results from thermal vacuum tests on MLI with simulated damage. The numerical model results agreed with experimental data.

Compact x-ray source and panel

DOEpatents

Sampayon, Stephen E [Manteca, CA

2008-02-12

A compact, self-contained x-ray source, and a compact x-ray source panel having a plurality of such x-ray sources arranged in a preferably broad-area pixelized array. Each x-ray source includes an electron source for producing an electron beam, an x-ray conversion target, and a multilayer insulator separating the electron source and the x-ray conversion target from each other. The multi-layer insulator preferably has a cylindrical configuration with a plurality of alternating insulator and conductor layers surrounding an acceleration channel leading from the electron source to the x-ray conversion target. A power source is connected to each x-ray source of the array to produce an accelerating gradient between the electron source and x-ray conversion target in any one or more of the x-ray sources independent of other x-ray sources in the array, so as to accelerate an electron beam towards the x-ray conversion target. The multilayer insulator enables relatively short separation distances between the electron source and the x-ray conversion target so that a thin panel is possible for compactness. This is due to the ability of the plurality of alternating insulator and conductor layers of the multilayer insulators to resist surface flashover when sufficiently high acceleration energies necessary for x-ray generation are supplied by the power source to the x-ray sources.

Improved Aerogel Vacuum Thermal Insulation

NASA Technical Reports Server (NTRS)

Ruemmele, Warren P.; Bue, Grant C.

2009-01-01

An improved design concept for aerogel vacuum thermal-insulation panels calls for multiple layers of aerogel sandwiched between layers of aluminized Mylar (or equivalent) poly(ethylene terephthalate), as depicted in the figure. This concept is applicable to both the rigid (brick) form and the flexible (blanket) form of aerogel vacuum thermal-insulation panels. Heretofore, the fabrication of a typical aerogel vacuum insulating panel has involved encapsulation of a single layer of aerogel in poly(ethylene terephthalate) and pumping of gases out of the aerogel-filled volume. A multilayer panel according to the improved design concept is fabricated in basically the same way: Multiple alternating layers of aerogel and aluminized poly(ethylene terephthalate) are assembled, then encapsulated in an outer layer of poly(ethylene terephthalate), and then the volume containing the multilayer structure is evacuated as in the single-layer case. The multilayer concept makes it possible to reduce effective thermal conductivity of a panel below that of a comparable single-layer panel, without adding weight or incurring other performance penalties. Implementation of the multilayer concept is simple and relatively inexpensive, involving only a few additional fabrication steps to assemble the multiple layers prior to evacuation. For a panel of the blanket type, the multilayer concept, affords the additional advantage of reduced stiffness.

An acoustic metamaterial composed of multi-layer membrane-coated perforated plates for low-frequency sound insulation

NASA Astrophysics Data System (ADS)

Fan, Li; Chen, Zhe; Zhang, Shu-yi; Ding, Jin; Li, Xiao-juan; Zhang, Hui

2015-04-01

Insulating against low-frequency sound (below 500 Hz ) remains challenging despite the progress that has been achieved in sound insulation and absorption. In this work, an acoustic metamaterial based on membrane-coated perforated plates is presented for achieving sound insulation in a low-frequency range, even covering the lower audio frequency limit, 20 Hz . Theoretical analysis and finite element simulations demonstrate that this metamaterial can effectively block acoustic waves over a wide low-frequency band regardless of incident angles. Two mechanisms, non-resonance and monopolar resonance, operate in the metamaterial, resulting in a more powerful sound insulation ability than that achieved using periodically arranged multi-layer solid plates.

Study of multilayer thermal insulation by inverse problems method

NASA Astrophysics Data System (ADS)

Alifanov, O. M.; Nenarokomov, A. V.; Gonzalez, V. M.

2009-11-01

The purpose of this paper is to introduce a new method in the research of radiative and thermal properties of materials with further applications in the design of thermal control systems (TCS) of spacecrafts. In this paper the radiative and thermal properties (emissivity and thermal conductance) of a multilayered thermal-insulating blanket (MLI), which is a screen-vacuum thermal insulation as a part of the TCS for perspective spacecrafts, are estimated. Properties of the materials under study are determined in the result of temperature and heat flux measurement data processing based on the solution of the inverse heat transfer problem (IHTP) technique. Given are physical and mathematical models of heat transfer processes in a specimen of the multilayered thermal-insulating blanket located in the experimental facility. A mathematical formulation of the inverse heat conduction problem is presented as well. The practical approves were made for specimen of the real MLI.

Predicting spacecraft multilayer insulation performance from heat transfer measurements

NASA Technical Reports Server (NTRS)

Stimpson, L. D.; Hagemeyer, W. A.

1974-01-01

Multilayer insulation (MLI) ideally consists of a series of radiation shields with low-conductivity spacers. When MLI blankets were installed on cryogenic tanks or spacecraft, a large discrepancy between the calorimeter measurements and the performance of the installed blankets was discovered. It was found that discontinuities such as exposed edges coupled with high lateral heat transfer created 'heat leaks' which overshadowed the basic heat transfer of the insulation. Approaches leading to improved performance predictions of MLI units are discussed.

Wrapped Multilayer Insulation

NASA Technical Reports Server (NTRS)

Dye, Scott A.

2015-01-01

New NASA vehicles, such as Earth Departure Stage (EDS), Orion, landers, and orbiting fuel depots, need improved cryogenic propellant transfer and storage for long-duration missions. Current cryogen feed line multilayer insulation (MLI) performance is 10 times worse per area than tank MLI insulation. During each launch, cryogenic piping loses approximately 150,000 gallons (equivalent to $300,000) in boil-off during transfer, chill down, and ground hold. Quest Product Development Corp., teaming with Ball Aerospace, developed an innovative advanced insulation system, Wrapped MLI (wMLI), to provide improved thermal insulation for cryogenic feed lines. wMLI is high-performance multilayer insulation designed for cryogenic piping. It uses Quest's innovative discrete-spacer technology to control layer spacing/ density and reduce heat leak. The Phase I project successfully designed, built, and tested a wMLI prototype with a measured heat leak 3.6X lower than spiral-wrapped conventional MLI widely used for piping insulation. A wMLI prototype had a heat leak of 7.3 W/sq m, or 27 percent of the heat leak of conventional MLI (26.7 W/sq m). The Phase II project is further developing wMLI technology with custom, molded polymer spacers and advancing the product toward commercialization via a rigorous testing program, including developing advanced vacuuminsulated pipe for ground support equipment.

Wrapped Multilayer Insulation

NASA Technical Reports Server (NTRS)

Dye, Scott A.

2015-01-01

New NASA vehicles, such as Earth Departure Stage (EDS), Orion, landers, and orbiting fuel depots, need improved cryogenic propellant transfer and storage for long-duration missions. Current cryogen feed line multilayer insulation (MLI) performance is 10 times worse per area than tank MLI insulation. During each launch, cryogenic piping loses approximately 150,000 gallons (equivalent to $300,000) in boil-off during transfer, chill down, and ground hold. Quest Product Development Corp., teaming with Ball Aerospace, developed an innovative advanced insulation system, Wrapped MLI (wMLI), to provide improved thermal insulation for cryogenic feed lines. wMLI is high-performance multilayer insulation designed for cryogenic piping. It uses Quest's innovative discrete-spacer technology to control layer spacing/ density and reduce heat leak. The Phase I project successfully designed, built, and tested a wMLI prototype with a measured heat leak 3.6X lower than spiral-wrapped conventional MLI widely used for piping insulation. A wMLI prototype had a heat leak of 7.3 W/m2, or 27 percent of the heat leak of conventional MLI (26.7 W/m2). The Phase II project is further developing wMLI technology with custom, molded polymer spacers and advancing the product toward commercialization via a rigorous testing program, including developing advanced vacuuminsulated pipe for ground support equipment.

Load responsive multilayer insulation performance testing

NASA Astrophysics Data System (ADS)

Dye, S.; Kopelove, A.; Mills, G. L.

2014-01-01

Cryogenic insulation designed to operate at various pressures from one atmosphere to vacuum, with high thermal performance and light weight, is needed for cryogenically fueled space launch vehicles and aircraft. Multilayer insulation (MLI) performs well in a high vacuum, but the required vacuum shell for use in the atmosphere is heavy. Spray-on foam insulation (SOFI) is often used in these systems because of its light weight, but can have a higher heat flux than desired. We report on the continued development of Load Responsive Multilayer Insulation (LRMLI), an advanced thermal insulation system that uses dynamic beam discrete spacers that provide high thermal performance both in atmosphere and vacuum. LRMLI consists of layers of thermal radiation barriers separated and supported by micromolded polymer spacers. The spacers have low thermal conductance, and self-support a thin, lightweight vacuum shell that provides internal high vacuum in the insulation. The dynamic load responsive spacers compress to support the external load of a vacuum shell in one atmosphere, and decompress under reduced atmospheric pressure for lower heat leak. Structural load testing was performed on the spacers with various configurations. LRMLI was installed on a 400 liter tank and boil off testing with liquid nitrogen performed at various chamber pressures from one atmosphere to high vacuum. Testing was also performed with an MLI blanket on the outside of the LRMLI.

Lightweight evacuated multilayer insulation systems for the space shuttle vehicle

NASA Technical Reports Server (NTRS)

Barclay, D. L.; Bell, J. E.; Zimmerman, D. K.

1973-01-01

The elements in the evacuated multilayer insulation system were investigated, and the major weight contributors for optimization selected. Outgassing tests were conducted on candidate vacuum jacket materials and experiments were conducted to determine the vacuum and structural integrity of selected vacuum jacket configurations. A nondestructive proof test method, applicable to externally pressurized shells, was validated on this program.

Multilayer modal actuator-based piezoelectric transformers.

PubMed

Huang, Yao-Tien; Wu, Wen-Jong; Wang, Yen-Chieh; Lee, Chih-Kung

2007-02-01

An innovative, multilayer piezoelectric transformer equipped with a full modal filtering input electrode is reported herein. This modal-shaped electrode, based on the orthogonal property of structural vibration modes, is characterized by full modal filtering to ensure that only the desired vibration mode is excited during operation. The newly developed piezoelectric transformer is comprised of three layers: a multilayered input layer, an insulation layer, and a single output layer. The electrode shape of the input layer is derived from its structural vibration modal shape, which takes advantage of the orthogonal property of the vibration modes to achieve a full modal filtering effect. The insulation layer possesses two functions: first, to couple the mechanical vibration energy between the input and output, and second, to provide electrical insulation between the two layers. To meet the two functions, a low temperature, co-fired ceramic (LTCC) was used to provide the high mechanical rigidity and high electrical insulation. It can be shown that this newly developed piezoelectric transformer has the advantage of possessing a more efficient energy transfer and a wider optimal working frequency range when compared to traditional piezoelectric transformers. A multilayer piezoelectric, transformer-based inverter applicable for use in LCD monitors or portable displays is presented as well.

Arcjet Testing and Thermal Model Development for Multilayer Felt Reusable Surface Insulation

NASA Technical Reports Server (NTRS)

Milos, Frank S.; Scott, Carl Douglas; Papa, Steven V.

2012-01-01

Felt Reusable Surface Insulation was used extensively on leeward external surfaces of the Shuttle Orbiter, where the material is reusable for temperatures up to 670 K. For application on leeward surfaces of the Orion Multi-Purpose Crew Vehicle, where predicted temperatures reach 1620 K, the material functions as a pyrolyzing conformal ablator. An arcjet test series was conducted to assess the performance of multilayer Felt Reusable Surface Insulation at high temperatures, and a thermal-response, pyrolysis, and ablation model was developed. Model predictions compare favorably with the arcjet test data

Heat Transfer in High Temperature Multilayer Insulation

NASA Technical Reports Server (NTRS)

Daryabeigi, Kamran; Miller, Steve D.; Cunnington, George R.

2007-01-01

High temperature multilayer insulations have been investigated as an effective component of thermal-protection systems for atmospheric re-entry of reusable launch vehicles. Heat transfer in multilayer insulations consisting of thin, gold-coated, ceramic reflective foils and Saffil(TradeMark) fibrous insulation spacers was studied both numerically and experimentally. A finite volume numerical thermal model using combined conduction (gaseous and solid) and radiation in porous media was developed. A two-flux model with anisotropic scattering was used for radiation heat transfer in the fibrous insulation spacers between the reflective foils. The thermal model was validated by comparison with effective thermal conductivity measurements in an apparatus based on ASTM standard C201. Measurements were performed at environmental pressures in the range from 1x10(exp -4) to 760 torr over the temperature range from 300 to 1300 K. Four multilayer samples with nominal densities of 48 kg/cu m were tested. The first sample was 13.3 mm thick and had four evenly spaced reflective foils. The other three samples were 26.6 mm thick and utilized either one, two, or four reflective foils, located near the hot boundary with nominal foil spacing of 1.7 mm. The validated thermal model was then used to study relevant design parameters, such as reflective foil spacing and location in the stack-up and coating of one or both sides of foils.

Flyweight 3D Graphene Scaffolds with Microinterface Barrier-Derived Tunable Thermal Insulation and Flame Retardancy.

PubMed

Zhang, Qiangqiang; Hao, Menglong; Xu, Xiang; Xiong, Guoping; Li, Hui; Fisher, Timothy S

2017-04-26

In this article, flyweight three-dimensional (3D) graphene scaffolds (GSs) have been demonstrated with a microinterface barrier-derived thermal insulation and flame retardancy characteristics. Such 3D GSs were fabricated by a modified hydrothermal method and a unidirectional freeze-casting process with hierarchical porous microstructures. Because of high porosity (99.9%), significant phonon scattering, and strong π-π interaction at the interface barriers of multilayer graphene cellular walls, the GSs demonstrate a sequence of multifunctional properties simultaneously, such as lightweight density, thermal insulating characteristics, and outstanding mechanical robustness. At 100 °C, oxidized GSs exhibit a thermal conductivity of 0.0126 ± 0.0010 W/(m K) in vacuum. The thermal conductivity of oxidized GSs remains relatively unaffected despite large-scale deformation-induced densification of the microstructures, as compared to the behavior of reduced GSs (rGSs) whose thermal conductivity increases dramatically under compression. The contrasting behavior of oxidized GSs and rGSs appears to derive from large differences in the intersheet contact resistance and varying intrinsic thermal conductivity between reduced and oxidized graphene sheets. The oxidized GSs also exhibit excellent flame retardant behavior and mechanical robustness, with only 2% strength decay after flame treatment. In a broader context, this work demonstrates a useful strategy to design porous nanomaterials with a tunable heat conduction behavior through interface engineering at the nanoscale.

Parameter Identification Of Multilayer Thermal Insulation By Inverse Problems

NASA Astrophysics Data System (ADS)

Nenarokomov, Aleksey V.; Alifanov, Oleg M.; Gonzalez, Vivaldo M.

2012-07-01

The purpose of this paper is to introduce an iterative regularization method in the research of radiative and thermal properties of materials with further applications in the design of Thermal Control Systems (TCS) of spacecrafts. In this paper the radiative and thermal properties (heat capacity, emissivity and thermal conductance) of a multilayered thermal-insulating blanket (MLI), which is a screen-vacuum thermal insulation as a part of the (TCS) for perspective spacecrafts, are estimated. Properties of the materials under study are determined in the result of temperature and heat flux measurement data processing based on the solution of the Inverse Heat Transfer Problem (IHTP) technique. Given are physical and mathematical models of heat transfer processes in a specimen of the multilayered thermal-insulating blanket located in the experimental facility. A mathematical formulation of the IHTP, based on sensitivity function approach, is presented too. The practical testing was performed for specimen of the real MLI. This paper consists of recent researches, which developed the approach suggested at [1].

Electrically controlled band gap and topological phase transition in two-dimensional multilayer germanane

NASA Astrophysics Data System (ADS)

Qi, Jingshan; Li, Xiao; Qian, Xiaofeng

2016-06-01

Electrically controlled band gap and topological electronic states are important for the next-generation topological quantum devices. In this letter, we study the electric field control of band gap and topological phase transitions in multilayer germanane. We find that although the monolayer and multilayer germananes are normal insulators, a vertical electric field can significantly reduce the band gap of multilayer germananes owing to the giant Stark effect. The decrease of band gap eventually leads to band inversion, transforming them into topological insulators with nontrivial Z2 invariant. The electrically controlled topological phase transition in multilayer germananes provides a potential route to manipulate topologically protected edge states and design topological quantum devices. This strategy should be generally applicable to a broad range of materials, including other two-dimensional materials and ultrathin films with controlled growth.

Load responsive multilayer insulation performance testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dye, S.; Kopelove, A.; Mills, G. L.

Cryogenic insulation designed to operate at various pressures from one atmosphere to vacuum, with high thermal performance and light weight, is needed for cryogenically fueled space launch vehicles and aircraft. Multilayer insulation (MLI) performs well in a high vacuum, but the required vacuum shell for use in the atmosphere is heavy. Spray-on foam insulation (SOFI) is often used in these systems because of its light weight, but can have a higher heat flux than desired. We report on the continued development of Load Responsive Multilayer Insulation (LRMLI), an advanced thermal insulation system that uses dynamic beam discrete spacers that providemore » high thermal performance both in atmosphere and vacuum. LRMLI consists of layers of thermal radiation barriers separated and supported by micromolded polymer spacers. The spacers have low thermal conductance, and self-support a thin, lightweight vacuum shell that provides internal high vacuum in the insulation. The dynamic load responsive spacers compress to support the external load of a vacuum shell in one atmosphere, and decompress under reduced atmospheric pressure for lower heat leak. Structural load testing was performed on the spacers with various configurations. LRMLI was installed on a 400 liter tank and boil off testing with liquid nitrogen performed at various chamber pressures from one atmosphere to high vacuum. Testing was also performed with an MLI blanket on the outside of the LRMLI.« less

Thin Aerogel as a Spacer in Multilayer Insulation

NASA Technical Reports Server (NTRS)

Moroz, Nancy

2015-01-01

Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on real-world tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

Thin Aerogel as a Spacer in Multilayer Insulation

NASA Technical Reports Server (NTRS)

Moroz, Nancy

2015-01-01

Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on rea-lworld tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

Design and development of pressure and repressurization purge system for reusable space shuttle multilayer insulation system

NASA Technical Reports Server (NTRS)

1973-01-01

The manufacturing tasks for the program included the fabrication and assembly of an epoxy fiberglass purge bag to encapsulate an insulated cryogenic propellant tank. Purge, repressurization and venting hardware were procured and installed on the purge bag assembly in preparation for performance testing. The fabrication and installation of the superfloc multilayer insulation (MLI) on the cryogenic tank was accomplished as part of a continuing program. An abstraction of the results of the MLI fabrication task is included to describe the complete fabrication requirements for a reusable cryogenic propellant space storage system.

Low Voltage Electrowetting-on-Dielectric Platform using Multi-Layer Insulators

PubMed Central

Lin, Yan-You; Evans, Randall D.; Welch, Erin; Hsu, Bang-Ning; Madison, Andrew C.; Fair, Richard B.

2010-01-01

A low voltage, two-level-metal, and multi-layer insulator electrowetting-on-dielectric (EWD) platform is presented. Dispensing 300pl droplets from 140nl closed on-chip reservoirs was accomplished with as little as 11.4V solely through EWD forces, and the actuation threshold voltage was 7.2V with a 1Hz voltage switching rate between electrodes. EWD devices were fabricated with a multilayer insulator consisting of 135nm sputtered tantalum pentoxide (Ta2O5) and 180nm parylene C coated with 70nm of CYTOP. Furthermore, the minimum actuation threshold voltage followed a previously published scaling model for the threshold voltage, VT, which is proportional to (t/εr)1/2, where t and εr are the insulator thickness and dielectric constant respectively. Device threshold voltages are compared for several insulator thicknesses (200nm, 500nm, and 1µm), different dielectric materials (parylene C and tantalum pentoxide), and homogeneous versus heterogeneous compositions. Additionally, we used a two-level-metal fabrication process, which enables the fabrication of smaller and denser electrodes with high interconnect routing flexibility. We also have achieved low dispensing and actuation voltages for scaled devices with 30pl droplets. PMID:20953362

Electrically controlled band gap and topological phase transition in two-dimensional multilayer germanane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Jingshan, E-mail: qijingshan@jsnu.edu.cn, E-mail: feng@tamu.edu; Li, Xiao; Qian, Xiaofeng, E-mail: qijingshan@jsnu.edu.cn, E-mail: feng@tamu.edu

2016-06-20

Electrically controlled band gap and topological electronic states are important for the next-generation topological quantum devices. In this letter, we study the electric field control of band gap and topological phase transitions in multilayer germanane. We find that although the monolayer and multilayer germananes are normal insulators, a vertical electric field can significantly reduce the band gap of multilayer germananes owing to the giant Stark effect. The decrease of band gap eventually leads to band inversion, transforming them into topological insulators with nontrivial Z{sub 2} invariant. The electrically controlled topological phase transition in multilayer germananes provides a potential route tomore » manipulate topologically protected edge states and design topological quantum devices. This strategy should be generally applicable to a broad range of materials, including other two-dimensional materials and ultrathin films with controlled growth.« less

Analysis of thermal performance of penetrated multi-layer insulation

NASA Technical Reports Server (NTRS)

Foster, Winfred A., Jr.; Jenkins, Rhonald M.; Yoo, Chai H.; Barrett, William E.

1988-01-01

Results of research performed for the purpose of studying the sensitivity of multi-layer insulation blanket performance caused by penetrations through the blanket are presented. The work described in this paper presents the experimental data obtained from thermal vacuum tests of various penetration geometries similar to those present on the Hubble Space Telescope. The data obtained from these tests is presented in terms of electrical power required sensitivity factors referenced to a multi-layer blanket without a penetration. The results of these experiments indicate that a significant increase in electrical power is required to overcome the radiation heat losses in the vicinity of the penetrations.

Thermal performance of multilayer insulations. [gas evacuation characteristics of three selected multilayer insulation composites

NASA Technical Reports Server (NTRS)

Keller, C. W.; Cunnington, G. R.; Glassford, A. P.

1974-01-01

Experimental and analytical studies were conducted in order to extend previous knowledge of the thermal performance and gas evacuation characteristics of three selected multilayer insulation (MLI) composites. Flat plate calorimeter heat flux measurements were obtained for 20- and 80- shield specimens using three representative layer densities over boundary temperatures ranging from 39 K (70 R) to 389 K (700 R). Laboratory gas evacuation tests were performed on representative specimens of each MLI composite after initially purging them with helium, nitrogen, or argon gases. In these tests, the specimens were maintained at temperatures between 128 K (230 R) and 300 K (540 R). Based on the results of the laboratory-scale tests, a composite MLI system consisting of 112 unperforated, double-aluminized Mylar reflective shields and 113 water preconditioned silk net spacer pairs was fabricated and installed on a 1.22-m-(4-ft-) diameter calorimeter tank.

Demonstration of Hybrid Multilayer Insulation for Fixed Thickness Applications

NASA Technical Reports Server (NTRS)

Johnson, Wesley; Fesmire, James; Heckle, Wayne

2015-01-01

Once on orbit, high performing insulation systems for cryogenic systems need just as good radiation (optical) properties as conduction properties. This requires the use of radiation shields with low conductivity spacers in between. By varying the height and cross-sectional area of the spacers between the radiation shields, the relative radiation and conduction heat transfers can be manipulated. However, in most systems, there is a fixed thickness or volume allocated to the insulation. In order to understand how various combinations of different multilayer insulation (MLI) systems work together and further validate thermal models of such a hybrid MLI set up, test data is needed. The MLI systems include combinations of Load Bearing MLI (LB-MLI) and traditional MLI. To further simulate the space launch vehicle case wherein both ambient pressure and vacuum environments are addressed, different cold-side thermal insulation substrates were included for select tests.

The Performance of Gas Filled Multilayer Insulation

NASA Astrophysics Data System (ADS)

Mills, G. L.; Zeller, C. M.

2008-03-01

The NASA Exploration Program is currently planning to use liquid oxygen, methane and hydrogen for propulsion in future spacecraft for the human exploration of the Moon and Mars. This will require the efficient long term, on-orbit storage of these cryogens. Multilayer insulation (MLI) will be critical to achieving the required thermal performance since it has much lower heat transfer than any other insulation when used in a vacuum. However, the size and mass constraints of these propulsion systems will not allow a structural shell to be used to provide vacuum for the MLI during ground hold and launch. One approach is to purge the MLI during ground hold with an inert gas which is then vented during launch ascent and on-orbit. In this paper, we report on experimental tests and modeling that we have done on MLI used to insulate a cryogenic tank. These include measurements of the heat transfer of gas filled insulation, evacuated insulation and during the transition in between.

Chiral magnetic conductivity and surface states of Weyl semimetals in topological insulator ultra-thin film multilayer.

PubMed

Owerre, S A

2016-06-15

We investigate an ultra-thin film of topological insulator (TI) multilayer as a model for a three-dimensional (3D) Weyl semimetal. We introduce tunneling parameters t S, [Formula: see text], and t D, where the former two parameters couple layers of the same thin film at small and large momenta, and the latter parameter couples neighbouring thin film layers along the z-direction. The Chern number is computed in each topological phase of the system and we find that for [Formula: see text], the tunneling parameter [Formula: see text] changes from positive to negative as the system transits from Weyl semi-metallic phase to insulating phases. We further study the chiral magnetic effect (CME) of the system in the presence of a time dependent magnetic field. We compute the low-temperature dependence of the chiral magnetic conductivity and show that it captures three distinct phases of the system separated by plateaus. Furthermore, we propose and study a 3D lattice model of Porphyrin thin film, an organic material known to support topological Frenkel exciton edge states. We show that this model exhibits a 3D Weyl semi-metallic phase and also supports a 2D Weyl semi-metallic phase. We further show that this model recovers that of 3D Weyl semimetal in topological insulator thin film multilayer. Thus, paving the way for simulating a 3D Weyl semimetal in topological insulator thin film multilayer. We obtain the surface states (Fermi arcs) in the 3D model and the chiral edge states in the 2D model and analyze their topological properties.

Heat transfer correlations for multilayer insulation systems

NASA Astrophysics Data System (ADS)

Krishnaprakas, C. K.; Badari Narayana, K.; Dutta, Pradip

2000-01-01

Multilayer insulation (MLI) blankets are extensively used in spacecrafts as lightweight thermal protection systems. Heat transfer analysis of MLI is sometimes too complex to use in practical design applications. Hence, for practical engineering design purposes, it is necessary to have simpler procedures to evaluate the heat transfer rate through MLI. In this paper, four different empirical models for heat transfer are evaluated by fitting against experimentally observed heat flux through MLI blankets of various configurations, and the results are discussed.

Thermal Performance of Cryogenic Piping Multilayer Insulation in Actual Field Installations

NASA Technical Reports Server (NTRS)

Fesmire, J.; Augustnynowicz, S.; Thompson, K. (Technical Monitor)

2002-01-01

A standardized way of comparing the thermal performance of different pipelines in different sizes is needed. Vendor data for vacuum-insulated piping are typically given in heat leak rate per unit length (W/m) for a specific diameter pipeline. An overall k-value for actual field installations (k(sub oafi)) is therefore proposed as a more generalized measure for thermal performance comparison and design calculation. The k(sub oafi) provides a direct correspondence to the k-values reported for insulation materials and illustrates the large difference between ideal multilayer insulation (MLI) and actual MLI performance. In this experimental research study, a section of insulated piping was tested under cryogenic vacuum conditions, including simulated spacers and bending. Several different insulation systems were tested using a 1-meter-long cylindrical cryostat test apparatus. The simulated spacers tests showed significant degradation in the thermal performance of a given insulation system. An 18-meter-long pipeline test apparatus is now in operation at the Cryogenics Test Laboratory, NASA Kennedy Space Center, for conducting liquid nitrogen thermal performance tests.

Research on cascading failure in multilayer network with different coupling preference

NASA Astrophysics Data System (ADS)

Zhang, Yong; Jin, Lei; Wang, Xiao Juan

This paper is aimed at constructing robust multilayer networks against cascading failure. Considering link protection strategies in reality, we design a cascading failure model based on load distribution and extend it to multilayer. We use the cascading failure model to deduce the scale of the largest connected component after cascading failure, from which we can find that the performance of four kinds of load distribution strategies associates with the load ratio of the current edge to its adjacent edge. Coupling preference is a typical characteristic in multilayer networks which corresponds to the network robustness. The coupling preference of multilayer networks is divided into two forms: the coupling preference in layers and the coupling preference between layers. To analyze the relationship between the coupling preference and the multilayer network robustness, we design a construction algorithm to generate multilayer networks with different coupling preferences. Simulation results show that the load distribution based on the node betweenness performs the best. When the coupling coefficient in layers is zero, the scale-free network is the most robust. In the random network, the assortative coupling in layers is more robust than the disassortative coupling. For the coupling preference between layers, the assortative coupling between layers is more robust than the disassortative coupling both in the scale free network and the random network.

Demonstration of Hybrid Multilayer Insulation for Fixed Thickness Applications

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Fesmire, J. E.; Heckle, K. W.

2015-12-01

Cryogenic multilayer insulation (MLI) systems provide both conductive and radiative thermal insulation performance. The use of radiation shields with low conductivity spacers in between are required. By varying the distance and types of the spacers between the radiation shields, the relative radiation and conduction heat transfers can be manipulated. However, in most systems, there is a fixed thickness or volume allocated to the insulation. To understand how various combinations of different multilayer insulation (MLI) systems work together and to further validate thermal models of hybrid MLI systems, test data are needed. The MLI systems include combinations of Load-Bearing MLI (LB-MLI) and traditional MLI (tMLI). To further simulate the space launch vehicle case wherein both ambient pressure and vacuum environments are addressed, different cold-side thermal insulation substrates were included for select tests. The basic hybrid construction consists of some number of layers of LB-MLI on the cold side of the insulation system followed by layers of tMLI on the warm side of the system. The advantages of LB-MLI on the cold side of the insulation blanket are that its low layer density (0.5 - 0.6 layer/mm) is better suited for lower temperature applications and is a structural component to support heat interception shields that may be placed within the blanket. The advantage of tMLI systems on the warm side is that radiation is more dominant than conduction at warmer temperatures, so that a higher layer density is desired (2 - 3 layer/mm) and less effort need be put into minimizing conduction heat transfer. Liquid nitrogen boiloff test data using a cylindrical calorimeter are presented along with analysis for spacecraft tank applications.

Analytical treatment of gas flows through multilayer insulation, project 1

NASA Technical Reports Server (NTRS)

Lin, J. T.

1972-01-01

A theoretical investigation of gas flow inside a multilayer insulation system was made for the case of the broadside pumping process. A set of simultaneous first-order differential equations for the temperature and pressure of the gas molecules through the perforations on the insulation layers. A modified Runge-Kutta method was used for numerical experiment. The numerical stability problem was also investigated. It was shown that when the relaxation time is less than the time period over which the gas properties change appreciably, the set of differential equations can be replaced by a set of algebraic equations for solution. Numerical examples were given and comparisons with experimental data were made.

Multilayer Insulation Ascent Venting Model

NASA Technical Reports Server (NTRS)

Tramel, R. W.; Sutherlin, S. G.; Johnson, W. L.

2017-01-01

The thermal and venting transient experienced by tank-applied multilayer insulation (MLI) in the Earth-to-orbit environment is very dynamic and not well characterized. This new predictive code is a first principles-based engineering model which tracks the time history of the mass and temperature (internal energy) of the gas in each MLI layer. A continuum-based model is used for early portions of the trajectory while a kinetic theory-based model is used for the later portions of the trajectory, and the models are blended based on a reference mean free path. This new capability should improve understanding of the Earth-to-orbit transient and enable better insulation system designs for in-space cryogenic propellant systems.

Inexpensive cryogenic insulation replaces vacuum jacketed line

NASA Technical Reports Server (NTRS)

Fuchs, C. E.

1967-01-01

Commercially available aluminized Mylar, cork and fiber glass form a multilayered sealed system and provide rugged and economical field installed insulation for cryogenic /liquid nitrogen or oxygen/ pipe lines in an exposed environment.

Integrated Multilayer Insulation

NASA Technical Reports Server (NTRS)

Dye, Scott

2009-01-01

Integrated multilayer insulation (IMLI) is being developed as an improved alternative to conventional multilayer insulation (MLI), which is more than 50 years old. A typical conventional MLI blanket comprises between 10 and 120 metallized polymer films separated by polyester nets. MLI is the best thermal- insulation material for use in a vacuum, and is the insulation material of choice for spacecraft and cryogenic systems. However, conventional MLI has several disadvantages: It is difficult or impossible to maintain the desired value of gap distance between the film layers (and consequently, it is difficult or impossible to ensure consistent performance), and fabrication and installation are labor-intensive and difficult. The development of IMLI is intended to overcome these disadvantages to some extent and to offer some additional advantages over conventional MLI. The main difference between IMLI and conventional MLI lies in the method of maintaining the gaps between the film layers. In IMLI, the film layers are separated by what its developers call a micro-molded discrete matrix, which can be loosely characterized as consisting of arrays of highly engineered, small, lightweight, polymer (typically, thermoplastic) frames attached to, and placed between, the film layers. The term "micro-molded" refers to both the smallness of the frames and the fact that they are fabricated in a process that forms precise small features, described below, that are essential to attainment of the desired properties. The term "discrete" refers to the nature of the matrix as consisting of separate frames, in contradistinction to a unitary frame spanning entire volume of an insulation blanket.

Multi-layer structures with thermal and acoustic properties for building rehabilitation

NASA Astrophysics Data System (ADS)

Bessa, J.; Mota, C.; Cunha, F.; Merino, F.; Fangueiro, R.

2017-10-01

This work compares the use of different sustainable materials in the design of multilayer structures for the rehabilitation of buildings in terms of thermal and acoustic properties. These structures were obtained by compression moulding and thermal and acoustic tests were further carried out for the quantification of the respective insulation properties of composite materials obtained. The experimental results show that the use of polyurethane (PUR) foams and jute fabric reinforcing biocomposites promotes interesting properties of thermal and acoustic insulation. A multi-layer structure composed by PUR foam on the intermediate layer revealed thermal resistances until 0.272 m2 K W-1. On the other hand, the use of jute fabric reinforcing biocomposites on exterior layer promoted a noise reduction at 500 Hz until 8.3 dB. These results allow to conclude that the use of PUR foams and jute fabric reinforcing biocomposites can be used successfully in rehabilitation of buildings, when the thermal and acoustic insulation is looked for.

Broadband planar multilayered absorbers tuned by VO2 phase transition

NASA Astrophysics Data System (ADS)

Peng, Hao; Ji, Chunhui; Lu, Lulu; Li, Zhe; Li, Haoyang; Wang, Jun; Wu, Zhiming; Jiang, Yadong; Xu, Jimmy; Liu, Zhijun

2017-08-01

The metal-insulator transition makes vanadium dioxide an attractive material for developing reconfigurable optoelectronic components. Here we report on dynamically tunable broadband absorbers consisting of planar multilayered thin films. By thermally triggering the phase transition of vanadium dioxide, the effective impedance of multilayered structures is tuned in or out of the condition of impedance matching to free-space, leading to switchable broadband absorptions. Two types of absorbers are designed and demonstrated by using either the insulating or metallic state of vanadium dioxide at the impedance matched condition. The planar multilayered absorbers exhibit tunable absorption bands over the wavelength ranges of 5-9.3 μm and 3.9-8.2 μm, respectively. A large modulation depth up to 88% is measured. The demonstrated broadband absorbance tunability is of potential interest for reconfigurable bolometric sensing, camouflaging, and modulation of mid-infrared lights.

THz Pulse Detection by Multilayered GeTe/Sb2Te3.

PubMed

Makino, Kotaro; Kuromiya, Shota; Takano, Keisuke; Kato, Kosaku; Nakajima, Makoto; Saito, Yuta; Tominaga, Junji; Iida, Hitoshi; Kinoshita, Moto; Nakano, Takashi

2016-11-30

We proposed and demonstrated terahertz (THz) pulse detection by means of multilayered GeTe/Sb 2 Te 3 phase-change memory materials that are also known as a multilayer topological insulator-normal insulator (MTN) system. THz time-domain spectroscopy measurement was performed for MTN films with different multilayer repetitions as well as a conventional as-grown Ge-Te-Sb (GST) alloy film. It was found that MTNs absorb THz waves and that the absorption coefficient depends on the number of layers, while the as-grown GST alloy film was almost transparent for THz waves. Simple MTN-based THz detection devices were fabricated, and the THz-induced change in the current signal was measured when a DC bias voltage was applied between the electrodes. We confirmed that irradiation of THz pulse causes a decrease in the resistance of the MTNs. This result indicates that our devices are capable of THz detection.

A General Strategy to Achieve Colossal Permittivity and Low Dielectric Loss Through Constructing Insulator/Semiconductor/Insulator Multilayer Structures

NASA Astrophysics Data System (ADS)

Liu, Kai; Sun, Yalong; Zheng, Fengang; Tse, Mei-Yan; Sun, Qingbo; Liu, Yun; Hao, Jianhua

2018-06-01

In this work, we propose a route to realize high-performance colossal permittivity (CP) by creating multilayer structures of insulator/semiconductor/insulator. To prove the new concept, we made heavily reduced rutile TiO2 via annealing route in Ar/H2 atmosphere. Dielectric studies show that the maximum dielectric permittivity ( 3.0 × 104) of our prepared samples is about 100 times higher than that ( 300) of conventional TiO2. The minimum dielectric loss is 0.03 (at 104-105 Hz). Furthermore, CP is almost independent of the frequency (100-106 Hz) and the temperature (20-350 K). We suggest that the colossal permittivity is attributed to the high carrier concentration of the inner TiO2 semiconductor, while the low dielectric loss is due to the presentation of the insulator layer on the surface of TiO2. The method proposed here can be expanded to other material systems, such as semiconductor Si sandwiched by top and bottom insulator layers of Ga2O3.

Multilayer insulation blanket, fabricating apparatus and method

DOEpatents

Gonczy, John D.; Niemann, Ralph C.; Boroski, William N.

1992-01-01

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Method of fabricating a multilayer insulation blanket

DOEpatents

Gonczy, John D.; Niemann, Ralph C.; Boroski, William N.

1993-01-01

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Method of fabricating a multilayer insulation blanket

DOEpatents

Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

1993-07-06

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Multilayer insulation blanket, fabricating apparatus and method

DOEpatents

Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

1992-09-01

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel. 7 figs.

Thermal performance of gaseous-helium-purged tank-mounted multilayer insulation system during ground-hold and space-hold thermal cycling and exposure to water vapor

NASA Technical Reports Server (NTRS)

Sumner, I. E.

1978-01-01

An experimental investigation was conducted to determine (1) the ground-hold and space-hold thermal performance of a multilayer insulation (MLI) system mounted on a spherical, liquid-hydrogen propellant tank and (2) the degradation to the space-hold thermal performance of the insulation system that resulted from both thermal cycling and exposure to moisture. The propellant tank had a diameter of 1.39 meters (4.57ft). The MLI consisted of two blankets of insulation; each blanket contained 15 double-aluminized Mylar radiation shields separated by double silk net spacers. Nineteen tests simulating basic cryogenic spacecraft thermal (environmental) conditions were conducted. These tests typically included initial helium purge, liquid-hydrogen fill and ground-hold, ascent, space-hold, and repressurization. No significant degradation of the space-hold thermal performance due to thermal cycling was noted.

The Structural Heat Intercept-Insulation-Vibration Evaluation Rig (SHIVER)

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Zoeckler, J. G.; Best-Ameen, L. M.

2015-01-01

NASA is currently investigating methods to reduce the boil-off rate on large cryogenic upper stages. Two such methods to reduce the total heat load on existing upper stages are vapor cooling of the cryogenic tank support structure and integration of thick multilayer insulation systems to the upper stage of a launch vehicle. Previous efforts have flown a 2-layer MLI blanket and shown an improved thermal performance, and other efforts have ground-tested blankets up to 70 layers thick on tanks with diameters between 2 3 meters. However, thick multilayer insulation installation and testing in both thermal and structural modes has not been completed on a large scale tank. Similarly, multiple vapor cooled shields are common place on science payload helium dewars; however, minimal effort has gone into intercepting heat on large structural surfaces associated with rocket stages. A majority of the vapor cooling effort focuses on metallic cylinders called skirts, which are the most common structural components for launch vehicles. In order to provide test data for comparison with analytical models, a representative test tank is currently being designed to include skirt structural systems with integral vapor cooling. The tank is 4 m in diameter and 6.8 m tall to contain 5000 kg of liquid hydrogen. A multilayer insulation system will be designed to insulate the tank and structure while being installed in a representative manner that can be extended to tanks up to 10 meters in diameter. In order to prove that the insulation system and vapor cooling attachment methods are structurally sound, acoustic testing will also be performed on the system. The test tank with insulation and vapor cooled shield installed will be tested thermally in the B2 test facility at NASAs Plumbrook Station both before and after being vibration tested at Plumbrooks Space Power Facility.

Improved multilayer insulation applications. [spacecraft thermal control

NASA Technical Reports Server (NTRS)

Mikk, G.

1982-01-01

Multilayer insulation blankets used for the attenuation of radiant heat transfer in spacecraft are addressed. Typically, blanket effectiveness is degraded by heat leaks in the joints between adjacent blankets and by heat leaks caused by the blanket fastener system. An approach to blanket design based upon modular sub-blankets with distributed seams and upon an associated fastener system that practically eliminates the through-the-blanket conductive path is described. Test results are discussed providing confirmation of the approach. The specific case of the thermal control system for the optical assembly of the Space Telescope is examined.

Rigid open-cell polyurethane foam for cryogenic insulation

NASA Technical Reports Server (NTRS)

Faddoul, J. R.; Lindquist, C. R.; Niendorf, L. R.; Nies, G. E.; Perkins, P. J., Jr.

1971-01-01

Lightweight polyurethane foam assembled in panels is effective spacer material for construction of self-evacuating multilayer insulation panels for cryogenic liquid tanks. Spacer material separates radiation shields with barrier that minimizes conductive and convective heat transfer between shields.

Systems and Methods for Providing Insulation

NASA Technical Reports Server (NTRS)

Golden, Johnny L. (Inventor)

2015-01-01

Systems and methods provide a multi-layer insulation (MLI) that includes a plurality of sealed metalized volumes in a stacked arrangement, wherein the plurality of sealed metalized volumes encapsulate a gas therein, with the gas having one of a thermal insulating property, an acoustic insulating property, or a combination insulating property thereof. The MLI also includes at least one spacer between adjacent sealed metalized volumes of the plurality of sealed metalized volumes and a protective cover surrounding the plurality of sealed metalized volumes.

Ceramic insulation/multifoil composite for thermal protection of reentry spacecraft

NASA Technical Reports Server (NTRS)

Pitts, W. C.; Kourtides, D. A.

1989-01-01

A new type of insulation blanket called Composite Flexible Blanket Insulation is proposed for thermal protection of advanced spacecraft in regions where the maximum temperature is not excessive. The blanket is a composite of two proven insulation materials: ceramic insulation blankets from Space Shuttle technology and multilayer insulation blankets from spacecraft thermal control technology. A potential heatshield weight saving of up to 500 g/sq m is predicted. The concept is described; proof of concept experimental data are presented; and a spaceflight experiment to demonstrate its actual performance is discussed.

Simulation and experimental research of heat leakage of cryogenic transfer lines

NASA Astrophysics Data System (ADS)

Deng, B. C.; Xie, X. J.; Pan, W.; Jiang, R. X.; Li, J.; Yang, S. Q.; Li, Q.

2017-12-01

The heat leakage of cryogenic transfer lines directly influences the performance of large-scale helium refrigerator. In this paper, a thermal model of cryogenic transfer line considering numerical simulation of support coupled with MLI was established. To validate the model, test platform of cryogenic transfer lines with the merits of disassembly outer pipe and changeable easily multi-layer insulation has been built. The experimental results of heat leakage through overall length of cryogenic transfer lines, support and multi-layer insulation were obtained. The heat leakages of multi-layer insulation, a support and the overall leakage are 1.02 W/m, 0.44 W and 1.46 W/m from experimental data, respectively. The difference of heat leakage of MLI between experiment and simulation were less than 5%. The temperature distribution of support and MLI obtained in presented model in good agreement with experimental data. It is expected to reduce the overall heat leakage of cryogenic transfer lines further by optimizing structure of support based on the above thermal model and test platform in this paper.

Thermal engineering research. [Runge-Kutta investigation of gas flow inside multilayer insulation system for rocket booster fuel tanks

NASA Technical Reports Server (NTRS)

Shih, C. C.

1973-01-01

A theoretical investigation of gas flow inside a multilayer insulation system has been made for the case of the broadside pumping process. A set of simultaneous first-order differential equations for the temperature and pressure of the gas mixture was obtained by considering the diffusion mechanism of the gas molecules through the perforations on the insulation layers. A modified Runge-Kutta method was used for numerical experiment. The numerical stability problem was investigated. It has been shown that when the relaxation time is small compared with the time period over which the gas properties change appreciably, the set of differential equations can be replaced by a set of algebraic equations for solution. Numerical examples were given, and comparisons with experimental data were made.

Development of a new multi-layer insulation blanket with non-interlayer-contact spacer for space cryogenic mission

NASA Astrophysics Data System (ADS)

Miyakita, Takeshi; Hatakenaka, Ryuta; Sugita, Hiroyuki; Saitoh, Masanori; Hirai, Tomoyuki

2014-11-01

For conventional Multi-Layer Insulation (MLI) blankets, it is difficult to control the layer density and the thermal insulation performance degrades due to the increase in conductive heat leak through interlayer contacts. At low temperatures, the proportion of conductive heat transfer through MLI blankets is large compared to that of radiative heat transfer, hence the decline in thermal insulation performance is significant. A new type of MLI blanket using new spacers; the Non-Interlayer-Contact Spacer MLI (NICS MLI) has been developed. This new MLI blanket uses small discrete spacers and can exclude uncertain interlayer contact between films. It is made of polyetheretherketone (PEEK) making it suitable for space use. The cross-sectional area to length ratio of the spacer is 1.0 × 10-5 m with a 10 mm diameter and 4 mm height. The insulation performance is measured with a boil-off calorimeter. Because the NICS MLI blanket can exclude uncertain interlayer contact, the test results showed good agreement with estimations. Furthermore, the NICS MLI blanket shows significantly good insulation performance (effective emissivity is 0.0046 at ordinary temperature), particularly at low temperatures, due to the high thermal resistance of this spacer.

Disordered Nanohole Patterns in Metal-Insulator Multilayer for Ultra-broadband Light Absorption: Atomic Layer Deposition for Lithography Free Highly repeatable Large Scale Multilayer Growth.

PubMed

Ghobadi, Amir; Hajian, Hodjat; Dereshgi, Sina Abedini; Bozok, Berkay; Butun, Bayram; Ozbay, Ekmel

2017-11-08

In this paper, we demonstrate a facile, lithography free, and large scale compatible fabrication route to synthesize an ultra-broadband wide angle perfect absorber based on metal-insulator-metal-insulator (MIMI) stack design. We first conduct a simulation and theoretical modeling approach to study the impact of different geometries in overall stack absorption. Then, a Pt-Al 2 O 3 multilayer is fabricated using a single atomic layer deposition (ALD) step that offers high repeatability and simplicity in the fabrication step. In the best case, we get an absorption bandwidth (BW) of 600 nm covering a range of 400 nm-1000 nm. A substantial improvement in the absorption BW is attained by incorporating a plasmonic design into the middle Pt layer. Our characterization results demonstrate that the best configuration can have absorption over 0.9 covering a wavelength span of 400 nm-1490 nm with a BW that is 1.8 times broader compared to that of planar design. On the other side, the proposed structure retains its absorption high at angles as wide as 70°. The results presented here can serve as a beacon for future performance enhanced multilayer designs where a simple fabrication step can boost the overall device response without changing its overall thickness and fabrication simplicity.

Supplemental multilayer insulation research facility

NASA Technical Reports Server (NTRS)

Dempsey, P. J.; Stochl, R. J.

1995-01-01

The Supplemental Multilayer Insulation Research Facility (SMIRF) provides a small scale test bed for conducting cryogenic experiments in a vacuum environment. The facility vacuum system is capable of simulating a Space Shuttle launch pressure profile as well as providing a steady space vacuum environment of 1.3 x 10(exp -4) Newton/sq meter (1 x 10(exp -6) torr). Warm side boundary temperatures can be maintained constant between 111 K (200 R) and 361 K (650 R) using a temperature controlled shroud. The shroud can also simulate a typical lunar day-night temperature profile. The test hardware consists of a cryogenic calorimeter supported by the lid of the vacuum chamber. A 0.45 cu meter (120 gallon) vacuum jacketed storage/supply tank is available for conditioning the cryogen prior to use in the calorimeter. The facility was initially designed to evaluate the thermal performance of insulation systems for long-term storage in space. The facility has recently been used to evaluate the performance of various new insulation systems for LH2 and LN2 ground storage dewars.

Effect of environment on insulation materials, volume 1

NASA Technical Reports Server (NTRS)

Parmley, R. T.; Smith, F. J.; Glassford, A. P.; Coleman, J.; Stevenson, D. R.

1973-01-01

Twenty candidate multilayer insulation and insulation related materials were subjected to eight conditions that represent possible operational environments. These exposures include ground contaminants, various operational temperatures, space vacuum, space-vented propellants, and tank leakage. The objective of this program was to obtain and evaluate the data from these exposures to provide both a quantitative and qualitative description of the degradation to certain physical and thermal properties, and from this, to obtain a better understanding of the environmental effects on the insulation performance.

Room Temperature Silicene Field-Effect Transistors

NASA Astrophysics Data System (ADS)

Akinwande, Deji

Silicene, a buckled Si analogue of graphene, holds significant promise for future electronics beyond traditional CMOS. In our predefined experiments via encapsulated delamination with native electrodes approach, silicene devices exhibit an ambipolar charge transport behavior, corroborating theories on Dirac band in Ag-free silicene. Monolayer silicene device has extracted field-effect mobility within the theoretical expectation and ON/OFF ratio greater than monolayer graphene, while multilayer silicene devices show decreased mobility and gate modulation. Air-stability of silicene devices depends on the number of layers of silicene and intrinsic material structure determined by growth temperature. Few or multi-layer silicene devices maintain their ambipolar behavior for days in contrast to minutes time scale for monolayer counterparts under similar conditions. Multilayer silicene grown at different temperatures below 300oC possess different intrinsic structures and yield different electrical property and air-stability. This work suggests a practical prospect to enable more air-stable silicene devices with layer and growth condition control, which can be leveraged for other air-sensitive 2D materials. In addition, we describe quantum and classical transistor device concepts based on silicene and related buckled materials that exploit the 2D topological insulating phenomenon. The transistor device physics offer the potential for ballistic transport that is robust against scattering and can be employed for both charge and spin transport. This work was supported by the ARO.

Solution-processed phase-change VO(2) metamaterials from colloidal vanadium oxide (VO(x)) nanocrystals.

PubMed

Paik, Taejong; Hong, Sung-Hoon; Gaulding, E Ashley; Caglayan, Humeyra; Gordon, Thomas R; Engheta, Nader; Kagan, Cherie R; Murray, Christopher B

2014-01-28

We demonstrate thermally switchable VO2 metamaterials fabricated using solution-processable colloidal nanocrystals (NCs). Vanadium oxide (VOx) NCs are synthesized through a nonhydrolytic reaction and deposited from stable colloidal dispersions to form NC thin films. Rapid thermal annealing transforms the VOx NC thin films into monoclinic, nanocrystalline VO2 thin films that show a sharp, reversible metal-insulator phase transition. Introduction of precise concentrations of tungsten dopings into the colloidal VOx NCs enables the still sharp phase transition of the VO2 thin films to be tuned to lower temperatures as the doping level increases. We fabricate "smart", differentially doped, multilayered VO2 films to program the phase and therefore the metal-insulator behavior of constituent vertically structured layers with temperature. With increasing temperature, we tailored the optical response of multilayered films in the near-IR and IR regions from that of a strong light absorber, in a metal-insulator structure, to that of a Drude-like reflector, characteristic of a pure metallic structure. We demonstrate that nanocrystal-based nanoimprinting can be employed to pattern multilayered subwavelength nanostructures, such as three-dimensional VO2 nanopillar arrays, that exhibit plasmonic dipolar responses tunable with a temperature change.

Equivalent circuit and optimum design of a multilayer laminated piezoelectric transformer.

PubMed

Dong, Shuxiang; Carazo, Alfredo Vazquez; Park, Seung Ho

2011-12-01

A multilayer laminated piezoelectric Pb(Zr(1-x)Ti(x))O(3) (PZT) ceramic transformer, operating in a half- wavelength longitudinal resonant mode (λ/2 mode), has been analyzed. This piezoelectric transformer is composed of one thickness-polarized section (T-section) for exciting the longitudinal mechanical vibrations, two longitudinally polarized sections (L-section) for generating high-voltage output, and two insulating layers laminated between the T-section and L-section layers to provide insulation between the input and output sections. Based on the piezoelectric constitutive and motion equations, an electro-elasto-electric (EEE) equivalent circuit has been developed, and correspondingly, an effective EEE coupling coefficient was proposed for optimum design of this multilayer transformer. Commercial finite element analysis software is used to determine the validity of the developed equivalent circuit. Finally, a prototype sample was manufactured and experimental data was collected to verify the model's validity.

A Method to have Multi-Layer Thermal Insulation Provide Damage Detection

NASA Technical Reports Server (NTRS)

Woodward, Stanley E.; Taylor, Bryant D.; Jones, Thomas W.; Shams, Qamar A.; Lyons, Frankel; Henderson, Donald

2007-01-01

Design and testing of a multi-layer thermal insulation system that also provides debris and micrometeorite damage detection is presented. One layer of the insulation is designed as an array of passive open-circuit electrically conductive spiral trace sensors. The sensors are a new class of sensors that are electrically open-circuits that have no electrical connections thereby eliminating one cause of failure to circuits. The sensors are powered using external oscillating magnetic fields. Once electrically active, they produce their own harmonic magnetic fields. The responding field frequency changes if any sensor is damaged. When the sensors are used together in close proximity, the inductive coupling between sensors provides a means of telemetry. The spiral trace design using reflective electrically conductive material provides sufficient area coverage for the sensor array to serves as a layer of thermal insulation. The other insulation layers are designed to allow the sensor s magnetic field to permeate the insulation layers while having total reflective surface area to reduce thermal energy transfer. Results of characterizing individual sensors and the sensor array s response to punctures are presented. Results of hypervelocity impact testing using projectiles of 1-3.6 millimeter diameter having speeds ranging from 6.7-7.1 kilometers per second are also presented.

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R

NASA Astrophysics Data System (ADS)

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on a 87.6 in diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R

NASA Astrophysics Data System (ADS)

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on an 87.6 in. diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr, respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

The numerical model of multi-layer insulation with a defined wrapping pattern immersed in superfluid helium

NASA Astrophysics Data System (ADS)

Malecha, Ziemowit; Lubryka, Eliza

2017-11-01

The numerical model of thin layers, characterized by a defined wrapping pattern can be a crucial element of many computational problems related to engineering and science. A motivating example is found in multilayer electrical insulation, which is an important component of superconducting magnets and other cryogenic installations. The wrapping pattern of the insulation can significantly affect heat transport and the performance of the considered instruments. The major objective of this study is to develop the numerical boundary conditions (BC) needed to model the wrapping pattern of thin insulation. An example of the practical application of the proposed BC includes the heat transfer of Rutherford NbTi cables immersed in super-fluid helium (He II) across thin layers of electrical insulation. The proposed BC and a mathematical model of heat transfer in He II are implemented in the open source CFD toolbox OpenFOAM. The implemented mathematical model and the BC are compared in the experiments. The study confirms that the thermal resistance of electrical insulation can be lowered by implementing the proper wrapping pattern. The proposed BC can be useful in the study of new patterns for wrapping schemes. The work has been supported by statutory funds from Polish Ministry for Science and Higher Education for the year of 2017.

Accelerated life testing and reliability of high K multilayer ceramic capacitors

NASA Technical Reports Server (NTRS)

Minford, W. J.

1981-01-01

The reliability of one lot of high K multilayer ceramic capacitors was evaluated using accelerated life testing. The degradation in insulation resistance was characterized as a function of voltage and temperature. The times to failure at a voltage-temperature stress conformed to a lognormal distribution with a standard deviation approximately 0.5.

Robust image features: concentric contrasting circles and their image extraction

NASA Astrophysics Data System (ADS)

Gatrell, Lance B.; Hoff, William A.; Sklair, Cheryl W.

1992-03-01

Many computer vision tasks can be simplified if special image features are placed on the objects to be recognized. A review of special image features that have been used in the past is given and then a new image feature, the concentric contrasting circle, is presented. The concentric contrasting circle image feature has the advantages of being easily manufactured, easily extracted from the image, robust extraction (true targets are found, while few false targets are found), it is a passive feature, and its centroid is completely invariant to the three translational and one rotational degrees of freedom and nearly invariant to the remaining two rotational degrees of freedom. There are several examples of existing parallel implementations which perform most of the extraction work. Extraction robustness was measured by recording the probability of correct detection and the false alarm rate in a set of images of scenes containing mockups of satellites, fluid couplings, and electrical components. A typical application of concentric contrasting circle features is to place them on modeled objects for monocular pose estimation or object identification. This feature is demonstrated on a visually challenging background of a specular but wrinkled surface similar to a multilayered insulation spacecraft thermal blanket.

Radiative-conductive inverse problem for lumped parameter systems

NASA Astrophysics Data System (ADS)

Alifanov, O. M.; Nenarokomov, A. V.; Gonzalez, V. M.

2008-11-01

The purpose of this paper is to introduce a iterative regularization method in the research of radiative and thermal properties of materials with applications in the design of Thermal Control Systems (TCS) of spacecrafts. In this paper the radiative and thermal properties (emissivity and thermal conductance) of a multilayered thermal-insulating blanket (MLI), which is a screen-vacuum thermal insulation as a part of the (TCS) for perspective spacecrafts, are estimated. Properties of the materials under study are determined in the result of temperature and heat flux measurement data processing based on the solution of the Inverse Heat Transfer Problem (IHTP) technique. Given are physical and mathematical models of heat transfer processes in a specimen of the multilayered thermal-insulating blanket located in the experimental facility. A mathematical formulation of the inverse heat conduction problem is presented too. The practical testing were performed for specimen of the real MLI.

Purging of multilayer insulation by gas diffusion

NASA Technical Reports Server (NTRS)

Sumner, I. E.; Spuckler, C. M.

1976-01-01

An experimental investigation was conducted to determine the time required to purge a multilayer insulation (MLI) panel with gaseous helium by means of gas diffusion to obtain a condensable (nitrogen) gas concentration of less than 1 percent within the panel. Two flat, rectangular MLI panel configurations, one incorporating a butt joint, were tested. The insulation panels consisted of 15 double-aluminized Mylar radiation shields separated by double silk net spacers. The test results indicated that the rate which the condensable gas concentration at the edge or at the butt joint of an MLI panel was reduced was a significant factor in the total time required to reduce the condensable gas concentration within the panel to less than 1 percent. The experimental data agreed well with analytical predictions made by using a simple, one-dimensional gas diffusion model in which the boundary conditions at the edge of the MLI panel were time dependent.

Selenide isotope generator for the Galileo Mission: SIG thermal insulation evaluaion tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1979-06-01

Since the SIG program required the use of very high performance thermal insulation materials in rather severe thermal and environmental conditions, a thorough screening and testing program was performed. Several types of materials were included in the preliminary survey. Most promising were oxide and carbonaceous fibrous insulations, oxide and carbonaceous foamed materials, and multilayer materials with both powder and cloth spacers. The latter were only viable for the vacuum option. In all, over one hundred materials from more than sixty manufacturers were evaluated from literature and manufacturers' data. The list was pared to eighteen candidates in seven basic types, i.e.,more » fibrous microporous SiO/sub 2/, fibrous SiO/sub 2//Al/sub 2/O/sub 3/, fibrous ZrO/sub 2/, fibrous carbon, foamed SiO/sub 2/, foamed carbon, and multilayer. Test results are presented.« less

Unexpected resonant response in [Fe(001)/Cr(001)]10/MgO(001) multilayers in a magnetic field.

PubMed

Aliev, F G; Pryadun, V V; Snoeck, E

2009-01-23

We observed unexpected resonant response in [Fe/Cr]10 multilayers epitaxially grown on MgO(100) substrates which exists only when both ac current and dc magnetic field are simultaneously applied. The magnitude of the resonances is determined by the multilayer magnetization proving their intrinsic character. The reduction of interface epitaxy leads to nonlinear dependence of the magnitude of resonances on the alternating current density. We speculate that the existence of the interface transition zone could facilitate the subatomic vibrations in thin metallic films and multilayers grown on bulk insulating substrates.

Cryogenic insulation development

NASA Technical Reports Server (NTRS)

Leonhard, K. E.

1972-01-01

Multilayer insulations for long term cryogenic storage are described. The development effort resulted in an insulation concept using lightweight radiation shields, separated by low conductive Dacron fiber tufts. The insulation is usually referred to as Superfloc. The fiber tufts are arranged in a triangular pattern and stand about .040 in. above the radiation shield base. Thermal and structural evaluation of Superfloc indicated that this material is a strong candidate for the development of high performance thermal protection systems because of its high strength, purge gas evacuation capability during boost, its density control and easy application to a tank.

High-Tech, Low-Temp Insulation

NASA Technical Reports Server (NTRS)

1998-01-01

Under an SBIR (Small Business Innovative Research) contract with Ames, S.D. Miller & Associates developed new manufacturing methods for multi-layer metal spacecraft insulation that could significantly reduce launch weight and launch costs. The new honeycomb structure is more efficient than fibers for insulation. Honeycombs can be made from metals for high temperature uses, even plastic insulation from recycled milk bottles. Under development are blankets made from recycled milk bottles which will be field tested by the Red Cross and ambulance companies. Currently available are honeycomb mittens based on the same technology.

Repeatability Measurements of Apparent Thermal Conductivity of Multilayer Insulation (MLI)

NASA Astrophysics Data System (ADS)

Vanderlaan, M.; Stubbs, D.; Ledeboer, K.; Ross, J.; Van Sciver, S.; Guo, W.

2017-12-01

This report presents and discusses the results of repeatability experiments gathered from the multi-layer insulation thermal conductivity experiment (MIKE) for the measurement of the apparent thermal conductivity of multi-layer insulation (MLI) at variable boundary temperatures. Our apparatus uses a calibrated thermal link between the lower temperature shield of a concentric cylinder insulation assembly and the cold head of a cryocooler to measure the heat leak. In addition, thermocouple readings are taken in-between the MLI layers. These measurements are part of a multi-phase NASA-Yetispace-FSU collaboration to better understand the repeatability of thermal conductivity measurements of MLI. NASA provided five 25 layer coupons and requested boundary temperatures of 20 K and 300 K. Yetispace provided ten 12-layer coupons and requested boundary temperatures of 77 K and 293 K. Test conditions must be met for a duration of four hours at a steady state variance of less than 0.1 K/hr on both cylinders. Temperatures from three Cernox® temperature sensors on each of the two cylinders are averaged to determine the boundary temperatures. A high vacuum, less than 10-5 torr, is maintained for the duration of testing. Layer density varied from 17.98 - 26.36 layers/cm for Yetispace coupons and 13.05 - 17.45 layers/cm for the NASA coupons. The average measured heat load for the Yetispace coupons was 2.40 W for phase-one and 2.92 W for phase-two. The average measured heat load for the NASA coupons was 1.10 W. This suggests there is still unknown variance of MLI performance. It has been concluded, variations in the insulation installation heavy effect the apparent thermal conductivity and are not solely dependent on layer density.

Thermal Analysis of Low Layer Density Multilayer Insulation Test Results

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.

2011-01-01

Investigation of the thermal performance of low layer density multilayer insulations is important for designing long-duration space exploration missions involving the storage of cryogenic propellants. Theoretical calculations show an analytical optimal layer density, as widely reported in the literature. However, the appropriate test data by which to evaluate these calculations have been only recently obtained. As part of a recent research project, NASA procured several multilayer insulation test coupons for calorimeter testing. These coupons were configured to allow for the layer density to be varied from 0.5 to 2.6 layer/mm. The coupon testing was completed using the cylindrical Cryostat-l00 apparatus by the Cryogenics Test Laboratory at Kennedy Space Center. The results show the properties of the insulation as a function of layer density for multiple points. Overlaying these new results with data from the literature reveals a minimum layer density; however, the value is higher than predicted. Additionally, the data show that the transition region between high vacuum and no vacuum is dependent on the spacing of the reflective layers. Historically this spacing has not been taken into account as thermal performance was calculated as a function of pressure and temperature only; however the recent testing shows that the data is dependent on the Knudsen number which takes into account pressure, temperature, and layer spacing. These results aid in the understanding of the performance parameters of MLI and help to complete the body of literature on the topic.

Insulating effectiveness of self-spacing dimpled foil

NASA Technical Reports Server (NTRS)

Bond, J. A.

1972-01-01

Experimental data are graphed for determining conductive heat losses of multilayer insulation as function of number of foil layers. Foil was 0.0051 cm thick Nb, 1% Zr refractory alloy, dimpled to 0.0254 cm with approximately 28 dimples/sq cm. Heat losses were determined at 0.1 microtorr between 700 and 1089 K.

Thermal Performance of Low Layer Density Multilayer Insu1ation Using Liquid Nitrogen

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.; Fesmire, James E.

2011-01-01

In order to support long duration cryogenic propellant storage, the Cryogenic Fluid Management (CFM) Project of the Exploration Technology Development Program (ETDP) is investigating the long duration storage propertie$ of liquid methane on the lunar surface. The Methane Lunar Surface Thermal Control (MLSTC) testing is using a tank of the approximate dimensions of the Altair ascent tanks inside of a vacuum chamber to simulate the environment in low earth orbit and on the lunar surface. The thermal performance testing of multilayer insulation (MLI) coupons that are fabricated identically to the tank applied insulation is necessary to understand the performance of the blankets and to be able to predict the performance of the insulation prior to testing. This coupon testing was completed in Cryostat-100 at the Cryogenics Test Laboratory. The results showed the properties of the insulation as a function of layer density, number of layers, and warm boundary temperature. These results aid in the understanding of the performance parameters o fMLI and help to complete the body of literature on the topic.

Tank Applied Testing of Load-Bearing Multilayer Insulation (LB-MLI)

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.; Valenzuela, Juan G.; Feller, Jerr; Plachta, Dave

2014-01-01

The development of long duration orbital cryogenic storage systems will require the reduction of heat loads into the storage tank. In the case of liquid hydrogen, complete elimination of the heat load at 20 K is currently impractical due to the limitations in lift available on flight cryocoolers. In order to reduce the heat load, without having to remove heat at 20 K, the concept of Reduced Boil-Off uses cooled shields within the insulation system at approximately 90 K. The development of Load-Bearing Multilayer Insulation (LB-MLI) allowed the 90 K shield with tubing and cryocooler attachments to be suspended within the MLI and still be structurally stable. Coupon testing both thermally and structurally were performed to verify that the LB-MLI should work at the tank applied level. Then tank applied thermal and structural (acoustic) testing was performed to demonstrate the functionality of the LB-MLI as a structural insulation system. The LB-MLI showed no degradation of thermal performance due to the acoustic testing and showed excellent thermal performance when integrated with a 90 K class cryocooler on a liquid hydrogen tank.

Tank Applied Testing of Load-Bearing Multilayer Insulation (LB-MLI)

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.; Valenzuela, Juan G.; Feller, Jeffrey R.; Plachta, David W.

2014-01-01

The development of long duration orbital cryogenic storage systems will require the reduction of heat loads into the storage tank. In the case of liquid hydrogen, complete elimination of the heat load at 20 K is currently impractical due to the limitations in lift available on flight cryocoolers. In order to reduce the heat load, without having to remove heat at 20 K, the concept of Reduced Boil-Off uses cooled shields within the insulation system at approximately 90 K. The development of Load-Bearing Multilayer Insulation (LB-MLI) allowed the 90 K shield with tubing and cryocooler attachments to be suspended within the MLI and still be structurally stable. Coupon testing, both thermal and structural was performed to verify that the LB-MLI should work at the tank applied level. Then tank applied thermal and structural (acoustic) testing was performed to demonstrate the functionality of the LB-MLI as a structural insulation system. The LB-MLI showed no degradation of thermal performance due to the acoustic testing and showed excellent thermal performance when integrated with a 90 K class cryocooler on a liquid hydrogen tank.

Nanostructured Anodic Multilayer Dielectric Stacked Metal-Insulator-Metal Capacitors.

PubMed

Karthik, R; Kannadassan, D; Baghini, Maryam Shojaei; Mallick, P S

2015-12-01

This paper presents the fabrication of Al2O3/TiO2/Al2O3 metal-insulator-metal (MIM) capacitor using anodization technique. High capacitance density of > 3.5 fF/μm2, low quadratic voltage coefficient of capacitance of < 115 ppm/V2 and a low leakage current density of 4.457 x 10(-11) A/cm2 at 3 V are achieved which are suitable for analog and mixed signal applications. We found that the anodization voltage played a major role in electrical and structural properties of the thin film. This work suggests that the anodization method can offer crystalline multilayer dielectric stack required for high performance MIM capacitor.

Micro-Satellite Impact Tests to Investigate Multi-Layer Insulation Fragments

NASA Astrophysics Data System (ADS)

Murakami, Junko; Hanada, Toshiya; Liou, J.-C.; Stansbery, Eugene

2009-03-01

This paper summarizes two satellite impact experiments completed in 2008. The objective of the experiments is to investigate the physical properties of satellite fragments, including those originated from Multi-Layer Insulation and a solar panel. One test generated approximately 1,800 fragments while the other produced only 1,000 fragments. This difference came from the number of needle-like fragments from carbon fiber reinforced plastics. All collected fragments were analyzed using the same method as described in the NASA standard breakup model and compared with the breakup model. This paper will present: (1) the area-to-mass ratio, size, and mass distributions of the fragments, and (2) the differences in fragment properties between the two tests.

Space vehicle integrated thermal protection/structural/meteoroid protection system, volume 1

NASA Technical Reports Server (NTRS)

Bartlett, D. H.; Zimmerman, D. K.

1973-01-01

A program was conducted to determine the merit of a combined structure/thermal meteoroid protection system for a cryogenic vehicle propulsion module. Structural concepts were evaluated to identify least weight designs. Thermal analyses determined optimum tank arrangements and insulation materials. Meteoroid penetration experiments provided data for design of protection systems. Preliminary designs were made and compared on the basis of payload capability. Thermal performance tests demonstrated heat transfer rates typical for the selected design. Meteoroid impact tests verified the protection characteristics. A mockup was made to demonstrate protection system installation. The best design found combined multilayer insulation with a truss structure vehicle body. The multilayer served as the thermal/meteoroid protection system.

Fabrication of Multilayer-Type Mn-Si Thermoelectric Device

NASA Astrophysics Data System (ADS)

Kajitani, T.; Ueno, T.; Miyazaki, Y.; Hayashi, K.; Fujiwara, T.; Ihara, R.; Nakamura, T.; Takakura, M.

2014-06-01

This research aims to develop a direct-contact manganese silicon p/ n multilayer-type thermoelectric power generation block. p-type MnSi1.74 and n-type Mn0.7Fe0.3Si1.68 ball-milled powders with diameter of about 10 μm or less were mixed with polyvinyl butyl alcohol diluted with methylbenzene at pigment volume concentration of approximately 70%. The doctor-blade method produced 45- μm-thick p- and n-type pigment plates. The insulator, i.e., powdered glass, was mixed with cellulose to form insulator slurry. Lamination of manganese silicide pigment layers and screen-printed insulator layers was carried out to fabricate multilayer direct-contact thermoelectric devices. Hot pressing and spark plasma sintering were carried out at 450°C and 900°C, respectively. Four to 30 thermoelectric (TE) p/ n pairs were fabricated in a 10 mm × 10 mm × 10 mm sintered TE block. The maximum output was 11.7 mW/cm2 at a temperature difference between 20°C and 700°C, which was about 1/85 of the ideal power generation estimated from the thermoelectric data of the bulk MnSi1.74 and Mn0.7Fe0.3Si1.68 materials. A power generation test using an engine test bench was also carried out.

Large-Scale Liquid Hydrogen Testing of Variable Density Multilayer Insulation with a Foam Substrate

NASA Technical Reports Server (NTRS)

Martin, J. J.; Hastings, L.

2001-01-01

The multipurpose hydrogen test bed (MHTB), with an 18-cu m liquid hydrogen tank, was used to evaluate a combination foam/multilayer combination insulation (MLI) concept. The foam element (Isofoam SS-1171) insulates during ground hold/ascent flight, and allowed a dry nitrogen purge as opposed to the more complex/heavy helium purge subsystem normally required. The 45-layer MLI was designed for an on-orbit storage period of 45 days. Unique WI features include a variable layer density, larger but fewer double-aluminized Mylar perforations for ascent to orbit venting, and a commercially established roll-wrap installation process that reduced assembly man-hours and resulted in a roust, virtually seamless MLI. Insulation performance was measured during three test series. The spray-on foam insulation (SOFI) successfully prevented purge gas liquefaction within the MLI and resulted in the expected ground hold heat leak of 63 W/sq m. The orbit hold tests resulted in heat leaks of 0.085 and 0.22 W/sq m with warm boundary temperatures of 164 and 305 K, respectively. Compared to the best previously measured performance with a traditional MLI system, a 41-percent heat leak reduction with 25 fewer MLI layers was achieved. The MHTB MLI heat leak is half that calculated for a constant layer density MLI.

Fully Solution-Processable Fabrication of Multi-Layered Circuits on a Flexible Substrate Using Laser Processing

PubMed Central

Ji, Seok Young; Choi, Wonsuk; Jeon, Jin-Woo; Chang, Won Seok

2018-01-01

The development of printing technologies has enabled the realization of electric circuit fabrication on a flexible substrate. However, the current technique remains restricted to single-layer patterning. In this paper, we demonstrate a fully solution-processable patterning approach for multi-layer circuits using a combined method of laser sintering and ablation. Selective laser sintering of silver (Ag) nanoparticle-based ink is applied to make conductive patterns on a heat-sensitive substrate and insulating layer. The laser beam path and irradiation fluence are controlled to create circuit patterns for flexible electronics. Microvia drilling using femtosecond laser through the polyvinylphenol-film insulating layer by laser ablation, as well as sequential coating of Ag ink and laser sintering, achieves an interlayer interconnection between multi-layer circuits. The dimension of microvia is determined by a sophisticated adjustment of the laser focal position and intensity. Based on these methods, a flexible electronic circuit with chip-size-package light-emitting diodes was successfully fabricated and demonstrated to have functional operations. PMID:29425144

Effective Thermal Conductivity of High Temperature Insulations for Reusable Launch Vehicles

NASA Technical Reports Server (NTRS)

Daryabeigi, Kamran

1999-01-01

An experimental apparatus was designed to measure the effective thermal conductivity of various high temperature insulations subject to large temperature gradients representative of typical launch vehicle re-entry aerodynamic heating conditions. The insulation sample cold side was maintained around room temperature, while the hot side was heated to temperatures as high as 1800 degrees Fahrenheit. The environmental pressure was varied from 0.0001 to 760 torr. All the measurements were performed in a dry gaseous nitrogen environment. The effective thermal conductivity of Saffil, Q-Fiber felt, Cerachrome, and three multi-layer insulation configurations were measured.

Variable Density Multilayer Insulation for Cryogenic Storage

NASA Technical Reports Server (NTRS)

Hedayat, A.; Brown, T. M.; Hastings, L. J.; Martin, J.

2000-01-01

Two analytical models for a foam/Variable Density Multi-Layer Insulation (VD-MLI) system performance are discussed. Both models are one-dimensional and contain three heat transfer mechanisms, namely conduction through the spacer material, radiation between the shields, and conduction through the gas. One model is based on the methodology developed by McIntosh while the other model is based on the Lockheed semi-empirical approach. All models input variables are based on the Multi-purpose Hydrogen Test Bed (MHTB) geometry and available values for material properties and empirical solid conduction coefficient. Heat flux predictions are in good agreement with the MHTB data, The heat flux predictions are presented for the foam/MLI combinations with 30, 45, 60, and 75 MLI layers

Survey and evaluation of multilayer insulation heat transfer measurements

NASA Astrophysics Data System (ADS)

Doenecke, Jochen

About 40 papers treating multilayer insulations were studied and compared. Most of these papers present heat transfer measurements in addition to thermal analysis. Here the equations are given which are required for an evaluation of the measurements and in particular for comparisons. Equations are presented which are required to predict the influences of the packing density, temperatures, fraction of perforation area and interstitial pressure. The equation giving gas conductivity versus pressure is modified according to measurements. In space the interstitial pressure is usually below 0.01 Pa and the heat transfer can be expressed as the sum of a conductive and radiative term. The equation finally proposed for spacecraft permits to consider the influence of temperature, number of layers, blanket size and perforation area.

Multilayered metal-insulator nanocavities: toward tunable multi-resonance nano-devices for integrated optics

NASA Astrophysics Data System (ADS)

Song, Junyeob; Zhou, Wei

2017-02-01

Plasmonic nanocavities can control light flows and enhance light-mater interactions at subwavelength scale, and thus can potentially be used as nanoscale components in integrated optics systems either for passive optical coupling, or for active optical modulation and emission. In this work, we investigated a new type of multilayered metal-insulator optical nanocavities that can support multiple localized plasmon resonances with ultra-small mode volumes. The total number of resonance peaks and their resonance wavelengths can be freely and accurately controlled by simple geometric design rules. Multi-resonance plasmonic nanocavities can serve as a nanoscale wavelength-multiplexed optical components in integrated optics systems, such as optical couplers, light emitters, nanolasers, optical sensors, and optical modulators.

Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

DOEpatents

Wrenn, Jr., George E.; Holcombe, Jr., Cressie E.

1988-01-01

A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

DOEpatents

Wrenn, G.E. Jr.; Holcombe, C.E. Jr.

1988-09-13

A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

Sunspot: A program to model the behavior of hypervelocity impact damaged multilayer insulation in the Sunspot thermal vacuum chamber of Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Rule, W. K.; Hayashida, K. B.

1992-01-01

The development of a computer program to predict the degradation of the insulating capabilities of the multilayer insulation (MLI) blanket of Space Station Freedom due to a hypervelocity impact with a space debris particle is described. A finite difference scheme is used for the calculations. The computer program was written in Microsoft BASIC. Also described is a test program that was undertaken to validate the numerical model. Twelve MLI specimens were impacted at hypervelocities with simulated debris particles using a light gas gun at Marshall Space Flight Center. The impact-damaged MLI specimens were then tested for insulating capability in the space environment of the Sunspot thermal vacuum chamber at MSFC. Two undamaged MLI specimens were also tested for comparison with the test results of the damaged specimens. The numerical model was found to adequately predict behavior of the MLI specimens in the Sunspot chamber. A parameter, called diameter ratio, was developed to relate the nominal MLI impact damage to the apparent (for thermal analysis purposes) impact damage based on the hypervelocity impact conditions of a specimen.

Venting and High Vacuum Performance of Low Density Multilayer Insulation

NASA Astrophysics Data System (ADS)

Riesco, M. E.; McLean, C. H.; Mills, G. L.; Buerger, S.; Meyer, M. L.

2010-04-01

The NASA Exploration Program is currently studying the use liquid oxygen, liquid methane and liquid hydrogen for propulsion in future spacecraft for Exploration of the Moon and Mars. This will require the efficient long term, on-orbit storage of these cryogenic propellants. Multilayer Insulation (MLI) will be critical to achieving the required thermal performance since it has much lower heat transfer than any other insulation when used in a vacuum. MLI with a low density (⩽10 layers/cm) has been shown in previous work to be the most mass efficient. The size and mass constraints of these propulsion systems will not allow a structural shell to be used to provide vacuum for the MLI during ground hold and launch. The baseline approach is to purge the MLI during ground hold with an inert gas which is then vented during launch ascent and on-orbit. This paper presents the results on experimental tests and modeling performed by Ball Aerospace on low density, non-perforated MLI used to insulate a cryogenic tank simulating an Exploration cryogenic propellant storage vessel. These include measurements of the rate of venting and of the heat transfer of gas filled insulation, fully evacuated insulation and during the transition in between. Results of transient computer modeling of the MLI venting and heat transfer process are also presented. Previous work by some of the authors performed vent testing using MLI with perforations and slits and a slow pump down rate.

Recent Ground Hold and Rapid Depressurization Testing of Multilayer Systems

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.

2014-01-01

In the development of flight insulation systems for large cryogenic orbital storage (spray on foam and multilayer insulation), testing need include all environments that are experienced during flight. While large efforts have been expended on studying, bounding, and modeling the orbital performance of the insulation systems, little effort has been expended on the ground hold and ascent phases of a mission. Historical cryogenic in-space systems that have flown have been able to ignore these phases of flight due to the insulation system being within a vacuum jacket. In the development phase of the Nuclear Mars Vehicle and the Shuttle Nuclear Vehicle, several insulation systems were evaluated for the full mission cycle. Since that time there had been minimal work on these phases of flight until the Constellation program began investigating cryogenic service modules and long duration upper stages. With the inception of the Cryogenic Propellant Storage and Transfer Technology Demonstration Mission, a specific need was seen for the data and as such, several tests were added to the Cryogenic Boil-off Reduction System liquid hydrogen test matrix to provide more data on a insulation system. Testing was attempted with both gaseous nitrogen (GN2) and gaseous helium (GHe) backfills. The initial tests with nitrogen backfill were not successfully completed due to nitrogen liquefaction and solidification preventing the rapid pumpdown of the vacuum chamber. Subsequent helium backfill tests were successful and showed minimal degradation. The results are compared to the historical data.

Multifunctional Hybrid Multilayer Gate Dielectrics with Tunable Surface Energy for Ultralow-Power Organic and Amorphous Oxide Thin-Film Transistors.

PubMed

Byun, Hye-Ran; You, Eun-Ah; Ha, Young-Geun

2017-03-01

For large-area, printable, and flexible electronic applications using advanced semiconductors, novel dielectric materials with excellent capacitance, insulating property, thermal stability, and mechanical flexibility need to be developed to achieve high-performance, ultralow-voltage operation of thin-film transistors (TFTs). In this work, we first report on the facile fabrication of multifunctional hybrid multilayer gate dielectrics with tunable surface energy via a low-temperature solution-process to produce ultralow-voltage organic and amorphous oxide TFTs. The hybrid multilayer dielectric materials are constructed by iteratively stacking bifunctional phosphonic acid-based self-assembled monolayers combined with ultrathin high-k oxide layers. The nanoscopic thickness-controllable hybrid dielectrics exhibit the superior capacitance (up to 970 nF/cm 2 ), insulating property (leakage current densities <10 -7 A/cm 2 ), and thermal stability (up to 300 °C) as well as smooth surfaces (root-mean-square roughness <0.35 nm). In addition, the surface energy of the hybrid multilayer dielectrics are easily changed by switching between mono- and bifunctional phosphonic acid-based self-assembled monolayers for compatible fabrication with both organic and amorphous oxide semiconductors. Consequently, the hybrid multilayer dielectrics integrated into TFTs reveal their excellent dielectric functions to achieve high-performance, ultralow-voltage operation (< ± 2 V) for both organic and amorphous oxide TFTs. Because of the easily tunable surface energy, the multifunctional hybrid multilayer dielectrics can also be adapted for various organic and inorganic semiconductors, and metal gates in other device configurations, thus allowing diverse advanced electronic applications including ultralow-power and large-area electronic devices.

Cryogenic Testing of Different Seam Concepts for Multilayer Insulation Systems

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.; Fesmire, J. E.

2009-01-01

Recent testing in a cylindrical, comparative cryostat at the Cryogenics Test Laboratory has focused on various seam concepts for multilayer insulation systems. Three main types of seams were investigated: straight overlap, fold-over, and roll wrapped. Each blanket was comprised of 40 layer pairs of reflector and spacer materials. The total thickness was approximately 12.5-mm, giving an average layer density of 32 layers per centimeter. The blankets were tested at high vacuum, soft vacuum, and no vacuum using liquid nitrogen to maintain the cold boundary temperature at 77 K. Test results show that all three seam concepts are all close in thermal performance; however the fold-over method provides the lowest heat flux. For the first series of tests, seams were located 120 degrees around the circumference of the cryostat from the previous seam. This technique appears to have lessened the degradation of the blanket due to the seams. In a follow-on test, a 20 layer blanket was tested in a roll wrapped configuration and then cut down the side of the cylinder, taped together, and re-tested. This test result shows the thermal performance impact of having the seams all in one location versus having the seams clocked around the vessel. This experimental investigation indicates that the method of joining the seams in multilayer insulation systems is not as critical as the quality of the installation process.

Multipurpose insulation system for a radioisotope fueled Mini-Brayton Heat Source Assembly

NASA Technical Reports Server (NTRS)

Aller, P.; Saylor, W.; Schmidt, G.; Wein, D.

1976-01-01

The Mini-Brayton Heat Source Assembly (HSA) consists of a radioisotope fueled heat source, a heat exchanger, a multifoil thermal insulation blanket, and a hermetically sealed housing. The thermal insulation blanket is a multilayer wrap of thin metal foil separated by a sparsely coated oxide. The objectives of the insulation blanket are related to the effective insulation of the HSA during operation, the transfer of the full thermal inventory to the housing when the primary coolant is not flowing, and the transfer of the full thermal inventory to the housing in the event of a flow stoppage of the primary coolant. A description is given of the approaches which have been developed to make it possible for the insulation blanket to meet these requirements.

Process for making ceramic insulation

DOEpatents

Akash, Akash [Salt Lake City, UT; Balakrishnan, G Nair [Sandy, UT

2009-12-08

A method is provided for producing insulation materials and insulation for high temperature applications using novel castable and powder-based ceramics. The ceramic components produced using the proposed process offers (i) a fine porosity (from nano-to micro scale); (ii) a superior strength-to-weight ratio; and (iii) flexibility in designing multilayered features offering multifunctionality which will increase the service lifetime of insulation and refractory components used in the solid oxide fuel cell, direct carbon fuel cell, furnace, metal melting, glass, chemical, paper/pulp, automobile, industrial heating, coal, and power generation industries. Further, the ceramic components made using this method may have net-shape and/or net-size advantages with minimum post machining requirements.

Investigation of high-performance insulation application problems

NASA Technical Reports Server (NTRS)

Fredrickson, G. O.

1973-01-01

The design, fabrication, and performance of a practical, flightworthy, multilayer insulation (MLI) system for a Modular Nuclear Vehicle (MNV) LH2 propellant tank is presented. An MLI system is now available. It may be applied to the MNV or any other space vehicle requiring MLI for thermal control. This design concept was adapted for an MLI installation that covered and was successfully flown on the Skylab forward dome.

Multilayer Impregnated Fibrous Thermal Insulation Tiles

NASA Technical Reports Server (NTRS)

Tran, Huy K.; Rasky, Daniel J.; Szalai, Christine e.; Hsu, Ming-ta; Carroll, Joseph A.

2007-01-01

The term "secondary polymer layered impregnated tile" ("SPLIT") denotes a type of ablative composite-material thermal- insulation tiles having engineered, spatially non-uniform compositions. The term "secondary" refers to the fact that each tile contains at least two polymer layers wherein endothermic reactions absorb considerable amounts of heat, thereby helping to prevent overheating of an underlying structure. These tiles were invented to afford lighter-weight alternatives to the reusable thermal-insulation materials heretofore variously used or considered for use in protecting the space shuttles and other spacecraft from intense atmospheric-entry heating.

Cylindrical cryogenic calorimeter testing of six types of multilayer insulation systems

NASA Astrophysics Data System (ADS)

Fesmire, J. E.; Johnson, W. L.

2018-01-01

Extensive cryogenic thermal testing of more than 100 different multilayer insulation (MLI) specimens was performed over the last 20 years for the research and development of evacuated reflective thermal insulation systems. From this data library, 26 MLI systems plus several vacuum-only systems are selected for analysis and comparison. The test apparatus, methods, and results enabled the adoption of two new technical consensus standards under ASTM International. Materials tested include reflectors of aluminum foil or double-aluminized Mylar and spacers of fiberglass paper, polyester netting, silk netting, polyester fabric, or discrete polymer standoffs. The six types of MLI systems tested are listed as follows: Mylar/Paper, Foil/Paper, Mylar/Net, Mylar/Blanket, Mylar/Fabric, Mylar/Discrete. Also tested are vacuum-only systems with different cold surface materials/finishes including stainless steel, black, copper, and aluminum. Testing was performed between the boundary temperatures of 78 K and 293 K (and up to 350 K) using a thermally guarded one-meter-long cylindrical calorimeter (Cryostat-100) for absolute heat flow measurement. Cold vacuum pressures include the full range from 1 × 10-6 torr to 760 torr with nitrogen as the residual gas. System variations include number of layers from one to 80 layers, layer densities from 0.5 to 5 layers per millimeter, and installation techniques such layer-by-layer, blankets (multi-layer assemblies), sub-blankets, seaming, butt-joining, spiral wrapping, and roll-wrapping. Experimental thermal performance data for the different MLI systems are presented in terms of heat flux and effective thermal conductivity. Benchmark cryogenic-vacuum thermal performance curves for MLI are given for comparison with different insulation approaches for storage and transfer equipment, cryostats, launch vehicles, spacecraft, or science instruments.

Formation of multiple levels of porous silicon for buried insulators and conductors in silicon device technologies

DOEpatents

Blewer, Robert S.; Gullinger, Terry R.; Kelly, Michael J.; Tsao, Sylvia S.

1991-01-01

A method of forming a multiple level porous silicon substrate for semiconductor integrated circuits including anodizing non-porous silicon layers of a multi-layer silicon substrate to form multiple levels of porous silicon. At least one porous silicon layer is then oxidized to form an insulating layer and at least one other layer of porous silicon beneath the insulating layer is metallized to form a buried conductive layer. Preferably the insulating layer and conductive layer are separated by an anodization barrier formed of non-porous silicon. By etching through the anodization barrier and subsequently forming a metallized conductive layer, a fully or partially insulated buried conductor may be fabricated under single crystal silicon.

Stronger multilayer acrylic dielectric elastomer actuators with silicone gel coatings

NASA Astrophysics Data System (ADS)

Lau, Gih-Keong; La, Thanh-Giang; Sheng-Wei Foong, Ervin; Shrestha, Milan

2016-12-01

Multilayer dielectric elastomer actuators (DEA) perform worst off than single-layer DEAs due to higher susceptibility to electro-thermal breakdown. This paper presents a hot-spot model to predict the electro-thermal breakdown field of DEAs and its dependence on thermal insulation. To inhibit the electrothermal breakdown, silicone gel coating was applied as barrier coating to multilayer acrylic DEA. The gel coating helps suppress the electro-thermally induced puncturing of DEA membrane at the hot spot. As a result, the gel-coated DEAs, in either a single layer or a multilayer stack, can produce 30% more isometric stress change as compared to those none-coated. These gel-coated acrylic DEAs show great potential to make stronger artificial muscles.

Insulation Progress since the Mid-1950s

NASA Astrophysics Data System (ADS)

Timmerhaus, K. D.

Storage vessel and cryostat design for modern cryogenic systems has become rather routine as the result of the wide use of and application of cryogenic fluids. Such vessels for these fluids range in size from 1 L flasks used in the laboratory for liquid nitrogen to the more than 200,000 m3 double-walled tanks used for temporary storage of liquefied natural gas before being transported overseas to their final destination. These storage vessels for cryogenic fluids range in type from low-performance containers insulated with rigid foam or fibrous insulation to high-performance containers insulated with evacuated multilayer insulations. The overriding factors in the type of container selected normally are of economics and safety. This paper will consider various insulation concepts used in such cryogenic storage systems and will review the progress that has been made over the past 50 years in these insulation systems.

Advanced Space Suit Insulation Feasibility Study

NASA Technical Reports Server (NTRS)

Trevino, Luis A.; Orndoff, Evelyne S.

2000-01-01

For planetary applications, the space suit insulation has unique requirements because it must perform in a dynamic mode to protect humans in the harsh dust, pressure and temperature environments. Since the presence of a gaseous planetary atmosphere adds significant thermal conductance to the suit insulation, the current multi-layer flexible insulation designed for vacuum applications is not suitable in reduced pressure planetary environments such as that of Mars. Therefore a feasibility study has been conducted at NASA to identify the most promising insulation concepts that can be developed to provide an acceptable suit insulation. Insulation concepts surveyed include foams, microspheres, microfibers, and vacuum jackets. The feasibility study includes a literature survey of potential concepts, an evaluation of test results for initial insulation concepts, and a development philosophy to be pursued as a result of the initial testing and conceptual surveys. The recommended focus is on microfibers due to the versatility of fiber structure configurations, the wide choice of fiber materials available, the maturity of the fiber processing industry, and past experience with fibers in insulation applications

Gas filled panel insulation

DOEpatents

Griffith, Brent T.; Arasteh, Dariush K.; Selkowitz, Stephen E.

1993-01-01

A structural or flexible highly insulative panel which may be translucent, is formed from multi-layer polymeric material in the form of an envelope surrounding a baffle. The baffle is designed so as to minimize heat transfer across the panel, by using material which forms substantially closed spaces to suppress convection of the low conductivity gas fill. At least a portion of the baffle carries a low emissivity surface for suppression of infrared radiation.

Thin-Film Power Transformers

NASA Technical Reports Server (NTRS)

Katti, Romney R.

1995-01-01

Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

Purging of a tank-mounted multilayer insulation system by gas diffusion

NASA Technical Reports Server (NTRS)

Sumner, I. E.

1978-01-01

The investigation was conducted on a multilayer insulation (MLI) system mounted on a spherical liquid hydrogen propellant tank. The MLI consisted of two blankets of insulation each containing 15 double-aluminized Mylar radiation shields separated by double silk net spacers. The gaseous nitrogen initially contained within the MLI system and vacuum chamber was purged with gaseous helium introduced both underneath the MLI and into the vacuum chamber. The MLI panels were assumed to be purged primarily by means of gas diffusion. Overall, test results indicated that nitrogen concentrations well below 1 percent could be achieved everywhere within the MLI system. Typical times to achieve 1 percent nitrogen concentration within the MLI panels ranged from 69 minutes at the top of the tank to 158 minutes at the bottom of the tank. Four space-hold thermal performance tests indicated no significant thermal degradation of the MLI system had occurred due to the purge tests conducted. The final measured heat input attributed to the MLI was 7.23 watts as compared to 7.18 watts for the initial baseline thermal performance test.

Investigation of Insulation Materials for Future Radioisotope Power Systems (RPS)

NASA Technical Reports Server (NTRS)

Cornell, Peggy A.; Hurwitz, Frances I.; Ellis, David L.; Schmitz, Paul C.

2013-01-01

NASA's Radioisotope Power System (RPS) Technology Advancement Project is developing next generation high temperature insulation materials that directly benefit thermal management and improve performance of RPS for future science missions. Preliminary studies on the use of multilayer insulation (MLI) for Stirling convertors used on the Advanced Stirling Radioisotope Generator (ASRG) have shown the potential benefits of MLI for space vacuum applications in reducing generator size and increasing specific power (W/kg) as compared to the baseline Microtherm HT (Microtherm, Inc.) insulation. Further studies are currently being conducted at NASA Glenn Research Center (GRC) on candidate MLI foils and aerogel composite spacers. This paper presents the method of testing of foils and spacers and experimental results to date.

Investigation of Insulation Materials for Future Radioisotope Power Systems

NASA Technical Reports Server (NTRS)

Cornell, Peggy A.; Hurwitz, Frances I.; Ellis, David L.; Schmitz, Paul C.

2013-01-01

NASA's Radioisotope Power Systems (RPS) Technology Advancement Project is developing next generation high-temperature insulation materials that directly benefit thermal management and improve performance of RPS for future science missions. Preliminary studies on the use of multilayer insulation (MLI) for Stirling convertors used on the Advanced Stirling Radioisotope Generator (ASRG) have shown the potential benefits of MLI for space vacuum applications in reducing generator size and increasing specific power (W/kg) as compared to the baseline Microtherm HT (Microtherm, Inc.) insulation. Further studies are currently being conducted at NASA Glenn Research Center on candidate MLI foils and aerogel composite spacers. This paper presents the method of testing of foils and spacers and experimental results to date.

Demonstration of Microsphere Insulation in Cryogenic Vessels

NASA Astrophysics Data System (ADS)

Baumgartner, R. G.; Myers, E. A.; Fesmire, J. E.; Morris, D. L.; Sokalski, E. R.

2006-04-01

While microspheres have been recognized as a legitimate insulation material for decades, actual use in full-scale cryogenic storage tanks has not been demonstrated until now. The performance and life-cycle-cost advantages previously predicted have now been proven. Most bulk cryogenic storage tanks are insulated with either multilayer insulation (MLI) or perlite. Microsphere insulation, consisting of hollow glass bubbles, combines in a single material the desirable properties that other insulations only have individually. The material has high crush strength, low density, is noncombustible, and performs well in soft vacuum. These properties were proven during recent field testing of two 22,700-L (6,000-gallon) liquid nitrogen tanks, one insulated with microsphere insulation and the other with perlite. Normal evaporation rates (NER) for both tanks were monitored with precision test equipment and insulation levels within the tanks were observed through view ports as an indication of insulation compaction. Specific industrial applications were evaluated based on the test results and beneficial properties of microsphere insulation. Over-the-road trailers previously insulated with perlite will benefit not only from the reduced heat leak, but also the reduced mass of microsphere insulation. Economic assessments for microsphere-insulated cryogenic vessels including life-cycle cost are also presented.

Theoretical analysis of sound transmission loss through graphene sheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Natsuki, Toshiaki, E-mail: natsuki@shinshu-u.ac.jp; Institute of Carbon Science and Technology, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553; Ni, Qing-Qing

2014-11-17

We examine the potential of using graphene sheets (GSs) as sound insulating materials that can be used for nano-devices because of their small size, super electronic, and mechanical properties. In this study, a theoretical analysis is proposed to predict the sound transmission loss through multi-layered GSs, which are formed by stacks of GS and bound together by van der Waals (vdW) forces between individual layers. The result shows that the resonant frequencies of the sound transmission loss occur in the multi-layered GSs and the values are very high. Based on the present analytical solution, we predict the acoustic insulation propertymore » for various layers of sheets under both normal incident wave and acoustic field of random incidence source. The scheme could be useful in vibration absorption application of nano devices and materials.« less

Insulation Resistance Degradation in Ni-BaTiO3 Multilayer Ceramic Capacitors

NASA Technical Reports Server (NTRS)

Liu, Donhang (David)

2015-01-01

Insulation resistance (IR) degradation in Ni-BaTiO3 multilayer ceramic capacitors has been characterized by the measurement of both time to failure and direct-current (DC) leakage current as a function of stress time under highly accelerated life test conditions. The measured leakage current-time dependence data fit well to an exponential form, and a characteristic growth time ?SD can be determined. A greater value of tau(sub SD) represents a slower IR degradation process. Oxygen vacancy migration and localization at the grain boundary region results in the reduction of the Schottky barrier height and has been found to be the main reason for IR degradation in Ni-BaTiO3 capacitors. The reduction of barrier height as a function of time follows an exponential relation of phi (??)=phi (0)e(exp -2?t), where the degradation rate constant ??=??o??(????/????) is inversely proportional to the mean time to failure (MTTF) and can be determined using an Arrhenius plot. For oxygen vacancy electromigration, a lower barrier height phi(0) will favor a slow IR degradation process, but a lower phi(0) will also promote electronic carrier conduction across the barrier and decrease the insulation resistance. As a result, a moderate barrier height phi(0) (and therefore a moderate IR value) with a longer MTTF (smaller degradation rate constant ??) will result in a minimized IR degradation process and the most improved reliability in Ni-BaTiO3 multilayer ceramic capacitors.

Measurements of the apparent thermal conductivity of multi-layer insulation between 20 K and 90 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurd, Joseph A.; Van Sciver, Steven W.

NASA has the need to efficiently store cryogenic propellants in space for long periods of time. One method to improve storage efficiency is to use multi-layer insulation (MLI), a technique that minimizes the boiling rate due to radiation heat transfer. Typically, the thermal performance of MLI is determined by measuring the rate of evaporation of liquid nitrogen from a calibrated cryostat. The main limitation with this method is that testing conditions are restricted by the boiling temperature of the LN{sub 2}, which may not match the requirements of the application. The Multi-Layer Insulation Thermal Conductivity Experiment (MIKE) at the Nationalmore » High Magnetic Field Laboratory is capable of measuring the effective thermal conductivity of MLI at variable boundary temperatures. MIKE uses cryo-refrigerators to control boundary temperatures in the calorimeter and a calibrated thermal link to measure the heat load. To make the measurements requested by NASA, MIKE needed to be recalibrated for the 20 K to 90 K range. Also, due to the expectation of a lower heat transfer rate, the heat load support rod material was changed to one with a lower thermal conductivity to ensure the temperature difference seen on the cold rod could be measurable at the estimated heat load. Presented are the alterations to MIKE including calibration data and heat load measurements on new load-bearing MLI supplied by NASA.« less

Novel load responsive multilayer insulation with high in-atmosphere and on-orbit thermal performance

NASA Astrophysics Data System (ADS)

Dye, S.; Kopelove, A.; Mills, G. L.

2012-04-01

Aerospace cryogenic systems require lightweight, high performance thermal insulation to preserve cryopropellants both pre-launch and on-orbit. Current technologies have difficulty meeting all requirements, and advances in insulation would benefit cryogenic upper stage launch vehicles, LH2 fueled aircraft and ground vehicles, and provide capabilities for sub-cooled cryogens for space-borne instruments and orbital fuel depots. This paper reports the further development of load responsive multilayer insulation (LRMLI) that has a lightweight integrated vacuum shell and provides high thermal performance both in-air and on-orbit. LRMLI is being developed by Quest Product Development and Ball Aerospace under NASA contract, with prototypes designed, built, installed and successfully tested. A 3-layer LRMLI blanket (0.63 cm thick, 77 K cold, 295 K hot) had a measured heat leak of 6.6 W/m2 in vacuum and 40.6 W/m2 in air at one atmosphere. In-air LRMLI has an 18× advantage over Spray On Foam Insulation (SOFI) in heat leak per thickness and a 16× advantage over aerogel. On-orbit LRMLI has a 78× lower heat leak than SOFI per thickness and 6× lower heat leak than aerogel. The Phase II development of LRMLI is reported with a modular, flexible, thin vacuum shell and improved on-orbit performance. Structural and thermal analysis and testing results are presented. LRMLI mass and thermal performance is compared to SOFI, aerogel and MLI over SOFI.

Cryogenic Vacuum Insulation for Vessels and Piping

NASA Technical Reports Server (NTRS)

Kogan, A.; Fesmire, J.; Johnson, W.; Minnick, J.

2010-01-01

Cryogenic vacuum insulation systems, with proper materials selection and execution, can offer the highest levels of thermal performance. Three areas of consideration are vital to achieve the optimum result: materials, representative test conditions, and engineering approach for the particular application. Deficiency in one of these three areas can prevent optimum performance and lead to severe inefficiency. Materials of interest include micro-fiberglass, multilayer insulation, and composite arrangements. Cylindrical liquid nitrogen boil-off calorimetry methods were used. The need for standard thermal conductivity data is addressed through baseline testing. Engineering analysis and design factors such as layer thickness, density, and practicality are also considered.

Environmental durability diagnostic for printed identification codes of polymer insulation for distribution pipelines

NASA Astrophysics Data System (ADS)

Zhuravleva, G. N.; Nagornova, I. V.; Kondratov, A. P.; Bablyuk, E. B.; Varepo, L. G.

2017-08-01

A research and modelling of weatherability and environmental durability of multilayer polymer insulation of both cable and pipelines with printed barcodes or color identification information were performed. It was proved that interlayer printing of identification codes in distribution pipelines insulation coatings provides high marking stability to light and atmospheric condensation. This allows to carry out their distant damage control. However, microbiological fouling of upper polymer layer hampers the distant damage pipelines identification. The color difference values and density changes of PE and PVC printed insolation due to weather and biological factors were defined.

NbTiN Based SIS Multilayer Structures for SRF Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valente, Anne-marie; Eremeev, Grigory; Phillips, H

2013-09-01

For the past three decades, bulk niobium has been the material of choice for SRF cavities applications. RF cavity performance is now approaching the theoretical limit for bulk niobium. For further improvement of RF cavity performance for future accelerator projects, Superconductor Insulator - Superconductor (SIS) multilayer structures (as recently proposed by Alex Gurevich) present the theoretical prospect to reach RF performance beyond bulk Nb, using thinly layered higher-Tc superconductors with enhanced Hc1. Jefferson Lab (JLab) is pursuing this approach with the development of NbTiN and AlN based multilayer SIS structures. This paper presents the results on the characteristics of NbTiNmore » films and the first RF measurements on NbTiN-based multilayer structure on thick Nb films.« less

Proximity effects across oxide-interfaces of superconductor-insulator-ferromagnet hybrid heterostructure.

PubMed

Prajapat, C L; Singh, Surendra; Bhattacharya, D; Ravikumar, G; Basu, S; Mattauch, S; Zheng, Jian-Guo; Aoki, T; Paul, Amitesh

2018-02-27

A case study of electron tunneling or charge-transfer-driven orbital ordering in superconductor (SC)-ferromagnet (FM) interfaces has been conducted in heteroepitaxial YBa 2 Cu 3 O 7 (YBCO)/La 0.67 Sr 0.33 MnO 3 (LSMO) multilayers interleaved with and without an insulating SrTiO 3 (STO) layer between YBCO and LSMO. X-ray magnetic circular dichroism experiments revealed anti-parallel alignment of Mn magnetic moments and induced Cu magnetic moments in a YBCO/LSMO multilayer. As compared to an isolated LSMO layer, the YBCO/LSMO multilayer displayed a (50%) weaker Mn magnetic signal, which is related to the usual proximity effect. It was a surprise that a similar proximity effect was also observed in a YBCO/STO/LSMO multilayer, however, the Mn signal was reduced by 20%. This reduced magnetic moment of Mn was further verified by depth sensitive polarized neutron reflectivity. Electron energy loss spectroscopy experiment showed the evidence of Ti magnetic polarization at the interfaces of the YBCO/STO/LSMO multilayer. This crossover magnetization is due to a transfer of interface electrons that migrate from Ti (4+)-δ to Mn at the STO/LSMO interface and to Cu 2+ at the STO/YBCO interface, with hybridization via O 2p orbitals. So charge-transfer driven orbital ordering is the mechanism responsible for the observed proximity effect and Mn-Cu anti-parallel coupling in YBCO/STO/LSMO. This work provides an effective pathway in understanding the aspect of long range proximity effect and consequent orbital degeneracy parameter in magnetic coupling.

Gas filled panel insulation

DOEpatents

Griffith, B.T.; Arasteh, D.K.; Selkowitz, S.E.

1993-12-14

A structural or flexible highly insulative panel which may be translucent, is formed from multi-layer polymeric material in the form of an envelope surrounding a baffle. The baffle is designed so as to minimize heat transfer across the panel, by using material which forms substantially closed spaces to suppress convection of the low conductivity gas fill. At least a portion of the baffle carries a low emissivity surface for suppression of infrared radiation. 18 figures.

Comparison of thermal insulation performance of fibrous materials for the advanced space suit.

PubMed

Paul, Heather L; Diller, Kenneth R

2003-10-01

The current multi-layer insulation used in the extravehicular mobility unit (EMU) will not be effective in the atmosphere of Mars due to the presence of interstitial gases. Alternative thermal insulation means have been subjected to preliminary evaluation by NASA to attempt to identify a material that will meet the target conductivity of 0.005 W/m-K. This study analyzes numerically the thermal conductivity performance for three of these candidate insulating fiber materials in terms of various denier (size), interstitial void fractions, interstitial void media, and orientations to the applied temperature gradient to evaluate their applicability for the new Mars suit insulation. The results demonstrate that the best conductive insulation is achieved for a high-void-fraction configuration with a grooved fiber cross section, aerogel void medium, and the fibers oriented normal to the heat flux vector. However, this configuration still exceeds the target thermal conductivity by a factor of 1.5.

High-temperature properties of ceramic fibers and insulations for thermal protection of atmospheric entry and hypersonic cruise vehicles

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A.; Pitts, William C.; Araujo, Myrian; Zimmerman, R. S.

1988-01-01

Multilayer insulations (MIs) which will operate in the 500 to 1000 C temperature range are being considered for possible applications on aerospace vehicles subject to convective and radiative heating during atmospheric entry. The insulations described consist of ceramic fibers, insulations, and metal foils quilted together with ceramic thread. As these types of insulations have highly anisotropic properties, the total heat transfer characteristics must be determined. Data are presented on the thermal diffusivity and thermal conductivity of four types of MIs and are compared to the baseline Advanced Flexible Reusable Surface Insulation currently used on the Space Shuttle Orbiter. In addition, the high temperature properties of the fibers used in these MIs are discussed. The fibers investigated included silica and three types of aluminoborosilicate (ABS). Static tension tests were performed at temperatures up to 1200 C and the ultimate strain, tensile strength, and tensile modulus of single fibers were determined.

High temperature properties of ceramic fibers and insulations for thermal protection of atmospheric entry and hypersonic cruise vehicles

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A.; Pitts, William C.; Araujo, Myrian; Zimmerman, R. S.

1988-01-01

Multilayer insulations (MIs) which will operate in the 500 to 1000 C temperature range are being considered for possible applications on aerospace vehicles subject to convective and radiative heating during atmospheric entry. The insulations described consist of ceramic fibers, insulations, and metal foils quilted together with ceramic thread. As these types of insulations have highly anisotropic properties, the total heat transfer characteristics must be determined. Data are presented on the thermal diffusivity and thermal conductivity of four types of MIs and are compared to the baseline Advanced Flexible Reusable Surface Insulation currently used on the Space Shuttle Orbiter. In addition, the high temperature properties of the fibers used in these MIs are discussed. The fibers investigated included silica and three types of aluminoborosilicate (ABS). Static tension tests were performed at temperatures up to 1200 C and the ultimate strain, tensile strength, and tensile modulus of single fibers were determined.

Curiosity Heat Shield in Detail

NASA Image and Video Library

2012-08-08

This color full-resolution image showing the heat shield of NASA Curiosity rover was obtained during descent to the surface of Mars. This image shows the inside surface of the heat shield, with its protective multi-layered insulation.

Cryogenic Boil-Off Reduction System Testing

NASA Technical Reports Server (NTRS)

Plachta, David W.; Johnson, Wesley L.; Feller, Jeffrey R.

2014-01-01

Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) are a part of NASA's future space exploration due to the high specific impulse that can be achieved using engines suitable for moving 10's to 100's of metric tons of payload mass to destinations outside of low earth orbit. However, the low storage temperatures of LH2 and LO2 cause substantial boil-off losses for missions with durations greater than several days. The losses can be greatly reduced by incorporating high performance cryocooler technology to intercept heat load to the propellant tanks and by the integration of self-supporting multi-layer insulation. The active thermal control technology under development is the integration of the reverse turbo- Brayton cycle cryocooler to the propellant tank through a distributed cooling network of tubes coupled to a shield in the tank insulation and to the tank wall itself. Also, the self-supporting insulation technology was utilized under the shield to obtain needed tank applied LH2 performance. These elements were recently tested at NASA Glenn Research Center in a series of three tests, two that reduced LH2 boil-off and one to eliminate LO2 boil-off. This test series was conducted in a vacuum chamber that replicated the vacuum of space and the temperatures of low Earth orbit. The test results show that LH2 boil-off was reduced 60% by the cryocooler system operating at 90K and that robust LO2 zero boil-off storage, including full tank pressure control was achieved.

Basic performance of a multilayer insulation system containing 20 to 160 layers. [thermal effectiveness of aluminized Mylar-silk net system

NASA Technical Reports Server (NTRS)

Stochl, R. J.

1974-01-01

An experimental investigation was conducted to determine the thermal effectiveness of an aluminized Mylar-silk net insulation system containing up to 160 layers. The experimentally measured heat flux was compared with results predicted by using (1) a previously developed semi-empirical equation and (2) an effective-thermal-conductivity value. All tests were conducted at a nominal hot-boundary temperature of 294 K (530 R) with liquid hydrogen as the heat sink. The experimental results show that the insulation performed as expected and that both the semi-empirical equation and effective thermal conductivity of a small number of layers were adequate in predicting the thermal performance of a large number of layers of insulation.

Transmissivity testing of multilayer insulation at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Van Dresar, N. T.; Chato, D. J.; Demers, J. R.

2017-09-01

The problem of degraded emissivity of thin films at low temperatures has been a long observed phenomena. Previous efforts at measuring properties have suggested that transmission of energy through the films may play a key role in the thermal performance of multilayer insulation systems at low temperatures. Similarly, recent testing on tank applied systems has suggested a radiative degradation at low temperatures. Two different approaches were used to attempt to measure the transmission of energy through MLI at low temperatures. A laser based measurement system was set up to directly measure transmittance and a calorimetric based measurement system was used to measure relative emittance of a single layer between aluminum foil and double aluminized Mylar. Minimal transmission at long wavelengths were observed through standard MLI blanket materials at deposition thicknesses of even 35 nm. Where transmission was measured, it was too low to effect the performance of a multilayers system. Similarly, the calorimeter showed similar increases of emissivity for both standard blanket materials and aluminum foils. Multiple different methodologies of measurement have all yielded the same result: that there is no transmission through standard MLI blanket materials at wavelengths associated with temperatures as low as 2 K.

Tunnel Magneto Resistance of Fe/Insulator/Fe

NASA Astrophysics Data System (ADS)

Aryee, Dennis; Seifu, Dereje

Tri-layer thin films of Fe/Insulator/Fe were synthesized using magnetron DC/ RF sputtering with MgO insulator and Bi2Te3 topological insulators as middle buffer layer. The multi-layered samples thus produced were studied using in-house built magneto-optic Kerr effect (MOKE) instrument, vibrating sample magnetometer (VSM), torque magnetometer (TMM), AFM, MFM, and magneto-resistance (MR). This system, that is Fe/Insulator/Fe on MgO(100) substrate, is a well-known tunnel magneto resistance (TMR) structure often used in magnetic tunnel junction (MTJ) devices. TMR effect is a method by which MTJs are used in developing magneto-resistive random access memory (MRAM), magnetic sensors, and novel logic devices. The main purpose behind this research is to measure the magnetic anisotropy of Fe/Insulator /Fe structure and correlate it to magneto-resistance. In this presentation, we will present results from MOKE, VSM, TMM, AFM, MFM, and MR studies of Fe/Insulator/Fe on MgO(100). We would like to acknowledge support by NSF-MRI-DMR-1337339.

Dielectrophoretic trapping of multilayer DNA origami nanostructures and DNA origami-induced local destruction of silicon dioxide.

PubMed

Shen, Boxuan; Linko, Veikko; Dietz, Hendrik; Toppari, J Jussi

2015-01-01

DNA origami is a widely used method for fabrication of custom-shaped nanostructures. However, to utilize such structures, one needs to controllably position them on nanoscale. Here we demonstrate how different types of 3D scaffolded multilayer origamis can be accurately anchored to lithographically fabricated nanoelectrodes on a silicon dioxide substrate by DEP. Straight brick-like origami structures, constructed both in square (SQL) and honeycomb lattices, as well as curved "C"-shaped and angular "L"-shaped origamis were trapped with nanoscale precision and single-structure accuracy. We show that the positioning and immobilization of all these structures can be realized with or without thiol-linkers. In general, structural deformations of the origami during the DEP trapping are highly dependent on the shape and the construction of the structure. The SQL brick turned out to be the most robust structure under the high DEP forces, and accordingly, its single-structure trapping yield was also highest. In addition, the electrical conductivity of single immobilized plain brick-like structures was characterized. The electrical measurements revealed that the conductivity is negligible (insulating behavior). However, we observed that the trapping process of the SQL brick equipped with thiol-linkers tended to induce an etched "nanocanyon" in the silicon dioxide substrate. The nanocanyon was formed exactly between the electrodes, that is, at the location of the DEP-trapped origami. The results show that the demonstrated DEP-trapping technique can be readily exploited in assembling and arranging complex multilayered origami geometries. In addition, DNA origamis could be utilized in DEP-assisted deformation of the substrates onto which they are attached. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SmNiO3/NdNiO3 thin film multilayers

NASA Astrophysics Data System (ADS)

Girardot, C.; Pignard, S.; Weiss, F.; Kreisel, J.

2011-06-01

Rare earth nickelates RENiO3 (RE =rare earth), which attract interest due to their sharp metal-insulator phase transition, are instable in bulk form due to the necessity of an important oxygen pressure to stabilize Ni in its 3+ state of oxidation. Here, we report the stabilization of RE nickelates in [(SmNiO3)t/(NdNiO3)t]n thin film multilayers, t being the thickness of layers alternated n times. Both bilayers and multilayers have been deposited by metal-organic chemical vapor deposition. The multilayer structure and the presence of the metastable phases SmNiO3 and NdNiO3 are evidenced from by x-ray and Raman scattering. Electric measurements of a bilayer structure further support the structural quality of the embedded RE nickelate layers.

Heat Loads Due to Small Penetrations in Multilayer Insulation Blankets

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Heckle, K. W.; Fesmire, J. E.

2017-01-01

The main penetrations (supports and piping) through multilayer insulation systems for cryogenic tanks have been previously addressed by heat flow measurements. Smaller penetrations due to fasteners and attachments are now experimentally investigated. The use of small pins or plastic garment tag fasteners to each the handling and construction of multilayer insulation (MLI) blankets goes back many years. While it has long been understood that penetrations and other discontinuities degrade the performance of the MLI blanket, quantification of this degradation has generally been lumped into gross performance multipliers (often called degradation factors or scale factors). Small penetrations contribute both solid conduction and radiation heat transfer paths through the blanket. The conduction is down the stem of the structural element itself while the radiation is through the hole formed during installation of the pin or fastener. Analytical models were developed in conjunction with MLI perforation theory and Fouriers Law. Results of the analytical models are compared to experimental testing performed on a 10 layer MLI blanket with approximately 50 small plastic pins penetrating the test specimen. The pins were installed at 76-mm spacing inches in both directions to minimize the compounding of thermal effects due to localized compression or lateral heat transfer. The testing was performed using a liquid nitrogen boil-off calorimeter (Cryostat-100) with the standard boundary temperatures of 293 K and 78 K. Results show that the added radiation through the holes is much more significant than the conduction down the fastener. The results are shown to be in agreement with radiation theory for perforated films.

Heat Loads Due To Small Penetrations In Multilayer Insulation Blankets

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Heckle, K. W.; E Fesmire, J.

2017-12-01

The main penetrations (supports and piping) through multilayer insulation systems for cryogenic tanks have been previously addressed by heat flow measurements. Smaller penetrations due to fasteners and attachments are now experimentally investigated. The use of small pins or plastic garment tag fasteners to ease the handling and construction of multilayer insulation (MLI) blankets goes back many years. While it has long been understood that penetrations and other discontinuities degrade the performance of the MLI blanket, quantification of this degradation has generally been lumped into gross performance multipliers (often called degradation factors or scale factors). Small penetrations contribute both solid conduction and radiation heat transfer paths through the blanket. The conduction is down the stem of the structural element itself while the radiation is through the hole formed during installation of the pin or fastener. Analytical models were developed in conjunction with MLI perforation theory and Fourier’s Law. Results of the analytical models are compared to experimental testing performed on a 10 layer MLI blanket with approximately 50 small plastic pins penetrating the test specimen. The pins were installed at ∼76-mm spacing inches in both directions to minimize the compounding of thermal effects due to localized compression or lateral heat transfer. The testing was performed using a liquid nitrogen boil-off calorimeter (Cryostat-100) with the standard boundary temperatures of 293 K and 78 K. Results show that the added radiation through the holes is much more significant than the conduction down the fastener. The results are shown to be in agreement with radiation theory for perforated films.

Adhesives for laminating polyimide insulated flat conductor cable

NASA Technical Reports Server (NTRS)

Montermoso, J. C.; Saxton, T. R.; Taylor, R. L.

1967-01-01

Polymer adhesive laminates polyimide-film flat conductor cable. It is obtained by reacting an appropriate diamine with a dianhydride. The adhesive has also been used in the lamination of copper to copper for the preparation of multilayer circuit boards.

High Voltage Hybrid Electric Propulsion - Multilayered Functional Insulation System (MFIS) NASA-GRC

NASA Technical Reports Server (NTRS)

Lizcano, M.

2017-01-01

High power transmission cables pose a key challenge in future Hybrid Electric Propulsion Aircraft. The challenge arises in developing safe transmission lines that can withstand the unique environment found in aircraft while providing megawatts of power. High voltage AC, variable frequency cables do not currently exist and present particular electrical insulation challenges since electrical arcing and high heating are more prevalent at higher voltages and frequencies. Identifying and developing materials that maintain their dielectric properties at high voltage and frequencies is crucial.

Optimisation of multi-layer rotationally moulded foamed structures

NASA Astrophysics Data System (ADS)

Pritchard, A. J.; McCourt, M. P.; Kearns, M. P.; Martin, P. J.; Cunningham, E.

2018-05-01

Multi-layer skin-foam and skin-foam-skin sandwich constructions are of increasing interest in the rotational moulding process for two reasons. Firstly, multi-layer constructions can improve the thermal insulation properties of a part. Secondly, foamed polyethylene sandwiched between solid polyethylene skins can increase the mechanical properties of rotationally moulded structural components, in particular increasing flexural properties and impact strength (IS). The processing of multiple layers of polyethylene and polyethylene foam presents unique challenges such as the control of chemical blowing agent decomposition temperature, and the optimisation of cooling rates to prevent destruction of the foam core; therefore, precise temperature control is paramount to success. Long cooling cycle times are associated with the creation of multi-layer foam parts due to their insulative nature; consequently, often making the costs of production prohibitive. Devices such as Rotocooler®, a rapid internal mould water spray cooling system, have been shown to have the potential to significantly decrease cooling times in rotational moulding. It is essential to monitor and control such devices to minimise the warpage associated with the rapid cooling of a moulding from only one side. The work presented here demonstrates the use of threaded thermocouples to monitor the polymer melt in multi-layer sandwich constructions, in order to analyse the cooling cycle of multi-layer foamed structures. A series of polyethylene skin-foam test mouldings were produced, and the effect of cooling medium on foam characteristics, mechanical properties, and process cycle time were investigated. Cooling cycle time reductions of 45%, 26%, and 29% were found for increasing (1%, 2%, and 3%) chemical blowing agent (CBA) amount when using internal water cooling technology from ˜123°C compared with forced air cooling (FAC). Subsequently, a reduction of IS for the same skin-foam parts was found to be 1%, 4%, and 16% compared with FAC.

Thermal Testing and Analysis of an Efficient High-Temperature Multi-Screen Internal Insulation

NASA Technical Reports Server (NTRS)

Weiland, Stefan; Handrick, Karin; Daryabeigi, Kamran

2007-01-01

Conventional multi-layer insulations exhibit excellent insulation performance but they are limited to the temperature range to which their components reflective foils and spacer materials are compatible. For high temperature applications, the internal multi-screen insulation IMI has been developed that utilizes unique ceramic material technology to produce reflective screens with high temperature stability. For analytical insulation sizing a parametric material model is developed that includes the main contributors for heat flow which are radiation and conduction. The adaptation of model-parameters based on effective steady-state thermal conductivity measurements performed at NASA Langley Research Center (LaRC) allows for extrapolation to arbitrary stack configurations and temperature ranges beyond the ones that were covered in the conductivity measurements. Experimental validation of the parametric material model was performed during the thermal qualification test of the X-38 Chin-panel, where test results and predictions showed a good agreement.

Floquet high Chern insulators in periodically driven chirally stacked multilayer graphene

NASA Astrophysics Data System (ADS)

Li, Si; Liu, Cheng-Cheng; Yao, Yugui

2018-03-01

Chirally stacked N-layer graphene is a semimetal with ±p N band-touching at two nonequivalent corners in its Brillioun zone. We predict that an off-resonant circularly polarized light (CPL) drives chirally stacked N-layer graphene into a Floquet Chern insulators (FCIs), aka quantum anomalous Hall insulators, with tunable high Chern number C F = ±N and large gaps. A topological phase transition between such a FCI and a valley Hall (VH) insulator with high valley Chern number C v = ±N induced by a voltage gate can be engineered by the parameters of the CPL and voltage gate. We propose a topological domain wall between the FCI and VH phases, along which perfectly valley-polarized N-channel edge states propagate unidirectionally without backscattering.

Topological interface modes in graphene multilayer arrays

NASA Astrophysics Data System (ADS)

Wang, Feng; Ke, Shaolin; Qin, Chengzhi; Wang, Bing; Long, Hua; Wang, Kai; Lu, Peixiang

2018-07-01

We investigate the topological interface modes of surface plasmon polaritons in a multilayer system composed of graphene waveguide arrays. The topological interface modes emerge when two topologically distinct graphene multilayer arrays are connected. In such multilayer system, the non-trivial topological interface modes and trivial modes coexist. By tuning the configuration of the graphene multilayer arrays, the associated non-trivial interface modes present robust against structural disorder. The total number of topological modes is related to that of graphene layers in a unit cell of the graphene multilayer array. The results provide a new paradigm for topologically protected plasmonics in the graphene multilayer arrays. The study suggests a promising approach to realize light transport and optical switching on a deep-subwavelength scale.

Maximum screening fields of superconducting multilayer structures

DOE PAGES

Gurevich, Alex

2015-01-07

Here, it is shown that a multilayer comprised of alternating thin superconducting and insulating layers on a thick substrate can fully screen the applied magnetic field exceeding the superheating fields H s of both the superconducting layers and the substrate, the maximum Meissner field is achieved at an optimum multilayer thickness. For instance, a dirty layer of thickness ~0.1 μm at the Nb surface could increase H s ≃ 240 mT of a clean Nb up to H s ≃ 290 mT. Optimized multilayers of Nb 3Sn, NbN, some of the iron pnictides, or alloyed Nb deposited onto the surfacemore » of the Nb resonator cavities could potentially double the rf breakdown field, pushing the peak accelerating electric fields above 100 MV/m while protecting the cavity from dendritic thermomagnetic avalanches caused by local penetration of vortices.« less

The Significance of Breakdown Voltages for Quality Assurance of Low-Voltage BME Ceramic Capacitors

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2014-01-01

Application of thin dielectric, base metal electrode (BME) ceramic capacitors for high-reliability applications requires development of testing procedures that can assure high quality and reliability of the parts. In this work, distributions of breakdown voltages (VBR) in variety of low-voltage BME multilayer ceramic capacitors (MLCCs) have been measured and analyzed. It has been shown that analysis of the distributions can indicate the proportion of defective parts in the lot and significance of the defects. Variations of the distributions after solder dip testing allow for an assessment of the robustness of capacitors to soldering-related stresses. The drawbacks of the existing screening and qualification methods to reveal defects in high-value, low-voltage MLCCs and the importance of VBR measurements are discussed. Analysis has shown that due to a larger concentration of oxygen vacancies, defect-related degradation of the insulation resistance (IR) and failures are more likely in BME compared to the precious metal electrode (PME) capacitors.

Nanostructure multilayer dielectric materials for capacitors and insulators

DOEpatents

Barbee, Jr., Troy W.; Johnson, Gary W.

1998-04-21

A capacitor is formed of at least two metal conductors having a multilayer dielectric and opposite dielectric-conductor interface layers in between. The multilayer dielectric includes many alternating layers of amorphous zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3). The dielectric-conductor interface layers are engineered for increased voltage breakdown and extended service life. The local interfacial work function is increased to reduce charge injection and thus increase breakdown voltage. Proper material choices can prevent electrochemical reactions and diffusion between the conductor and dielectric. Physical vapor deposition is used to deposit the zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3) in alternating layers to form a nano-laminate.

Nanostructure multilayer dielectric materials for capacitors and insulators

DOEpatents

Barbee, T.W. Jr.; Johnson, G.W.

1998-04-21

A capacitor is formed of at least two metal conductors having a multilayer dielectric and opposite dielectric-conductor interface layers in between. The multilayer dielectric includes many alternating layers of amorphous zirconium oxide (ZrO{sub 2}) and alumina (Al{sub 2}O{sub 3}). The dielectric-conductor interface layers are engineered for increased voltage breakdown and extended service life. The local interfacial work function is increased to reduce charge injection and thus increase breakdown voltage. Proper material choices can prevent electrochemical reactions and diffusion between the conductor and dielectric. Physical vapor deposition is used to deposit the zirconium oxide (ZrO{sub 2}) and alumina (Al{sub 2}O{sub 3}) in alternating layers to form a nano-laminate. 1 fig.

Multiple infrared bands absorber based on multilayer gratings

NASA Astrophysics Data System (ADS)

Liu, Xiaoyi; Gao, Jinsong; Yang, Haigui; Wang, Xiaoyi; Guo, Chengli

2018-03-01

The present study offers an Ag/Si multilayer-grating microstructure based on an Si substrate. The microstructure exhibits designable narrowband absorption in multiple infrared wavebands, especially in mid- and long-wave infrared atmospheric windows. We investigate its resonance mode mechanism, and calculate the resonance wavelengths by the Fabry-Perot and metal-insulator-metal theories for comparison with the simulation results. Furthermore, we summarize the controlling rules of the absorption peak wavelength of the microstructure to provide a new method for generating a Si-based device with multiple working bands in infrared.

Mars transit vehicle thermal protection system: Issues, options, and trades

NASA Technical Reports Server (NTRS)

Brown, Norman

1986-01-01

A Mars mission is characterized by different mission phases. The thermal control of cryogenic propellant in a propulsive vehicle must withstand the different mission environments. Long term cryogenic storage may be achieved by passive or active systems. Passive cryo boiloff management features will include multilayer insulation, vapor cooled shield, and low conductance structural supports and penetrations. Active boiloff management incorporates the use of a refrigeration system. Key system trade areas include active verses passive system boiloff management (with respect to safety, reliability, and cost) and propellant tank insulation optimizations. Technology requirements include refrigeration technology advancements, insulation performance during long exposure, and cryogenic fluid transfer system for mission vehicle propellant tanking during vehicle buildip in LEO.

Evaluation of inter-laminar shear strength of GFRP composed of bonded glass/polyimide tapes and cyanate-ester/epoxy blended resin for ITER TF coils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hemmi, T.; Matsui, K.; Koizumi, N.

2014-01-27

The insulation system of the ITER TF coils consists of multi-layer glass/polyimide tapes impregnated a cyanate-ester/epoxy resin. The ITER TF coils are required to withstand an irradiation of 10 MGy from gamma-ray and neutrons since the ITER TF coils is exposed by fast neutron (>0.1 MeV) of 10{sup 22} n/m{sup 2} during the ITER operation. Cyanate-ester/epoxy blended resins and bonded glass/polyimide tapes are developed as insulation materials to realize the required radiation-hardness for the insulation of the ITER TF coils. To evaluate the radiation-hardness of the developed insulation materials, the inter-laminar shear strength (ILSS) of glass-fiber reinforced plastics (GFRP) fabricatedmore » using developed insulation materials is measured as one of most important mechanical properties before/after the irradiation in a fission reactor of JRR-3M. As a result, it is demonstrated that the GFRPs using the developed insulation materials have a sufficient performance to apply for the ITER TF coil insulation.« less

Cryogenic Boil-Off Reduction System

NASA Astrophysics Data System (ADS)

Plachta, David W.; Guzik, Monica C.

2014-03-01

A computational model of the cryogenic boil-off reduction system being developed by NASA as part of the Cryogenic Propellant Storage and Transfer technology maturation project has been applied to a range of propellant storage tanks sizes for high-performing in-space cryogenic propulsion applications. This effort focuses on the scaling of multi-layer insulation (MLI), cryocoolers, broad area cooling shields, radiators, solar arrays, and tanks for liquid hydrogen propellant storage tanks ranging from 2 to 10 m in diameter. Component scaling equations were incorporated into the Cryogenic Analysis Tool, a spreadsheet-based tool used to perform system-level parametric studies. The primary addition to the evolution of this updated tool is the integration of a scaling method for reverse turbo-Brayton cycle cryocoolers, as well as the development and inclusion of Self-Supporting Multi-Layer Insulation. Mass, power, and sizing relationships are traded parametrically to establish the appropriate loiter period beyond which this boil-off reduction system application reduces mass. The projected benefit compares passive thermal control to active thermal control, where active thermal control is evaluated for reduced boil-off with a 90 K shield, zero boil-off with a single heat interception stage at the tank wall, and zero boil-off with a second interception stage at a 90 K shield. Parametric studies show a benefit over passive storage at loiter durations under one month, in addition to showing a benefit for two-stage zero boil-off in terms of reducing power and mass as compared to single stage zero boil-off. Furthermore, active cooling reduces the effect of varied multi-layer insulation performance, which, historically, has been shown to be significant.

Electrically insulated MLI and thermal anchor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamiya, Koji; Furukawa, Masato; Murakami, Haruyuki

2014-01-29

The thermal shield of JT-60SA is kept at 80 K and will use the multilayer insulation (MLI) to reduce radiation heat load to the superconducting coils at 4.4 K from the cryostat at 300 K. Due to plasma pulse operation, the MLI is affected by eddy current in toroidal direction. The MLI is designed to suppress the current by electrically insulating every 20 degree in the toroidal direction by covering the MLI with polyimide films. In this paper, two kinds of designs for the MLI system are proposed, focusing on a way to overlap the layers. A boil-off calorimeter methodmore » and temperature measurement has been performed to determine the thermal performance of the MLI system. The design of the electrical insulated thermal anchor between the toroidal field (TF) coil and the thermal shield is also explained.« less

Magnon detection using a ferroic collinear multilayer spin valve.

PubMed

Cramer, Joel; Fuhrmann, Felix; Ritzmann, Ulrike; Gall, Vanessa; Niizeki, Tomohiko; Ramos, Rafael; Qiu, Zhiyong; Hou, Dazhi; Kikkawa, Takashi; Sinova, Jairo; Nowak, Ulrich; Saitoh, Eiji; Kläui, Mathias

2018-03-14

Information transport and processing by pure magnonic spin currents in insulators is a promising alternative to conventional charge-current-driven spintronic devices. The absence of Joule heating and reduced spin wave damping in insulating ferromagnets have been suggested for implementing efficient logic devices. After the successful demonstration of a majority gate based on the superposition of spin waves, further components are required to perform complex logic operations. Here, we report on magnetization orientation-dependent spin current detection signals in collinear magnetic multilayers inspired by the functionality of a conventional spin valve. In Y 3 Fe 5 O 12 |CoO|Co, we find that the detection amplitude of spin currents emitted by ferromagnetic resonance spin pumping depends on the relative alignment of the Y 3 Fe 5 O 12 and Co magnetization. This yields a spin valve-like behavior with an amplitude change of 120% in our systems. We demonstrate the reliability of the effect and identify its origin by both temperature-dependent and power-dependent measurements.

A review of candidate multilayer insulation systems for potential use on wet-launched LH2 tankage for the Space Exploration Initiative lunar missions

NASA Technical Reports Server (NTRS)

Knoll, Richard H.; Stochl, Robert J.; Sanabria, Rafael

1991-01-01

The storage of cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) for the future Space Exploration Initiative (SEI) will require lightweight, high performance thermal protection systems (TPSs). For the near-term lunar missions, the major weight element for most of the TPSs will be multilayer insulation (MLI) and/or the special structures/systems required to accommodate the MLI. Methods of applying MLI to LH2 tankage to avoid condensation or freezing of condensible gases such as nitrogen or oxygen while in the atmosphere are discussed. Because relatively thick layers of MLI will be required for storage times of a month or more, the transient performance from ground-hold to space-hold of the systems will become important in optimizing the TPSs for many of the missions. The ground-hold performance of several candidate systems are given as well as a qualitative assessment of the transient performance effects.

Multilayer graphene on insulator formed by Co-induced layer exchange

NASA Astrophysics Data System (ADS)

Murata, Hiromasa; Toko, Kaoru; Suemasu, Takashi

2017-05-01

The direct synthesis of multilayer graphene (MLG) on arbitrary substrates is essential for incorporating carbon wirings and heat spreaders into electronic devices. Here, we applied the metal-induced layer exchange (MILE) technique, developed for group-IV semiconductors, to a sputtered amorphous carbon (a-C) thin film using Co as a catalyst. MLG was formed on a SiO2 substrate at 800 °C for 10 min; however, it disappeared during wet etching for removing Co. This behavior was attributed to the small contact area between MLG and SiO2 caused by the deformation of the Co layer during annealing. By preparing the Co layer at 200 °C, its thermal stability was improved, resulting in the synthesis of MLG on the substrate through MILE. Raman measurements indicated good crystal quality of the MLG compared with that obtained by conventional metal-induced solid-phase crystallization. MILE was thus proven to be useful not only for group-IV semiconductors but also for carbon materials on insulators.

Purging of a multilayer insulation with dacron tuft spacer by gas diffusion

NASA Technical Reports Server (NTRS)

Sumner, I. E.; Fisk, W. J.

1976-01-01

The time and purge gas usage required to purge a multilayer insulation (MLI) panel with gaseous helium by means of gas diffusion to obtain a condensable gas (nitrogen) concentration of less than 1 percent within the panel are stipulated. Two different, flat, rectangular MLI panels, one incorporating a butt joint, were constructed of of 11 double-aluminized Mylar (DAM) radiation shields separated by Dacron tuft spacers. The DAM/Dacron tuft concept is known commercially as Superfloc. The nitrogen gas concentration as a function of time within the MLI panel could be adequately predicted by using a simple, one dimensional gas diffusion model in which the boundary conditions at the edge of the MLI panel were time dependent. The time and purge gas usage required to achieve 1 percent nitrogen gas concentration within the MLI panel varied from 208 to 86 minutes and 34.1 to 56.5 MLI panel purge volumes, respectively, for gaseous helium purge rates from 10 to 40 MLI panel volumes per hour.

A review of candidate multilayer insulation systems for potential use on wet-launched LH2 tankage for the space exploration initiative lunar missions

NASA Technical Reports Server (NTRS)

Knoll, Richard H.; Stochl, Robert J.; Sanabria, Rafael

1991-01-01

The storage of cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) for the future Space Exploration Initiative (SEI) will require lightweight, high performance thermal protection systems (TPS's). For the near-term lunar missions, the major weight element for most of the TPS's will be multilayer insulation (MLI) and/or the special structures/systems required to accommodate the MLI. Methods of applying MLI to LH2 tankage to avoid condensation or freezing of condensible gases such as nitrogen or oxygen while in the atmosphere are discussed. Because relatively thick layers of MLI will be required for storage times of a month or more, the transient performance from ground-hold to space-hold of the systems will become important in optimizing the TPS's for many of the missions. The ground-hold performance of several candidate systems are given as well as a qualitative assessment of the transient performance effects.

Analytical Modeling and Test Correlation of Variable Density Multilayer Insulation for Cryogenic Storage

NASA Technical Reports Server (NTRS)

Hastings, L. J.; Hedayat, A.; Brown, T. M.

2004-01-01

A unique foam/multilayer insulation (MLI) combination concept for orbital cryogenic storage was experimentally evaluated using a large-scale hydrogen tank. The foam substrate insulates for ground-hold periods and enables a gaseous nitrogen purge as opposed to helium. The MLI, designed for an on-orbit storage period for 45 days, includes several unique features including a variable layer density and larger but fewer perforations for venting during ascent to orbit. Test results with liquid hydrogen indicated that the MLI weight or tank heat leak is reduced by about half in comparison with standard MLI. The focus of this effort is on analytical modeling of the variable density MLI (VD-MLI) on-orbit performance. The foam/VD-MLI model is considered to have five segments. The first segment represents the optional foam layer. The second, third, and fourth segments represent three different MLI layer densities. The last segment is an environmental boundary or shroud that surrounds the last MLI layer. Two approaches are considered: a variable density MLI modeled layer by layer and a semiempirical model or "modified Lockheed equation." Results from the two models were very comparable and were within 5-8 percent of the measured data at the 300 K boundary condition.

Optimization of Layer Densities for Spacecraft Multilayered Insulation Systems

NASA Technical Reports Server (NTRS)

Johnson, W. L.

2009-01-01

Numerous tests of various multilayer insulation systems have indicated that there are optimal densities for these systems. However, the only method of calculating this optimal density was by a complex physics based algorithm developed by McIntosh. In the 1970's much data were collected on the performance of these insulation systems with many different variables analyzed. All formulas generated included number of layers and layer density as geometric variables in solving for the heat flux, none of them was in a differentiable form for a single geometric variable. It was recently discovered that by converting the equations from heat flux to thermal conductivity using Fourier's Law, the equations became functions of layer density, temperatures, and material properties only. The thickness and number of layers of the blanket were merged into a layer density. These equations were then differentiated with respect to layer density. By setting the first derivative equal to zero, and solving for the layer density, the critical layer density was determined. Taking a second derivative showed that the critical layer density is a minimum in the function and thus the optimum density for minimal heat leak, this is confirmed by plotting the original function. This method was checked and validated using test data from the Multipurpose Hydrogen Testbed which was designed using McIntosh's algorithm.

Orbital Debris: Quarterly News, Volume 14, Issue 2

NASA Technical Reports Server (NTRS)

Liou, J. C. (Editor); Shoots, Debi (Editor)

2010-01-01

This bulletin contains articles from the Orbital Debris Program office. This issue's articles are: "Orbital Debris Success Story --A Decade in the Making", "Old and New Satellite Breakups Identified," "Update on Three Major Debris Clouds," and "MMOD Inspection of the HST Bay 5 Multi-Layer Insulation Panel" about micrometeoroid and orbital debris (MMOD) inspection of the Hubble Space Telescope (HST) insulation panel. A project review is also included (i.e., "Small Debris Observations from the Iridium 33/Cosmos 2251 Collision.") There are also abstra cts of conference papers from the staff of the program office.

A functional protein retention and release multilayer with high stability

NASA Astrophysics Data System (ADS)

Nie, Kun; An, Qi; Zhang, Yihe

2016-04-01

Effective and robust interfacial protein retention lies at the heart of the fabrication of protein-based functional interfaces, which is potentially applicable in catalysis, medical therapy, antifouling, and smart devices, but remains challenging due to the sensitive nature of proteins. This study reports a general protein retention strategy to spatial-temporally confine various types of proteins at interfacial regions. The proteins were preserved in mesoporous silica nanoparticles embedded in covalently woven multilayers. It is worth noting that the protein retention strategy effectively preserves the catalytic capabilities of the proteins, and the multilayer structure is robust enough to withstand the bubbling catalytic reactions and could be repeatedly used due to conservation of proteins. The spatiotemporal retention of proteins could be adjusted by varying the number of capping layers. Furthermore, we demonstrate that the protein-loaded interfacial layers could not only be used to construct catalytic-active interfaces, but also be integrated as the power-generating unit to propel a macroscopic floating device.Effective and robust interfacial protein retention lies at the heart of the fabrication of protein-based functional interfaces, which is potentially applicable in catalysis, medical therapy, antifouling, and smart devices, but remains challenging due to the sensitive nature of proteins. This study reports a general protein retention strategy to spatial-temporally confine various types of proteins at interfacial regions. The proteins were preserved in mesoporous silica nanoparticles embedded in covalently woven multilayers. It is worth noting that the protein retention strategy effectively preserves the catalytic capabilities of the proteins, and the multilayer structure is robust enough to withstand the bubbling catalytic reactions and could be repeatedly used due to conservation of proteins. The spatiotemporal retention of proteins could be adjusted by varying the number of capping layers. Furthermore, we demonstrate that the protein-loaded interfacial layers could not only be used to construct catalytic-active interfaces, but also be integrated as the power-generating unit to propel a macroscopic floating device. Electronic supplementary information (ESI) available: UV-vis spectra of the substrate covered by only polymeric (PAH/PAA)5/(PAH/DAS)5 multilayers, UV-vis spectra of the covalently cross-linked (PAH/SiO2 NP)5/(PAH/DAS)5 hybrid multilayers and (CAT/PAH)5/(PAH/DAS)5 films. TEM of the mesoporous silica. See DOI: 10.1039/c6nr01671e

Heat Transfer Study for HTS Power Transfer Cables

NASA Technical Reports Server (NTRS)

Augustynowicz, S.; Fesmire, J.

2002-01-01

Thermal losses are a key factor in the successful application of high temperature superconducting (HTS) power cables. Existing concepts and prototypes rely on the use of multilayer insulation (MLI) systems that are subject to large variations in actual performance. The small space available for the thermal insulation materials makes the application even more difficult because of bending considerations, mechanical loading, and the arrangement between the inner and outer piping. Each of these mechanical variables affects the heat leak rate. These factors of bending and spacing are examined in this study. Furthermore, a maintenance-free insulation system (high vacuum level for 20 years or longer) is a practical requirement. A thermal insulation system simulating a section of a flexible FITS power cable was constructed for test and evaluation on a research cryostat. This paper gives experimental data for the comparison of ideal MLI, MLI on rigid piping, and MLI between flexible piping. A section of insulated flexible piping was tested under cryogenic vacuum conditions including simulated bending and spacers.

Printable Top-Gate-Type Polymer Light-Emitting Transistors with Surfaces of Amorphous Fluoropolymer Insulators Modified by Vacuum Ultraviolet Light Treatment

NASA Astrophysics Data System (ADS)

Kajii, Hirotake; Terashima, Daiki; Kusumoto, Yusuke; Ikezoe, Ikuya; Ohmori, Yutaka

2013-04-01

We investigated the fabrication and electrical and optical properties of top-gate-type polymer light-emitting transistors with the surfaces of amorphous fluoropolymer insulators, CYTOP (Asahi Glass) modified by vacuum ultraviolet light (VUV) treatment. The surface energy of CYTOP, which has a good solution barrier property was increased by VUV irradiation, and the gate electrode was fabricated by solution processing on the CYTOP film using the Ag nano-ink. The influence of VUV irradiation on the optical properties of poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) films with various gate insulators was investigated to clarify the passivation effect of gate insulators. It was found that the poly(methyl methacrylate) (PMMA) film prevented the degradation of the F8BT layer under VUV irradiation because the PMMA film can absorb VUV. The solution-processed F8BT device with multilayer PMMA/CYTOP insulators utilizing a gate electrode fabricated using the Ag nano-ink exhibited both the ambipolar characteristics and yellow-green emission.

Lightweight Thermal Insulation for a Liquid-Oxygen Tank

NASA Technical Reports Server (NTRS)

Willen, G. Scott; Lock, Jennifer; Nieczkoski, Steve

2005-01-01

A proposed lightweight, reusable thermal-insulation blanket has been designed for application to a tank containing liquid oxygen, in place of a non-reusable spray-on insulating foam. The blanket would be of the multilayer-insulation (MLI) type and equipped with a pressure-regulated nitrogen purge system. The blanket would contain 16 layers in two 8-layer sub-blankets. Double-aluminized polyimide 0.3 mil (.0.008 mm) thick was selected as a reflective shield material because of its compatibility with oxygen and its ability to withstand ionizing radiation and high temperature. The inner and outer sub-blanket layers, 1 mil (approximately equals 0.025 mm) and 3 mils (approximately equals 0.076 mm) thick, respectively, would be made of the double-aluminized polyimide reinforced with aramid. The inner and outer layers would provide structural support for the more fragile layers between them and would bear the insulation-to-tank attachment loads. The layers would be spaced apart by lightweight, low-thermal-conductance netting made from polyethylene terephthalate.

Prediction of a Large-Gap and Switchable Kane-Mele Quantum Spin Hall Insulator

NASA Astrophysics Data System (ADS)

Marrazzo, Antimo; Gibertini, Marco; Campi, Davide; Mounet, Nicolas; Marzari, Nicola

2018-03-01

Fundamental research and technological applications of topological insulators are hindered by the rarity of materials exhibiting a robust topologically nontrivial phase, especially in two dimensions. Here, by means of extensive first-principles calculations, we propose a novel quantum spin Hall insulator with a sizable band gap of ˜0.5 eV that is a monolayer of jacutingaite, a naturally occurring layered mineral first discovered in 2008 in Brazil and recently synthesized. This system realizes the paradigmatic Kane-Mele model for quantum spin Hall insulators in a potentially exfoliable two-dimensional monolayer, with helical edge states that are robust and that can be manipulated exploiting a unique strong interplay between spin-orbit coupling, crystal-symmetry breaking, and dielectric response.

Comparison of reusable insulation systems for cryogenically-tanked earth-based space vehicles

NASA Technical Reports Server (NTRS)

Sumner, I. E.; Barber, J. R.

1978-01-01

Three reusable insulation systems concepts have been developed for use with cryogenic tanks of earth-based space vehicles. Two concepts utilized double-goldized Kapton (DGK) or double-aluminized Mylar (DAM) multilayer insulation (MLI), while the third utilized a hollow-glass-microsphere, load-bearing insulation (LBI). All three insulation systems have recently undergone experimental testing and evaluation under NASA-sponsored programs. Thermal performance measurements were made under space-hold (vacuum) conditions for insulation warm boundary temperatures of approximately 291 K. The resulting effective thermal conductivity was approximately .00008 W/m-K for the MLI systems (liquid hydrogen test results) and .00054 W/m-K for the LBI system (liquid nitrogen test results corrected to liquid hydrogen temperature). The DGK MLI system experienced a maximum thermal degradation of 38 percent, the DAM MLI system 14 percent, and the LBI system 6.7 percent due to repeated thermal cycling representing typical space flight conditions. Repeated exposure of the DAM MLI system to a high humidity environment for periods as long as 8 weeks provided a maximum degradation of only 24 percent.

Thermal performance of a modularized replaceable multilayer insulation system for a cryogenic stage

NASA Technical Reports Server (NTRS)

Knoll, R. H.

1977-01-01

A rugged modularized MLI system for a 2.23-meter-diameter (87.6-in.-diam) liquid hydrogen tank was designed, fabricated, and tested under simulated near-earth and deep-space environments. The two blankets of the system were each composed of 17 double-aluminized Mylar radiation shields separated by silk net. The unit area weight of the installed system was 1.54 kg/sqm (0.32 lb/sq ft). The overall average heat transferred into the insulated tank was 22.7 and 0.98 watts (77.4 and 3.3 Btu/hr) during simulated near-earth and deep-space testing, respectively. The near-earth result was only 2.6 times that predicted for an undisturbed insulation system (i.e., no seams or penetrations). Tests indicate that this insulation concept could be useful for a cryogenic space tug or orbit transfer vehicle application.

Soft Coulomb gap and asymmetric scaling towards metal-insulator quantum criticality in multilayer MoS2.

PubMed

Moon, Byoung Hee; Bae, Jung Jun; Joo, Min-Kyu; Choi, Homin; Han, Gang Hee; Lim, Hanjo; Lee, Young Hee

2018-05-24

Quantum localization-delocalization of carriers are well described by either carrier-carrier interaction or disorder. When both effects come into play, however, a comprehensive understanding is not well established mainly due to complexity and sparse experimental data. Recently developed two-dimensional layered materials are ideal in describing such mesoscopic critical phenomena as they have both strong interactions and disorder. The transport in the insulating phase is well described by the soft Coulomb gap picture, which demonstrates the contribution of both interactions and disorder. Using this picture, we demonstrate the critical power law behavior of the localization length, supporting quantum criticality. We observe asymmetric critical exponents around the metal-insulator transition through temperature scaling analysis, which originates from poor screening in insulating regime and conversely strong screening in metallic regime due to free carriers. The effect of asymmetric scaling behavior is weakened in monolayer MoS 2 due to a dominating disorder.

Solar electric propulsion system thermal analysis. [including heat pipes and multilayer insulation

NASA Technical Reports Server (NTRS)

1975-01-01

Thermal control elements applicable to the solar electric propulsion stage are discussed along with thermal control concepts. Boundary conditions are defined, and a thermal analysis was conducted with special emphasis on the power processor and equipment compartment thermal control system. Conclusions and recommendations are included.

Whiskerless Schottky diode

NASA Technical Reports Server (NTRS)

Bishop, William L. (Inventor); Mcleod, Kathleen A. (Inventor); Mattauch, Robert J. (Inventor)

1991-01-01

A Schottky diode for millimeter and submillimeter wave applications is comprised of a multi-layered structure including active layers of gallium arsenide on a semi-insulating gallium arsenide substrate with first and second insulating layers of silicon dioxide on the active layers of gallium arsenide. An ohmic contact pad lays on the silicon dioxide layers. An anode is formed in a window which is in and through the silicon dioxide layers. An elongated contact finger extends from the pad to the anode and a trench, preferably a transverse channel or trench of predetermined width, is formed in the active layers of the diode structure under the contact finger. The channel extends through the active layers to or substantially to the interface of the semi-insulating gallium arsenide substrate and the adjacent gallium arsenide layer which constitutes a buffer layer. Such a structure minimizes the effect of the major source of shunt capacitance by interrupting the current path between the conductive layers beneath the anode contact pad and the ohmic contact. Other embodiments of the diode may substitute various insulating or semi-insulating materials for the silicon dioxide, various semi-conductors for the active layers of gallium arsenide, and other materials for the substrate, which may be insulating or semi-insulating.

Bulk and interface quantum states of electrons in multi-layer heterostructures with topological materials

NASA Astrophysics Data System (ADS)

Nikolic, Aleksandar; Zhang, Kexin; Barnes, C. H. W.

2018-06-01

In this article we describe the bulk and interface quantum states of electrons in multi-layer heterostructures in one dimension, consisting of topological insulators (TIs) and topologically trivial materials. We use and extend an effective four-band continuum Hamiltonian by introducing position dependence to the eight material parameters of the Hamiltonian. We are able to demonstrate complete conduction-valence band mixing in the interface states. We find evidence for topological features of bulk states of multi-layer TI heterostructures, as well as demonstrating both complete and incomplete conduction-valence band inversion at different bulk state energies. We show that the linear k z terms in the low-energy Hamiltonian, arising from overlap of p z orbitals between different atomic layers in the case of chalcogenides, control the amount of tunneling from TIs to trivial insulators. Finally, we show that the same linear k z terms in the low-energy Hamiltonian affect the material’s ability to form the localised interface state, and we demonstrate that due to this effect the spin and probability density localisation in a thin film of Sb2Te3 is incomplete. We show that changing the parameter that controls the magnitude of the overlap of p z orbitals affects the transport characteristics of the topologically conducting states, with incomplete topological state localisation resulting in increased backscattering.

Bulk and interface quantum states of electrons in multi-layer heterostructures with topological materials.

PubMed

Nikolic, Aleksandar; Zhang, Kexin; Barnes, C H W

2018-06-13

In this article we describe the bulk and interface quantum states of electrons in multi-layer heterostructures in one dimension, consisting of topological insulators (TIs) and topologically trivial materials. We use and extend an effective four-band continuum Hamiltonian by introducing position dependence to the eight material parameters of the Hamiltonian. We are able to demonstrate complete conduction-valence band mixing in the interface states. We find evidence for topological features of bulk states of multi-layer TI heterostructures, as well as demonstrating both complete and incomplete conduction-valence band inversion at different bulk state energies. We show that the linear k z terms in the low-energy Hamiltonian, arising from overlap of p z orbitals between different atomic layers in the case of chalcogenides, control the amount of tunneling from TIs to trivial insulators. Finally, we show that the same linear k z terms in the low-energy Hamiltonian affect the material's ability to form the localised interface state, and we demonstrate that due to this effect the spin and probability density localisation in a thin film of Sb 2 Te 3 is incomplete. We show that changing the parameter that controls the magnitude of the overlap of p z orbitals affects the transport characteristics of the topologically conducting states, with incomplete topological state localisation resulting in increased backscattering.

Evaluation of propellant tank insulation concepts for low-thrust chemical propulsion systems

NASA Technical Reports Server (NTRS)

Kramer, T.; Brogren, E.; Seigel, B.

1984-01-01

An analytical evaluation of cryogenic propellant tank insulations for liquid oxygen/liquid hydrogen low-thrust 2224N (500 lbf) propulsion systems (LTPS) was conducted. The insulation studied consisted of combinations of N2-purged foam and multilayer insulation (MLI) as well as He-purged MLI-only. Heat leak and payload performance predictions were made for three Shuttle-launched LTPS designed for Shuttle bay packaged payload densities of 56 kg/cu m, 40 kg/cu m and 24 kg/cu m. Foam/MLI insulations were found to increase LTPS payload delivery capability when compared with He-purged MLI-only. An additional benefit of foam/MLI was reduced operational complexity because Orbiter cargo bay N2 purge gas could be used for MLI purging. Maximum payload mass benefit occurred when an enhanced convection, rather than natural convection, heat transfer was specified for the insulation purge enclosure. The enhanced convection environment allowed minimum insulation thickness to be used for the foam/MLI interface temperature selected to correspond to the moisture dew point in the N2 purge gas. Experimental verification of foam/MLI benefits was recommended. A conservative program cost estimate for testing a MLI-foam insulated tank was 2.1 million dollars. It was noted this cost could be reduced significantly without increasing program risk.

Thermal Performance of Cryogenic Multilayer Insulation at Various Layer Spacings

NASA Technical Reports Server (NTRS)

Johnson, Wesley Louis

2010-01-01

Multilayer insulation (MLI) has been shown to be the best performing cryogenic insulation system at high vacuum (less that 10 (exp 3) torr), and is widely used on spaceflight vehicles. Over the past 50 years, many investigations into MLI have yielded a general understanding of the many variables that are associated with MLI. MLI has been shown to be a function of variables such as warm boundary temperature, the number of reflector layers, and the spacer material in between reflectors, the interstitial gas pressure and the interstitial gas. Since the conduction between reflectors increases with the thickness of the spacer material, yet the radiation heat transfer is inversely proportional to the number of layers, it stands to reason that the thermal performance of MLI is a function of the number of layers per thickness, or layer density. Empirical equations that were derived based on some of the early tests showed that the conduction term was proportional to the layer density to a power. This power depended on the material combination and was determined by empirical test data. Many authors have graphically shown such optimal layer density, but none have provided any data at such low densities, or any method of determining this density. Keller, Cunnington, and Glassford showed MLI thermal performance as a function of layer density of high layer densities, but they didn't show a minimal layer density or any data below the supposed optimal layer density. However, it was recently discovered that by manipulating the derived empirical equations and taking a derivative with respect to layer density yields a solution for on optimal layer density. Various manufacturers have begun manufacturing MLI at densities below the optimal density. They began this based on the theory that increasing the distance between layers lowered the conductive heat transfer and they had no limitations on volume. By modifying the circumference of these blankets, the layer density can easily be varied. The simplest method of determining the thermal performance of MLI at cryogenic temperature is by boil-off calorimetry. Several blankets were procured and tested at various layer densities at the Cryogenics Test Laboratory at Kennedy Space Center. The densities that the blankets were tested over covered a wide range of layer densities including the analytical minimum. Several of the blankets were tested at the same insulation thickness while changing the layer density (thus a different number of reflector layers). Optimizing the layer density of multilayer insulation systems for heat transfer would remove a layer density from the complex method of designing such insulation systems. Additional testing was performed at various warm boundary temperatures and pressures. The testing and analysis was performed to simplify the analysis of cryogenic thermal insulation systems. This research was funded by the National Aeronautics and Space Administration's Exploration Technology Development Program's Cryogenic Fluid Management Project

Reliability of large superconducting magnets through design

NASA Astrophysics Data System (ADS)

Henning, C. D.

1981-01-01

Design and quality control of large superconducting magnets for reliability comparable to pressure vessels are discussed. The failure modes are analyzed including thermoelectric instabilities, electrical shorts, cryogenic/vacuum defects, and mechanical malfunctions. Design must take into consideration conductor stability, insulation based on the Paschen curves, and the possible burnout of cryogenic transition leads if the He flow is interrupted. The final stage of the metal drawing process should stress the superconductor material to a stress value higher than the magnet design stress, cabled conductors should be used to achieve mechanical redundancy, and ground-plane insulation must be multilayered for arc prevention.

Vision-based localization for on-orbit servicing of a partially cooperative satellite

NASA Astrophysics Data System (ADS)

Oumer, Nassir W.; Panin, Giorgio; Mülbauer, Quirin; Tseneklidou, Anastasia

2015-12-01

This paper proposes ground-in-the-loop, model-based visual localization system based on transmitted images to ground, to aid rendezvous and docking maneuvers between a servicer and a target satellite. In particular, we assume to deal with a partially cooperative target, i.e. passive and without fiducial markers, but supposed at least to keep a controlled attitude, up to small fluctuations, so that the approach mainly involves translational motion. For the purpose of localization, video cameras provide an effective and relatively inexpensive solution, working at a wide range of distances with an increasing accuracy and robustness during the approach. However, illumination conditions in space are especially challenging, due to the direct sunlight exposure and to the glossy surface of a satellite, that creates strong reflections and saturations and therefore a high level of background clutter and missing detections. We employ a monocular camera for mid-range tracking (20 - 5 m) and stereo camera at close-range (5 - 0.5 m), with the respective detection and tracking methods, both using intensity edges and robustly dealing with the above issues. Our tracking system has been extensively verified at the facility of the European Proximity Operations Simulator (EPOS) of DLR, which is a very realistic ground simulation able to reproduce sunlight conditions through a high power floodlight source, satellite surface properties using multilayer insulation foils, as well as orbital motion trajectories with ground-truth data, by means of two 6 DOF industrial robots. Results from this large dataset show the effectiveness and robustness of our method against the above difficulties.

Comparison of Multilayer Dielectric Thin Films for Future Metal-Insulator-Metal Capacitors: Al2O3/HfO2/Al2O3 versus SiO2/HfO2/SiO2

NASA Astrophysics Data System (ADS)

Park, Sang-Uk; Kwon, Hyuk-Min; Han, In-Shik; Jung, Yi-Jung; Kwak, Ho-Young; Choi, Woon-Il; Ha, Man-Lyun; Lee, Ju-Il; Kang, Chang-Yong; Lee, Byoung-Hun; Jammy, Raj; Lee, Hi-Deok

2011-10-01

In this paper, two kinds of multilayered metal-insulator-metal (MIM) capacitors using Al2O3/HfO2/Al2O3 (AHA) and SiO2/HfO2/SiO2 (SHS) were fabricated and characterized for radio frequency (RF) and analog mixed signal (AMS) applications. The experimental results indicate that the AHA MIM capacitor (8.0 fF/µm2) is able to provide a higher capacitance density than the SHS MIM capacitor (5.1 fF/µm2), while maintaining a low leakage current of about 50 nA/cm2 at 1 V. The quadratic voltage coefficient of capacitance, α gradually decreases as a function of stress time under constant voltage stress (CVS). The parameter variation of SHS MIM capacitors is smaller than that of AHA MIM capacitors. The effects of CVS on voltage linearity and time-dependent dielectric breakdown (TDDB) characteristics were also investigated.

Hazards protection for space suits and spacecraft

NASA Technical Reports Server (NTRS)

Kosmo, Joseph J. (Inventor); Dawn, Frederic S. (Inventor)

1990-01-01

A flexible multi-layered covering article for protection against the hazards of exposure to the environment of outer space is disclosed. The covering includes an outer layer section comprising an outermost lamina of woven expanded tetrafluoroethylene yarns (Gore Tex) for protecting against abrasion and tearing, an underlying weave of meta-aramid yarns (Nomex) and para-aramid yarns (Kevlar) for particle impart protection, and electrostatic charge dissipation and control system incorporated therein, and a chemical contaminants control barrier applied as a coating. A middle section includes a succession of thermal insulating layers of polymeric thermoplastic or thermoforming material, each of which is coated with a metal deposit of high infra-red emissivity and low solar radiation absorption characteristics and separated from adjacent insulating layers by a low thermal conductance material. The covering further includes a radiation attenuating layer of a tungsten-loaded polymeric elastomer binder for protecting against bremsstrahlung radiation and an inner layer of rip-stop polyester material for abrasion protection. A chloroprene coating may be supplied the polyester-material for added micrometeroid protection. Securing means of low heat conductance material secures the multi-layers together as a laminar composite.

Multilayer capacitor suitable for substrate integration and multimegahertz filtering

DOEpatents

Ngo, Khai D. T.

1990-01-01

A multilayer capacitor comprises stacked, spaced-apart electrodes of sheet form, dielectric layers between the electrodes, and first and second groups of spaced-apart conductive vias extending transversely of the sheet-form electrodes and through aligned holes in the dielectric layers. Alternate electrodes are instantaneously positive, and the remaining electrodes are instantaneously negative. Each via of the first group is electrically connected to the positive electrodes and passes insulatingly through the negative electrodes. Similarly, each via of the second group is electrically connected to the negative electrodes and passes insulatingly through the positive electrodes. Each via has, in the plane of the electrodes, a cross-sectional form in the shape of an elongated rib of greater length than width. The elongated ribs of the first group are disposed in a first plurality of rows with their lengths in spaced-apart, aligned relationship, and the ribs of the second group are disposed in a second plurality of rows with their lengths in spaced-apart, aligned relationship. The first plurality of rows is disposed substantially orthogonally with respect to the second plurality of rows.

Direct synthesis of multilayer graphene on an insulator by Ni-induced layer exchange growth of amorphous carbon

NASA Astrophysics Data System (ADS)

Murata, H.; Toko, K.; Saitoh, N.; Yoshizawa, N.; Suemasu, T.

2017-01-01

Multilayer graphene (MLG) growth on arbitrary substrates is desired for incorporating carbon wiring and heat spreaders into electronic devices. We investigated the metal-induced layer exchange growth of a sputtered amorphous C layer using Ni as a catalyst. A MLG layer uniformly formed on a SiO2 substrate at 600 °C by layer exchange between the C and Ni layers. Raman spectroscopy and electron microscopy showed that the resulting MLG layer was highly oriented and contained relatively few defects. The present investigation will pave the way for advanced electronic devices integrated with carbon materials.

Polyimide/Carbon Nanotube Composite Films for Electrostatic Charge Mitigation

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Delozier, Donavon M.; Connell, John W.; Watson, Kent A.

2004-01-01

Low color, space environmentally durable polymeric films with sufficient electrical conductivity to mitigate electrostatic charge (ESC) build-up have potential applications on large, deployable, ultra-light weight Gossamer spacecraft as thin film membranes on antennas, solar sails, thermal/optical coatings, multi-layer insulation blankets, etc.. The challenge has been to develop a method to impart robust electrical conductivity into these materials without increasing solar absorptivity (alpha ) or decreasing optical transparency or film flexibility. Since these spacecraft will require significant compaction prior to launch, the film portion of the spacecraft will require folding. The state-of-the-art clear, conductive coating (e.g. indium-tin-oxide, ITO) is brittle and cannot tolerate folding. In this report, doping a polymer with single-walled carbon nanotubes (SWNTs) using two different methods afforded materials with good flexibility and surface conductivities in the range sufficient for ESC mitigation. A coating method afforded materials with minimal effects on the mechanical, optical, and thermo-optical properties as compared to dispersal of SWNTs in the matrix. The chemistry and physical properties of these nanocomposites are discussed.

Probing topological protection using a designer surface plasmon structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Fei; Gao, Zhen; Shi, Xihang

Topological photonic states, inspired by robust chiral edge states in topological insulators, have recently been demonstrated in a few photonic systems, including an array of coupled on-chip ring resonators at communication wavelengths. However, the intrinsic difference between electrons and photons determines that the 'topological protection' in time-reversal-invariant photonic systems does not share the same robustness as its counterpart in electronic topological insulators. Here in a designer surface plasmon platform consisting of tunable metallic sub-wavelength structures, we construct photonic topological edge states and probe their robustness against a variety of defect classes, including some common time-reversal-invariant photonic defects that can breakmore » the topological protection, but do not exist in electronic topological insulators. Furthermore, this is also an experimental realization of anomalous Floquet topological edge states, whose topological phase cannot be predicted by the usual Chern number topological invariants.« less

Probing topological protection using a designer surface plasmon structure

DOE PAGES

Gao, Fei; Gao, Zhen; Shi, Xihang; ...

2016-05-20

Topological photonic states, inspired by robust chiral edge states in topological insulators, have recently been demonstrated in a few photonic systems, including an array of coupled on-chip ring resonators at communication wavelengths. However, the intrinsic difference between electrons and photons determines that the 'topological protection' in time-reversal-invariant photonic systems does not share the same robustness as its counterpart in electronic topological insulators. Here in a designer surface plasmon platform consisting of tunable metallic sub-wavelength structures, we construct photonic topological edge states and probe their robustness against a variety of defect classes, including some common time-reversal-invariant photonic defects that can breakmore » the topological protection, but do not exist in electronic topological insulators. Furthermore, this is also an experimental realization of anomalous Floquet topological edge states, whose topological phase cannot be predicted by the usual Chern number topological invariants.« less

Thermal Insulation Performance of Flexible Piping for Use in HTS Power Cables

NASA Technical Reports Server (NTRS)

Fesmire, James E.; Augustynowicz, S. D.; Demko, J. A.; Thompson, Karen (Technical Monitor)

2001-01-01

High-temperature superconducting (HTS) cables that typically operate at temperatures below 80 K are being developed for power transmission. The practical application of HTS power cables will require the use of flexible piping to contain the cable and the liquid nitrogen coolant. A study of thermal performance of multilayer insulation (MLI) was conducted in geometries representing both rigid and flexible piping. This experimental study performed at the Cryogenics Test Laboratory of NASA Kennedy Space Center provides a framework for the development of cost-effective, efficient thermal insulation systems that will support these long-distance flexible lines containing HTS power cables. The overall thermal performance of the insulation system for a rigid configuration and for a flexible configuration, simulating a flexible HTS power cable, was determined by the steady-state liquid nitrogen boiloff method under the full range of vacuum levels. Two different cylindrically rolled material systems were tested: a standard MLI and a layered composite insulation (LCI). Comparisons of ideal MLI, MLI on rigid piping, and MLI between flexible piping are presented.

Thermal test of the insulation structure for LH 2 tank by using the large experimental apparatus

NASA Astrophysics Data System (ADS)

Kamiya, S.; Onishi, K.; Konshima, N.; Nishigaki, K.

Conceptual designs of large mass LH 2 (liquid hydrogen) storage systems, whose capacity is 50,000 m3, have been studied in the Japanese hydrogen project, World Energy Network (WE-NET) [K. Fukuda, in: WE-NET Hydrogen Energy Symposium, 1999, P1-P41]. This study has concluded that their thermal insulation structures for the huge LH 2 tanks should be developed. Their actual insulation structures comprise not only the insulation material but also reinforced members and joints. To evaluate their thermal performance correctly, a large test specimen including reinforced members and joints will be necessary. After verifying the thermal performance of a developed large experimental apparatus [S. Kamiya, Cryogenics 40 (1) (2000) 35] for measuring the thermal conductance of various insulation structures, we tested two specimens, a vacuum multilayer insulation (MLI) with a glass fiber reinforced plastic (GFRP) support and a vacuum solid insulation (microtherm ®) with joints. The thermal background test for verifying the thermal design of the experimental apparatus showed that the background heat leak is 0.1 W, small enough to satisfy apparatus performance requirement. The thermal conductance measurements of specimens also showed that thermal heat fluxes of MLI with a GFRP support and microtherm ® are 8 and 5.4 W/m2, respectively.

Aerogel-Based Multilayer Insulation with Micrometeoroid Protection

NASA Technical Reports Server (NTRS)

Begag, Redouane; White, Shannon

2013-01-01

Ultra-low-density, highly hydrophobic, fiber-reinforced aerogel material integrated with MLI (aluminized Mylar reflectors and B4A Dacron separators) offers a highly effective insulation package by providing unsurpassed thermal performance and significant robustness, delivering substantial MMOD protection via the addition of a novel, durable, external aerogel layer. The hydrophobic nature of the aerogel is an important property for maintaining thermal performance if the material is exposed to the environment (i.e. rain, snow, etc.) during ground installations. The hybrid aerogel/MLI/MMOD solution affords an attractive alternative because it will perform thermally in the same range as MLI at all vacuum levels (including high vacuum), and offers significant protection from micrometeoroid damage. During this effort, the required low-density and resilient aerogel materials have been developed that are needed to optimize the thermal performance for space (high vacuum) cryotank applications. The proposed insulation/MMOD package is composed of two sections: a stack of interleaved aerogel layers and MLI intended for cryotank thermal insulation, and a 1.5- to 1-in. (.2.5- to 3.8- cm) thick aerogel layer (on top of the insulation portion) for MMOD protection. Learning that low-density aerogel cannot withstand the hypervelocity impact test conditions, the innovators decided during the course of the program to fabricate a high-density and strong material based on a cross-linked aerogel (X-aerogel; developed elsewhere by the innovators) for MMOD protection. This system has shown a very high compressive strength that is capable of withstanding high-impact tests if a proper configuration of the MMOD aerogel layer is used. It was learned that by stacking two X-aerogel layers [1.5-in. (.3.8-cm) thick] separated by an air gap, the system would be able to hold the threat at a speed of 5 km/s and gpass h the test. The first aerogel panel stopped the projectile from damaging the second aerogel panel. The impacted X-aerogel (the back specimen from the successful test) was further tested in comparison to another similar sample (not impacted) at Kennedy Space Center for thermal conductivity evaluation at cryogenic conditions. The specimens were tested under high vacuum and cryogenic temperatures, using Cryostat 500. The results show that the specimen did not lose a significant amount of thermal performance due to the impact test, especially at high vacuum.

Design of Chern insulating phases in honeycomb lattices

NASA Astrophysics Data System (ADS)

Pickett, Warren E.; Lee, Kwan-Woo; Pentcheva, Rossitza

2018-06-01

The search for robust examples of the magnetic version of topological insulators, referred to as quantum anomalous Hall insulators or simply Chern insulators, so far lacks success. Our groups have explored two distinct possibilities based on multiorbital 3d oxide honeycomb lattices. Each has a Chern insulating phase near the ground state, but materials parameters were not appropriate to produce a viable Chern insulator. Further exploration of one of these classes, by substituting open shell 3d with 4d and 5d counterparts, has led to realistic prediction of Chern insulating ground states. Here we recount the design process, discussing the many energy scales that are active in participating (or resisting) the desired Chern insulator phase.

Annealing effects on capacitance-voltage characteristics of a-Si/SiN(x) multilayer prepared using hot-wire chemical vapour deposition.

PubMed

Panchal, A K; Rai, D K; Solanki, C S

2011-04-01

Post-deposition annealing of a-Si/SiN(x) multilayer films at different temperature shows varying shift in high frequency (1 MHz) capacitance-voltage (HFCV) characteristics. Various a-Si/SiN(x) multilayer films were deposited using hot wire chemical vapor deposition (HWCVD) and annealed in the temperature range of 800 to 900 degrees C to precipitate Si quantum dots (Si-QD) in a-Si layers. HFCV measurements of the as-deposited and annealed films in metal-insulator-semiconductor (MIS) structures show hysterisis in C-V curves. The hysteresis in the as-deposited films and annealed films is attributed to charge trapping in Si-dangling bonds in a-Si layer and in Si-QD respectively. The charge trapping density in Si-QD increases with temperature while the interface defects density (D(it)) remains constant.

USAF/WL robust 300 C wire insulation system program status

NASA Technical Reports Server (NTRS)

Wong, Wing

1995-01-01

The objective of this program is to identify, develop, and demonstrate an optimum wire insulation system capable of continuous operation at 300 C which possesses a combination of superior electrical (AC or DC), mechanical, and physical properties over Kapton derived insulations described in MIL-W-81381 and those hybrid materials commonly known as TKT constructions.

USAF/WL robust 300 C wire insulation system program status

NASA Astrophysics Data System (ADS)

Wong, Wing

1995-11-01

The objective of this program is to identify, develop, and demonstrate an optimum wire insulation system capable of continuous operation at 300 C which possesses a combination of superior electrical (AC or DC), mechanical, and physical properties over Kapton derived insulations described in MIL-W-81381 and those hybrid materials commonly known as TKT constructions.

Insulation Resistance Degradation in Ni-BaTiO3 Multilayer Ceramic Capacitors

NASA Technical Reports Server (NTRS)

Liu, Donhang David

2015-01-01

Insulation resistance (IR) degradation in NiBaTiO3 multilayer ceramic capacitors has been characterized by the measurement of both time to failure (TTF) and direct current leakage current as a function of stress time under highly accelerated life test conditions. The measured leakage current time dependence data fit well to an exponential form, and a characteristic growth time tau (sub SD) can be determined. A greater value of tau (sub SD) represents a slower IR degradation process. Oxygen vacancy migration and localization at the grain boundary region results in the reduction of the Schottky barrier height and has been found to be the main reason for IR degradation in NiBaTiO3 capacitors. The reduction of barrier height as a function oftime follows an exponential relation of phi (t ) = phi (0) e (exp -2Kt), where 13 the degradation rate constant K Koe (Ek/kT) is inversely proportional to the mean TTF (MTTF) and can be determined using an Arrhenius plot. For oxygen vacancy electromigration, a lower barrier height phi (0) will favor a slow IR degradation process, but a lower phi (0) will also promote electronic carrier conduction across the barrier and decrease the IR. As a result, a moderate barrier height phi (0) (and therefore a moderate IR value) with a longer MTTF (smaller degradation rate constant K) will result in a minimized IR degradation process and the most improved reliability in NiBaTiO3 multilayer ceramic capacitors.

Evaluation of propellent tank insulation concepts for low-thrust chemical propulsion systems: Executive summary

NASA Technical Reports Server (NTRS)

Kramer, T.; Brogren, E.; Siegel, B.

1984-01-01

Cryogenic propellant tank insulations or liquid oxygen/liquid hydrogen low-thrust 2224N (500 lbf) propulsion systems (LTPS) were assessed. The insulation studied consisted of combinations of N2-purged foam and multilayer insulation (MLI) as well as He-purged MLI-only. Heat leak and payload performance predictions were made for three shuttle-launched LTPS designed for shuttle bay packaged payload densities of 56 kg cu/m (3.5 lbm/cu ft), 40 kg/cu m (2.5 lbm/cu ft) and 24 kg/cu m (1.5 lbm/cu ft). Foam/MLI insulations were found to increase LTPS payload delivery capability when compared with He-purged MLI-only. An additional benefit of foam/MLI was reduced operational complexity because orbiter cargo bay N2 purge gas could be used for MLI purging. Maximum payload mass benefit occurred when an enhanced convection, rather than natural convection, heat transfer was specified for the insulation purge enclosure. The enhanced convection environment allowed minimum insulation thickness to be used for the foam/MLI interface temperature selected to correspond to the moisture dew point in the N2 purge gas. Experimental verification of foam/MLI benefits was recommended. A conservative program cost estimate for testing a MLI-foam insulated tank was 2.1 million dollars. This cost could be reduced significantly without increasing program risk.

Preparation of multilayer graphene sheets and their applications for particle accelerators

NASA Astrophysics Data System (ADS)

Tatami, Atsushi; Tachibana, Masamitsu; Yagi, Takashi; Murakami, Mutsuaki

2018-05-01

Multilayer graphene sheets were prepared by heat treatment of polyimide films at temperatures of up to 3000 °C. The sheets consist of highly oriented graphite layers with excellent mechanical robustness and flexibility. Key features of these sheets include their high thermal conductivity in the in-plane direction, good mechanical properties, and high carbon purity. The results suggest that the multilayer graphene sheets have great potential for charge stripping foils that persist even under the highest ion beam intensities irradiation and can be used for accelerator applications.

Synthesis of large-area multilayer hexagonal boron nitride for high material performance.

PubMed

Kim, Soo Min; Hsu, Allen; Park, Min Ho; Chae, Sang Hoon; Yun, Seok Joon; Lee, Joo Song; Cho, Dae-Hyun; Fang, Wenjing; Lee, Changgu; Palacios, Tomás; Dresselhaus, Mildred; Kim, Ki Kang; Lee, Young Hee; Kong, Jing

2015-10-28

Although hexagonal boron nitride (h-BN) is a good candidate for gate-insulating materials by minimizing interaction from substrate, further applications to electronic devices with available two-dimensional semiconductors continue to be limited by flake size. While monolayer h-BN has been synthesized on Pt and Cu foil using chemical vapour deposition (CVD), multilayer h-BN is still absent. Here we use Fe foil and synthesize large-area multilayer h-BN film by CVD with a borazine precursor. These films reveal strong cathodoluminescence and high mechanical strength (Young's modulus: 1.16 ± 0.1 TPa), reminiscent of formation of high-quality h-BN. The CVD-grown graphene on multilayer h-BN film yields a high carrier mobility of ∼ 24,000 cm(2) V(-1) s(-1) at room temperature, higher than that (∼ 13,000 (2) V(-1) s(-1)) with exfoliated h-BN. By placing additional h-BN on a SiO2/Si substrate for a MoS2 (WSe2) field-effect transistor, the doping effect from gate oxide is minimized and furthermore the mobility is improved by four (150) times.

Theory of topological insulator waveguides: polarization control and the enhancement of the magneto-electric effect

NASA Astrophysics Data System (ADS)

Crosse, J. A.

2017-02-01

Topological insulators subject to a time-reversal-symmetry-breaking perturbation are predicted to display a magneto-electric effect that causes the electric and magnetic induction fields to mix at the material’s surface. This effect induces polarization rotations of between ≈1-10 mrad per interface in an incident plane-polarized electromagnetic wave normal to a multilayered structure. Here we show, theoretically and numerically, that by using a waveguide geometry with a topological insulator guide layer and magneto-dielectric cladding it is possible to achieve rotations of ≈100 mrad and generate an elliptical polarization with only a three-layered structure. This geometry is beneficial, not only as a way to enhance the magneto-electric effect, rendering it easier to observe, but also as a method for controlling the polarization of electromagnetic radiation.

Study for fabrication, evaluation, and testing of monolayer woven type materials for space suit insulation

NASA Technical Reports Server (NTRS)

Merrick, E. B.

1979-01-01

An alternative space suit insulation concept using a monolayer woven pile material is discussed. The material reduces cost and improves the durability of the overgarment, while providing protection similar to that provided by multilayer insulation (MLI). Twelve samples of different configurations were fabricated and tested for compressibility and thermal conductivity as a function of compression loading. Two samples which showed good results in the initial tests were further tested for thermal conductivity with respect to ambient pressure and temperature. Results of these tests were similar to results of the MLI tests, indicating the potential of the monolayer fabric to replace the present MLI. A seaming study illustrated that the fabric can be sewn in a structurally sound seam with minimal heat loss. It is recommended that a prototype thermal meteroid garment be fabricated.

Cryogenic thermal control technology summaries

NASA Technical Reports Server (NTRS)

Stark, J. A.; Leonhard, K. E.; Bennett, F. O., Jr.

1974-01-01

A summarization and categorization is presented of the pertinent literature associated with cryogenic thermal control technology having potential application to in-orbit fluid transfer systems and/or associated space storage. Initially, a literature search was conducted to obtain pertinent documents for review. Reports determined to be of primary significance were summarized in detail. Each summary, where applicable, consists of; (1) report identification, (2) objective(s) of the work, (3) description of pertinent work performed, (4)major results, and (5) comments of the reviewer (GD/C). Specific areas covered are; (1) multilayer insulation of storage tanks with and without vacuum jacketing, (2) other insulation such as foams, shadow shields, microspheres, honeycomb, vent cooling and composites, (3) vacuum jacketed and composite fluid lines, and (4) low conductive tank supports and insulation penetrations. Reports which were reviewed and not summarized, along with reasons for not summarizing, are also listed.

Advanced Polymer For Multilayer Insulating Blankets

NASA Technical Reports Server (NTRS)

Haghighat, R. Ross; Shepp, Allan

1996-01-01

Polymer resisting degradation by monatomic oxygen undergoing commercial development under trade name "Aorimide" ("atomic-oxygen-resistant imidazole"). Intended for use in thermal blankets for spacecraft in low orbit, useful on Earth in outdoor applications in which sunlight and ozone degrades other plastics. Also used, for example, to make threads and to make films coated with metals for reflectivity.

Lightweight Vacuum Jacket for Cryogenic Insulation. Volume 1

NASA Technical Reports Server (NTRS)

Barclay, D. L.; Bell, J. E.; Brogren, E. W.; Straayer, J. W.

1975-01-01

The feasibility of producing a lightweight vacuum jacket using state-of-the-art technology and materials was examined. Design and analytical studies were made on a full-scale, orbital maneuvering system fuel tank. Preliminary design details were made for the tank assembly, including an optimized vacuum jacket and multilayer insulation system. A half-scale LH2 test model was designed and fabricated, and a force/stiffness proof test was conducted on the vacuum jacket. A vacuum leak rate of .000001 atmosphere ml of helium per second was measured, approximately 1500 hours of vacuum pressure were sustained, and 29 vacuum-pressure cycles were experienced prior to failure.

Theoretical study on the perpendicular anisotropic magnetoresistance using Rashba-type ferromagnetic model

NASA Astrophysics Data System (ADS)

Yahagi, Y.; Miura, D.; Sakuma, A.

2018-05-01

We investigated the anisotropic magnetoresistance (AMR) effects in ferromagnetic-metal multi-layers stacked on non-magnetic insulators in the context of microscopic theory. We represented this situation with tight-binding models that included the exchange and Rashba fields, where the Rashba field was assumed to originate from spin-orbit interactions as junction effects with the insulator. To describe the AMR ratios, the DC conductivity was calculated based on the Kubo formula. As a result, we showed that the Rashba field induced both perpendicular and in-plane AMR effects and that the perpendicular AMR effect rapidly decayed with increasing film thickness.

Lightweight Vacuum Jacket for Cryogenic Insulation - Appendices to Final Report. Volume 2

NASA Technical Reports Server (NTRS)

Barclay, D. L.; Bell, J. E.; Brogren, E. W.; Straayer, J. W.

1975-01-01

The feasibility is demonstrated of producing a lightweight vacuum jacket using state-of-the-art technology and materials. Design and analytical studies were made on an orbital maneuvering system fuel tank. Preliminary design details were completed for the tank assembly which included an optimized vacuum jacket and multilayered insulation system. A half-scale LH2 test model was designed and fabricated and a force/stiffness proof test was conducted on the vacuum jacket. A vacuum leak rate of 0.00001 was measured, approximately 1500 hours of vacuum pressure was sustained, and 29 vacuum pressure cycles were experienced prior to failure. For vol. 1, see N75-26192.

Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

NASA Technical Reports Server (NTRS)

Liu, Donhang; Fetter, Lula; Meinhold, Bruce

2015-01-01

A multi-layer ceramic capacitor (MLCC) is a high-temperature (1350C typical) co-fired ceramic monolithic that is composed of many layers of alternately stacked oxide-based dielectric and internal metal electrodes. To make the dielectric layers insulating and the metal electrode layers conducting, only highly oxidation-resistant precious metals, such as platinum, palladium, and silver, can be used for the co-firing of insulating MLCCs in a regular air atmosphere. MLCCs made with precious metals as internal electrodes and terminations are called precious-metal electrode (PME) capacitors. Currently, all military and space-level applications only address the use of PME capacitors.

NASA Microclimate Cooling Challenges

NASA Technical Reports Server (NTRS)

Trevino, Luis A.

2004-01-01

The purpose of this outline form presentation is to present NASA's challenges in microclimate cooling as related to the spacesuit. An overview of spacesuit flight-rated personal cooling systems is presented, which includes a brief history of cooling systems from Gemini through Space Station missions. The roles of the liquid cooling garment, thermal environment extremes, the sublimator, multi-layer insulation, and helmet visor UV and solar coatings are reviewed. A second section is presented on advanced personal cooling systems studies, which include heat acquisition studies on cooling garments, heat rejection studies on water boiler & radiators, thermal storage studies, and insulation studies. Past and present research and development and challenges are summarized for the advanced studies.

Aerogels Insulate Missions and Consumer Products

NASA Technical Reports Server (NTRS)

2008-01-01

Aspen Aerogels, of Northborough, Massachusetts, worked with NASA through an SBIR contract with Kennedy Space Center to develop a robust, flexible form of aerogel for cryogenic insulation for space shuttle launch applications. The company has since used the same manufacturing process developed under the SBIR award to expand its product offerings into the more commercial realms, making the naturally fragile aerogel available for the first time as a standard insulation that can be handled and installed just like standard insulation.

Analytical Models for Variable Density Multilayer Insulation Used in Cryogenic Storage

NASA Technical Reports Server (NTRS)

Hedayat, A.; Hastings, L. J.; Brown, T.

2001-01-01

A unique multilayer insulation concept for orbital cryogenic storage was experimentally evaluated at NASA Marshall Space Flight Center (MSFC) using the Multipurpose Hydrogen Test Bed (MHTB). A combination of foam/Multi layer Insulation (MLI) was used. The MLI (45 layers of Double Aluminized Mylar (DAM) with Dacron net spacers) was designed for an on-orbit storage period of 45 days and included several unique features such as: a variable layer density and larger but fewer DAM perforations for venting during ascent to orbit. The focus of this paper is on analytical modeling of the variable density MLI performance during orbital coast periods. The foam/MLI combination model is considered to have five segments. The first segment represents the foam layer. The second, third, and fourth segments represent the three layers of MLI with different layer densities and number of shields. Finally, the last segment is considered to be a shroud that surrounds the last MLI layer. The hot boundary temperature is allowed to vary from 164 K to 305 K. To simulate MLI performance, two approaches are considered. In the first approach, the variable density MLI is modeled layer by layer while in the second approach, a semi-empirical model is applied. Both models account for thermal radiation between shields, gas conduction, and solid conduction through the separator materials. The heat flux values predicted by each approach are compared for different boundary temperatures and MLI systems with 30, 45, 60, and 75 layers.

Heat transfer and phase transitions of water in multi-layer cryolithozone-surface systems

NASA Astrophysics Data System (ADS)

Khabibullin, I. L.; Nigametyanova, G. A.; Nazmutdinov, F. F.

2018-01-01

A mathematical model for calculating the distribution of temperature and the dynamics of the phase transfor-mations of water in multilayer systems on permafrost-zone surface is proposed. The model allows one to perform calculations in the annual cycle, taking into account the distribution of temperature on the surface in warm and cold seasons. A system involving four layers, a snow or land cover, a top layer of soil, a layer of thermal-insulation materi-al, and a mineral soil, is analyzed. The calculations by the model allow one to choose the optimal thickness and com-position of the layers which would ensure the stability of structures built on the permafrost-zone surface.

Magnetic and electrical control of engineered materials

DOEpatents

Schuller, Ivan K.; de La Venta Granda, Jose; Wang, Siming; Ramirez, Gabriel; Erekhinskiy, Mikhail; Sharoni, Amos

2016-08-16

Methods, systems, and devices are disclosed for controlling the magnetic and electrical properties of materials. In one aspect, a multi-layer structure includes a first layer comprising a ferromagnetic or ferrimagnetic material, and a second layer positioned within the multi-layer structure such that a first surface of the first layer is in direct physical contact with a second surface of the second layer. The second layer includes a material that undergoes structural phase transitions and metal-insulator transitions upon experiencing a change in temperature. One or both of the first and second layers are structured to allow a structural phase change associated with the second layer cause a change magnetic properties of the first layer.

Superconducting nanowire single-photon detectors with non-periodic dielectric multilayers.

PubMed

Yamashita, Taro; Waki, Kentaro; Miki, Shigehito; Kirkwood, Robert A; Hadfield, Robert H; Terai, Hirotaka

2016-10-24

We present superconducting nanowire single-photon detectors (SSPDs) on non-periodic dielectric multilayers, which enable us to design a variety of wavelength dependences of optical absorptance by optimizing the dielectric multilayer. By adopting a robust simulation to optimize the dielectric multilayer, we designed three types of SSPDs with target wavelengths of 500 nm, 800 nm, and telecom range respectively. We fabricated SSPDs based on the optimized designs for 500 and 800 nm, and evaluated the system detection efficiency at various wavelengths. The results obtained confirm that the designed SSPDs with non-periodic dielectric multilayers worked well. This versatile device structure can be effective for multidisciplinary applications in fields such as the life sciences and remote sensing that require high efficiency over a precise spectral range and strong signal rejection at other wavelengths.

Thermal analysis of continuous and patterned multilayer films in the presence of a nanoscale hot spot

NASA Astrophysics Data System (ADS)

Juang, Jia-Yang; Zheng, Jinglin

2016-10-01

Thermal responses of multilayer films play essential roles in state-of-the-art electronic systems, such as photo/micro-electronic devices, data storage systems, and silicon-on-insulator transistors. In this paper, we focus on the thermal aspects of multilayer films in the presence of a nanoscale hot spot induced by near field laser heating. The problem is set up in the scenario of heat assisted magnetic recording (HAMR), the next-generation technology to overcome the data storage density limit imposed by superparamagnetism. We characterized thermal responses of both continuous and patterned multilayer media films using transient thermal modeling. We observed that material configurations, in particular, the thermal barriers at the material layer interfaces crucially impact the temperature field hence play a key role in determining the hot spot geometry, transient response and power consumption. With a representative generic media model, we further explored the possibility of optimizing thermal performances by designing layers of heat sink and thermal barrier. The modeling approach demonstrates an effective way to characterize thermal behaviors of micro and nano-scale electronic devices with multilayer thin film structures. The insights into the thermal transport scheme will be critical for design and operations of such electronic devices.

Magnetic second-order topological insulators and semimetals

NASA Astrophysics Data System (ADS)

Ezawa, Motohiko

2018-04-01

We propose magnetic second-order topological insulators (SOTIs). First, we study a three-dimensional model. It is pointed out that the previously proposed topological hinge insulator has actually surface states along the [001] direction in addition to hinge states. We gap out these surface states by introducing magnetization, obtaining a SOTI only with hinge states. The bulk topological number is the Z2 index protected by the combined symmetry of the fourfold rotation and the inversion symmetry. We next study two-dimensional magnetic SOTIs, where the corner states are robust also in the presence of the magnetization. Finally, we construct a magnetic second-order topological semimetal by layering the two-dimensional magnetic SOTIs, where hinge-arc states are robust also in the presence of the magnetization.

Experimental verification of acoustic pseudospin multipoles in a symmetry-broken snowflakelike topological insulator

NASA Astrophysics Data System (ADS)

Zhang, Zhiwang; Tian, Ye; Cheng, Ying; Liu, Xiaojun; Christensen, Johan

2017-12-01

Topologically protected wave engineering in artificially structured media resides at the frontier of ongoing metamaterials research, which is inspired by quantum mechanics. Acoustic analogs of electronic topological insulators have recently led to a wealth of new opportunities in manipulating sound propagation by means of robust edge mode excitations through analogies drawn to exotic quantum states. A variety of artificial acoustic systems hosting topological edge states have been proposed analogous to the quantum Hall effect, topological insulators, and Floquet topological insulators in electronic systems. However, those systems were characterized by a fixed geometry and a very narrow frequency response, which severely hinders the exploration and design of useful applications. Here we establish acoustic multipolar pseudospin states as an engineering degree of freedom in time-reversal invariant flow-free phononic crystals and develop reconfigurable topological insulators through rotation of their meta-atoms and reshaping of the metamolecules. Specifically, we show how rotation forms man-made snowflakelike molecules, whose topological phase mimics pseudospin-down (pseudospin-up) dipolar and quadrupolar states, which are responsible for a plethora of robust edge confined properties and topological controlled refraction disobeying Snell's law.

Small satellite generic bus structure

NASA Astrophysics Data System (ADS)

Fiore, John N.; Summers, George D.

1993-02-01

A 'Smallsat' generic structure has been developed for LEO and expendable launch vehicles. The structure makes extensive use of Al-alloy honeycomb-stabilized panels in order to satisfy stiffness, weight, strength and thermal stability requirements in the LEO environment, in conjunction with discrete applications of multilayered insulation blankets and silverized Teflon radiators. The Smallsat structure is ideally suited for assembly-line manufacturing and storage until required.

Robust odd-parity superconductivity in the doped topological insulator Nb x Bi 2 Se 3

DOE PAGES

Smylie, M. P.; Willa, K.; Claus, H.; ...

2017-09-15

We present resistivity and magnetization measurements on proton-irradiated crystals demonstrating that the superconducting state in the doped topological insulator Nb xBi 2Se 3 (x = 0.25) is surprisingly robust against disorder-induced electron scattering. The superconducting transition temperature Tc decreases without indication of saturation with increasing defect concentration, and the corresponding scattering rates far surpass expectations based on conventional theory. The low-temperature variation of the London penetration depth Δλ(T) follows a power law [Δλ(T)~T 2] indicating the presence of symmetry-protected point nodes. Lastly, our results are consistent with the proposed robust nematic E u pairing state in this material.

Robust odd-parity superconductivity in the doped topological insulator NbxBi2Se3

NASA Astrophysics Data System (ADS)

Smylie, M. P.; Willa, K.; Claus, H.; Snezhko, A.; Martin, I.; Kwok, W.-K.; Qiu, Y.; Hor, Y. S.; Bokari, E.; Niraula, P.; Kayani, A.; Mishra, V.; Welp, U.

2017-09-01

We present resistivity and magnetization measurements on proton-irradiated crystals demonstrating that the superconducting state in the doped topological insulator NbxBi2Se3 (x =0.25 ) is surprisingly robust against disorder-induced electron scattering. The superconducting transition temperature Tc decreases without indication of saturation with increasing defect concentration, and the corresponding scattering rates far surpass expectations based on conventional theory. The low-temperature variation of the London penetration depth Δ λ (T ) follows a power law [Δ λ (T ) ˜T2] indicating the presence of symmetry-protected point nodes. Our results are consistent with the proposed robust nematic Eu pairing state in this material.

High-quality multilayer graphene on an insulator formed by diffusion controlled Ni-induced layer exchange

NASA Astrophysics Data System (ADS)

Murata, H.; Saitoh, N.; Yoshizawa, N.; Suemasu, T.; Toko, K.

2017-12-01

The Ni-induced layer-exchange growth of amorphous carbon is a unique method used to fabricate uniform multilayer graphene (MLG) directly on an insulator. To improve the crystal quality of MLG, we prepare AlOx or SiO2 interlayers between amorphous C and Ni layers, which control the extent of diffusion of C atoms into the Ni layer. The growth morphology and Raman spectra observed from MLG formed by layer exchange strongly depend on the material type and thickness of the interlayers; a 1-nm-thick AlOx interlayer is found to be ideal for use in experiments. Transmission electron microscopy and electron energy-loss spectra reveal that the crystal quality of the resulting MLG is much higher than that of a sample without an interlayer. The grain size reaches a few μm, leading to an electrical conductivity of 1290 S/cm. The grain size and the electrical conductivity are the highest among MLG synthesized using a solid-phase reaction including metal-induced crystallization. The direct synthesis of uniform, high-quality MLG on arbitrary substrates will pave the way for advanced electronic devices integrated with carbon materials.

Theory of topological insulator waveguides: polarization control and the enhancement of the magneto-electric effect

PubMed Central

Crosse, J. A.

2017-01-01

Topological insulators subject to a time-reversal-symmetry-breaking perturbation are predicted to display a magneto-electric effect that causes the electric and magnetic induction fields to mix at the material’s surface. This effect induces polarization rotations of between ≈1–10 mrad per interface in an incident plane-polarized electromagnetic wave normal to a multilayered structure. Here we show, theoretically and numerically, that by using a waveguide geometry with a topological insulator guide layer and magneto-dielectric cladding it is possible to achieve rotations of ≈100 mrad and generate an elliptical polarization with only a three-layered structure. This geometry is beneficial, not only as a way to enhance the magneto-electric effect, rendering it easier to observe, but also as a method for controlling the polarization of electromagnetic radiation. PMID:28220875

Integrated Cryogenic Experiment (ICE) microsphere investigation

NASA Technical Reports Server (NTRS)

Spradley, I.; Read, D.

1989-01-01

The main objective is to determine the performance of microsphere insulation in a 0-g environment and compare its performance to reference insulations such as multilayer insulation. The Lockheed Helium Extended-Life Dewar (HELD) is used to provide superfluid-helium cold sink for the experiment. The use of HELD allows the low-g dynamic properties of Passive Orbital Disconnect Struts (PODS) to be characterized and provides a flight demonstration of the PODS system. The thermal performance of microspheres in 1 and 0 g was predicted, a flight experiment was designed to determine microsphere thermal performance, and the interface was also designed between the experimental package and the shuttle through HELD and the Hitchhiker-M carrier. A single test cell was designed and fabricated. The cell was filled with uncoated glass microspheres and tested with a liquid-nitrogen cold sink. The data were found to agree with predictions of microsphere performance in 1 g.

Capacitance Variation Induced by Microfluidic Two-Phase Flow across Insulated Interdigital Electrodes in Lab-On-Chip Devices

PubMed Central

Dong, Tao; Barbosa, Cátia

2015-01-01

Microfluidic two-phase flow detection has attracted plenty of interest in various areas of biology, medicine and chemistry. This work presents a capacitive sensor using insulated interdigital electrodes (IDEs) to detect the presence of droplets in a microchannel. This droplet sensor is composed of a glass substrate, patterned gold electrodes and an insulation layer. A polydimethylsiloxane (PDMS) cover bonded to the multilayered structure forms a microchannel. Capacitance variation induced by the droplet passage was thoroughly investigated with both simulation and experimental work. Olive oil and deionized water were employed as the working fluids in the experiments to demonstrate the droplet sensor. The results show a good sensitivity of the droplet with the appropriate measurement connection. This capacitive droplet sensor is promising to be integrated into a lab-on-chip device for in situ monitoring/counting of droplets or bubbles. PMID:25629705

Low thrust chemical orbit to orbit propulsion system propellant management study

NASA Technical Reports Server (NTRS)

Dergance, R. H.; Hamlyn, K. M.; Tegart, J. R.

1981-01-01

Low thrust chemical propulsion systems were sized for transfer of large space systems from LEO to GEO. The influence of propellant combination, tankage and insulation requirements, and propellant management techniques on the LTPS mass and volume were studied. Liquid oxygen combined with hydrogen, methane or kerosene were the propellant combinations. Thrust levels of 445, 2230, and 4450 N were combined with 1, 4 and 8 perigee burn strategies. This matrix of systems was evaluated using multilayer insulation and spray-on-foam insulation systems. Various combinations of toroidal, cylindrical with ellipsoidal domes, and ellipsoidal tank shapes were investigated. Results indicate that low thrust (445 N) and single perigee burn approaches are considerably less efficient than the higher thrust level and multiple burn strategies. A modified propellant settling approach minimized propellant residuals and decreased system complexity, in addition, the toroid/ellipsoidal tank combination was predicted to be shortest.

Photo-crosslinkable polymers for fabrication of photonic multilayer sensors

NASA Astrophysics Data System (ADS)

Chiappelli, Maria; Hayward, Ryan C.

2013-03-01

We have used photo-crosslinkable polymers to fabricate photonic multilayer sensors. Benzophenone is utilized as a covalently incorporated pendent photo-crosslinker, providing a convenient means of fabricating multilayer films by sequential spin-coating and crosslinking processes. Colorimetric temperature sensors were designed from thermally-responsive, low-refractive index poly(N-isopropylacrylamide) (PNIPAM) and high-refractive index poly(para-methyl styrene) (P pMS). Copolymer chemistries and layer thicknesses were selected to provide robust multilayer sensors which show color changes across nearly the full visible spectrum due to changes in temperature of the hydrated film stack. We have characterized the uniformity and interfacial broadening within the multilayers, the kinetics of swelling and de-swelling, and the reversibility over multiple hydration/dehydration cycles. We also describe how the approach can be extended to alternative sensor designs through the ability to tailor each layer independently, as well as to additional stimuli by selecting alternative copolymer chemistries.

Process For Cutting Polymers Electrolyte Multi-Layer Batteries And Batteries Obtained Thereby

DOEpatents

Gauthier, Michel; Lessard, Ginette; Dussault, Gaston; Rouillard, Roger; Simoneau, Martin; Miller, Alan Paul

2003-09-09

A stacking of battery laminate is prepared, each battery consisting of anode, polymer electrolyte, cathode films and possibly an insulating film, under conditions suitable to constitute a rigid monoblock assembly, in which the films are unitary with one another. The assembly obtained is thereafter cut in predetermined shape by using a mechanical device without macroscopic deformation of the films constituting the assembly and without inducing permanent short circuits. The battery which is obtained after cutting includes at least one end which appears as a uniform cut, the various films constituting the assembly having undergone no macroscopic deformation, the edges of the films of the anode including an electronically insulating passivation film.

Light emitting ceramic device

DOEpatents

Valentine, Paul; Edwards, Doreen D.; Walker, Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

2010-05-18

A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, is herein claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

Cryogenic insulation standard data and methodologies

NASA Astrophysics Data System (ADS)

Demko, J. A.; Fesmire, J. E.; Johnson, W. L.; Swanger, A. M.

2014-01-01

Although some standards exist for thermal insulation, few address the sub-ambient temperature range and cold-side temperatures below 100 K. Standards for cryogenic insulation systems require cryostat testing and data analysis that will allow the development of the tools needed by design engineers and thermal analysts for the design of practical cryogenic systems. Thus, this critically important information can provide reliable data and methodologies for industrial efficiency and energy conservation. Two Task Groups have been established in the area of cryogenic insulation systems Under ASTM International's Committee C16 on Thermal Insulation. These are WK29609 - New Standard for Thermal Performance Testing of Cryogenic Insulation Systems and WK29608 - Standard Practice for Multilayer Insulation in Cryogenic Service. The Cryogenics Test Laboratory of NASA Kennedy Space Center and the Thermal Energy Laboratory of LeTourneau University are conducting Inter-Laboratory Study (ILS) of selected insulation materials. Each lab carries out the measurements of thermal properties of these materials using identical flat-plate boil-off calorimeter instruments. Parallel testing will provide the comparisons necessary to validate the measurements and methodologies. Here we discuss test methods, some initial data in relation to the experimental approach, and the manner reporting the thermal performance data. This initial study of insulation materials for sub-ambient temperature applications is aimed at paving the way for further ILS comparative efforts that will produce standard data sets for several commercial materials. Discrepancies found between measurements will be used to improve the testing and data reduction techniques being developed as part of the future ASTM International standards.

Robust 300 C wire insulation system

NASA Technical Reports Server (NTRS)

Nairus, John G.

1994-01-01

The objective of this program is to identify, develop, and demonstrate an optimum wire insulation system that is capable of continuous operation at 300 C. The system is to possess a combination of superior electrical (AC or DC), mechanical, and physical properties over the KAPTON (trademark) derived insulations described in MIL-W-81381 and those hybrid constructions identified in Air Force contract F33615-89-C-5606, commonly known as TKT constructions.

The symmetry and coupling properties of solutions in general anisotropic multilayer waveguides.

PubMed

Hernando Quintanilla, F; Lowe, M J S; Craster, R V

2017-01-01

Multilayered plate and shell structures play an important role in many engineering settings where, for instance, coated pipes are commonplace such as in the petrochemical, aerospace, and power generation industries. There are numerous demands, and indeed requirements, on nondestructive evaluation (NDE) to detect defects or to measure material properties using guided waves; to choose the most suitable inspection approach, it is essential to know the properties of the guided wave solutions for any given multilayered system and this requires dispersion curves computed reliably, robustly, and accurately. Here, the circumstances are elucidated, and possible layer combinations, under which guided wave solutions, in multilayered systems composed of generally anisotropic layers in flat and cylindrical geometries, have specific properties of coupling and parity; the partial wave decomposition of the wave field is utilised to unravel the behaviour. A classification into five families is introduced and the authors claim that this is the fundamental way to approach generally anisotropic waveguides. This coupling and parity provides information to be used in the design of more efficient and robust dispersion curve tracing algorithms. A critical benefit is that the analysis enables the separation of solutions into categories for which dispersion curves do not cross; this allows the curves to be calculated simply and without ambiguity.

Magnetic interactions in anisotropic Nd-Dy-Fe-Co-B/α-Fe multilayer magnets

NASA Astrophysics Data System (ADS)

Dai, Z. M.; Liu, W.; Zhao, X. T.; Han, Z.; Kim, D.; Choi, C. J.; Zhang, Z. D.

2016-10-01

The magnetic properties and the possible interaction mechanisms of anisotropic soft- and hard-magnetic multilayers have been investigated by altering the thickness of different kinds of spacer layers. The metal Ta and the insulating oxides MgO, Cr2O3 have been chosen as spacer layers to investigate the characteristics of the interactions between soft- and hard-magnetic layers in the anisotropic Nd-Dy-Fe-Co-B/α-Fe multilayer system. The dipolar and exchange interaction between hard and soft phases are evaluated with the help of the first order reversal curve method. The onset of the nucleation field and the magnetization reversal by domain wall movement are also evident from the first-order-reversal-curve measurements. Reversible/irreversible distributions reveal the natures of the soft- and hard-magnetic components. Incoherent switching fields are observed and the calculations show the semiquantitative contributions of hard and soft components to the system. An antiferromagnetic spacer layer will weaken the interaction between ferromagnetic layers and the effective interaction length decreases. As a consequence, the dipolar magnetostatic interaction may play an important role in the long-range interaction in anisotropic multilayer magnets.

Synthesis of large-area multilayer hexagonal boron nitride for high material performance

PubMed Central

Kim, Soo Min; Hsu, Allen; Park, Min Ho; Chae, Sang Hoon; Yun, Seok Joon; Lee, Joo Song; Cho, Dae-Hyun; Fang, Wenjing; Lee, Changgu; Palacios, Tomás; Dresselhaus, Mildred; Kim, Ki Kang; Lee, Young Hee; Kong, Jing

2015-01-01

Although hexagonal boron nitride (h-BN) is a good candidate for gate-insulating materials by minimizing interaction from substrate, further applications to electronic devices with available two-dimensional semiconductors continue to be limited by flake size. While monolayer h-BN has been synthesized on Pt and Cu foil using chemical vapour deposition (CVD), multilayer h-BN is still absent. Here we use Fe foil and synthesize large-area multilayer h-BN film by CVD with a borazine precursor. These films reveal strong cathodoluminescence and high mechanical strength (Young's modulus: 1.16±0.1 TPa), reminiscent of formation of high-quality h-BN. The CVD-grown graphene on multilayer h-BN film yields a high carrier mobility of ∼24,000 cm2 V−1 s−1 at room temperature, higher than that (∼13,000 2 V−1 s−1) with exfoliated h-BN. By placing additional h-BN on a SiO2/Si substrate for a MoS2 (WSe2) field-effect transistor, the doping effect from gate oxide is minimized and furthermore the mobility is improved by four (150) times. PMID:26507400

Thermal Analysis on Cryogenic Liquid Hydrogen Tank on an Unmanned Aerial Vehicle System

NASA Technical Reports Server (NTRS)

Wang, Xiao-Yen; Harpster, George; Hunter, James

2007-01-01

Thermal analyses are performed on the liquid hydrogen (LH2) tank designed for an unmanned aerial vehicle (UAV) powered by solar arrays and a regenerative proton-exchange membrane (PEM) fuel cell. A 14-day cruise mission at a 65,000 ft altitude is considered. Thermal analysis provides the thermal loads on the tank system and the boiling-off rates of LH2. Different approaches are being considered to minimize the boiling-off rates of the LH2. It includes an evacuated multilayer insulation (MLI) versus aerogel insulation on the LH2 tank and aluminum versus stainless steel spacer rings between the inner and outer tank. The resulting boil-off rates of LH2 provided by the one-dimensional model and three-dimensional finite element analysis (FEA) on the tank system are presented and compared to validate the results of the three-dimensional FEA. It concludes that heat flux through penetrations by conduction is as significant as that through insulation around the tank. The tank system with MLI insulation and stainless steel spacer rings result in the lowest boiling-off rate of LH2.

A method to restrain the charging effect on an insulating substrate in high energy electron beam lithography

NASA Astrophysics Data System (ADS)

Mingyan, Yu; Shirui, Zhao; Yupeng, Jing; Yunbo, Shi; Baoqin, Chen

2014-12-01

Pattern distortions caused by the charging effect should be reduced while using the electron beam lithography process on an insulating substrate. We have developed a novel process by using the SX AR-PC 5000/90.1 solution as a spin-coated conductive layer, to help to fabricate nanoscale patterns of poly-methyl-methacrylate polymer resist on glass for phased array device application. This method can restrain the influence of the charging effect on the insulating substrate effectively. Experimental results show that the novel process can solve the problems of the distortion of resist patterns and electron beam main field stitching error, thus ensuring the accuracy of the stitching and overlay of the electron beam lithography system. The main characteristic of the novel process is that it is compatible to the multi-layer semiconductor process inside a clean room, and is a green process, quite simple, fast, and low cost. It can also provide a broad scope in the device development on insulating the substrate, such as high density biochips, flexible electronics and liquid crystal display screens.

Flat-walled multilayered anechoic linings: Optimization and application

NASA Astrophysics Data System (ADS)

Xu, Jingfeng; Buchholz, Jörg M.; Fricke, Fergus R.

2005-11-01

The concept of flat-walled multilayered absorbent linings for anechoic rooms was proposed three decades ago. Flat-walled linings have the advantage of being less complicated and, hence, less costly to manufacture and install than the individual units such as wedges. However, there are difficulties in optimizing the design of such absorbent linings. In the present work, the design of a flat-walled multilayered anechoic lining that targeted a 250 Hz cut-off frequency and a 300 mm maximum lining thickness was first optimized using an evolutionary algorithm. Sixteen of the most commonly used commercial fibrous building insulation materials available in Australia were investigated and fourteen design options (i.e., material combinations) were found by the evolutionary algorithm. These options were then evaluated in accordance with their costs and measured acoustic absorption performances. Finally, the completed anechoic room, where the optimized design was applied, was qualified and the results showed that a large percentage (75%-85%) of the distance between the sound source and the room boundaries, on the traverses made, were anechoic.

Multilayered photonic integration on SOI platform using waveguide-based bridge structure

NASA Astrophysics Data System (ADS)

Majumder, Saikat; Chakraborty, Rajib

2018-06-01

A waveguide based structure on silicon on insulator platform is proposed for vertical integration in photonic integrated circuits. The structure consists of two multimode interference couplers connected by a single mode (SM) section which can act as a bridge over any other underlying device. Two more SM sections acts as input and output of the first and second multimode couplers respectively. Potential application of this structure is in multilayered photonic links. It is shown that the efficiency of the structure can be improved by making some design modifications. The entire simulation is done using effective-index based matrix method. The feature size chosen are comparable to waveguides fabricated previously so as to fabricate the proposed structure easily.

NASTRAN thermal analyzer: Theory and application including a guide to modeling engineering problems, volume 2. [sample problem library guide

NASA Technical Reports Server (NTRS)

Jackson, C. E., Jr.

1977-01-01

A sample problem library containing 20 problems covering most facets of Nastran Thermal Analyzer modeling is presented. Areas discussed include radiative interchange, arbitrary nonlinear loads, transient temperature and steady-state structural plots, temperature-dependent conductivities, simulated multi-layer insulation, and constraint techniques. The use of the major control options and important DMAP alters is demonstrated.

Humidity Steady State Low Voltage Testing of MLCCs (Based on NESC Technical Assessment Report)

NASA Technical Reports Server (NTRS)

Sampson, Mike; Brusse, Jay; Teverovsky, Alexander

2011-01-01

Review of the low voltage reduced Insulation Resistance (IR) failure phenomenon in Multilayer ceramic capacitors (MLCCs)and NASA approaches to contend with this risk. 1. Analyze published materials on root cause mechanisms. 2. Investigate suitability of current test methods to assess MLCC lots for susceptibility. 3. Review current NASA parts selection and application guidelines in consideration of benefits vs. disadvantages.

Control of Multilayer Networks

PubMed Central

Menichetti, Giulia; Dall’Asta, Luca; Bianconi, Ginestra

2016-01-01

The controllability of a network is a theoretical problem of relevance in a variety of contexts ranging from financial markets to the brain. Until now, network controllability has been characterized only on isolated networks, while the vast majority of complex systems are formed by multilayer networks. Here we build a theoretical framework for the linear controllability of multilayer networks by mapping the problem into a combinatorial matching problem. We found that correlating the external signals in the different layers can significantly reduce the multiplex network robustness to node removal, as it can be seen in conjunction with a hybrid phase transition occurring in interacting Poisson networks. Moreover we observe that multilayer networks can stabilize the fully controllable multiplex network configuration that can be stable also when the full controllability of the single network is not stable. PMID:26869210

Engineering spin-orbit torque in Co/Pt multilayers with perpendicular magnetic anisotropy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Kuo-Feng; Wang, Ding-Shuo; Lai, Chih-Huang, E-mail: chlai@mx.nthu.edu.tw

To address thermal stability issues for spintronic devices with a reduced size, we investigate spin-orbit torque in Co/Pt multilayers with strong perpendicular magnetic anisotropy. Note that the spin-orbit torque arises from the global imbalance of the spin currents from the top and bottom interfaces for each Co layer. By inserting Ta or Cu layers to strengthen the top-down asymmetry, the spin-orbit torque efficiency can be greatly modified without compromised perpendicular magnetic anisotropy. Above all, the efficiency builds up as the number of layers increases, realizing robust thermal stability and high spin-orbit-torque efficiency simultaneously in the multilayers structure.

Robust optimization of the laser induced damage threshold of dielectric mirrors for high power lasers.

PubMed

Chorel, Marine; Lanternier, Thomas; Lavastre, Éric; Bonod, Nicolas; Bousquet, Bruno; Néauport, Jérôme

2018-04-30

We report on a numerical optimization of the laser induced damage threshold of multi-dielectric high reflection mirrors in the sub-picosecond regime. We highlight the interplay between the electric field distribution, refractive index and intrinsic laser induced damage threshold of the materials on the overall laser induced damage threshold (LIDT) of the multilayer. We describe an optimization method of the multilayer that minimizes the field enhancement in high refractive index materials while preserving a near perfect reflectivity. This method yields a significant improvement of the damage resistance since a maximum increase of 40% can be achieved on the overall LIDT of the multilayer.

SHIIVER_Interview_And_Move

NASA Image and Video Library

2017-08-10

A technical challenge that NASA is working to solve is how to maintain super-cooled liquid propellants to be used as fuel for deep space missions. Heat intercept concepts such as advanced insulation blankets, foam insulation and vapor-based concepts will be evaluated with the Structural Heat Intercept Insulation Vibration Evaluation Rig or SHIIVER. The SHIIVER tank arrived Aug. 10 at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for application of its first round of insulation. While at Marshall, the tank will have sensors installed. The team will then apply spray-on foam insulation (SOFI) to the 13-foot-long tank in Marshall’s Thermal Protection System Facility. A rotisserie-style fixture allows for even spraying of large objects. Following SOFI trimming, the tank will undergo a white-light scan to measure its final dimensions to assist with eventual Multi-Layer Insulation (MLI) application. The SOFI and MLI will reduce future propellant storage tank heat leak while on the launch pad where it is subject to atmospheric temperature and pressure conditions. After the spray-on foam insulation application, the tank will travel to Plum Brook Station in Sandusky, Ohio, which is managed by Glenn, for assembly, integration and testing in the B2 test chamber. The assembly will first undergo thermal vacuum testing with only SOFI on the tank surface. This will be the baseline heat load from which to assess future improvements. Then, the tank will be insulated on the top and bottom domes with MLI over the layer of SOFI and will undergo further cryogenic testing.

Multilayer Perceptron for Robust Nonlinear Interval Regression Analysis Using Genetic Algorithms

PubMed Central

2014-01-01

On the basis of fuzzy regression, computational models in intelligence such as neural networks have the capability to be applied to nonlinear interval regression analysis for dealing with uncertain and imprecise data. When training data are not contaminated by outliers, computational models perform well by including almost all given training data in the data interval. Nevertheless, since training data are often corrupted by outliers, robust learning algorithms employed to resist outliers for interval regression analysis have been an interesting area of research. Several approaches involving computational intelligence are effective for resisting outliers, but the required parameters for these approaches are related to whether the collected data contain outliers or not. Since it seems difficult to prespecify the degree of contamination beforehand, this paper uses multilayer perceptron to construct the robust nonlinear interval regression model using the genetic algorithm. Outliers beyond or beneath the data interval will impose slight effect on the determination of data interval. Simulation results demonstrate that the proposed method performs well for contaminated datasets. PMID:25110755

Multilayer perceptron for robust nonlinear interval regression analysis using genetic algorithms.

PubMed

Hu, Yi-Chung

2014-01-01

On the basis of fuzzy regression, computational models in intelligence such as neural networks have the capability to be applied to nonlinear interval regression analysis for dealing with uncertain and imprecise data. When training data are not contaminated by outliers, computational models perform well by including almost all given training data in the data interval. Nevertheless, since training data are often corrupted by outliers, robust learning algorithms employed to resist outliers for interval regression analysis have been an interesting area of research. Several approaches involving computational intelligence are effective for resisting outliers, but the required parameters for these approaches are related to whether the collected data contain outliers or not. Since it seems difficult to prespecify the degree of contamination beforehand, this paper uses multilayer perceptron to construct the robust nonlinear interval regression model using the genetic algorithm. Outliers beyond or beneath the data interval will impose slight effect on the determination of data interval. Simulation results demonstrate that the proposed method performs well for contaminated datasets.

Aerogel Beads as Cryogenic Thermal Insulation System

NASA Technical Reports Server (NTRS)

Fesmire, J. E.; Augustynowicz, S. D.; Rouanet, S.; Thompson, Karen (Technical Monitor)

2001-01-01

An investigation of the use of aerogel beads as thermal insulation for cryogenic applications was conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. Steady-state liquid nitrogen boiloff methods were used to characterize the thermal performance of aerogel beads in comparison with conventional insulation products such as perlite powder and multilayer insulation (MLI). Aerogel beads produced by Cabot Corporation have a bulk density below 100 kilograms per cubic meter (kg/cubic m) and a mean particle diameter of 1 millimeter (mm). The apparent thermal conductivity values of the bulk material have been determined under steady-state conditions at boundary temperatures of approximately 293 and 77 kelvin (K) and at various cold vacuum pressures (CVP). Vacuum levels ranged from 10(exp -5) torr to 760 torr. All test articles were made in a cylindrical configuration with a typical insulation thickness of 25 mm. Temperature profiles through the thickness of the test specimens were also measured. The results showed the performance of the aerogel beads was significantly better than the conventional materials in both soft-vacuum (1 to 10 torr) and no-vacuum (760 torr) ranges. Opacified aerogel beads performed better than perlite powder under high-vacuum conditions. Further studies for material optimization and system application are in progress.

Long-term cryogenic space storage system

NASA Technical Reports Server (NTRS)

Hopkins, R. A.; Chronic, W. L.

1973-01-01

Discussion of the design, fabrication and testing of a 225-cu ft spherical cryogenic storage system for long-term subcritical applications under zero-g conditions in storing subcritical cryogens for space vehicle propulsion systems. The insulation system design, the analytical methods used, and the correlation between the performance test results and analytical predictions are described. The best available multilayer insulation materials and state-of-the-art thermal protection concepts were applied in the design, providing a boiloff rate of 0.152 lb/hr, or 0.032% per day, and an overall heat flux of 0.066 Btu/sq ft hr based on a 200 sq ft surface area. A six to eighteen month cryogenic storage is provided by this system for space applications.

Highly ductile multilayered films by layer-by-layer assembly of oppositely charged polyurethanes for biomedical applications.

PubMed

Podsiadlo, Paul; Qin, Ming; Cuddihy, Meghan; Zhu, Jian; Critchley, Kevin; Kheng, Eugene; Kaushik, Amit K; Qi, Ying; Kim, Hyoung-Sug; Noh, Si-Tae; Arruda, Ellen M; Waas, Anthony M; Kotov, Nicholas A

2009-12-15

Multilayered thin films prepared with the layer-by-layer (LBL) assembly technique are typically "brittle" composites, while many applications such as flexible electronics or biomedical devices would greatly benefit from ductile, and tough nanostructured coatings. Here we present the preparation of highly ductile multilayered films via LBL assembly of oppositely charged polyurethanes. Free-standing films were found to be robust, strong, and tough with ultimate strains as high as 680% and toughness of approximately 30 MJ/m(3). These results are at least 2 orders of magnitude greater than most LBL materials presented until today. In addition to enhanced ductility, the films showed first-order biocompatibility with animal and human cells. Multilayered structures incorporating polyurethanes open up a new research avenue into the preparation of multifunctional nanostructured films with great potential in biomedical applications.

Architecture for high critical current superconducting tapes

DOEpatents

Jia, Quanxi; Foltyn, Stephen R.

2002-01-01

Improvements in critical current capacity for superconducting film structures are disclosed and include the use of, e.g., multilayer YBCO structures where individual YBCO layers are separated by a layer of an insulating material such as CeO.sub.2 and the like, a layer of a conducting material such as strontium ruthenium oxide and the like or by a second superconducting material such as SmBCO and the like.

High thermal conductivity lossy dielectric using co-densified multilayer configuration

DOEpatents

Tiegs, Terry N.; Kiggans, Jr., James O.

2003-06-17

Systems and methods are described for loss dielectrics. A method of manufacturing a lossy dielectric includes providing at least one high dielectric loss layer and providing at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer and then densifying together. The systems and methods provide advantages because the lossy dielectrics are less costly and more environmentally friendly than the available alternatives.

Analytical Modeling of Variable Density Multilayer Insulation for Cryogenic Storage

NASA Technical Reports Server (NTRS)

Hedayat, A.; Hastings, L. J.; Brown, T.; Cruit, Wendy (Technical Monitor)

2001-01-01

A unique foam/Multilayer Insulation (MLI) combination concept for orbital cryogenic storage was experimentally evaluated at NASA Marshall Space Flight Center (MSFC) using the Multipurpose Hydrogen Test Bed (MHTB). The MLI was designed for an on-orbit storage period of 45 days and included several unique features such as: a variable layer density and larger but fewer perforations for venting during ascent to orbit. Test results with liquid hydrogen indicated that the MLI weight or heat leak is reduced by about half in comparison with standard MLI. The focus of this paper is on analytical modeling of the Variable Density MLI (VD-MLI) on-orbit performance (i.e. vacuum/low pressure environment). The foam/VD-MLI combination model is considered to have five segments. The first segment represents the optional foam layer. The second, third, and fourth segments represent three MLI segments with different layer densities. The last segment is considered to be a shroud that surrounds the last MLI layer. Two approaches are considered. In the first approach, the variable density MLI is modeled layer by layer while in the second approach, a semi-empirical model is applied. Both models account for thermal radiation between shields, gas conduction, and solid conduction through the layer separator materials.

Effect of multi-layer thermal insulation thickness and location on the hypervelocity impact response of dual-wall structures

NASA Astrophysics Data System (ADS)

Schonberg, William P.

Traditional perforation-resistant wall design for long-duration spacecraft consists of a "bumper" that is placed a small distance away from the main "pressure wall" of a spacecraft compartment or module. This concept has been studied extensively as a means of reducing the perforation threat of hypervelocity projectiles such as meteoroids and orbital debris. If a dual-wall system is employed on an earth-orbiting spacecraft, then a blanket of multi-layer insulation (MLI) will typically be included within the dual-wall system for thermal protection purposes. This paper presents the results of an experimental study in which aluminum dual-wall structures were tested under a variety of high-speed impact conditions to study the effect of MLI thickness and location on perforation resistance. The results presented consist of test-by-test comparisons of the damage sustained by similar dual-wall systems with blanket MLI of various thicknesses and at various locations within the dual-wall systems under similar impact loading conditions. The analyses performed revealed that the placement of the MLI had a significant effect on the ballistic limit of the dual-wall structures considered while reducing the thickness of the MLI by as much as 1/3 did not.

Direct Observation of Surface Potential Distribution in Insulation Resistance Degraded Acceptor-Doped BaTiO3 Multilayered Ceramic Capacitors

NASA Astrophysics Data System (ADS)

Hong, Kootak; Lee, Tae Hyung; Suh, Jun Min; Park, Jae-Sung; Kwon, Hyung-Soon; Choi, Jaeho; Jang, Ho Won

2018-05-01

Insulation resistance (IR) degradation in BaTiO3 is a key issue for developing miniaturized multilayer ceramic capacitors (MLCCs) with high capacity. Despite rapid progress in BaTiO3-based MLCCs, the mechanism of IR degradation is still controversial. In this study, we demonstrate the Al doping effect on IR degradation behavior of BaTiO3 MLCCs by electrical measurements and scanning Kelvin probe microscopy (SKPM). As the Al doping concentration in BaTiO3 increases, IR degradation of MLCCs seems to be suppressed from electrical characterization results. However, SKPM results reveal that the conductive regions near the cathode become lager with Al doping after IR degradation. The formation of conducting regions is attributed to the migration of oxygen vacancies, which is the origin of IR degradation in BaTiO3, in dielectric layers. These results imply that acceptor doping in BaTiO3 solely cannot suppress the IR degradation in MLCC even though less asymmetric IR characteristics and IR degradation in MLCCs with higher Al doping concentration are observed from electrical characterization. Our results strongly suggest that observing the surface potential distribution in IR degraded dielectric layers using SKPM is an effective method to unravel the mechanism of IR degradation in MLCCs.

International Test Program for Synergistic Atomic Oxygen and VUV Exposure of Spacecraft Materials

NASA Technical Reports Server (NTRS)

Rutledge, Sharon; Banks, Bruce; Dever, Joyce; Savage, William

2000-01-01

Spacecraft in low Earth orbit (LEO) are subject to degradation in thermal and optical performance of components and materials through interaction with atomic oxygen and vacuum ultraviolet radiation which are predominant in LEO. Due to the importance of LEO durability and performance to manufacturers and users, an international test program for assessing the durability of spacecraft materials and components was initiated. Initial tests consisted of exposure of samples representing a variety of thermal control paints and multilayer insulation materials that have been used in space. Materials donated from various international sources were tested alongside a material whose performance is well known such as Teflon FEP or Kapton H for multilayer insulation, or Z-93-P for white thermal control paints. The optical, thermal or mass loss data generated during the test was then provided to the participating material supplier. Data was not published unless the participant donating the material consented to publication. This paper presents a description of the types of tests and facilities that have been used for the test program as well as some examples of data that have been generated. The test program is intended to give spacecraft builders and users a better understanding of degradation processes and effects to enable improved prediction of spacecraft performance.

A multi-layer steganographic method based on audio time domain segmented and network steganography

NASA Astrophysics Data System (ADS)

Xue, Pengfei; Liu, Hanlin; Hu, Jingsong; Hu, Ronggui

2018-05-01

Both audio steganography and network steganography are belong to modern steganography. Audio steganography has a large capacity. Network steganography is difficult to detect or track. In this paper, a multi-layer steganographic method based on the collaboration of them (MLS-ATDSS&NS) is proposed. MLS-ATDSS&NS is realized in two covert layers (audio steganography layer and network steganography layer) by two steps. A new audio time domain segmented steganography (ATDSS) method is proposed in step 1, and the collaboration method of ATDSS and NS is proposed in step 2. The experimental results showed that the advantage of MLS-ATDSS&NS over others is better trade-off between capacity, anti-detectability and robustness, that means higher steganographic capacity, better anti-detectability and stronger robustness.

Fabricating microfluidic valve master molds in SU-8 photoresist

NASA Astrophysics Data System (ADS)

Dy, Aaron J.; Cosmanescu, Alin; Sluka, James; Glazier, James A.; Stupack, Dwayne; Amarie, Dragos

2014-05-01

Multilayer soft lithography has become a powerful tool in analytical chemistry, biochemistry, material and life sciences, and medical research. Complex fluidic micro-circuits require reliable components that integrate easily into microchips. We introduce two novel approaches to master mold fabrication for constructing in-line micro-valves using SU-8. Our fabrication techniques enable robust and versatile integration of many lab-on-a-chip functions including filters, mixers, pumps, stream focusing and cell-culture chambers, with in-line valves. SU-8 created more robust valve master molds than the conventional positive photoresists used in multilayer soft lithography, but maintained the advantages of biocompatibility and rapid prototyping. As an example, we used valve master molds made of SU-8 to fabricate PDMS chips capable of precisely controlling beads or cells in solution.

Evolution of topological skyrmions across the spin reorientation transition in Pt/Co/Ta multilayers

NASA Astrophysics Data System (ADS)

He, Min; Li, Gang; Zhu, Zhaozhao; Zhang, Ying; Peng, Licong; Li, Rui; Li, Jianqi; Wei, Hongxiang; Zhao, Tongyun; Zhang, X.-G.; Wang, Shouguo; Lin, Shi-Zeng; Gu, Lin; Yu, Guoqiang; Cai, J. W.; Shen, Bao-gen

2018-05-01

Magnetic skyrmions in multilayers are particularly appealing as next generation memory devices due to their topological compact size, the robustness against external perturbations, the capability of electrical driving and detection, and the compatibility with the existing spintronic technologies. To date, Néel-type skyrmions at room temperature (RT) have been studied mostly in multilayers with easy-axis magnetic anisotropy. Here, we systematically broadened the evolution of magnetic skyrmions with sub-50-nm size in a series of Pt/Co/Ta multilayers where the magnetic anisotropy is tuned continuously from easy axis to easy plane by increasing the ferromagnetic Co layer thickness. The existence of nontrivial skyrmions is identified via the combination of in situ Lorentz transmission electron microscopy (L-TEM) and Hall transport measurements. A high density of magnetic skyrmions over a wide temperature range is observed in the multilayers with easy-plane anisotropy, which will stimulate further exploration for new materials and accelerate the development of skyrmion-based spintronic devices.

Tunable photonic multilayer sensors from photo-crosslinkable polymers

NASA Astrophysics Data System (ADS)

Chiappelli, Maria; Hayward, Ryan

2014-03-01

The fabrication of tunable photonic multilayer sensors from stimuli-responsive, photo-crosslinkable polymers will be described. Benzophenone is covalently incorporated as a pendent photo-crosslinker, allowing for facile preparation of multilayer films by sequential spin-coating and crosslinking processes. Copolymer chemistries and layer thicknesses are selected to provide robust multilayer sensors which can show color changes across nearly the full visible spectrum due to the specific stimulus-responsive nature of the hydrated film stack. We will describe how this approach is extended to alternative sensor designs by tailoring the thickness and chemistry of each layer independently, allowing for the preparation of sensors which depend not only on the shift in wavelength of a reflectance peak, but also on the transition between Bragg mirrors and filters. Device design is optimized by photo-patterning sensor arrays on a single substrate, providing more efficient fabrication time as well as multi-functional sensors. Finally, radiation-sensitive multilayers, designed by choosing polymers which will preferentially degrade or crosslink under ionizing radiation, will also be described.

Superferromagnetic domain state of a discontinuous metal insulator multilayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bedanta, S.; Petracic, O.; Kleemann, W.

2005-07-01

Polarized neutron reflectivity (PNR) and magnetometry studies have been performed on the granular multilayer [Co{sub 80}Fe{sub 20}(1.3 nm)/Al{sub 2}O{sub 3}(3 nm)]{sub 10}. Due to strong interparticle interactions, a collective superferromagnetic state is encountered. Cole-Cole plots drawn from the complex ac susceptibility are measured as functions of frequency, temperature, and field amplitudes that hint at the relaxation, creep, sliding, and switching regimes of pinned domain walls that are in close agreement with results obtained from simulations. Very slow switching with exponential relaxation under near-coercive fields is confirmed by PNR measurements. The complete absence of spin-flip scattering confirms that the magnetization reversalmore » is achieved merely by domain nucleation and growth.« less

Numerical modeling of the effect of heat and mass transfer in porous low-temperature heat insulation in composite material structures on the magnitude of stresses which develop

NASA Astrophysics Data System (ADS)

Kuznetsov, G. V.; Rudzinskaya, N. V.

1997-05-01

The stressed state of multilayer low-temperature heat insulation for a cryogenic fuel tank is considered. Account is taken of heat and mass transfer in foam plastic (the main heat insulation material) occurring at cryogenic temperatures. A method is developed for solving a set of differential equations and boundary conditions. Numerical studies of the main features of these processes are performed. It is established that below 200 K the stresses which arise in foam plastic markedly exceed the ultimate strength for this material. Stresses develop as a result of both a reduction in temperature and a drop in pressure in the foam plastic pores connected with material cooling. On the basis of the results obtained it is established that the combination of thermophysical processes which occur in foam plastic during cooling to cryogenic temperatures leads to changes in the stress-strained state of structure, which should be considered in planning aerospace technology.

Stanene cyanide: a novel candidate of Quantum Spin Hall insulator at high temperature

PubMed Central

Ji, Wei-xiao; Zhang, Chang-wen; Ding, Meng; Li, Ping; Li, Feng; Ren, Miao-juan; Wang, Pei-ji; Hu, Shu-jun; Yan, Shi-shen

2015-01-01

The search for quantum spin Hall (QSH) insulators with high stability, large and tunable gap and topological robustness, is critical for their realistic application at high temperature. Using first-principle calculations, we predict the cyanogen saturated stanene SnCN as novel topological insulators material, with a bulk gap as large as 203 meV, which can be engineered by applying biaxial strain and electric field. The band topology is identified by Z2 topological invariant together with helical edge states, and the mechanism is s-pxy band inversion at G point induced by spin-orbit coupling (SOC). Remarkably, these systems have robust topology against chemical impurities, based on the calculations on halogen and cyano group co-decorated stanene SnXxX′1−x (X,X′  =  F, Cl, Br, I and CN), which makes it an appropriate and flexible candidate material for spintronic devices. PMID:26688269

Testing Seam Concepts for Advanced Multilayer Insulation

NASA Technical Reports Server (NTRS)

Chato, D. J.; Johnson, W. L.; Alberts, Samantha J.

2017-01-01

Multilayer insulation (MLI) is considered the state of the art insulation for cryogenic propellant tanks in the space environment. MLI traditionally consists of multiple layers of metalized films separated by low conductivity spacers. In order to better understand some of the details within MLI design and construction, GRC has been investigating the heat loads caused by multiple types of seams. To date testing has been completed with 20 layer and 50 layer blankets. Although a truly seamless blanket is not practical, a blanket lay-up where each individual layer was overlapped and tapped together was used as a baseline for the other seams tests. Other seams concepts tested included: an overlap where the complete blanket was overlapped on top of itself; a butt joint were the blankets were just trimmed and butted up against each other, and a staggered butt joint where the seam in the out layers is offset from the seam in the inner layers. Measured performance is based on a preliminary analysis of rod calibration tests conducted prior to the start of seams testing. Baseline performance for the 50 layer blanket showed a measured heat load of 0.46 Watts with a degradation to about 0.47 Watts in the seamed blankets. Baseline performance for the 20 layer blanket showed a measured heat load of 0.57 Watts. Heat loads for the seamed tests are still begin analyzed. So far analysis work has suggested the need for corrections due to heat loads from both the heater leads and the instrumentation wires. A careful re-examination of the calibration test results with these factors accounted for is also underway. This presentation will discuss the theory of seams in MLI, our test results to date, and the uncertainties in our measurements.

Analyses of Hubble Space Telescope Aluminized-Teflon Multilayer Insulation Blankets Retrieved After 19 Years of Space Exposure

NASA Technical Reports Server (NTRS)

de Groh, Kim K.; Perry, Bruce A.; Mohammed, Jelila S.; Banks, Bruce

2015-01-01

Since its launch in April 1990, the Hubble Space Telescope (HST) has made many important observations from its vantage point in low Earth orbit (LEO). However, as seen during five servicing missions, the outer layer of multilayer insulation (MLI) has become increasingly embrittled and has cracked in many areas. In May 2009, during the 5th servicing mission (called SM4), two MLI blankets were replaced with new insulation and the space-exposed MLI blankets were retrieved for degradation analyses by teams at NASA Glenn Research Center (GRC) and NASA Goddard Space Flight Center (GSFC). The retrieved MLI blankets were from Equipment Bay 8, which received direct sunlight, and Equipment Bay 5, which received grazing sunlight. Each blanket was divided into several regions based on environmental exposure and/or physical appearance. The aluminized-Teflon (DuPont, Wilmington, DE) fluorinated ethylene propylene (Al-FEP) outer layers of the retrieved MLI blankets have been analyzed for changes in optical, physical, and mechanical properties, along with chemical and morphological changes. Pristine and as-retrieved samples (materials) were heat treated to help understand degradation mechanisms. When compared to pristine material, the analyses have shown how the Al-FEP was severely affected by the space environment. Most notably, the Al-FEP was highly embrittled, fracturing like glass at strains of 1 to 8 percent. Across all measured properties, more significant degradation was observed for Bay 8 material as compared to Bay 5 material. This paper reviews the tensile and bend-test properties, density, thickness, solar absorptance, thermal emittance, x-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) elemental composition measurements, surface and crack morphologies, and atomic oxygen erosion yields of the Al-FEP outer layer of the retrieved HST blankets after 19 years of space exposure.

Thermal Insulation Test Apparatuses

NASA Technical Reports Server (NTRS)

Berman, Brion

2005-01-01

The National Aeronautics and Space Administration (NASA) seeks to license its Thermal Insulation Test Apparatuses. Designed by the Cryogenics Test Laboratory at the John F. Kennedy Space Center (KSC) in Florida, these patented technologies (U.S. Patent Numbers: Cryostat 1 - 6,742,926, Cryostat 2 - 6,487,866, and Cryostat 4 - 6,824,306) allow manufacturers to fabricate and test cryogenic insulation at their production and/or laboratory facilities. These new inventions allow for the thermal performance characterization of cylindrical and flat specimens (e.g., bulk-fill, flat-panel, multilayer, or continuously rolled) over the full range of pressures, from high vacuum to no vacuum, and over the full range of temperatures from 77K to 300K. In today's world, efficient, low-maintenance, low-temperature refrigeration is taking a more significant role, from the food industry, transportation, energy, and medical applications to the Space Shuttle. Most countries (including the United States) have laws requiring commercially available insulation materials to be tested and rated by an accepted methodology. The new Cryostat methods go beyond the formal capabilities of the ASTM methods to provide testing for real systems, including full-temperature differences plus full-range vacuum conditions.

Fabrication of interface-modified ramp-edge junction on YBCO ground plane with multilayer structure

NASA Astrophysics Data System (ADS)

Wakana, H.; Adachi, S.; Kamitani, A.; Sugiyama, H.; Sugano, T.; Horibe, M.; Ishimaru, Y.; Tarutani, Y.; Tanabe, K.

2003-10-01

We examined the fabrication conditions to obtain high-quality ramp-edge Josephson junctions on a liquid-phase-epitaxy YBa 2Cu 3O y (LPE-YBCO) ground plane, in particular, focusing on the fabrication of a suitable insulating layer on the ground plane and the post-annealing conditions to load oxygen to the ground plane. A (LaAlO 3) 0.3-(SrAl 0.5Ta 0.5O 3) 0.7 (LSAT) insulating film on the ground planes exhibited a conductance ranging from 10 -4 to 10 -8 S after deposition of an upper superconducting film, suggesting existence of some leak paths through the LSAT insulating layer. By introducing approximately 30 nm thick SrTiO 3 (STO) buffer layers on both side of the LSAT insulating layer. We reproducibly obtained a conductance lower than 10 -8 S. The dielectric constant of the STO/LSAT/STO layer was 32, which was slightly larger than that of the single LSAT layer. It was found that a very slow cooling rate of 1.0 °C/h in oxygen was needed to fully oxidize the ground plane through the STO/LSAT/STO insulating layers, while the oxidation time could be effectively reduced by introducing via holes in the insulating layer at an interval of 200 μm. Ramp-edge junctions on LPE-YBCO ground planes with STO/LSAT/STO insulating layers exhibited a 1 σ-spread in Ic of 8% for 100-junction series-arrays and a sheet inductance of 0.7 pH/□ at 4.2 K.

Nature and function of insulator protein binding sites in the Drosophila genome

PubMed Central

Schwartz, Yuri B.; Linder-Basso, Daniela; Kharchenko, Peter V.; Tolstorukov, Michael Y.; Kim, Maria; Li, Hua-Bing; Gorchakov, Andrey A.; Minoda, Aki; Shanower, Gregory; Alekseyenko, Artyom A.; Riddle, Nicole C.; Jung, Youngsook L.; Gu, Tingting; Plachetka, Annette; Elgin, Sarah C.R.; Kuroda, Mitzi I.; Park, Peter J.; Savitsky, Mikhail; Karpen, Gary H.; Pirrotta, Vincenzo

2012-01-01

Chromatin insulator elements and associated proteins have been proposed to partition eukaryotic genomes into sets of independently regulated domains. Here we test this hypothesis by quantitative genome-wide analysis of insulator protein binding to Drosophila chromatin. We find distinct combinatorial binding of insulator proteins to different classes of sites and uncover a novel type of insulator element that binds CP190 but not any other known insulator proteins. Functional characterization of different classes of binding sites indicates that only a small fraction act as robust insulators in standard enhancer-blocking assays. We show that insulators restrict the spreading of the H3K27me3 mark but only at a small number of Polycomb target regions and only to prevent repressive histone methylation within adjacent genes that are already transcriptionally inactive. RNAi knockdown of insulator proteins in cultured cells does not lead to major alterations in genome expression. Taken together, these observations argue against the concept of a genome partitioned by specialized boundary elements and suggest that insulators are reserved for specific regulation of selected genes. PMID:22767387

Robust Guar Gum/Cellulose Nanofibrils Multilayer Films with Good Barrier Properties.

PubMed

Dai, Lei; Long, Zhu; Chen, Jie; An, Xingye; Cheng, Dong; Khan, Avik; Ni, Yonghao

2017-02-15

The pursuit of sustainable functional materials requires development of materials based on renewable resources and efficient fabrication methods. Hereby, we fabricated all-polysaccharides multilayer films using cationic guar gum (CGG) and anionic cellulose nanofibrils (i.e., TEMPO-oxidized cellulose nanofibrils, TOCNs) through a layer-by-layer casting method. This technique is based on alternate depositions of oppositely charged water-based CGG and TOCNs onto laminated films. The resultant polyelectrolyte multilayer films were transparent, ductile, and strong. More importantly, the self-standing films exhibited excellent gas (water vapor and oxygen) and oil barrier performances. Another outstanding feature of these resultant films was their resistance to various organic solvents including methanol, acetone, N,N-dimethylacetamide (DMAc) and tetrahydrofuran (THF). The proposed film fabrication process is environmentally benign, cost-effective, and easy to scale-up. The developed CGG/TOCNs multilayer films can be used as a renewable material for industrial applications such as packaging.

Robust electromagnetic absorption by graphene/polymer heterostructures

NASA Astrophysics Data System (ADS)

Lobet, Michaël; Reckinger, Nicolas; Henrard, Luc; Lambin, Philippe

2015-07-01

Polymer/graphene heterostructures present good shielding efficiency against GHz electromagnetic perturbations. Theory and experiments demonstrate that there is an optimum number of graphene planes, separated by thin polymer spacers, leading to maximum absorption for millimeter waves Batrakov et al (2014 Sci. Rep. 4 7191). Here, electrodynamics of ideal polymer/graphene multilayered material is first approached with a well-adapted continued-fraction formalism. In a second stage, rigorous coupled wave analysis is used to account for the presence of defects in graphene that are typical of samples produced by chemical vapor deposition, namely microscopic holes, microscopic dots (embryos of a second layer) and grain boundaries. It is shown that the optimum absorbance of graphene/polymer multilayers does not weaken to the first order in defect concentration. This finding testifies to the robustness of the shielding efficiency of the proposed absorption device.

Wide gap Chern Mott insulating phases achieved by design

NASA Astrophysics Data System (ADS)

Guo, Hongli; Gangopadhyay, Shruba; Köksal, Okan; Pentcheva, Rossitza; Pickett, Warren E.

2017-12-01

Quantum anomalous Hall insulators, which display robust boundary charge and spin currents categorized in terms of a bulk topological invariant known as the Chern number (Thouless et al Phys. Rev. Lett. 49, 405-408 (1982)), provide the quantum Hall anomalous effect without an applied magnetic field. Chern insulators are attracting interest both as a novel electronic phase and for their novel and potentially useful boundary charge and spin currents. Honeycomb lattice systems such as we discuss here, occupied by heavy transition-metal ions, have been proposed as Chern insulators, but finding a concrete example has been challenging due to an assortment of broken symmetry phases that thwart the topological character. Building on accumulated knowledge of the behavior of the 3d series, we tune spin-orbit and interaction strength together with strain to design two Chern insulator systems with bandgaps up to 130 meV and Chern numbers C = -1 and C = 2. We find, in this class, that a trade-off between larger spin-orbit coupling and strong interactions leads to a larger gap, whereas the stronger spin-orbit coupling correlates with the larger magnitude of the Hall conductivity. Symmetry lowering in the course of structural relaxation hampers obtaining quantum anomalous Hall character, as pointed out previously; there is only mild structural symmetry breaking of the bilayer in these robust Chern phases. Recent growth of insulating, magnetic phases in closely related materials with this orientation supports the likelihood that synthesis and exploitation will follow.

Corrugated grating on organic multilayer Bragg reflector

NASA Astrophysics Data System (ADS)

Jaquet, Sylvain; Scharf, Toralf; Herzig, Hans Peter

2007-08-01

Polymeric multilayer Bragg structures are combined with diffractive gratings to produce artificial visual color effects. A particular effect is expected due to the angular reflection dependence of the multilayer Bragg structure and the dispersion caused by the grating. The combined effects can also be used to design particular filter functions and various resonant structures. The multilayer Bragg structure is fabricated by spin-coating of two different low-cost polymer materials in solution on a cleaned glass substrate. These polymers have a refractive index difference of about 0.15 and permit multilayer coatings without interlayer problems. Master gratings of different periods are realized by laser beam interference and replicated gratings are superimposed on the multilayer structure by soft embossing in a UV curing glue. The fabrication process requires only polymer materials. The obtained devices are stable and robust. Angular dependent reflection spectrums for the visible are measured. These results show that it is possible to obtain unexpected reflection effects. A rich variety of color spectra can be generated, which is not possible with a single grating. This can be explained by the coupling of transmission of grating orders and the Bragg reflection band. A simple model permits to explain some of the spectral vs angular dependence of reflected light.

Multilayer SnSb4-SbSe Thin Films for Phase Change Materials Possessing Ultrafast Phase Change Speed and Enhanced Stability.

PubMed

Liu, Ruirui; Zhou, Xiao; Zhai, Jiwei; Song, Jun; Wu, Pengzhi; Lai, Tianshu; Song, Sannian; Song, Zhitang

2017-08-16

A multilayer thin film, comprising two different phase change material (PCM) components alternatively deposited, provides an effective means to tune and leverage good properties of its components, promising a new route toward high-performance PCMs. The present study systematically investigated the SnSb 4 -SbSe multilayer thin film as a potential PCM, combining experiments and first-principles calculations, and demonstrated that these multilayer thin films exhibit good electrical resistivity, robust thermal stability, and superior phase change speed. In particular, the potential operating temperature for 10 years is shown to be 122.0 °C and the phase change speed reaches 5 ns in the device test. The good thermal stability of the multilayer thin film is shown to come from the formation of the Sb 2 Se 3 phase, whereas the fast phase change speed can be attributed to the formation of vacancies and a SbSe metastable phase. It is also demonstrated that the SbSe metastable phase contributes to further enhancing the electrical resistivity of the crystalline state and the thermal stability of the amorphous state, being vital to determining the properties of the multilayer SnSb 4 -SbSe thin film.

Strong modification of thin film properties due to screening across the interface

NASA Astrophysics Data System (ADS)

Altendorf, S. G.; Reisner, A.; Tam, B.; Meneghin, F.; Wirth, S.; Tjeng, L. H.

2018-04-01

We report on our investigation of the influence of screening across the interface on the properties of semiconducting thin films. Using EuO as a well-defined model material, layers of various thickness deposited on yttria-stabilized zirconia (100) substrates were covered half with Mg metal and half with the wide-band-gap insulator MgO. We observed that the Curie temperature for the thinnest films is significantly higher for the part which is interfaced with the metal compared to the part which is interfaced with the insulator. We infer that the proximity of a polarizable medium reduces the energies of virtual charge excitations and thus increases the effective exchange interactions, a strong effect that can be utilized systematically for the design of thin film and multilayer systems.

Cryogenic propellant thermal control system design considerations, analyses, and concepts applied to a Mars human exploration mission

NASA Technical Reports Server (NTRS)

Plachta, David W.; Tucker, Stephen; Hoffman, David J.

1993-01-01

This paper analyzes, defines, and sizes cryogenic storage thermal control systems that meet the requirements of future NASA Mars human exploration missions. The design issues of this system include the projection of the existing Multilayer Insulation data base for cryogenic storage to much thicker (10 cm or more) insulation systems, the unknown heat leak from mechanical interfaces, and the thermal and structural performance effects of the large tank sizes required for a Mars mission. Acknowledging these unknown effects, heat loss projections are made based on extrapolation of the existing data base. The results indicate that hydrogen, methane, and oxygen are feasible propellants, and that the best suited thermal control sytems are 'thick' MLI, thermodynamic vent sytems, cryocoolers, and vacuum jackets.

Sensitivity enhancement of a surface plasmon resonance sensor using porous metamaterial layers

NASA Astrophysics Data System (ADS)

Cherifi, Abdellatif; Bouhafs, Benamar

2017-12-01

In this work, the surface plasmon resonance (SPR) device with two porous left handed metamaterial (LHM) layers separated by an insulator gap, is investigated. The effect of the insulator gap thickness and its refractive index (RI) on the angular response of the device is analyzed. The results show that the sensitivity of the SPR sensor is enhanced compared to the standard SPR sensors. Here, the multilayer structure is probed with 738 nm-wavelength, and electromagnetic properties of active porous LHM layers are described from the effective medium theory (EMT). Furthermore, in the increase of the porosity from 0 to 0.6, the designed nanocavity exhibits a fundamental SPR mode long-range (LR) type and it can be of interest in high-performance SPR sensing.

Thermally tunable VO2-SiO2 nanocomposite thin-film capacitors

NASA Astrophysics Data System (ADS)

Sun, Yifei; Narayanachari, K. V. L. V.; Wan, Chenghao; Sun, Xing; Wang, Haiyan; Cooley, Kayla A.; Mohney, Suzanne E.; White, Doug; Duwel, Amy; Kats, Mikhail A.; Ramanathan, Shriram

2018-03-01

We present a study of co-sputtered VO2-SiO2 nanocomposite dielectric thin-film media possessing continuous temperature tunability of the dielectric constant. The smooth thermal tunability is a result of the insulator-metal transition in the VO2 inclusions dispersed within an insulating matrix. We present a detailed comparison of the dielectric characteristics of this nanocomposite with those of a VO2 control layer and of VO2/SiO2 laminate multilayers of comparable overall thickness. We demonstrated a nanocomposite capacitor that has a thermal capacitance tunability of ˜60% between 25 °C and 100 °C at 1 MHz, with low leakage current. Such thermally tunable capacitors could find potential use in applications such as sensing, thermal cloaks, and phase-change energy storage devices.

Thermal barrier coatings for gas-turbine engine applications.

PubMed

Padture, Nitin P; Gell, Maurice; Jordan, Eric H

2002-04-12

Hundreds of different types of coatings are used to protect a variety of structural engineering materials from corrosion, wear, and erosion, and to provide lubrication and thermal insulation. Of all these, thermal barrier coatings (TBCs) have the most complex structure and must operate in the most demanding high-temperature environment of aircraft and industrial gas-turbine engines. TBCs, which comprise metal and ceramic multilayers, insulate turbine and combustor engine components from the hot gas stream, and improve the durability and energy efficiency of these engines. Improvements in TBCs will require a better understanding of the complex changes in their structure and properties that occur under operating conditions that lead to their failure. The structure, properties, and failure mechanisms of TBCs are herein reviewed, together with a discussion of current limitations and future opportunities.

Light emitting ceramic device and method for fabricating the same

DOEpatents

Valentine, Paul; Edwards, Doreen D.; Walker Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

2004-11-30

A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, and alternative methods of fabrication for the same are claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

Design of a -1 MV dc UHV power supply for ITER NBI

NASA Astrophysics Data System (ADS)

Watanabe, K.; Yamamoto, M.; Takemoto, J.; Yamashita, Y.; Dairaku, M.; Kashiwagi, M.; Taniguchi, M.; Tobari, H.; Umeda, N.; Sakamoto, K.; Inoue, T.

2009-05-01

Procurement of a dc -1 MV power supply system for the ITER neutral beam injector (NBI) is shared by Japan and the EU. The Japan Atomic Energy Agency as the Japan Domestic Agency (JADA) for ITER contributes to the procurement of dc -1 MV ultra-high voltage (UHV) components such as a dc -1 MV generator, a transmission line and a -1 MV insulating transformer for the ITER NBI power supply. The inverter frequency of 150 Hz in the -1 MV power supply and major circuit parameters have been proposed and adopted in the ITER NBI. The dc UHV insulation has been carefully designed since dc long pulse insulation is quite different from conventional ac insulation or dc short pulse systems. A multi-layer insulation structure of the transformer for a long pulse up to 3600 s has been designed with electric field simulation. Based on the simulation the overall dimensions of the dc UHV components have been finalized. A surge energy suppression system is also essential to protect the accelerator from electric breakdowns. The JADA contributes to provide an effective surge suppression system composed of core snubbers and resistors. Input energy into the accelerator from the power supply can be reduced to about 20 J, which satisfies the design criteria of 50 J in total in the case of breakdown at -1 MV.

Origin of colossal dielectric response of CaCu3Ti4O12 studied by using CaTiO3/CaCu3Ti4O12/CaTiO3 multilayer thin films

NASA Astrophysics Data System (ADS)

Mitsugi, Masakazu; Asanuma, Shutaro; Uesu, Yoshiaki; Fukunaga, Mamoru; Kobayashi, Wataru; Terasaki, Ichiro

2007-06-01

To elucidate the origin of the colossal dielectric response (CDR) of CaCu3Ti4O12 (CCTO), multilayer thin films of CCTO interposed in insulating CaTiO3 (CTO) were synthesized using a pulsed laser deposition technique. The capacitance C of CTO/CCTO/CTO films with different layer thicknesses is measured. After removing the capacitance of CTO by extrapolating C to zero CTO thickness, the real part of dielectric constant of CCTO is estimated to be 329-435, which is much smaller than the reported value for CCTO thin films. This fact indicates that the CDR of CCTO is extrinsic and originates from an internal barrier layer capacitor.

Investigation of the thermal stability of 1T'-MoTe2 multilayers via Raman spectroscopy

NASA Astrophysics Data System (ADS)

Herman, Irving P.; Wang, Dennis; Smyser, Kori; Rhodes, Daniel; Pasupathy, Abhay N.

The distorted octahedral (1T') form of MoTe2 has garnered much interest in recent years because of its potential applications as a quantum spin hall insulator. Here we study the structural stability of 1T'-MoTe2 multilayers encapsulated by hexagonal boron nitride (hBN) above room temperature by tracking the evolution of its Raman spectrum and cross-checking the results with atomic force microscopy (AFM). Our data indicate the presence of both linear and nonlinear redshifts in peak positions upon heating and, furthermore, suggest the irreversible degradation of the original compound into tellurium nanocrystals at higher temperatures. We discuss the implications of these findings for related optical and transport experiments involving this material and how encapsulation may help extend the lifetime of such devices. NSF IGERT (DGE-1069240).

Fast Self-Healing of Polyelectrolyte Multilayer Nanocoating and Restoration of Super Oxygen Barrier.

PubMed

Song, Yixuan; Meyers, Kevin P; Gerringer, Joseph; Ramakrishnan, Ramesh K; Humood, Mohammad; Qin, Shuang; Polycarpou, Andreas A; Nazarenko, Sergei; Grunlan, Jaime C

2017-05-01

A self-healable gas barrier nanocoating, which is fabricated by alternate deposition of polyethyleneimine (PEI) and polyacrylic acid (PAA) polyelectrolytes, is demonstrated in this study. This multilayer film, with high elastic modulus, high glass transition temperature, and small free volume, has been shown to be a super oxygen gas barrier. An 8-bilayer PEI/PAA multilayer assembly (≈700 nm thick) exhibits an oxygen transmission rate (OTR) undetectable to commercial instrumentation (<0.005 cc (m -2 d -1 atm -1 )). The barrier property of PEI/PAA nanocoating is lost after a moderate amount of stretching due to its rigidity, which is then completely restored after high humidity exposure, therefore achieving a healing efficiency of 100%. The OTR of the multilayer nanocoating remains below the detection limit after ten stretching-healing cycles, which proves this healing process to be highly robust. The high oxygen barrier and self-healing behavior of this polymer multilayer nanocoating makes it ideal for packaging (food, electronics, and pharmaceutical) and gas separation applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Normal metal - insulator - superconductor thermometers and coolers with titanium-gold bilayer as the normal metal

NASA Astrophysics Data System (ADS)

Räisänen, I. M. W.; Geng, Z.; Kinnunen, K. M.; Maasilta, I. J.

2018-03-01

We have fabricated superconductor - insulator - normal metal - insulator - superconductor (SINIS) tunnel junctions in which Al acts as the superconductor, AlOx is the insulator, and the normal metal consists of a thin Ti layer (5 nm) covered with a thicker Au layer (40 nm). We have characterized the junctions by measuring their current-voltage curves between 60 mK and 750 mK. For comparison, the same measurements have been performed for a SINIS junction pair whose normal metal is Cu. The Ti-Au bilayer decreases the SINIS tunneling resistance by an order of magnitude compared to junctions where Cu is used as normal metal, made with the same oxidation parameters. The Ti-Au devices are much more robust against chemical attacks, and their lower tunneling resistance makes them more robust against static charge. More significantly, they exhibit significantly stronger electron cooling than Cu devices with identical fabrication steps, when biased close to the energy gap of the superconducting Al. By using a self-consistent thermal model, we can fit the current-voltage characteristics well, and show an electron cooling from 200 mK to 110 mK, with a non-optimized device.

Design and development of pressure and repressurization purge system for reusable space shuttle multilayer insulation system

NASA Technical Reports Server (NTRS)

1971-01-01

Preliminary design and analysis of purge system concepts and purge subsystem approaches are defined and evaluated. Acceptable purge subsystem approaches were combined into four predesign layouts which are presented for comparison and evaluation. Two predesigns were selected for further detailed design and evaluation for eventual selection of the best design for a full scale test configuration. An operation plan is included as an appendix for reference to shuttle-oriented operational parameters.

Low RF Reflectivity Spacecraft Thermal Blanket by Using High-Impedance Surface Absorbers

NASA Astrophysics Data System (ADS)

Costa, F.; Monorchio, A.; Carrubba, E.; Zolesi, V.

2012-05-01

A technique for designing a low-RF reflectivity thermal blanket is presented. Multi-layer insulation (MLI) blankets are employed to stabilize the temperature on spacecraft unit but they can be responsible of passive intermodulation products and high-mutual coupling between antennas since they are realized with metallic materials. The possibility to replace the last inner layer of a MLI blanket with an ultra-thin absorbing layer made of high-impedance surface absorber is discussed.

Broadband Spectral-Polarimetric BRDF Scan System and Data for Spacecraft Materials

DTIC Science & Technology

2011-09-01

Function ( BRDF ) measurement system from 350nm to 2500nm with 1nm wavelength resolution is providing data for satellite radiance modeling and specifically...multilayer insulation (MLI) and solar cells is presented. The continuum nature of the data indicates that either dedicated BRDF models or a method for...but the BRDFs will be difficult to model . Judgments whether to use texturing, or an average BRDF , or perhaps optical cross section (OCS) values, or

Repeatability of Cryogenic Multilayer Insulation

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-01-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between multiple identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five GRC provided coupons with 25 layers was shown to be +/- 8.4 whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0. A second group of 10 coupons have been fabricated by Yetispace and tested by Florida State University, through the first 4 tests, the repeatability has been shown to be +/- 16. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Repeatability of Cryogenic Multilayer Insulation

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-01-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between multiple identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five GRC provided coupons with 25 layers was shown to be +/- 8.4% whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0%. A second group of 10 coupons have been fabricated by Yetispace and tested by Florida State University, through the first 4 tests, the repeatability has been shown to be +/- 15-25%. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Fluoroalkylsilane-Modified Textile-Based Personal Energy Management Device for Multifunctional Wearable Applications.

PubMed

Guo, Yinben; Li, Kerui; Hou, Chengyi; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

2016-02-01

The rapid development of wearable electronics in recent years has brought increasing energy consumption, making it an urgent need to focus on personal energy harvesting, storage and management. Herein, a textile-based personal energy management device with multilayer-coating structure was fabricated by encapsulating commercial nylon cloth coated with silver nanowires into polydimethylsiloxane using continuous and facile dip-coating method. This multilayer-coating structure can not only harvest mechanical energy from human body motion to power wearable electronics but also save energy by keeping people warm without losing heat to surroundings and wasting energy to heat empty space and inanimate objects. Fluoroalkylsilanes (FAS) were grafted onto the surface of the film through one single dip-coating process to improve its energy harvesting performance, which has hardly adverse effect to heat insulation and Joule heating property. In the presence of FAS modification, the prepared film harvested mechanical energy to reach a maximum output power density of 2.8 W/m(2), charged commercial capacitors and lighted LEDs, showing its potential in powering wearable electronics. Furthermore, the film provided 8% more thermal insulation than normal cloth at 37 °C and efficiently heated to 40 °C within 4 min when applied the voltage of only 1.5 V due to Joule heating effect. The high flexibility and stability of the film ensures its wide and promising application in the wearable field.

Repeatability of Cryogenic Multilayer Insulation

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-12-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation (MLI) has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five Glenn Research Center (GRC) provided coupons with 25 layers was shown to be +/- 8.4% whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0%. A second group of 10 coupons has been fabricated by Yetispace and tested by Florida State University, the repeatability between coupons has been shown to be +/- 15-25%. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Issue of Changes in Adhesion of Bitumen Sheet to Primary Layer over the Course of Time in Multilayer Waterproofing during Shear Testing

NASA Astrophysics Data System (ADS)

Plachý, Jan; Vysoká, Jana; Vejmelka, Radek; Horský, Jan; Vacek, Vítězslav

2017-10-01

This paper is based on research dealing with defects that appear on concrete bridge decks with an insulating layer from asphalt strips on the interface between the asphalt strip and its basis. The durability and lifespan of the bearing structure of concrete bridge is determined by insulating layer that constitutes, together with the primary layer and a protective layer, the insulation system of the concrete bridge deck. Paints based on low viscosity epoxy resigns are one of the possibilities of primary layer implementation. These paints may be performed as anchoring-impregnation paints that usually represent single layer paint on the bridge deck surface. Sealing layer is another variant. Sealing layer is a multilayer consisting of anchoring- impregnation paint and sealing paint. The primary layers mainly provide vapour closing of the concrete surface, and partly, through roughening the surface, contribute to adhesion of bitumen (asphalt) insulation (waterproofing) layer. Application of the primary layer has been spreading in the Czech Republic since the 1990s. Now, after approximately 30 years of use defects in these epoxy based sealing layers at the interface between primary layer and waterproofing layer of reinforced bitumen sheets (RBS) are being solved in the Czech Republic. After performance of the first test focusing on breaking-strength, it was found that the strength between the asphalt and the primary belt layer in some types of low-viscosity resin-epoxy decreases and after a certain period of time again increases, depending on the time. Tensile strength test is carried out on a sample of asphalt strip, which is fused onto the substrate with a primer coat. It was therefore proceeded to test the shear adhesion. Testing of the shear adhesion is conducted on the entire concrete deck waterproofing system. It was supposed that the decrease of adhesion at this test become evident in higher extent. Adhesion tests in shear were performed on the primary layer consisting of an anchoring impregnation coating and sealing layer.

Topological acoustic polaritons: robust sound manipulation at the subwavelength scale

NASA Astrophysics Data System (ADS)

Yves, Simon; Fleury, Romain; Lemoult, Fabrice; Fink, Mathias; Lerosey, Geoffroy

2017-07-01

Topological insulators, a hallmark of condensed matter physics, have recently reached the classical realm of acoustic waves. A remarkable property of time-reversal invariant topological insulators is the presence of unidirectional spin-polarized propagation along their edges, a property that could lead to a wealth of new opportunities in the ability to guide and manipulate sound. Here, we demonstrate and study the possibility to induce topologically non-trivial acoustic states at the deep subwavelength scale, in a structured two-dimensional metamaterial composed of Helmholtz resonators. Radically different from previous designs based on non-resonant sonic crystals, our proposal enables robust sound manipulation on a surface along predefined, subwavelength pathways of arbitrary shapes.

Thermal Insulation Performance of Textile Structures for Spacesuit Applications at Martian Pressure and Temperature

NASA Technical Reports Server (NTRS)

Orndoff, Evelyne; Trevino, Luis A.

2000-01-01

Protection of astronauts from the extreme temperatures in the space environment has been provided in the past using multi-layer insulation in ultra-high vacuum environments of low earth orbit and the lunar surface. For planetary environments with residual gas atmospheres such as Mars with ambient pressures between 8 to 14 hPa (8 to 14 mbar), new protection techniques are required because of the dominating effect of the ambient gas on heat loss through the insulation. At Mars ambient pressure levels, the heat loss can be excessive at expected suit external temperatures of 172 K with state-of-the-art suit insulation, requiring an active heat source and its accompanying weight and volume penalties. Micro-fibers have been identified as one potential structure to reduce the heat losses, but existing fundamental data on fiber heat transfer at low pressure is lacking for integrated fabric structures. This baseline study presents insulation performance test data at different pressures and fabric loads for selected polyesters and aramids as a function of fiber density, fiber diameter, fabric density, and fabric construction. A set of trend data of thermal conductivity versus ambient pressure is presented for each fiber and fabric construction design to identify the design effects on thermal conductivity at various ambient pressures, and to select a fiber and fabric design for further development as a suit insulation. The trend data also shows the pressure level at which thermal conductivity approaches a minimum, below which no further improvement is possible for a given fiber and fabric design. The pressure levels and resulting thermal conductivities from the trend data can then be compared to the ambient pressure at a planetary surface, Mars for example, to determine if a particular fiber and fabric design has potential as a suit insulation.

Non-Dirac Chern insulators with large band gaps and spin-polarized edge states.

PubMed

Xue, Y; Zhang, J Y; Zhao, B; Wei, X Y; Yang, Z Q

2018-05-10

Based on first-principles calculations and k·p models, we demonstrate that PbC/MnSe heterostructures are a non-Dirac type of Chern insulator with very large band gaps (244 meV) and exotically half-metallic edge states, providing the possibilities of realizing very robust, completely spin polarized, and dissipationless spintronic devices from the heterostructures. The achieved extraordinarily large nontrivial band gap can be ascribed to the contribution of the non-Dirac type electrons (composed of px and py) and the very strong atomic spin-orbit coupling (SOC) interaction of the heavy Pb element in the system. Surprisingly, the band structures are found to be sensitive to the different exchange and correlation functionals adopted in the first-principles calculations. Chern insulators with various mechanisms are acquired from them. These discoveries show that the predicted nontrivial topology in PbC/MnSe heterostructures is robust and can be observed in experiments at high temperatures. The system has great potential to have attractive applications in future spintronics.

Above 400-K robust perpendicular ferromagnetic phase in a topological insulator

PubMed Central

Tang, Chi; Chang, Cui-Zu; Zhao, Gejian; Liu, Yawen; Jiang, Zilong; Liu, Chao-Xing; McCartney, Martha R.; Smith, David J.; Chen, Tingyong; Moodera, Jagadeesh S.; Shi, Jing

2017-01-01

The quantum anomalous Hall effect (QAHE) that emerges under broken time-reversal symmetry in topological insulators (TIs) exhibits many fascinating physical properties for potential applications in nanoelectronics and spintronics. However, in transition metal–doped TIs, the only experimentally demonstrated QAHE system to date, the QAHE is lost at practically relevant temperatures. This constraint is imposed by the relatively low Curie temperature (Tc) and inherent spin disorder associated with the random magnetic dopants. We demonstrate drastically enhanced Tc by exchange coupling TIs to Tm3Fe5O12, a high-Tc magnetic insulator with perpendicular magnetic anisotropy. Signatures showing that the TI surface states acquire robust ferromagnetism are revealed by distinct squared anomalous Hall hysteresis loops at 400 K. Point-contact Andreev reflection spectroscopy confirms that the TI surface is spin-polarized. The greatly enhanced Tc, absence of spin disorder, and perpendicular anisotropy are all essential to the occurrence of the QAHE at high temperatures. PMID:28691097

Increased Multilayer Fabrication and RF Characterization of a High-Density Stacked MIM Capacitor Based on Selective Etching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tseng, VFG; Xie, HK

2014-07-01

This paper presents the fabrication and characterization of a high-density multilayer stacked metal-insulator-metal (MIM) capacitor based on a novel process of depositing the MIM multilayer on pillars followed by polishing and selective etching steps to form a stacked capacitor with merely three photolithography steps. In this paper, the pillars were made of glass to prevent substrate loss, whereas an oxide-nitride-oxide dielectric was employed for lower leakage, better voltage/frequency linearity, and better stress compensation. MIM capacitors with six dielectric layers were successfully fabricated, yielding capacitance density of 3.8 fF/mu m(2), maximum capacitance of 2.47 nF, and linear and quadratic voltage coefficientsmore » of capacitance below 21.2 ppm/V and 2.31 ppm/V-2. The impedance was measured from 40 Hz to 3 GHz, and characterized by an analytically derived equivalent circuit model to verify the radio frequency applicability. The multilayer stacking-induced plate resistance mismatch and its effect on the equivalent series resistance (ESR) and effective capacitance was also investigated, which can be counteracted by a corrected metal thickness design. A low ESR of 800 m Omega was achieved, whereas the self-resonance frequency was >760 MHz, successfully demonstrating the feasibility of this method to scale up capacitance densities for high-quality-factor, high-frequency, and large-value MIM capacitors.« less

Low voltage electrowetting lenticular lens by using multilayer dielectric structure

NASA Astrophysics Data System (ADS)

Lee, Junsik; Kim, Junoh; Kim, Cheoljoong; Shin, Dooseub; Koo, Gyohyun; Sim, Jee Hoon; Won, Yong Hyub

2017-02-01

Lenticular type multi-view display is one of the most popular ways for implementing three dimensional display. This method has a simple structure and exhibits a high luminance. However, fabricating the lenticular lens is difficult because it requires optically complex calculations. 2D-3D conversion is also impossible due to the fixed shape of the lenticular lens. Electrowetting based liquid lenticular lens has a simple fabrication process compared to the solid lenticular lens and the focal length of the liquid lenticular lens can be changed by applying the voltage. 3D and 2D images can be observed with a convex and a flat lens state respectively. Despite these advantages, the electrowetting based liquid lenticular lens demands high driving voltage and low breakdown voltage with a single dielectric layer structure. A certain degree of thickness of the dielectric layer is essential for a uniform operation and a low degradation over time. This paper presents multilayer dielectric structure which results in low driving voltage and the enhanced dielectric breakdown. Aluminum oxide (Al2O3), silicon oxide (SiO2) and parylene C were selected as the multilayer insulators. The total thickness of the dielectric layer of all samples was the same. This method using the multilayer dielectric structure can achieve the lower operating voltage than when using the single dielectric layer. We compared the liquid lenticular lens with three kinds of the multilayer dielectric structure to one with the parylene C single dielectric layer in regard to operational characteristics such as the driving voltage and the dielectric breakdown.

Composite Aerogel Multifoil Protective Shielding

NASA Technical Reports Server (NTRS)

Jones, Steven M.

2013-01-01

New technologies are needed to survive the temperatures, radiation, and hypervelocity particles that exploration spacecraft encounter. Multilayer insulations (MLIs) have been used on many spacecraft as thermal insulation. Other materials and composites have been used as micrometeorite shielding or radiation shielding. However, no material composite has been developed and employed as a combined thermal insulation, micrometeorite, and radiation shielding. By replacing the scrims that have been used to separate the foil layers in MLIs with various aerogels, and by using a variety of different metal foils, the overall protective performance of MLIs can be greatly expanded to act as thermal insulation, radiation shielding, and hypervelocity particle shielding. Aerogels are highly porous, low-density solids that are produced by the gelation of metal alkoxides and supercritical drying. Aerogels have been flown in NASA missions as a hypervelocity particle capture medium (Stardust) and as thermal insulation (2003 MER). Composite aerogel multifoil protective shielding would be used to provide thermal insulation, while also shielding spacecraft or components from radiation and hypervelocity particle impacts. Multiple layers of foil separated by aerogel would act as a thermal barrier by preventing the transport of heat energy through the composite. The silica aerogel would act as a convective and conductive thermal barrier, while the titania powder and metal foils would absorb and reflect the radiative heat. It would also capture small hypervelocity particles, such as micrometeorites, since it would be a stuffed, multi-shock Whipple shield. The metal foil layers would slow and break up the impacting particles, while the aerogel layers would convert the kinetic energy of the particles to thermal and mechanical energy and stop the particles.

Low-Temperature Fabrication of Robust, Transparent, and Flexible Thin-Film Transistors with a Nanolaminated Insulator.

PubMed

Kwon, Jeong Hyun; Park, Junhong; Lee, Myung Keun; Park, Jeong Woo; Jeon, Yongmin; Shin, Jeong Bin; Nam, Minwoo; Kim, Choong-Ki; Choi, Yang-Kyu; Choi, Kyung Cheol

2018-05-09

The lack of reliable, transparent, and flexible electrodes and insulators for applications in thin-film transistors (TFTs) makes it difficult to commercialize transparent, flexible TFTs (TF-TFTs). More specifically, conventional high process temperatures and the brittleness of these elements have been hurdles in developing flexible substrates vulnerable to heat. Here, we propose electrode and insulator fabrication techniques considering process temperature, transmittance, flexibility, and environmental stability. A transparent and flexible indium tin oxide (ITO)/Ag/ITO (IAI) electrode and an Al 2 O 3 /MgO (AM)-laminated insulator were optimized at the low temperature of 70 °C for the fabrication of TF-TFTs on a polyethylene terephthalate (PET) substrate. The optimized IAI electrode with a sheet resistance of 7 Ω/sq exhibited the luminous transmittance of 85.17% and maintained its electrical conductivity after exposure to damp heat conditions because of an environmentally stable ITO capping layer. In addition, the electrical conductivity of IAI was maintained after 10 000 bending cycles with a tensile strain of 3% because of the ductile Ag film. In the metal/insulator/metal structure, the insulating and mechanical properties of the optimized AM-laminated film deposited at 70 °C were significantly improved because of the highly dense nanolaminate system, compared to those of the Al 2 O 3 film deposited at 70 °C. In addition, the amorphous indium-gallium-zinc oxide (a-IGZO) was used as the active channel for TF-TFTs because of its excellent chemical stability. In the environmental stability test, the ITO, a-IGZO, and AM-laminated films showed the excellent environmental stability. Therefore, our IGZO-based TFT with IAI electrodes and the 70 °C AM-laminated insulator was fabricated to evaluate robustness, transparency, flexibility, and process temperature, resulting in transfer characteristics comparable to those of an IGZO-based TFT with a 150 °C Al 2 O 3 insulator.

Helicon wave excitation to produce energetic electrons for manufacturing semiconductors

DOEpatents

Molvik, Arthur W.; Ellingboe, Albert R.

1998-01-01

A helicon plasma source is controlled by varying the axial magnetic field or rf power controlling the formation of the helicon wave. An energetic electron current is carried on the wave when the magnetic field is 90 G; but there is minimal energetic electron current when the magnetic field is 100 G in one particular plasma source. Similar performance can be expected from other helicon sources by properly adjusting the magnetic field and power to the particular geometry. This control for adjusting the production of energetic electrons can be used in the semiconductor and thin-film manufacture process. By applying energetic electrons to the insulator layer, such as silicon oxide, etching ions are attracted to the insulator layer and bombard the insulator layer at higher energy than areas that have not accumulated the energetic electrons. Thus, silicon and metal layers, which can neutralize the energetic electron currents will etch at a slower or non-existent rate. This procedure is especially advantageous in the multilayer semiconductor manufacturing because trenches can be formed that are in the range of 0.18-0.35 mm or less.

Helicon wave excitation to produce energetic electrons for manufacturing semiconductors

DOEpatents

Molvik, A.W.; Ellingboe, A.R.

1998-10-20

A helicon plasma source is controlled by varying the axial magnetic field or rf power controlling the formation of the helicon wave. An energetic electron current is carried on the wave when the magnetic field is 90 G; but there is minimal energetic electron current when the magnetic field is 100 G in one particular plasma source. Similar performance can be expected from other helicon sources by properly adjusting the magnetic field and power to the particular geometry. This control for adjusting the production of energetic electrons can be used in the semiconductor and thin-film manufacture process. By applying energetic electrons to the insulator layer, such as silicon oxide, etching ions are attracted to the insulator layer and bombard the insulator layer at higher energy than areas that have not accumulated the energetic electrons. Thus, silicon and metal layers, which can neutralize the energetic electron currents will etch at a slower or non-existent rate. This procedure is especially advantageous in the multilayer semiconductor manufacturing because trenches can be formed that are in the range of 0.18--0.35 mm or less. 16 figs.

Spin filter effect of hBN/Co detector electrodes in a 3D topological insulator spin valve

NASA Astrophysics Data System (ADS)

Vaklinova, Kristina; Polyudov, Katharina; Burghard, Marko; Kern, Klaus

2018-03-01

Topological insulators emerge as promising components of spintronic devices, in particular for applications where all-electrical spin control is essential. While the capability of these materials to generate spin-polarized currents is well established, only very little is known about the spin injection/extraction into/out of them. Here, we explore the switching behavior of lateral spin valves comprising the 3D topological insulator Bi2Te2Se as channel, which is separated from ferromagnetic Cobalt detector contacts by an ultrathin hexagonal boron nitride (hBN) tunnel barrier. The corresponding contact resistance displays a notable variation, which is correlated with a change of the switching characteristics of the spin valve. For contact resistances below ~5 kΩ, the hysteresis in the switching curve reverses upon reversing the applied current, as expected for spin-polarized currents carried by the helical surface states. By contrast, for higher contact resistances an opposite polarity of the hysteresis loop is observed, which is independent of the current direction, a behavior signifying negative spin detection efficiency of the multilayer hBN/Co contacts combined with bias-induced spin signal inversion. Our findings suggest the possibility to tune the spin exchange across the interface between a ferromagnetic metal and a topological insulator through the number of intervening hBN layers.

Evacuated load-bearing high performance insulation study

NASA Technical Reports Server (NTRS)

Parmley, R. T.; Cunnington, G. R.

1977-01-01

A light weight, vacuum jacketed, load bearing cryogenic insulation system was developed and tested on a 1.17-m (46-in.) spherical test tank. The vacuum jacket consists of 0.08 mm (0.003 in.) thick 321 stainless steel formed into a wedge design that allows elastic jacket movements as the tank shrinks (cools) or expands (warms up or is pressurized). Hollow glass spheres, approximately 80 micrometers in diameter with a bulk density of 0.069 g/cc (4.3 lb cubic foot), provide the insulating qualities and one atmosphere load bearing capability required. The design, fabrication, and test effort developed the manufacturing methods and engineering data needed to scale the system to other tank sizes, shapes, and applications. The program demonstrated that thin wall jackets can be formed and welded to maintain the required vacuum level of .013 Pa yet flex elastically for multiple reuses. No significant shifting or breakage of the microspheres occurred after 13 simulated Space Tug flight cycles on the test tank and a hundred 1 atmosphere load cycles in a flat plate calorimeter. The test data were then scaled to the Space Tug LO2 and LH2 tanks, and weight, thermal performance, payload performance, and costs were compared with a helium purged multilayer insulation system.

Multi-criteria thermal evaluation of wall enclosures of high-rise buildings insulated products based on modified fibers

NASA Astrophysics Data System (ADS)

Pavlov, Alexey; Pavlova, Larisa; Pavlova, Lyudmila

2018-03-01

In article results of research of versions of offered types of heaters on the basis of products from the modified fibers for designing energy efficient building enclosures residential high-rise buildings are presented. Traditional building materials (reinforced concrete, brick, wood) are not able to provide the required value of thermal resistance in areas with a temperate and harsh Russia climate in a single-layered enclosing structure. It can be achieved in a multi-layered enclosing structure, where the decisive role is played by new insulating materials with high thermal properties. In general, modern design solutions for external walls are based on the use of new effective thermal insulation materials with the use of the latest technology. The relevance of the proposed topic is to research thermoinsulation properties of new mineral heaters. Theoretical researches of offered heaters from mineral wool on slime-colloidal binder, bentocolloid and microdispersed binders are carried out. In addition, theoretical studies were carried out with several types of facade systems. Comprehensive studies were conducted on the resistance to heat transfer, resistance to vapor permeation and air permeability. According to the received data, recommendations on the use of insulation types depending on the number of storeys of buildings are proposed.

Investigations of Heat Transfer in Vacuum between Room Temperature and 80 K

NASA Astrophysics Data System (ADS)

Hooks, J.; Demko, J. A.; E Fesmire, J.; Matsumoto, T.

2017-12-01

The heat transfer between room temperature and 80 K is controlled using various insulating material combinations. The modes of heat transfer are well established to be conduction and thermal radiation when in a vacuum. Multi-Layer Insulation (MLI) in a vacuum has long been the best approach. Typically this layered system is applied to the cold surface. This paper investigates the application of MLI to both the cold and warm surface to see whether there is a significant difference. In addition if MLI is on the warm surface, the cold side of the MLI may be below the critical temperature of some high temperature superconducting (HTS) materials. It has been proposed that HTS materials can serve to block thermal radiation. An experiment is conducted to measure this effect. Boil-off calorimetry is the method of measuring the heat transfer.

Realization of zero-field skyrmions with high-density via electromagnetic manipulation in Pt/Co/Ta multilayers

NASA Astrophysics Data System (ADS)

He, Min; Peng, Licong; Zhu, Zhaozhao; Li, Gang; Cai, Jianwang; Li, Jianqi; Wei, Hongxiang; Gu, Lin; Wang, Shouguo; Zhao, Tongyun; Shen, Baogen; Zhang, Ying

2017-11-01

Taking advantage of the electron-current ability to generate, stabilize, and manipulate skyrmions prompts the application of skyrmion multilayers in room-temperature spintronic devices. In this study, the robust high-density skyrmions are electromagnetically generated from Pt/Co/Ta multilayers using Lorentz transmission electron microscopy. The skyrmion density is tunable and can be significantly enhanced. Remarkably, these generated skyrmions after optimized manipulation sustain at zero field with both the in-plane current and perpendicular magnetic field being switched off. The skyrmion generation and manipulation method demonstrated in this study opens up an alternative way to engineer skyrmion-based devices. The results also provide key data for further theoretical study to discover the nature of the interaction between the electric current and different spin configurations.

Adhesive and robust multilayered poly(lactic acid) nanosheets for hemostatic dressing in liver injury model.

PubMed

Komachi, Takuya; Sumiyoshi, Hideaki; Inagaki, Yutaka; Takeoka, Shinji; Nagase, Yu; Okamura, Yosuke

2017-10-01

Freestanding biodegradable nanosheets composed of poly(l-lactic acid) (PLLA) have been developed for various biomedical applications. These nanosheets exhibit unique properties such as high adhesiveness and exquisite flexibility; however, they burst easily due to their nanometer thickness. We herein describe a freestanding, multilayered nanosheet composed of PLLA fabricated using a simple combination procedure: (i) multilayering of PLLA and alginate, (ii) gelation of the alginate layers, (iii) fusion-cut sealing, and (iv) elution of the alginate layers. The multilayered nanosheets not only reinforced the bursting strength but also provided a high level of adhesive strength. In fact, they were found to show potential as a hemostatic dressing, and they tended to show reduced tissue adhesion that accompanies liver injury. Therefore, we propose this biomaterial as a candidate for an alternative to conventional therapy in hemorrhage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1747-1757, 2017. © 2016 Wiley Periodicals, Inc.

Joint adsorption of light hydrogen by CuO and 5A molecular sieves

NASA Astrophysics Data System (ADS)

Wang, J.; Zhan, Y.; Wang, W.; Wang, R. S.

2018-03-01

H2 is the primary cause of the deteriorating vacuum degree of high-vacuum multilayer insulation tank (HVMLIT). At present, the precious metal PdO is used to adsorb H2 and maintain the high vacuum of HVMLIT. In this study, CA, a compound hydrogen adsorbent integrated with the cheap metal CuO and 5A molecular sieves, is adopted to jointly adsorb light hydrogen in HVMLIT. This work also investigates the adsorption characteristics and mechanisms of CA.

Metallized Products

NASA Technical Reports Server (NTRS)

1980-01-01

Since the early 1960's, virtually all NASA spacecraft have used metallized films for a variety of purposes, principally thermal radiation insulation. King Seeley manufactures a broad line of industrial and consumer oriented metallized film, fabric, paper and foam in single layer sheets and multi-layer laminates. A few examples, commercialized by MPI Outdoor Safety Products, are the three ounce Thermos Emergency Blanket which reflects and retains up to 80 percent of the user's body heat helping prevent post accident shock or keeping a person warm for hours under emergency cold weather conditions.

Separation of spin Seebeck effect and anomalous Nernst effect in Co/Cu/YIG

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Dai; State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433; Li, Yufan

2015-05-25

The spin Seebeck effect (SSE) and Anomalous Nernst effect (ANE) have been observed in Co/Cu/YIG (yttrium iron garnet) multi-layer structure, where the ferromagnetic insulator YIG acts as the pure spin injector and the ferromagnetic metal Co layer acts as the spin current detector. With the insertion of 5 nm Cu layer, the two ferromagnetic layers are decoupled, thus allowing unambiguous separation of the SSE and ANE contributions under the same experimental conditions in the same sample.

Separation of spin Seebeck effect and anomalous Nernst effect in Co/Cu/YIG

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Dai; Li, Yufan; Qu, D.

2015-05-25

The spin Seebeck effect (SSE) and Anomalous Nernst effect (ANE) have been observed in Co/Cu/YIG (yttrium iron garnet) multi-layer structure, where the ferromagnetic insulator YIG acts as the pure spin injector and the ferromagnetic metal Co layer acts as the spin current detector. With the insertion of 5 nm Cu layer, the two ferromagnetic layers are decoupled, thus allowing unambiguous separation of the SSE and ANE contributions under the same experimental conditions in the same sample.

Aluminum induced crystallization of amorphous Ge thin films on insulating substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Ch. Kishan, E-mail: kisn@igcar.gov.in; Tah, T.; Sunitha, D. T.

2016-05-23

Aluminium (metal) induced crystallization of amorphous Ge in bilayer and multilayer Ge/Al thin films deposited on quartz substrate at temperature well below the crystallization temperature of bulk Ge is reported. The crystallization of poly-Ge proceeds via formations of dendritic crystalline Ge grains in the Al matrix. The observed phases were characterized by Raman spectroscopy and X-ray diffraction. The microstructure of Al thin film layer was found to have a profound influence on such crystallization process and formation of dendritic grains.

Observation of zone folding induced acoustic topological insulators and the role of spin-mixing defects

NASA Astrophysics Data System (ADS)

Deng, Yuanchen; Ge, Hao; Tian, Yuan; Lu, Minghui; Jing, Yun

2017-11-01

This article reports on the experimental realization of a flow-free, pseudospin-based acoustic topological insulator designed using the strategy of zone folding. Robust sound one-way propagation is demonstrated with the presence of non-spin-mixing defects. On the other hand, it is shown that spin-mixing defects, which break the geometric symmetry and therefore the pseudo-time-reversal symmetry, can open up nontrivial band gaps within the edge state frequency band, and their width can be tailored by the extent of the defect. This provides a possible route for realizing tunable acoustic topological insulators.

Robust estimation of cerebral hemodynamics in neonates using multilayered diffusion model for normal and oblique incidences

NASA Astrophysics Data System (ADS)

Steinberg, Idan; Harbater, Osnat; Gannot, Israel

2014-07-01

The diffusion approximation is useful for many optical diagnostics modalities, such as near-infrared spectroscopy. However, the simple normal incidence, semi-infinite layer model may prove lacking in estimation of deep-tissue optical properties such as required for monitoring cerebral hemodynamics, especially in neonates. To answer this need, we present an analytical multilayered, oblique incidence diffusion model. Initially, the model equations are derived in vector-matrix form to facilitate fast and simple computation. Then, the spatiotemporal reflectance predicted by the model for a complex neonate head is compared with time-resolved Monte Carlo (TRMC) simulations under a wide range of physiologically feasible parameters. The high accuracy of the multilayer model is demonstrated in that the deviation from TRMC simulations is only a few percent even under the toughest conditions. We then turn to solve the inverse problem and estimate the oxygen saturation of deep brain tissues based on the temporal and spatial behaviors of the reflectance. Results indicate that temporal features of the reflectance are more sensitive to deep-layer optical parameters. The accuracy of estimation is shown to be more accurate and robust than the commonly used single-layer diffusion model. Finally, the limitations of such approaches are discussed thoroughly.

Multi-Target Regression via Robust Low-Rank Learning.

PubMed

Zhen, Xiantong; Yu, Mengyang; He, Xiaofei; Li, Shuo

2018-02-01

Multi-target regression has recently regained great popularity due to its capability of simultaneously learning multiple relevant regression tasks and its wide applications in data mining, computer vision and medical image analysis, while great challenges arise from jointly handling inter-target correlations and input-output relationships. In this paper, we propose Multi-layer Multi-target Regression (MMR) which enables simultaneously modeling intrinsic inter-target correlations and nonlinear input-output relationships in a general framework via robust low-rank learning. Specifically, the MMR can explicitly encode inter-target correlations in a structure matrix by matrix elastic nets (MEN); the MMR can work in conjunction with the kernel trick to effectively disentangle highly complex nonlinear input-output relationships; the MMR can be efficiently solved by a new alternating optimization algorithm with guaranteed convergence. The MMR leverages the strength of kernel methods for nonlinear feature learning and the structural advantage of multi-layer learning architectures for inter-target correlation modeling. More importantly, it offers a new multi-layer learning paradigm for multi-target regression which is endowed with high generality, flexibility and expressive ability. Extensive experimental evaluation on 18 diverse real-world datasets demonstrates that our MMR can achieve consistently high performance and outperforms representative state-of-the-art algorithms, which shows its great effectiveness and generality for multivariate prediction.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyaya, Mihir; Jindal, Vibhu; Basavalingappa, Adarsh

The availability of defect-free masks is considered to be a critical issue for enabling extreme ultraviolet lithography (EUVL) as the next generation technology. Since completely defect-free masks will be hard to achieve, it is essential to have a good understanding of the printability of the native EUV mask defects. In this work, we performed a systematic study of native mask defects to understand the defect printability caused by them. The multilayer growth over native substrate mask blank defects was correlated to the multilayer growth over regular-shaped defects having similar profiles in terms of their width and height. To model themore » multilayer growth over the defects, a novel level-set multilayer growth model was used that took into account the tool deposition conditions of the Veeco Nexus ion beam deposition tool. The same tool was used for performing the actual deposition of the multilayer stack over the characterized native defects, thus ensuring a fair comparison between the actual multilayer growth over native defects, and modeled multilayer growth over regular-shaped defects. Further, the printability of the characterized native defects was studied with the SEMATECH-Berkeley Actinic Inspection Tool (AIT), an EUV mask-imaging microscope at Lawrence Berkeley National Laboratory (LBNL). Printability of the modeled regular-shaped defects, which were propagated up the multilayer stack using level-set growth model was studied using defect printability simulations implementing the waveguide algorithm. Good comparison was observed between AIT and the simulation results, thus demonstrating that multilayer growth over a defect is primarily a function of a defect’s width and height, irrespective of its shape. This would allow us to predict printability of the arbitrarily-shaped native EUV mask defects in a systematic and robust manner.« less

Robust Multilayer Graphene-Organic Frameworks for Selective Separation of Monovalent Anions.

PubMed

Zhao, Yan; Zhu, Jiajie; Li, Jian; Zhao, Zhijuan; Charchalac Ochoa, Sebastian Ignacio; Shen, Jiangnan; Gao, Congjie; Van der Bruggen, Bart

2018-05-30

The chemical and mechanical stability of graphene nanosheets was used in this work to design a multilayer architecture of graphene, grafted with sulfonated 4,4'-diaminodiphenyl sulfone (SDDS). Quaternized poly(phenylene oxide) (QPPO) was synthesized and mixed with SDDS (rGO-SDDS-rGO@QPPO), yielding a multilayer graphene-organic framework (MGOF) with positive as well as negative functional groups that can be applied as a versatile electrodriven membrane in electrodialysis (ED). Multilayer graphene-organic frameworks are a new class of multilayer structures, with an architecture having a tunable interlayer spacing connected by cationic polymer material. MGOF membranes were demonstrated to allow for an excellent selective separation of monovalent anions in aqueous solution. Furthermore, different types of rGO-SDDS-rGO@QPPO membranes were found to have a good mechanical strength, with a tensile strength up to 66.43 MPa. The membrane (rGO-SDDS-rGO@QPPO-2) also has a low surface electric resistance (2.79 Ω·cm 2 ) and a low water content (14.5%) and swelling rate (4.7%). In addition, the selective separation between Cl - and SO 4 2- of the MGOF membranes could be as high as 36.6%.

Application of low-coherence interferometry for in situ nondestructive evaluation of thin and thick multilayered transparent composites

NASA Astrophysics Data System (ADS)

Khomenko, Anton; Cloud, Gary Lee; Haq, Mahmoodul

2015-12-01

Multilayered transparent composites having laminates with polymer interlayers and backing sheets are commonly used in a wide range of applications where visibility, transparency, impact resistance, and safety are essential. Manufacturing flaws or damage during operation can seriously compromise both safety and performance. Most fabrication defects are not discernible until after the entire multilayered transparent composite assembly has been completed, and in-the-field inspection for damage is a problem not yet solved. A robust and reliable nondestructive evaluation (NDE) technique is needed to evaluate structural integrity and identify defects that result from manufacturing issues as well as in-service damage arising from extreme environmental conditions in addition to normal mechanical and thermal loads. Current optical techniques have limited applicability for NDE of such structures. This work presents a technique that employs a modified interferometer utilizing a laser diode or femtosecond fiber laser source to acquire in situ defect depth location inside a thin or thick multilayered transparent composite, respectively. The technique successfully located various defects inside examined composites. The results show great potential of the technique for defect detection, location, and identification in multilayered transparent composites.

Improved Thermal-Insulation Systems for Low Temperatures

NASA Technical Reports Server (NTRS)

Fesmire, James E.; Augustynowicz, Stanislaw D.

2003-01-01

Improved thermal-insulation materials and structures and the techniques for manufacturing them are undergoing development for use in low-temperature applications. Examples of low-temperature equipment for which these thermal insulation systems could provide improved energy efficiency include storage tanks for cryogens, superconducting electric-power-transmission equipment, containers for transport of food and other perishable commodities, and cold boxes for low-temperature industrial processes. These systems could also be used to insulate piping used to transfer cryogens and other fluids, such as liquefied natural gas, refrigerants, chilled water, crude oil, or low-pressure steam. The present thermal-insulation systems are layer composites based partly on the older class of thermal-insulation systems denoted generally as multilayer insulation (MLI). A typical MLI structure includes an evacuated jacket, within which many layers of radiation shields are stacked or wrapped close together. Low-thermal-conductivity spacers are typically placed between the reflection layers to keep them from touching. MLI can work very well when a high vacuum level (less than 10(exp-4) torr) is maintained and utmost care is taken during installation, but its thermal performance deteriorates sharply as the pressure in the evacuated space rises into the soft vacuum range [pressures greater than 0.1 torr (greater than 13 Pa)]. In addition, the thermal performance of MLI is extremely sensitive to mechanical compression and edge effects and can easily decrease from one to two orders of magnitude from its ideal value even when the MLI is kept under high vacuum condition. The present thermal-insulation systems are designed to perform well under soft vacuum level, in particular the range of 1 to 10 torr. They are also designed with larger interlayer spacings to reduce vulnerability to compression (and consequent heat leak) caused by installation and use. The superiority of these systems is the synergistic effect of improvements in materials, design, and manufacture.

A Solution-Doped Polymer Semiconductor:Insulator Blend for Thermoelectrics.

PubMed

Kiefer, David; Yu, Liyang; Fransson, Erik; Gómez, Andrés; Primetzhofer, Daniel; Amassian, Aram; Campoy-Quiles, Mariano; Müller, Christian

2017-01-01

Poly(ethylene oxide) is demonstrated to be a suitable matrix polymer for the solution-doped conjugated polymer poly(3-hexylthiophene). The polarity of the insulator combined with carefully chosen processing conditions permits the fabrication of tens of micrometer-thick films that feature a fine distribution of the F4TCNQ dopant:semiconductor complex. Changes in electrical conductivity from 0.1 to 0.3 S cm -1 and Seebeck coefficient from 100 to 60 μV K -1 upon addition of the insulator correlate with an increase in doping efficiency from 20% to 40% for heavily doped ternary blends. An invariant bulk thermal conductivity of about 0.3 W m -1 K -1 gives rise to a thermoelectric Figure of merit ZT ∼ 10 -4 that remains unaltered for an insulator content of more than 60 wt%. Free-standing, mechanically robust tapes illustrate the versatility of the developed dopant:semiconductor:insulator ternary blends.

Experimental demonstration of anomalous Floquet topological insulator for sound

NASA Astrophysics Data System (ADS)

Peng, Yu-Gui; Qin, Cheng-Zhi; Zhao, De-Gang; Shen, Ya-Xi; Xu, Xiang-Yuan; Bao, Ming; Jia, Han; Zhu, Xue-Feng

2016-11-01

Time-reversal invariant topological insulator is widely recognized as one of the fundamental discoveries in condensed matter physics, for which the most fascinating hallmark is perhaps a spin-based topological protection, the absence of scattering of conduction electrons with certain spins on matter surface. Recently, it has created a paradigm shift for topological insulators, from electronics to photonics, phononics and mechanics as well, bringing about not only involved new physics but also potential applications in robust wave transport. Despite the growing interests in topologically protected acoustic wave transport, T-invariant acoustic topological insulator has not yet been achieved. Here we report experimental demonstration of anomalous Floquet topological insulator for sound: a strongly coupled metamaterial ring lattice that supports one-way propagation of pseudo-spin-dependent edge states under T-symmetry. We also demonstrate the formation of pseudo-spin-dependent interface states due to lattice dislocations and investigate the properties of pass band and band gap states.

Experimental demonstration of anomalous Floquet topological insulator for sound

PubMed Central

Peng, Yu-Gui; Qin, Cheng-Zhi; Zhao, De-Gang; Shen, Ya-Xi; Xu, Xiang-Yuan; Bao, Ming; Jia, Han; Zhu, Xue-Feng

2016-01-01

Time-reversal invariant topological insulator is widely recognized as one of the fundamental discoveries in condensed matter physics, for which the most fascinating hallmark is perhaps a spin-based topological protection, the absence of scattering of conduction electrons with certain spins on matter surface. Recently, it has created a paradigm shift for topological insulators, from electronics to photonics, phononics and mechanics as well, bringing about not only involved new physics but also potential applications in robust wave transport. Despite the growing interests in topologically protected acoustic wave transport, T-invariant acoustic topological insulator has not yet been achieved. Here we report experimental demonstration of anomalous Floquet topological insulator for sound: a strongly coupled metamaterial ring lattice that supports one-way propagation of pseudo-spin-dependent edge states under T-symmetry. We also demonstrate the formation of pseudo-spin-dependent interface states due to lattice dislocations and investigate the properties of pass band and band gap states. PMID:27834375

Data transmission element for downhole drilling components

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Fox, Joe; Sneddon, Cameron; Briscoe, Michael

2006-01-31

A robust data transmission element for transmitting information between downhole components, such as sections of drill pipe, in the presence of hostile environmental conditions, such as heat, dirt, rocks, mud, fluids, lubricants, and the like. The data transmission element components include a generally U-shaped annular housing, a generally U-shaped magnetically conductive, electrically insulating element such as ferrite, and an insulated conductor. Features on the magnetically conducting, electrically insulating element and the annular housing create a pocket when assembled. The data transmission element is filled with a polymer to retain the components within the annular housing by filling the pocket with the polymer. The polymer can bond with the annular housing and the insulated conductor but preferably not the magnetically conductive, electrically insulating element. A data transmission element is mounted within a recess proximate a mating surface of a downhole drilling component, such as a section of drill pipe.

A Solution‐Doped Polymer Semiconductor:Insulator Blend for Thermoelectrics

PubMed Central

Kiefer, David; Yu, Liyang; Fransson, Erik; Gómez, Andrés; Primetzhofer, Daniel; Amassian, Aram; Campoy‐Quiles, Mariano

2016-01-01

Poly(ethylene oxide) is demonstrated to be a suitable matrix polymer for the solution‐doped conjugated polymer poly(3‐hexylthiophene). The polarity of the insulator combined with carefully chosen processing conditions permits the fabrication of tens of micrometer‐thick films that feature a fine distribution of the F4TCNQ dopant:semiconductor complex. Changes in electrical conductivity from 0.1 to 0.3 S cm−1 and Seebeck coefficient from 100 to 60 μV K−1 upon addition of the insulator correlate with an increase in doping efficiency from 20% to 40% for heavily doped ternary blends. An invariant bulk thermal conductivity of about 0.3 W m−1 K−1 gives rise to a thermoelectric Figure of merit ZT ∼ 10−4 that remains unaltered for an insulator content of more than 60 wt%. Free‐standing, mechanically robust tapes illustrate the versatility of the developed dopant:semiconductor:insulator ternary blends. PMID:28105396

HST Multi Layer Insulation Failure Review Board Findings

NASA Technical Reports Server (NTRS)

Townsend, Jacqueline; Hansen, Patricia

1998-01-01

The mechanical and optical properties of the thermal control materials on the Hubble Space Telescope (HST) have degraded over the nearly seven years the telescope has been in orbit. Astronaut observations and photographs from the Second Servicing Mission (SM2) revealed large cracks in the metallized Teflon fluorinated ethylene propylene (FEP), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. Also, the absorptance of the bonded metallized Teflon FEP radiator surfaces of the telescope has increased over time. A Failure Review Board was established to determine the damage mechanism and to identify a replacement material. Samples of the top layer of the MLI and radiator material were retrieved during SM2, and a thorough investigation into the degradation followed in order to determine the primary cause of the damage. Mapping of the cracks on HST and the ground testing showed that thermal cycling with deep-layer damage from electron and proton radiation are necessary to cause the observed embrittlement. Further, strong evidence was found indicating that chain scission (reduced molecular weight) is the dominant form of damage to the metallized Teflon FEP. Given the damage to the outer layer of the multi-layer insulation (MLI) that was apparent during the second servicing mission (SM2), the decision was made to replace the outer layer during subsequent servicing missions. The replacement material had to meet the stringent thermal requirements of the spacecraft and maintain structural integrity for at least ten years. Ten candidate materials were exposed to simulated orbital environments and a replacement material was selected. This presentation will summarize the FRB results, in particular, the analysis of the retrieved specimens, the results of the simulated environmental exposures, and the selection of the replacement material. The NASA Space Environments and Effects community needs to hear these results because they reveal that Teflon (FEP) films should not be used in LEO as routinely as they are today.

Compact multilayer film structure for angle insensitive color filtering.

PubMed

Yang, Chenying; Shen, Weidong; Zhang, Yueguang; Li, Kan; Fang, Xu; Zhang, Xing; Liu, Xu

2015-03-19

Here we report a compact multilayer film structure for angle robust color filtering, which is verified by theoretical calculations and experiment results. The introduction of the amorphous silicon in the proposed unsymmetrical resonant cavity greatly reduces the angular sensitivity of the filters, which is confirmed by the analysis of the phase shift within the structure. The temperature of the substrate during the deposition is expressly investigated to obtain the best optical performance with high peak reflectance and good angle insensitive color filtering by compromising the refractive index of dielectric layer and the surface roughness of the multilayer film. And the outlayer of the structure, worked as the anti-reflection layer, have an enormous impact on the filtering performance. This method, described in this paper, can have enormous potential for diverse applications in display, colorful decoration, anti-counterfeiting and so forth.

Topologically robust sound propagation in an angular-momentum-biased graphene-like resonator lattice

NASA Astrophysics Data System (ADS)

Khanikaev, Alexander B.; Fleury, Romain; Mousavi, S. Hossein; Alù, Andrea

2015-10-01

Topological insulators do not allow conduction in the bulk, yet they support edge modes that travel along the boundary only in one direction, determined by the carried electron spin, with inherent robustness to defects and disorder. Topological insulators have inspired analogues in photonics and optics, in which one-way edge propagation in topologically protected two-dimensional materials is achieved breaking time-reversal symmetry with a magnetic bias. Here, we introduce the concept of topological order in classical acoustics, realizing robust topological protection and one-way edge propagation of sound in a suitably designed resonator lattice biased with angular momentum, forming the acoustic analogue of a magnetically biased graphene layer. Extending the concept of an acoustic nonreciprocal circulator based on angular-momentum bias, time-reversal symmetry is broken here using moderate rotational motion of air within each element of the lattice, which takes the role of the electron spin in determining the direction of modal edge propagation.

500 C Electronic Packaging and Dielectric Materials for High Temperature Applications

NASA Technical Reports Server (NTRS)

Chen, Liang-yu; Neudeck, Philip G.; Spry, David J.; Beheim, Glenn M.; Hunter, Gary W.

2016-01-01

High-temperature environment operable sensors and electronics are required for exploring the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and application of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high temperature electronics, and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by these high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed. High-temperature environment operable sensors and electronics are required for probing the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and eventual applications of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high electronics and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed.

Charging/discharging behavior and mechanism of silicon quantum dots embedded in amorphous silicon carbide films

NASA Astrophysics Data System (ADS)

Wen, Xixing; Zeng, Xiangbin; Zheng, Wenjun; Liao, Wugang; Feng, Feng

2015-01-01

The charging/discharging behavior of Si quantum dots (QDs) embedded in amorphous silicon carbide (a-SiCx) was investigated based on the Al/insulating layer/Si QDs embedded in a-SiCx/SiO2/p-Si (metal-insulator-quantum dots-oxide-silicon) multilayer structure by capacitance-voltage (C-V) and conductance-voltage (G-V) measurements. Transmission electron microscopy and Raman scattering spectroscopy measurements reveal the microstructure and distribution of Si QDs. The occurrence and shift of conductance peaks indicate the carrier transfer and the charging/discharging behavior of Si QDs. The multilayer structure shows a large memory window of 5.2 eV at ±8 V sweeping voltage. Analysis of the C-V and G-V results allows a quantification of the Coulomb charging energy and the trapped charge density associated with the charging/discharging behavior. It is found that the memory window is related to the size effect, and Si QDs with large size or low Coulomb charging energy can trap two or more electrons by changing the charging voltage. Meanwhile, the estimated lower potential barrier height between Si QD and a-SiCx, and the lower Coulomb charging energy of Si QDs could enhance the charging and discharging effect of Si QDs and lead to an enlarged memory window. Further studies of the charging/discharging mechanism of Si QDs embedded in a-SiCx can promote the application of Si QDs in low-power consumption semiconductor memory devices.

Acoustic and Thermal Testing of an Integrated Multilayer Insulation and Broad Area Cooling Shield System

NASA Technical Reports Server (NTRS)

Wood, Jessica J.; Foster, Lee W.

2013-01-01

A Multilayer Insulation (MLI) and Broad Area Cooling (BAC) shield thermal control system shows promise for long-duration storage of cryogenic propellant. The NASA Cryogenic Propellant Storage and Transfer (CPST) project is investigating the thermal and structural performance of this tank-applied integrated system. The MLI/BAC Shield Acoustic and Thermal Test was performed to evaluate the MLI/BAC shield's structural performance by subjecting it to worst-case launch acoustic loads. Identical thermal tests using Liquid Nitrogen (LN2) were performed before and after the acoustic test. The data from these tests was compared to determine if any degradation occurred in the thermal performance of the system as a result of exposure to the acoustic loads. The thermal test series consisted of two primary components: a passive boil-off test to evaluate the MLI performance and an active cooling test to evaluate the integrated MLI/BAC shield system with chilled vapor circulating through the BAC shield tubes. The acoustic test used loads closely matching the worst-case envelope of all launch vehicles currently under consideration for CPST. Acoustic test results yielded reasonable responses for the given load. The thermal test matrix was completed prior to the acoustic test and successfully repeated after the acoustic test. Data was compared and yielded near identical results, indicating that the MLI/BAC shield configuration tested in this series is an option for structurally implementing this thermal control system concept.

Assessment of Cumulative Trauma Disorder (CTD) Risk for 3 Different Tasks Constructing and Repairing Multi-Layer Insulation (MLI) Blankets, Preparing the Dough for a Pizza, and Operating the Becton-Dickinson FACSAria Flow Cytometer

NASA Technical Reports Server (NTRS)

Gentzler, Marc; Kline, Martin; Palmer, Andrew; Terrone, Mark

2007-01-01

The Cumulative Trauma Disorder (CTD) risks for three different tasks using McCauley-Bell and Badiru's (1993) formula based on task, personal, and organizational factors were examined. For the Multi-Layer Insulation (MLI) blanket task, the results showed that the task, personal, and organizational risks were at about the same level. The personal risk factors for this task were evaluated using a hypothetical female employee age 52. For the pizza dough task, it was shown that the organizational risk was particularly high, with task related factors also at quite dangerous levels. On the other hand, there was a very low level of personal risk factors, based on a female age 17. The flow cytometer task was assessed with three different participants, a11 of whom had quite disparate levels of personal risk, which slightly affected the overall CTD risk. This reveals how individual difference variables certainly need to be considered. The task and organizational risks for this task were rated at about the same moderate level. The overall CTD risk averaged across the three participants was .335, indicating some risk. Compruing across the tasks revealed that the pizza dough task created the greatest overall CTD risk by far (.568), with the MLI (.325) and flow cytometer task (.335) having some risk associated with them. Future research should look into different tasks for more of a comparison

METAShield: Hot Metallic Aeroshell Concept for RLV/SOV

NASA Technical Reports Server (NTRS)

Scotti, Stephen J.; Poteet, Carl C.; Daryabeigi, Kamran; Nowak, Robert J.; Hsu, Su-Yuen; Schmidt, Irvin H.; Ku, Shih-Huei P.

2003-01-01

An innovative fuselage design approach that combines many desirable operational features with a simple and efficient structural approach is being developed by NASA. The approach, named METAShield for MEtallic TransAtmospheric Shield, utilizes lightly loaded, hot aeroshell structures surrounding integral propellant tanks that carry the primary structural loads. The aeroshells are designed to withstand the local pressure loads, transmitting them to the tanks with minimal restraint of thermal growth. No additional thermal protection system protects the METAShield, and a fibrous or multilayer insulation blanket, located in the space between the aeroshell and the tanks, serves as both high temperature and cryogenic insulation for the tanks. The concept is described in detail, and the performance and operational features are highlighted. Initial design results and analyses of the structural, thermal, and thermal-structural performance are described. Computational results evaluating resistance to hypervelocity impact damage, as well as some supporting aerothermal wind tunnel results. are also presented. Future development needs are summarized.

Insulation Resistance and Leakage Currents in Low-Voltage Ceramic Capacitors with Cracks

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2014-01-01

Measurement of insulation resistance (IR) in multilayer ceramic capacitors (MLCCs) is considered a screening technique that ensures the dielectric is defect-free. This work analyzes the effectiveness of this technique for revealing cracks in ceramic capacitors. It is shown that absorption currents prevail over the intrinsic leakage currents during standard IR measurements at room temperature. Absorption currents, and consequently IR, have a weak temperature dependence, increase linearly with voltage (before saturation), and are not sensitive to the presence of mechanical defects. In contrary, intrinsic leakage currents increase super-linearly with voltage and exponentially with temperature (activation energy is in the range from 0.6 eV to 1.1 eV). Leakage currents associated with the presence of cracks have a weaker dependence on temperature and voltage compared to the intrinsic leakage currents. For this reason, intrinsic leakage currents prevail at high temperatures and voltages, thus masking the presence of defects.

HIRDLS Cryocooler Subsystem on-orbit Performance

NASA Astrophysics Data System (ADS)

Lock, J.; Stack, R.; Glaister, D. S.; Gully, W.

2006-04-01

This paper describes the HIRDLS (High Resolution Dynamic Limb Sounder) Cryocooler Subsystem (CSS) and its on-orbit flight performance. The HIRDLS Instrument was launched on July 15, 2004 as part of the NASA GSFC EOS Aura platform. Ball Aerospace provided the CSS, which includes the long life Stirling cryocooler (cooling at 59 K), cold plumbing to connect the cooler to the instrument Detector Subsystem, an ambient radiator to reject the cooler dissipation, and a vacuum enclosure system that enabled bench top ground testing. As of August 20, 2005, the cryocooler has over 9,000 hours of continuous operation with performance that exceeds requirements. Of note is that the CSS has experienced virtually no change in performance, including no indication of external contamination related degradation that has been evident on several other cryocooler systems in space flights. This steady performance can be attributed to the multi-layer insulation (MLI) based insulation design, which will be described in the paper.

Insulation Resistance and Leakage Currents in Low-Voltage Ceramic Capacitors with Cracks

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2016-01-01

Measurement of insulation resistance (IR) in multilayer ceramic capacitors (MLCCs) is considered a screening technique that ensures the dielectric is defect-free. This work analyzes the effectiveness of this technique for revealing cracks in ceramic capacitors. It is shown that absorption currents prevail over the intrinsic leakage currents during standard IR measurements at room temperature. Absorption currents, and consequently IR, have a weak temperature dependence, increase linearly with voltage (before saturation), and are not sensitive to the presence of mechanical defects. In contrary, intrinsic leakage currents increase super-linearly with voltage and exponentially with temperature (activation energy is in the range from 0.6 eV to 1.1 eV). Leakage currents associated with the presence of cracks have a weaker dependence on temperature and voltage compared to the intrinsic leakage currents. For this reason, intrinsic leakage currents prevail at high temperatures and voltages, thus masking the presence of defects.

Multipurpose hardened spacecraft insulation

NASA Technical Reports Server (NTRS)

Steimer, Carlos H.

1990-01-01

A Multipurpose Hardened Spacecraft Multilayer Insulation (MLI) system was developed and implemented to meet diverse survivability and performance requirements. Within the definition and confines of a MLI assembly (blanket), the design: (1) provides environmental protection from natural and induced nuclear, thermal, and electromagnetic radiation; (2) provides adequate electrostatic discharge protection for a geosynchronous satellite; (3) provides adequate shielding to meet radiated emission needs; and (4) will survive ascent differential pressure loads between enclosed volume and space. The MLI design is described which meets these requirements and design evolution and verification is discussed. The application is for MLI blankets which closeout the area between the laser crosslink subsystem (LCS) equipment and the DSP spacecraft cabin. Ancillary needs were implemented to ease installation at launch facility and to survive ascent acoustic and vibration loads. Directional venting accommodations were also incorporated to avoid contamination of LCS telescope, spacecraft sensors, and second surface mirrors (SSMs).

Propellant management for low thrust chemical propulsion systems

NASA Technical Reports Server (NTRS)

Hamlyn, K. M.; Dergance, R. H.; Aydelott, J. C.

1981-01-01

Low-thrust chemical propulsion systems (LTPS) will be required for orbital transfer of large space systems (LSS). The work reported in this paper was conducted to determine the propellant requirements, preferred propellant management technique, and propulsion system sizes for the LTPS. Propellants were liquid oxygen (LO2) combined with liquid hydrogen (LH2), liquid methane or kerosene. Thrust levels of 100, 500, and 1000 lbf were combined with 1, 4, and 8 perigee burns for transfer from low earth orbit to geosynchronous earth orbit. This matrix of systems was evaluated with a multilayer insulation (MLI) or a spray-on-foam insulation. Vehicle sizing results indicate that a toroidal tank configuration is needed for the LO2/LH2 system. Multiple perigee burns and MLI allow far superior LSS payload capability. Propellant settling, combined with a single screen device, was found to be the lightest and least complex propellant management technique.

Topological phononic insulator with robust pseudospin-dependent transport

NASA Astrophysics Data System (ADS)

Xia, Bai-Zhan; Liu, Ting-Ting; Huang, Guo-Liang; Dai, Hong-Qing; Jiao, Jun-Rui; Zang, Xian-Guo; Yu, De-Jie; Zheng, Sheng-Jie; Liu, Jian

2017-09-01

Topological phononic states, which facilitate unique acoustic transport around defects and disorders, have significantly revolutionized our scientific cognition of acoustic systems. Here, by introducing a zone folding mechanism, we realize the topological phase transition in a double Dirac cone of the rotatable triangular phononic crystal with C3 v symmetry. We then investigate the distinct topological edge states on two types of interfaces of our phononic insulators. The first one is a zigzag interface which simultaneously possesses a symmetric mode and an antisymmetric mode. Hybridization of the two modes leads to a robust pseudospin-dependent one-way propagation. The second one is a linear interface with a symmetric mode or an antisymmetric mode. The type of mode is dependent on the topological phase transition of the phononic insulators. Based on the rotatability of triangular phononic crystals, we consider several complicated contours defined by the topological zigzag interfaces. Along these contours, the acoustic waves can unimpededly transmit without backscattering. Our research develops a route for the exploration of the topological phenomena in experiments and provides an excellent framework for freely steering the acoustic backscattering-immune propagation within topological phononic structures.

Flexible transparent aerogels as window retrofitting films and optical elements with tunable birefringence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Qingkun; Frazier, Allister W.; Zhao, Xinpeng

Experimental realization of optically transparent, mechanically robust and flexible aerogels has been a longstanding challenge, which limits their practical applications in energy-saving devices, such as thermally insulating films for enhancing energy efficiency of windows. The poor transparency precluded even hypothetical consideration of the possibility of birefringent aerogels. We develop birefringent and optically isotropic aerogels that combine properties of thermal super-insulation, mechanical robustness and flexibility, and transparency to visible-spectrum light. This unusual combination of physical properties is achieved by combining liquid crystalline self-organization of cellulose nanofibers with polysiloxane cross-linking and control of the nanoscale porosity to form hybrid organic-inorganic mesostructured aerogels.more » Potential applications of these inexpensive materials range from single pane window retrofitting to smart fabrics.« less

Robust edge states in amorphous gyromagnetic photonic lattices

NASA Astrophysics Data System (ADS)

Mansha, Shampy; Chong, Y. D.

2017-09-01

We numerically study amorphous analogs of a two-dimensional photonic Chern insulator. The amorphous lattices consist of gyromagnetic rods that break time-reversal symmetry, with the lattice sites generated by a close-packing algorithm. The level of short-range order is adjustable, and there is no long-range order. The topologically nontrivial gaps of the photonic Chern insulator are found to persist into the amorphous regime, so long as there is sufficient short-range order. Strongly nonreciprocal robust transmission occurs via edge states, which are shown to propagate ballistically despite the absence of long-range order, and to be exponentially localized along the lattice edge. Interestingly, there is an enhancement of nonreciprocal transmission even at very low levels of short-range order, where there are no discernible spectral gaps.

Optimization of Multilayer Laminated Film and Absorbent of Vacuum Insulation Panel for Use at High Temperature

NASA Astrophysics Data System (ADS)

Araki, Kuninari; Echigoya, Wataru; Tsuruga, Toshimitsu; Kamoto, Daigorou; Matsuoka, Shin-Ichi

For the energy saving regulation and larger capacity, Vacuum Insulation Panel (VIP) has been used in refrigerators with urethane foam in recent years. VIP for low temperature is constructed by laminated plastic film, using heat welding of each neighboring part for keeping vacuum, so that the performance decrement is very large under high temperature. But recently high efficiency insulation material is desired for high temperature water holding devices (automatic vending machine, heat pump water heater, electric hot-water pot water, etc.), and we especially focused on cost and ability of the laminated plastic film and absorbent for high temperature VIP. We measured the heatproof temperature of plastic films and checked the amount of water vapor and out coming gas on temperature-programmed adsorption in absorbent. These results suggest the suitable laminated film and absorbent system for VIP use at high temperature, and the long-term reliability was evaluated by measuring thermal conductivity of high temperature. As a result it was found that high-retort pouch of CPP (cast polypropylene film) and adding of aluminum coating are the most suitable materials for use in the welded layers of high-temperature VIPs (105°C).

Reorganization energy upon charging a single molecule on an insulator measured by atomic force microscopy

NASA Astrophysics Data System (ADS)

Fatayer, Shadi; Schuler, Bruno; Steurer, Wolfram; Scivetti, Ivan; Repp, Jascha; Gross, Leo; Persson, Mats; Meyer, Gerhard

2018-05-01

Intermolecular single-electron transfer on electrically insulating films is a key process in molecular electronics1-4 and an important example of a redox reaction5,6. Electron-transfer rates in molecular systems depend on a few fundamental parameters, such as interadsorbate distance, temperature and, in particular, the Marcus reorganization energy7. This crucial parameter is the energy gain that results from the distortion of the equilibrium nuclear geometry in the molecule and its environment on charging8,9. The substrate, especially ionic films10, can have an important influence on the reorganization energy11,12. Reorganization energies are measured in electrochemistry13 as well as with optical14,15 and photoemission spectroscopies16,17, but not at the single-molecule limit and nor on insulating surfaces. Atomic force microscopy (AFM), with single-charge sensitivity18-22, atomic-scale spatial resolution20 and operable on insulating films, overcomes these challenges. Here, we investigate redox reactions of single naphthalocyanine (NPc) molecules on multilayered NaCl films. Employing the atomic force microscope as an ultralow current meter allows us to measure the differential conductance related to transitions between two charge states in both directions. Thereby, the reorganization energy of NPc on NaCl is determined as (0.8 ± 0.2) eV, and density functional theory (DFT) calculations provide the atomistic picture of the nuclear relaxations on charging. Our approach presents a route to perform tunnelling spectroscopy of single adsorbates on insulating substrates and provides insight into single-electron intermolecular transport.

Design and demonstrate the performance of cryogenic components representative of space vehicles: Start basket liquid acquisition device performance analysis

NASA Technical Reports Server (NTRS)

1987-01-01

The objective was to design, fabricate and test an integrated cryogenic test article incorporating both fluid and thermal propellant management subsystems. A 2.2 m (87 in) diameter aluminum test tank was outfitted with multilayer insulation, helium purge system, low-conductive tank supports, thermodynamic vent system, liquid acquisition device and immersed outflow pump. Tests and analysis performed on the start basket liquid acquisition device and studies of the liquid retention characteristics of fine mesh screens are discussed.

Materials Development for Hypersonic Flight Vehicles

NASA Technical Reports Server (NTRS)

Glass, David E.; Dirling, Ray; Croop, Harold; Fry, Timothy J.; Frank, Geoffrey J.

2006-01-01

The DARPA/Air Force Falcon program is planning to flight test several hypersonic technology vehicles (HTV) in the next several years. A Materials Integrated Product Team (MIPT) was formed to lead the development of key thermal protection system (TPS) and hot structures technologies. The technologies being addressed by the MIPT are in the following areas: 1) less than 3000 F leading edges, 2) greater than 3000 F refractory composite materials, 3) high temperature multi-layer insulation, 4) acreage TPS, and 5) high temperature seals. Technologies being developed in each of these areas are discussed in this paper.

[Plumage structure and skin weight in nestlings of cranes (Gruidae, Gruiformes)].

PubMed

Il'iashenko, V Iu; Chernova, O F

2008-01-01

A decrease in the down density and integument relative weight has been demonstrated in the ontogeny of nestlings. Coupled with the differentiation of the down cover (several generations of the down and down plumages with a typical heterochrony), this provides for the development of a multilayer thermal insulation cover evenly distributed over the nestling body and required for homeothermy. Comparative analysis of the structure of natal and mesoptile down, accessory feathers, and downy part of the vane of contour feathers has demonstrated the highest generalization in the mesoptile down generation.

Microelectronic superconducting device with multi-layer contact

DOEpatents

Wellstood, Frederick C.; Kingston, John J.; Clarke, John

1993-01-01

A microelectronic component comprising a crossover is provided comprising a substrate, a first high T.sub.c superconductor thin film, a second insulating thin film comprising SrTiO.sub.3 ; and a third high T.sub.c superconducting film which has strips which crossover one or more areas of the first superconductor film. An insitu method for depositing all three films on a substrate is provided which does not require annealing steps. The photolithographic process is used to separately pattern the high T.sub.c superconductor thin films.

Control of magnetic direction in multi-layer ferromagnetic devices by bias voltage

DOEpatents

You, Chun-Yeol; Bader, Samuel D.

2001-01-01

A system for controlling the direction of magnetization of materials comprising a ferromagnetic device with first and second ferromagnetic layers. The ferromagnetic layers are disposed such that they combine to form an interlayer with exchange coupling. An insulating layer and a spacer layer are located between the first and second ferromagnetic layers. A direct bias voltage is applied to the interlayer exchange coupling, causing the direction of magnetization of the second ferromagnetic layer to change. This change of magnetization direction occurs in the absence of any applied external magnetic field.

Microelectronic superconducting device with multi-layer contact

DOEpatents

Wellstood, F.C.; Kingston, J.J.; Clarke, J.

1993-10-26

A microelectronic component comprising a crossover is provided comprising a substrate, a first high T[sub c] superconductor thin film, a second insulating thin film comprising SrTiO[sub 3] ; and a third high T[sub c] superconducting film which has strips which crossover one or more areas of the first superconductor film. An in situ method for depositing all three films on a substrate is provided which does not require annealing steps. The photolithographic process is used to separately pattern the high T[sub c] superconductor thin films. 14 figures.

Multi-layered nanocomposite dielectrics for high density organic memory devices

NASA Astrophysics Data System (ADS)

Kang, Moonyeong; Chung, Kyungwha; Baeg, Kang-Jun; Kim, Dong Ha; Kim, Choongik

2015-01-01

We fabricated organic memory devices with metal-pentacene-insulator-silicon structure which contain double dielectric layers comprising 3D pattern of Au nanoparticles (Au NPs) and block copolymer (PS-b-P2VP). The role of Au NPs is to charge/discharge carriers upon applied voltage, while block copolymer helps to form highly ordered Au NP patterns in the dielectric layer. Double-layered nanocomposite dielectrics enhanced the charge trap density (i.e., trapped charge per unit area) by Au NPs, resulting in increase of the memory window (ΔVth).

Polymer multilayer tattooing for enhanced DNA vaccination

NASA Astrophysics Data System (ADS)

Demuth, Peter C.; Min, Younjin; Huang, Bonnie; Kramer, Joshua A.; Miller, Andrew D.; Barouch, Dan H.; Hammond, Paula T.; Irvine, Darrell J.

2013-04-01

DNA vaccines have many potential benefits but have failed to generate robust immune responses in humans. Recently, methods such as in vivo electroporation have demonstrated improved performance, but an optimal strategy for safe, reproducible, and pain-free DNA vaccination remains elusive. Here we report an approach for rapid implantation of vaccine-loaded polymer films carrying DNA, immune-stimulatory RNA, and biodegradable polycations into the immune-cell-rich epidermis, using microneedles coated with releasable polyelectrolyte multilayers. Films transferred into the skin following brief microneedle application promoted local transfection and controlled the persistence of DNA and adjuvants in the skin from days to weeks, with kinetics determined by the film composition. These ‘multilayer tattoo’ DNA vaccines induced immune responses against a model HIV antigen comparable to electroporation in mice, enhanced memory T-cell generation, and elicited 140-fold higher gene expression in non-human primate skin than intradermal DNA injection, indicating the potential of this strategy for enhancing DNA vaccination.

A microdot multilayer oxide device: let us tune the strain-ionic transport interaction.

PubMed

Schweiger, Sebastian; Kubicek, Markus; Messerschmitt, Felix; Murer, Christoph; Rupp, Jennifer L M

2014-05-27

In this paper, we present a strategy to use interfacial strain in multilayer heterostructures to tune their resistive response and ionic transport as active component in an oxide-based multilayer microdot device on chip. For this, fabrication of strained multilayer microdot devices with sideways attached electrodes is reported with the material system Gd0.1Ce0.9O(2-δ)/Er2O3. The fast ionic conducting Gd0.1Ce0.9O(2-δ) single layers are altered in lattice strain by the electrically insulating erbia phases of a microdot. The strain activated volume of the Gd0.1Ce0.9O(2-δ) is investigated by changing the number of individual layers from 1 to 60 while keeping the microdot at a constant thickness; i.e., the proportion of strained volume was systematically varied. Electrical measurements showed that the activation energy of the devices could be altered by Δ0.31 eV by changing the compressive strain of a microdot ceria-based phase by more than 1.16%. The electrical conductivity data is analyzed and interpreted with a strain volume model and defect thermodynamics. Additionally, an equivalent circuit model is presented for sideways contacted multilayer microdots. We give a proof-of-concept for microdot contacting to capture real strain-ionic transport effects and reveal that for classic top-electrode contacting the effect is nil, highlighting the need for sideways electric contacting on a nanoscopic scale. The near order ionic transport interaction is supported by Raman spectroscopy measurements. These were conducted and analyzed together with fully relaxed single thin film samples. Strain states are described relative to the strain activated volumes of Gd0.1Ce0.9O(2-δ) in the microdot multilayer. These findings reveal that strain engineering in microfabricated devices allows altering the ionic conduction over a wide range beyond classic doping strategies for single films. The reported fabrication route and concept of strained multilayer microdots is a promising path for applying strained multilayer oxides as active new building blocks relevant for a broad range of microelectrochemical devices, e.g., resistive switching memory prototypes, resistive or electrochemical sensors, or as active catalytic solid state surface components for microfuel cells or all-solid-state batteries.

Robust, Multi-layered Plan Execution and Revision for Operation of a Network of Communication Antennas

NASA Technical Reports Server (NTRS)

Chien, S. A.; Hill, R. W., Jr.; Govindjee, A.; Wang, X.; Estlin, T.; Griesel, M. A.; Lam, R.; Fayyad, K. V.

1996-01-01

This paper describes a hierarchical scheduling, planning, control, and execution monitoring architecture for automating operations of a worldwide network of communications antennas. The purpose of this paper is to describe an architecture for automating the process of capturing spacecraft data.

Phase coherent transport in hybrid superconductor-topological insulator devices

NASA Astrophysics Data System (ADS)

Finck, Aaron

2015-03-01

Heterostructures of superconductors and topological insulators are predicted to host unusual zero energy bound states known as Majorana fermions, which can robustly store and process quantum information. Here, I will discuss our studies of such heterostructures through phase-coherent transport, which can act as a unique probe of Majorana fermions. We have extensively explored topological insulator Josephson junctions through SQUID and single-junction diffraction patterns, whose unusual behavior give evidence for low-energy Andreev bound states. In topological insulator devices with closely spaced normal and superconducting leads, we observe prominent Fabry-Perot oscillations, signifying gate-tunable, quasi-ballistic transport that can elegantly interact with Andreev reflection. Superconducting disks deposited on the surface of a topological insulator generate Aharonov-Bohm-like oscillations, giving evidence for unusual states lying near the interface between the superconductor and topological insulator surface. Our results point the way towards sophisticated interferometers that can detect and read out the state of Majorana fermions in topological systems. This work was done in collaboration with Cihan Kurter, Yew San Hor, and Dale Van Harlingen. We acknowledge funding from Microsoft Project Q.

Multilayer Regulation of Atomic Boron Nitride Films to Improve Oxidation and Corrosion Resistance of Cu.

PubMed

Ren, Siming; Cui, Mingjun; Pu, Jibin; Xue, Qunji; Wang, Liping

2017-08-16

The boron nitride (BN) monolayer (1L) with high impermeability and resistivity seems to hold promise as a long-term corrosion barrier for Cu under ambient condition, which is supported by recent researches. Here, we perform a complete study of the alternating temperature tests (the sample is exposed in air for 30 days and subsequently heated at 200 °C for 2 h) and electrochemical measurements on 1L and multilayer BN-coated Cu foils. Results imply that the BN-coated Cu foils are less oxidized than uncoated Cu foils after alternating temperature tests, regardless of the layers of BN. Particularly, the oxidation process proceeds slowly in multilayers because most of the underlying defects are covered with BN layers to suppress the oxygen diffusion in the vertical direction and the oxidation mainly occurs on the wrinkled region of BN films. Electrochemical analyses reveal that the BN layers provide an effective physical barrier against the corrosive medium and inhibit the electron diffusion because of their high electrical insulating behavior and the corrosion resistance of the samples increases with increasing BN layers. These findings indicate that BN films with adequate layers are good candidates for oxidation and corrosion protection at the atomic level, which is vital to many industrial and academic applications.

Bulk-heterojunction organic solar cells sandwiched by solution processed molybdenum oxide and titania nanosheet layers

NASA Astrophysics Data System (ADS)

Itoh, Eiji; Goto, Yoshinori; Fukuda, Katsutoshi

2014-02-01

The contributions of ultrathin titania nanosheet (TN) crystallites were studied in both an inverted bulk-heterojunction (BHJ) cell in an indium-tin oxide (ITO)/titania nanosheet (TN)/poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methylester (PCBM) active layer/MoOx/Ag multilayered photovoltaic device and a conventional BHJ cell in ITO/MoOx/P3HT:PCBM active layer/TN/Al multilayered photovoltaic device. The insertion of only one or two layers of poly(diallyldimethylammonium chloride) (PDDA) and TN multilayered film prepared by the layer-by-layer deposition technique effectively decreased the leakage current and increased the open circuit voltage (VOC), fill factor (FF), and power conversion efficiency (η). The conventional cell sandwiched between a solution-processed, partially crystallized molybdenum oxide hole-extracting buffer layer and a TN electron extracting buffer layer showed comparable cell performance to a device sandwiched between vacuum-deposited molybdenum oxide and TN layers, whereas the inverted cell with solution-processed molybdenum oxide showed a poorer performance probably owing to the increment in the leakage current across the film. The abnormal S-shaped curves observed in the inverted BHJ cell above VOC disappeared with the use of a polyfluorene-based cationic semiconducting polymer as a substitute for an insulating PDDA film, resulting in the improved cell performance.

A "Politically Robust" Experimental Design for Public Policy Evaluation, with Application to the Mexican Universal Health Insurance Program

ERIC Educational Resources Information Center

King, Gary; Gakidou, Emmanuela; Ravishankar, Nirmala; Moore, Ryan T.; Lakin, Jason; Vargas, Manett; Tellez-Rojo, Martha Maria; Avila, Juan Eugenio Hernandez; Avila, Mauricio Hernandez; Llamas, Hector Hernandez

2007-01-01

We develop an approach to conducting large-scale randomized public policy experiments intended to be more robust to the political interventions that have ruined some or all parts of many similar previous efforts. Our proposed design is insulated from selection bias in some circumstances even if we lose observations; our inferences can still be…

Fabrication and design of vanadium oxide microbolometer

NASA Astrophysics Data System (ADS)

Abdel-Rahman, M.; Al-Khalli, N.; Zia, M. F.; Alduraibi, M.; Ilahi, B.; Awad, E.; Debbar, N.

2017-02-01

Vanadium oxide (VxOy) multilayer sandwich structures previously studied by our group were found to yield a sensitive thermometer thin film material suitable for microbolometer applications. In this work, we aim to estimate the performance of a proposed air-bridge microbolometer configuration based on VxOy multilayer sandwich structure thermometer thin films. For this purpose, a microbolometer was fabricated on silicon (Si) substrate covered with a silicon nitride (Si3N4) insulating layer using VxOy thermometer thin film material. The fabricated microbolometer was patterned using electron-beam lithography and liftoff techniques and it was characterized in terms of its voltage repsonsivity (Rv), signal to noise ratio (SNR), noise equivalent power (NEP) and detectivity D*. A model was then developed by the aid of numerical optical/thermal simulations and experimentally measured parameters to estimate the performance of the microbolometer when fabricated in an air-bridge configuration. The estimated D* was found to be 1.55×107 cm.√Hz/ W.

Enhancing sound absorption and transmission through flexible multi-layer micro-perforated structures.

PubMed

Bravo, Teresa; Maury, Cédric; Pinhède, Cédric

2013-11-01

Theoretical and experimental results are presented into the sound absorption and transmission properties of multi-layer structures made up of thin micro-perforated panels (ML-MPPs). The objective is to improve both the absorption and insulation performances of ML-MPPs through impedance boundary optimization. A fully coupled modal formulation is introduced that predicts the effect of the structural resonances onto the normal incidence absorption coefficient and transmission loss of ML-MPPs. This model is assessed against standing wave tube measurements and simulations based on impedance translation method for two double-layer MPP configurations of relevance in building acoustics and aeronautics. Optimal impedance relationships are proposed that ensure simultaneous maximization of both the absorption and the transmission loss under normal incidence. Exhaustive optimization of the double-layer MPPs is performed to assess the absorption and/or transmission performances with respect to the impedance criterion. It is investigated how the panel volumetric resonances modify the excess dissipation that can be achieved from non-modal optimization of ML-MPPs.

Digital modulation of the nickel valence state in a cuprate-nickelate heterostructure

NASA Astrophysics Data System (ADS)

Wrobel, F.; Geisler, B.; Wang, Y.; Christiani, G.; Logvenov, G.; Bluschke, M.; Schierle, E.; van Aken, P. A.; Keimer, B.; Pentcheva, R.; Benckiser, E.

2018-03-01

Layer-by-layer oxide molecular-beam epitaxy has been used to synthesize cuprate-nickelate multilayer structures of composition (La2CuO4)m/LaO /(LaNiO3)n . In a combined experimental and theoretical study, we show that these structures allow a clean separation of dopant and doped layers. Specifically, the LaO layer separating cuprate and nickelate blocks provides an additional charge that, according to density-functional theory calculations, is predominantly accommodated in the interfacial nickelate layers. This is reflected in an elongation of bond distances and changes in valence state, as observed by scanning transmission electron microscopy and x-ray absorption spectroscopy. Moreover, the predicted charge disproportionation in the nickelate interface layers leads to a metal-to-insulator transition when the thickness is reduced to n =2 , as observed in electrical transport measurements. The results exemplify the perspectives of charge transfer in metal-oxide multilayers to induce doping without introducing chemical and structural disorder.

Advanced Ablative Insulators and Methods of Making Them

NASA Technical Reports Server (NTRS)

Congdon, William M.

2005-01-01

Advanced ablative (more specifically, charring) materials that provide temporary protection against high temperatures, and advanced methods of designing and manufacturing insulators based on these materials, are undergoing development. These materials and methods were conceived in an effort to replace the traditional thermal-protection systems (TPSs) of re-entry spacecraft with robust, lightweight, better-performing TPSs that can be designed and manufactured more rapidly and at lower cost. These materials and methods could also be used to make improved TPSs for general aerospace, military, and industrial applications.

Energy management and control of active distribution systems

NASA Astrophysics Data System (ADS)

Shariatzadeh, Farshid

Advancements in the communication, control, computation and information technologies have driven the transition to the next generation active power distribution systems. Novel control techniques and management strategies are required to achieve the efficient, economic and reliable grid. The focus of this work is energy management and control of active distribution systems (ADS) with integrated renewable energy sources (RESs) and demand response (DR). Here, ADS mean automated distribution system with remotely operated controllers and distributed energy resources (DERs). DER as active part of the next generation future distribution system includes: distributed generations (DGs), RESs, energy storage system (ESS), plug-in hybrid electric vehicles (PHEV) and DR. Integration of DR and RESs into ADS is critical to realize the vision of sustainability. The objective of this dissertation is the development of management architecture to control and operate ADS in the presence of DR and RES. One of the most challenging issues for operating ADS is the inherent uncertainty of DR and RES as well as conflicting objective of DER and electric utilities. ADS can consist of different layers such as system layer and building layer and coordination between these layers is essential. In order to address these challenges, multi-layer energy management and control architecture is proposed with robust algorithms in this work. First layer of proposed multi-layer architecture have been implemented at the system layer. Developed AC optimal power flow (AC-OPF) generates fair price for all DR and non-DR loads which is used as a control signal for second layer. Second layer controls DR load at buildings using a developed look-ahead robust controller. Load aggregator collects information from all buildings and send aggregated load to the system optimizer. Due to the different time scale at these two management layers, time coordination scheme is developed. Robust and deterministic controllers are developed to maximize the energy usage from rooftop photovoltaic (PV) generation locally and minimize heat-ventilation and air conditioning (HVAC) consumption while maintaining inside temperature within comfort zone. The performance of the developed multi-layer architecture has been analyzed using test case studies and results show the robustness of developed controller in the presence of uncertainty.

Tetragonal bismuth bilayer: A stable and robust quantum spin hall insulator

DOE PAGES

Kou, Liangzhi; Tan, Xin; Ma, Yandong; ...

2015-11-23

In this study, topological insulators (TIs) exhibit novel physics with great promise for new devices, but considerable challenges remain to identify TIs with high structural stability and large nontrivial band gap suitable for practical applications. Here we predict by first-principles calculations a two-dimensional (2D) TI, also known as a quantum spin Hall (QSH) insulator, in a tetragonal bismuth bilayer (TB-Bi) structure that is dynamically and thermally stable based on phonon calculations and finite-temperature molecular dynamics simulations. Density functional theory and tight-binding calculations reveal a band inversion among the Bi-p orbits driven by the strong intrinsic spin–orbit coupling, producing a largemore » nontrivial band gap, which can be effectively tuned by moderate strains. The helical gapless edge states exhibit a linear dispersion with a high Fermi velocity comparable to that of graphene, and the QSH phase remains robust on a NaCl substrate. These remarkable properties place TB-Bi among the most promising 2D TIs for high-speed spintronic devices, and the present results provide insights into the intriguing QSH phenomenon in this new Bi structure and offer guidance for its implementation in potential applications.« less

Design and evaluation of a robust dynamic neurocontroller for a multivariable aircraft control problem

NASA Technical Reports Server (NTRS)

Troudet, T.; Garg, S.; Merrill, W.

1992-01-01

The design of a dynamic neurocontroller with good robustness properties is presented for a multivariable aircraft control problem. The internal dynamics of the neurocontroller are synthesized by a state estimator feedback loop. The neurocontrol is generated by a multilayer feedforward neural network which is trained through backpropagation to minimize an objective function that is a weighted sum of tracking errors, and control input commands and rates. The neurocontroller exhibits good robustness through stability margins in phase and vehicle output gains. By maintaining performance and stability in the presence of sensor failures in the error loops, the structure of the neurocontroller is also consistent with the classical approach of flight control design.

Band and Correlated Insulators of Cold Fermions in a Mesoscopic Lattice

NASA Astrophysics Data System (ADS)

Lebrat, Martin; Grišins, Pjotrs; Husmann, Dominik; Häusler, Samuel; Corman, Laura; Giamarchi, Thierry; Brantut, Jean-Philippe; Esslinger, Tilman

2018-01-01

We investigate the transport properties of neutral, fermionic atoms passing through a one-dimensional quantum wire containing a mesoscopic lattice. The lattice is realized by projecting individually controlled, thin optical barriers on top of a ballistic conductor. Building an increasingly longer lattice, one site after another, we observe and characterize the emergence of a band insulating phase, demonstrating control over quantum-coherent transport. We explore the influence of atom-atom interactions and show that the insulating state persists as contact interactions are tuned from moderately to strongly attractive. Using bosonization and classical Monte Carlo simulations, we analyze such a model of interacting fermions and find good qualitative agreement with the data. The robustness of the insulating state supports the existence of a Luther-Emery liquid in the one-dimensional wire. Our work realizes a tunable, site-controlled lattice Fermi gas strongly coupled to reservoirs, which is an ideal test bed for nonequilibrium many-body physics.

Robust antiferromagnetic spin waves across the metal-insulator transition in hole-doped BaMn2As2

NASA Astrophysics Data System (ADS)

Ramazanoglu, M.; Sapkota, A.; Pandey, Abhishek; Lamsal, J.; Abernathy, D. L.; Niedziela, J. L.; Stone, M. B.; Kreyssig, A.; Goldman, A. I.; Johnston, D. C.; McQueeney, R. J.

2017-06-01

BaMn2As2 is an antiferromagnetic insulator where a metal-insulator transition occurs with hole doping via the substitution of Ba with K. The metal-insulator transition causes only a small suppression of the Néel temperature (TN) and the ordered moment, suggesting that doped holes interact weakly with the Mn spin system. Powder inelastic neutron scattering measurements were performed on three different samples of Ba1 -xKxMn2As2 with x =0 , 0.125, and 0.25 to study the effect of hole doping and metallization on the spin dynamics. We compare the neutron intensities to a linear spin-wave theory approximation to the J1-J2-Jc Heisenberg model. Hole doping is found to introduce only minor modifications to the exchange energies and spin gap. The changes observed in the exchange constants are consistent with the small drop of TN with doping.

Generalized GW+Boltzmann Approach for the Description of Ultrafast Electron Dynamics in Topological Insulators

PubMed Central

Battiato, Marco; Sánchez-Barriga, Jaime

2017-01-01

Quantum-phase transitions between trivial insulators and topological insulators differ from ordinary metal-insulator transitions in that they arise from the inversion of the bulk band structure due to strong spin–orbit coupling. Such topological phase transitions are unique in nature as they lead to the emergence of topological surface states which are characterized by a peculiar spin texture that is believed to play a central role in the generation and manipulation of dissipationless surface spin currents on ultrafast timescales. Here, we provide a generalized GW+Boltzmann approach for the description of ultrafast dynamics in topological insulators driven by electron–electron and electron–phonon scatterings. Taking the prototypical insulator Bi2Te3 as an example, we test the robustness of our approach by comparing the theoretical prediction to results of time- and angle-resolved photoemission experiments. From this comparison, we are able to demonstrate the crucial role of the excited spin texture in the subpicosecond relaxation of transient electrons, as well as to accurately obtain the magnitude and strength of electron–electron and electron–phonon couplings. Our approach could be used as a generalized theory for three-dimensional topological insulators in the bulk-conducting transport regime, paving the way for the realization of a unified theory of ultrafast dynamics in topological materials. PMID:28773171

Generalized GW+Boltzmann Approach for the Description of Ultrafast Electron Dynamics in Topological Insulators.

PubMed

Battiato, Marco; Aguilera, Irene; Sánchez-Barriga, Jaime

2017-07-17

Quantum-phase transitions between trivial insulators and topological insulators differ from ordinary metal-insulator transitions in that they arise from the inversion of the bulk band structure due to strong spin-orbit coupling. Such topological phase transitions are unique in nature as they lead to the emergence of topological surface states which are characterized by a peculiar spin texture that is believed to play a central role in the generation and manipulation of dissipationless surface spin currents on ultrafast timescales. Here, we provide a generalized G W +Boltzmann approach for the description of ultrafast dynamics in topological insulators driven by electron-electron and electron-phonon scatterings. Taking the prototypical insulator Bi 2 Te 3 as an example, we test the robustness of our approach by comparing the theoretical prediction to results of time- and angle-resolved photoemission experiments. From this comparison, we are able to demonstrate the crucial role of the excited spin texture in the subpicosecond relaxation of transient electrons, as well as to accurately obtain the magnitude and strength of electron-electron and electron-phonon couplings. Our approach could be used as a generalized theory for three-dimensional topological insulators in the bulk-conducting transport regime, paving the way for the realization of a unified theory of ultrafast dynamics in topological materials.

Three-Dimensional Models of Topological Insulators: Engineering of Dirac Cones and Robustness of the Spin Texture

NASA Astrophysics Data System (ADS)

Soriano, David; Ortmann, Frank; Roche, Stephan

2012-12-01

We design three-dimensional models of topological insulator thin films, showing a tunability of the odd number of Dirac cones driven by the atomic-scale geometry at the boundaries. A single Dirac cone at the Γ-point can be obtained as well as full suppression of quantum tunneling between Dirac states at geometrically differentiated surfaces. The spin texture of surface states changes from a spin-momentum-locking symmetry to a surface spin randomization upon the introduction of bulk disorder. These findings illustrate the richness of the Dirac physics emerging in thin films of topological insulators and may prove utile for engineering Dirac cones and for quantifying bulk disorder in materials with ultraclean surfaces.

Highly accurate thickness measurement of multi-layered automotive paints using terahertz technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krimi, Soufiene; Beigang, René; Klier, Jens

2016-07-11

In this contribution, we present a highly accurate approach for thickness measurements of multi-layered automotive paints using terahertz time domain spectroscopy in reflection geometry. The proposed method combines the benefits of a model-based material parameters extraction method to calibrate the paint coatings, a generalized Rouard's method to simulate the terahertz radiation behavior within arbitrary thin films, and the robustness of a powerful evolutionary optimization algorithm to increase the sensitivity of the minimum thickness measurement limit. Within the framework of this work, a self-calibration model is introduced, which takes into consideration the real industrial challenges such as the effect of wet-on-wetmore » spray in the painting process.« less

Acoustic topological insulator and robust one-way sound transport

NASA Astrophysics Data System (ADS)

He, Cheng; Ni, Xu; Ge, Hao; Sun, Xiao-Chen; Chen, Yan-Bin; Lu, Ming-Hui; Liu, Xiao-Ping; Chen, Yan-Feng

2016-12-01

Topological design of materials enables topological symmetries and facilitates unique backscattering-immune wave transport. In airborne acoustics, however, the intrinsic longitudinal nature of sound polarization makes the use of the conventional spin-orbital interaction mechanism impossible for achieving band inversion. The topological gauge flux is then typically introduced with a moving background in theoretical models. Its practical implementation is a serious challenge, though, due to inherent dynamic instabilities and noise. Here we realize the inversion of acoustic energy bands at a double Dirac cone and provide an experimental demonstration of an acoustic topological insulator. By manipulating the hopping interaction of neighbouring ’atoms’ in this new topological material, we successfully demonstrate the acoustic quantum spin Hall effect, characterized by robust pseudospin-dependent one-way edge sound transport. Our results are promising for the exploration of new routes for experimentally studying topological phenomena and related applications, for example, sound-noise reduction.

Robust transport signatures of topological superconductivity in topological insulator nanowires.

PubMed

de Juan, Fernando; Ilan, Roni; Bardarson, Jens H

2014-09-05

Finding a clear signature of topological superconductivity in transport experiments remains an outstanding challenge. In this work, we propose exploiting the unique properties of three-dimensional topological insulator nanowires to generate a normal-superconductor junction in the single-mode regime where an exactly quantized 2e2/h zero-bias conductance can be observed over a wide range of realistic system parameters. This is achieved by inducing superconductivity in half of the wire, which can be tuned at will from trivial to topological with a parallel magnetic field, while a perpendicular field is used to gap out the normal part, except for two spatially separated chiral channels. The combination of chiral mode transport and perfect Andreev reflection makes the measurement robust to moderate disorder, and the quantization of conductance survives to much higher temperatures than in tunnel junction experiments. Our proposal may be understood as a variant of a Majorana interferometer which is easily realizable in experiments.

Frontier molecular orbitals of a single molecule adsorbed on thin insulating films supported by a metal substrate: electron and hole attachment energies.

PubMed

Scivetti, Iván; Persson, Mats

2017-09-06

We present calculations of vertical electron and hole attachment energies to the frontier orbitals of a pentacene molecule absorbed on multi-layer sodium chloride films supported by a copper substrate using a simplified density functional theory (DFT) method. The adsorbate and the film are treated fully within DFT, whereas the metal is treated implicitly by a perfect conductor model. We find that the computed energy gap between the highest and lowest unoccupied molecular orbitals-HOMO and LUMO -from the vertical attachment energies increases with the thickness of the insulating film, in agreement with experiments. This increase of the gap can be rationalised in a simple dielectric model with parameters determined from DFT calculations and is found to be dominated by the image interaction with the metal. We find, however, that this simplified model overestimates the downward shift of the energy gap in the limit of an infinitely thick film.

Thermal architecture for the SPIDER flight cryostat

NASA Astrophysics Data System (ADS)

Gudmundsson, J. E.; Ade, P. A. R.; Amiri, M.; Benton, S. J.; Bihary, R.; Bock, J. J.; Bond, J. R.; Bonetti, J. A.; Bryan, S. A.; Burger, B.; Chiang, H. C.; Contaldi, C. R.; Crill, B. P.; Doré, O.; Farhang, M.; Filippini, J.; Fissel, L. M.; Gandilo, N. N.; Golwala, S. R.; Halpern, M.; Hasselfield, M.; Hilton, G.; Holmes, W.; Hristov, V. V.; Irwin, K. D.; Jones, W. C.; Kuo, C. L.; MacTavish, C. J.; Mason, P. V.; Montroy, T. E.; Morford, T. A.; Netterfield, C. B.; O'Dea, D. T.; Rahlin, A. S.; Reintsema, C. D.; Ruhl, J. E.; Runyan, M. C.; Schenker, M. A.; Shariff, J. A.; Soler, J. D.; Trangsrud, A.; Tucker, C.; Tucker, R. S.; Turner, A. D.

2010-07-01

We describe the cryogenic system for SPIDER, a balloon-borne microwave polarimeter that will map 8% of the sky with degree-scale angular resolution. The system consists of a 1284 L liquid helium cryostat and a 16 L capillary-filled superfluid helium tank, which provide base operating temperatures of 4 K and 1.5 K, respectively. Closed-cycle 3He adsorption refrigerators supply sub-Kelvin cooling power to multiple focal planes, which are housed in monochromatic telescope inserts. The main helium tank is suspended inside the vacuum vessel with thermally insulating fiberglass flexures, and shielded from thermal radiation by a combination of two vapor cooled shields and multi-layer insulation. This system allows for an extremely low instrumental background and a hold time in excess of 25 days. The total mass of the cryogenic system, including cryogens, is approximately 1000 kg. This enables conventional long duration balloon flights. We will discuss the design, thermal analysis, and qualification of the cryogenic system.

Design and Fabrication of a Tank-Applied Broad Area Cooling Shield Coupon

NASA Technical Reports Server (NTRS)

Wood, J. J.; Middlemas, M. R.

2012-01-01

The small-scale broad area cooling (BAC) shield test panel represents a section of the cryogenic propellant storage and transfer ground test article, a flight-like cryogenic propellant storage tank. The test panel design includes an aluminum tank shell, primer, spray-on foam insulation, multilayer insulation (MLI), and BAC shield hardware. This assembly was sized to accurately represent the character of the MLI/BAC shield system, be quickly and inexpensively assembled, and be tested in the Marshall Space Flight Center Acoustic Test Facility. Investigating the BAC shield response to a worst-case launch dynamic load was the key purpose for developing the test article and performing the test. A preliminary method for structurally supporting the BAC shield using low-conductivity standoffs was designed, manufactured, and evaluated as part of the test. The BAC tube-standoff interface and unsupported BAC tube lengths were key parameters for evaluation. No noticeable damage to any system hardware element was observed after acoustic testing.

Spin-orbit torques from interfacial spin-orbit coupling for various interfaces

NASA Astrophysics Data System (ADS)

Kim, Kyoung-Whan; Lee, Kyung-Jin; Sinova, Jairo; Lee, Hyun-Woo; Stiles, M. D.

2017-09-01

We use a perturbative approach to study the effects of interfacial spin-orbit coupling in magnetic multilayers by treating the two-dimensional Rashba model in a fully three-dimensional description of electron transport near an interface. This formalism provides a compact analytic expression for current-induced spin-orbit torques in terms of unperturbed scattering coefficients, allowing computation of spin-orbit torques for various contexts, by simply substituting scattering coefficients into the formulas. It applies to calculations of spin-orbit torques for magnetic bilayers with bulk magnetism, those with interface magnetism, a normal-metal/ferromagnetic insulator junction, and a topological insulator/ferromagnet junction. It predicts a dampinglike component of spin-orbit torque that is distinct from any intrinsic contribution or those that arise from particular spin relaxation mechanisms. We discuss the effects of proximity-induced magnetism and insertion of an additional layer and provide formulas for in-plane current, which is induced by a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in the same formalism.

Spin-orbit torques from interfacial spin-orbit coupling for various interfaces.

PubMed

Kim, Kyoung-Whan; Lee, Kyung-Jin; Sinova, Jairo; Lee, Hyun-Woo; Stiles, M D

2017-09-01

We use a perturbative approach to study the effects of interfacial spin-orbit coupling in magnetic multilayers by treating the two-dimensional Rashba model in a fully three-dimensional description of electron transport near an interface. This formalism provides a compact analytic expression for current-induced spin-orbit torques in terms of unperturbed scattering coefficients, allowing computation of spin-orbit torques for various contexts, by simply substituting scattering coefficients into the formulas. It applies to calculations of spin-orbit torques for magnetic bilayers with bulk magnetism, those with interface magnetism, a normal metal/ferromagnetic insulator junction, and a topological insulator/ferromagnet junction. It predicts a dampinglike component of spin-orbit torque that is distinct from any intrinsic contribution or those that arise from particular spin relaxation mechanisms. We discuss the effects of proximity-induced magnetism and insertion of an additional layer and provide formulas for in-plane current, which is induced by a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in the same formalism.

Spin-orbit torques from interfacial spin-orbit coupling for various interfaces

PubMed Central

Kim, Kyoung-Whan; Lee, Kyung-Jin; Sinova, Jairo; Lee, Hyun-Woo; Stiles, M. D.

2017-01-01

We use a perturbative approach to study the effects of interfacial spin-orbit coupling in magnetic multilayers by treating the two-dimensional Rashba model in a fully three-dimensional description of electron transport near an interface. This formalism provides a compact analytic expression for current-induced spin-orbit torques in terms of unperturbed scattering coefficients, allowing computation of spin-orbit torques for various contexts, by simply substituting scattering coefficients into the formulas. It applies to calculations of spin-orbit torques for magnetic bilayers with bulk magnetism, those with interface magnetism, a normal metal/ferromagnetic insulator junction, and a topological insulator/ferromagnet junction. It predicts a dampinglike component of spin-orbit torque that is distinct from any intrinsic contribution or those that arise from particular spin relaxation mechanisms. We discuss the effects of proximity-induced magnetism and insertion of an additional layer and provide formulas for in-plane current, which is induced by a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in the same formalism. PMID:29333523

Study of noise reduction characteristics of double-wall panels

NASA Technical Reports Server (NTRS)

Navaneethan, R.; Quayle, B.; Stevenson, S.; Graham, M.

1983-01-01

The noise reduction characteristics of general aviation type, flat, double-wall structures were investigated. The experimental study was carried out on 20-by-20 inch panels with an exposed area of 18 by 18 inches. A frequency range from 20 to 5000 Hz was covered. The experimental results, in general, follow the expected trends. At low frequencies the double-wall structures are no better than the single-wall structures. However, for depths normally used in the general aviation industry, the double-wall panels are very attractive. The graphite-spoxy skin panels have higher noise reduction at very low frequencies ( 100 Hz) than the Kevlar skin panels. But the aluminum panels have higher noise reduction in the high frequency region, due to their greater mass. Use of fiberglass insulation is not effective in the low frequency region, and at times it is even negative. But the insulation is effective in the high-frequency region. The theoretical model for predicting the transmission loss of these multilayered panels is also discussed.

Improving yield and performance in ZnO thin-film transistors made using selective area deposition.

PubMed

Nelson, Shelby F; Ellinger, Carolyn R; Levy, David H

2015-02-04

We describe improvements in both yield and performance for thin-film transistors (TFTs) fabricated by spatial atomic layer deposition (SALD). These improvements are shown to be critical in forming high-quality devices using selective area deposition (SAD) as the patterning method. Selective area deposition occurs when the precursors for the deposition are prevented from reacting with some areas of the substrate surface. Controlling individual layer quality and the interfaces between layers is essential for obtaining good-quality thin-film transistors and capacitors. The integrity of the gate insulator layer is particularly critical, and we describe a method for forming a multilayer dielectric using an oxygen plasma treatment between layers that improves crossover yield. We also describe a method to achieve improved mobility at the important interface between the semiconductor and the gate insulator by, conversely, avoiding oxygen plasma treatment. Integration of the best designs results in wide design flexibility, transistors with mobility above 15 cm(2)/(V s), and good yield of circuits.

Study of noise reduction characteristics of double-wall panels

NASA Astrophysics Data System (ADS)

Navaneethan, R.; Quayle, B.; Stevenson, S.; Graham, M.

1983-05-01

The noise reduction characteristics of general aviation type, flat, double-wall structures were investigated. The experimental study was carried out on 20-by-20 inch panels with an exposed area of 18 by 18 inches. A frequency range from 20 to 5000 Hz was covered. The experimental results, in general, follow the expected trends. At low frequencies the double-wall structures are no better than the single-wall structures. However, for depths normally used in the general aviation industry, the double-wall panels are very attractive. The graphite-spoxy skin panels have higher noise reduction at very low frequencies ( 100 Hz) than the Kevlar skin panels. But the aluminum panels have higher noise reduction in the high frequency region, due to their greater mass. Use of fiberglass insulation is not effective in the low frequency region, and at times it is even negative. But the insulation is effective in the high-frequency region. The theoretical model for predicting the transmission loss of these multilayered panels is also discussed.

Frontier molecular orbitals of a single molecule adsorbed on thin insulating films supported by a metal substrate: electron and hole attachment energies

NASA Astrophysics Data System (ADS)

Scivetti, Iván; Persson, Mats

2017-09-01

We present calculations of vertical electron and hole attachment energies to the frontier orbitals of a pentacene molecule absorbed on multi-layer sodium chloride films supported by a copper substrate using a simplified density functional theory (DFT) method. The adsorbate and the film are treated fully within DFT, whereas the metal is treated implicitly by a perfect conductor model. We find that the computed energy gap between the highest and lowest unoccupied molecular orbitals—HOMO and LUMO -from the vertical attachment energies increases with the thickness of the insulating film, in agreement with experiments. This increase of the gap can be rationalised in a simple dielectric model with parameters determined from DFT calculations and is found to be dominated by the image interaction with the metal. We find, however, that this simplified model overestimates the downward shift of the energy gap in the limit of an infinitely thick film.

Multilayered Functional Insulation System (MFIS) for AC Power Transmission in High Voltage Hybrid Electrical Propulsion

NASA Technical Reports Server (NTRS)

Lizcano, Maricela

2017-01-01

High voltage hybrid electric propulsion systems are now pushing new technology development efforts for air transportation. A key challenge in hybrid electric aircraft is safe high voltage distribution and transmission of megawatts of power (>20 MW). For the past two years, a multidisciplinary materials research team at NASA Glenn Research Center has investigated the feasibility of distributing high voltage power on future hybrid electric aircraft. This presentation describes the team's approach to addressing this challenge, significant technical findings, and next steps in GRC's materials research effort for MW power distribution on aircraft.

Deposition and characterization of B4C/CeO2 multilayers at 6.x nm extreme ultraviolet wavelengths

NASA Astrophysics Data System (ADS)

Sertsu, M. G.; Giglia, A.; Brose, S.; Park, D.; Wang, Z. S.; Mayer, J.; Juschkin, L.; Nicolosi, P.

2016-03-01

New multilayers of boron carbide/cerium dioxide (B4C/CeO2) combination on silicon (Si) substrate are manufactured to represent reflective-optics candidates for future lithography at 6.x nm wavelength. This is one of only a few attempts to make multilayers of this kind. Combination of several innovative experiments enables detailed study of optical properties, structural properties, and interface profiles of the multilayers in order to open up a room for further optimization of the manufacturing process. The interface profile is visualized by high-angle annular dark-field imaging which provides highly sensitive contrast to atomic number. Synchrotron based at-wavelength extreme ultraviolet (EUV) reflectance measurements near the boron (B) absorption edge allow derivation of optical parameters with high sensitivity to local atom interactions. X-ray reflectivity measurements at Cu-Kalpha (8 keV ) determine the period of multilayers with high in-depth resolution. By combining these measurements and choosing robust nonlinear curve fitting algorithms, accuracy of the results has been significantly improved. It also enables a comprehensive characterization of multilayers. Interface diffusion is determined to be a major cause for the low reflectivity performance. Optical constants of B4C and CeO2 layers are derived in EUV wavelengths. Besides, optical properties and asymmetric thicknesses of inter-diffusion layers (interlayers) in EUV wavelengths near the boron edge are determined. Finally, ideal reflectivity of the B4C/CeO2 combination is calculated by using optical constants derived from the proposed measurements in order to evaluate the potentiality of the design.

Single-crystal-like GdNdO{sub x} thin films on silicon substrates by magnetron sputtering and high-temperature annealing for crystal seed layer application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ziwei; Xiao, Lei; Liang, Renrong, E-mail: wang-j@tsinghua.edu.cn, E-mail: liangrr@tsinghua.edu.cn

2016-06-15

Single-crystal-like rare earth oxide thin films on silicon (Si) substrates were fabricated by magnetron sputtering and high-temperature annealing processes. A 30-nm-thick high-quality GdNdO{sub x} (GNO) film was deposited using a high-temperature sputtering process at 500°C. A Gd{sub 2}O{sub 3} and Nd{sub 2}O{sub 3} mixture was used as the sputtering target, in which the proportions of Gd{sub 2}O{sub 3} and Nd{sub 2}O{sub 3} were controlled to make the GNO’s lattice parameter match that of the Si substrate. To further improve the quality of the GNO film, a post-deposition annealing process was performed at a temperature of 1000°C. The GNO films exhibitedmore » a strong preferred orientation on the Si substrate. In addition, an Al/GNO/Si capacitor was fabricated to evaluate the dielectric constant and leakage current of the GNO films. It was determined that the single-crystal-like GNO films on the Si substrates have potential for use as an insulator layer for semiconductor-on-insulator and semiconductor/insulator multilayer applications.« less

Polymer multilayer tattooing for enhanced DNA vaccination

PubMed Central

DeMuth, Peter C.; Min, Younjin; Huang, Bonnie; Kramer, Joshua A.; Miller, Andrew D.; Barouch, Dan H.; Hammond, Paula T.; Irvine, Darrell J.

2014-01-01

DNA vaccines have many potential benefits but have failed to generate robust immune responses in humans. Recently, methods such as in vivo electroporation have demonstrated improved performance, but an optimal strategy for safe, reproducible, and pain-free DNA vaccination remains elusive. Here we report an approach for rapid implantation of vaccine-loaded polymer films carrying DNA, immune-stimulatory RNA, and biodegradable polycations into the immune-cell-rich epidermis, using microneedles coated with releasable polyelectrolyte multilayers. Films transferred into the skin following brief microneedle application promoted local transfection and controlled the persistence of DNA and adjuvants in the skin from days to weeks, with kinetics determined by the film composition. These “multilayer tattoo” DNA vaccines induced immune responses against a model HIV antigen comparable to electroporation in mice, enhanced memory T-cell generation, and elicited 140-fold higher gene expression in non-human primate skin than intradermal DNA injection, indicating the potential of this strategy for enhancing DNA vaccination. PMID:23353628

From dots to doughnuts: Two-dimensionally confined deposition of polyelectrolytes on block copolymer templates

DOE PAGES

Oded, Meirav; Kelly, Stephen T.; Gilles, Mary K.; ...

2016-07-05

The combination of block copolymer templating with electrostatic self-assembly provides a simple and robust method for creating nano-patterned polyelectrolyte multilayers over large areas. The deposition of the first polyelectrolyte layer provides important insights on the initial stages of multilayer buildup. Here, we focus on two-dimensionally confined “dots” patterns afforded by block copolymer films featuring hexagonally-packed cylinders that are oriented normal to the substrate. Rendering the cylinder caps positively charged enables the selective deposition of negatively charged polyelectrolytes on them under salt-free conditions. The initially formed polyelectrolyte nanostructures adopt a toroidal (“doughnut”) shape, which results from retraction of dangling polyelectrolyte segmentsmore » into the “dots” upon drying. With increasing exposure time to the polyelectrolyte solution, the final shape of the deposited polyelectrolyte transitions from a doughnut to a hemisphere. In conclusion, these insights would enable the creation of patterned polyelectrolyte multilayers with increased control over adsorption selectivity of the additional incoming polyelectrolytes.« less

From dots to doughnuts: Two-dimensionally confined deposition of polyelectrolytes on block copolymer templates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oded, Meirav; Kelly, Stephen T.; Gilles, Mary K.

The combination of block copolymer templating with electrostatic self-assembly provides a simple and robust method for creating nano-patterned polyelectrolyte multilayers over large areas. The deposition of the first polyelectrolyte layer provides important insights on the initial stages of multilayer buildup. Here, we focus on two-dimensionally confined “dots” patterns afforded by block copolymer films featuring hexagonally-packed cylinders that are oriented normal to the substrate. Rendering the cylinder caps positively charged enables the selective deposition of negatively charged polyelectrolytes on them under salt-free conditions. The initially formed polyelectrolyte nanostructures adopt a toroidal (“doughnut”) shape, which results from retraction of dangling polyelectrolyte segmentsmore » into the “dots” upon drying. With increasing exposure time to the polyelectrolyte solution, the final shape of the deposited polyelectrolyte transitions from a doughnut to a hemisphere. In conclusion, these insights would enable the creation of patterned polyelectrolyte multilayers with increased control over adsorption selectivity of the additional incoming polyelectrolytes.« less

A Complex Systems Approach to More Resilient Multi-Layered Security Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Nathanael J. K.; Jones, Katherine A.; Bandlow, Alisa

In July 2012, protestors cut through security fences and gained access to the Y-12 National Security Complex. This was believed to be a highly reliable, multi-layered security system. This report documents the results of a Laboratory Directed Research and Development (LDRD) project that created a consistent, robust mathematical framework using complex systems analysis algorithms and techniques to better understand the emergent behavior, vulnerabilities and resiliency of multi-layered security systems subject to budget constraints and competing security priorities. Because there are several dimensions to security system performance and a range of attacks that might occur, the framework is multi-objective for amore » performance frontier to be estimated. This research explicitly uses probability of intruder interruption given detection (P I) as the primary resilience metric. We demonstrate the utility of this framework with both notional as well as real-world examples of Physical Protection Systems (PPSs) and validate using a well-established force-on-force simulation tool, Umbra.« less

Stoichiometry and thickness dependence of superconducting properties of niobium nitride thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beebe, Melissa R., E-mail: mrbeebe@email.wm.edu; Beringer, Douglas B.; Burton, Matthew C.

2016-03-15

The current technology used in linear particle accelerators is based on superconducting radio frequency (SRF) cavities fabricated from bulk niobium (Nb), which have smaller surface resistance and therefore dissipate less energy than traditional nonsuperconducting copper cavities. Using bulk Nb for the cavities has several advantages, which are discussed elsewhere; however, such SRF cavities have a material-dependent accelerating gradient limit. In order to overcome this fundamental limit, a multilayered coating has been proposed using layers of insulating and superconducting material applied to the interior surface of the cavity. The key to this multilayered model is to use superconducting thin films tomore » exploit the potential field enhancement when these films are thinner than their London penetration depth. Such field enhancement has been demonstrated in MgB{sub 2} thin films; here, the authors consider films of another type-II superconductor, niobium nitride (NbN). The authors present their work correlating stoichiometry and superconducting properties in NbN thin films and discuss the thickness dependence of their superconducting properties, which is important for their potential use in the proposed multilayer structure. While there are some previous studies on the relationship between stoichiometry and critical temperature T{sub C}, the authors are the first to report on the correlation between stoichiometry and the lower critical field H{sub C1}.« less

Multi-layered foil capture of micrometeoroids and orbital debris in low Earth orbit

NASA Astrophysics Data System (ADS)

Kearsley, A.; Graham, G.

Much of our knowledge concerning the sub-millimetre orbital debris population that poses a threat to orbiting satellites has been gleaned from examination of surfaces retrieved and subsequently analysed as part of post-flight investigations. The preservation of the hypervelocity impact-derived remnants located on these surfaces is very variable, whether of space debris or micrometeoroid origin. Whilst glass and metallic materials show highly visible impact craters when examined using optical and electron microscopes, complex mixing between the target material and the impacting particle may make unambiguous interpretation of the impactor origin difficult or impossible. Our recent detailed examination of selected multi-layered insulation (MLI) foils from the ISAS Space Flyer Unit (SFU), and our preliminary study of NASA's Trek blanket, exposed on the Mir station, show that these constructions have the potential to preserve abundant residue material of a quality sufficient for detailed analysis. Although there are still limitations on the recognition of certain sources of orbital debris, the foils complement the metal and glass substrates. We suggest that a purpose-built multi-layered foil structure may prove to be extremely effective for rapid collection and unambiguous analysis of impact- derived residues. Such a collector could be used an environmental monitor for ISS, as it would have low mass, high durability, easy deployment, recovery and storage, making it an economically viable and attractive option.

Intelligent, Robust Control of Deteriorated Turbofan Engines via Linear Parameter Varying Quadratic Lyapunov Function Design

NASA Technical Reports Server (NTRS)

Turso, James A.; Litt, Jonathan S.

2004-01-01

A method for accommodating engine deterioration via a scheduled Linear Parameter Varying Quadratic Lyapunov Function (LPVQLF)-Based controller is presented. The LPVQLF design methodology provides a means for developing unconditionally stable, robust control of Linear Parameter Varying (LPV) systems. The controller is scheduled on the Engine Deterioration Index, a function of estimated parameters that relate to engine health, and is computed using a multilayer feedforward neural network. Acceptable thrust response and tight control of exhaust gas temperature (EGT) is accomplished by adjusting the performance weights on these parameters for different levels of engine degradation. Nonlinear simulations demonstrate that the controller achieves specified performance objectives while being robust to engine deterioration as well as engine-to-engine variations.

Refractive Secondary Solar Concentrator Demonstrated High-Temperature Operation

NASA Technical Reports Server (NTRS)

Wong, Wayne A.

2002-01-01

Space applications that utilize solar thermal energy--such as electric power conversion systems, thermal propulsion systems, and furnaces--require highly efficient solar concentration systems. The NASA Glenn Research Center is developing the refractive secondary concentrator, which uses refraction and total internal reflection to efficiently concentrate and direct solar energy. When used in combination with advanced lightweight primary concentrators, such as inflatable thin films, the refractive secondary concentrator enables very high system concentration ratios and very high temperatures. Last year, Glenn successfully demonstrated a secondary concentrator throughput efficiency of 87 percent, with a projected efficiency of 93 percent using an antireflective coating. Building on this achievement, Glenn recently successfully demonstrated high-temperature operation of the secondary concentrator when it was used to heat a rhenium receiver to 2330 F. The high-temperature demonstration of the concentrator was conducted in Glenn's 68-ft long Tank 6 thermal vacuum facility equipped with a solar simulator. The facility has a rigid panel primary concentrator that was used to concentrate the light from the solar simulator onto the refractive secondary concentrator. NASA Marshall Space Flight Center provided a rhenium cavity, part of a solar thermal propulsion engine, to serve as the high-temperature receiver. The prototype refractive secondary concentrator, measuring 3.5 in. in diameter and 11.2 in. long, is made of single-crystal sapphire. A water-cooled splash shield absorbs spillage light outside of the 3.5-in. concentrator aperture. Multilayer foil insulation composed of tungsten, molybdenum, and niobium is used to minimize heat loss from the hightemperature receiver. A liquid-cooled canister calorimeter is used to measure the heat loss through the multilayer foil insulation.

Insulator function and topological domain border strength scale with architectural protein occupancy

PubMed Central

2014-01-01

Background Chromosome conformation capture studies suggest that eukaryotic genomes are organized into structures called topologically associating domains. The borders of these domains are highly enriched for architectural proteins with characterized roles in insulator function. However, a majority of architectural protein binding sites localize within topological domains, suggesting sites associated with domain borders represent a functionally different subclass of these regulatory elements. How topologically associating domains are established and what differentiates border-associated from non-border architectural protein binding sites remain unanswered questions. Results By mapping the genome-wide target sites for several Drosophila architectural proteins, including previously uncharacterized profiles for TFIIIC and SMC-containing condensin complexes, we uncover an extensive pattern of colocalization in which architectural proteins establish dense clusters at the borders of topological domains. Reporter-based enhancer-blocking insulator activity as well as endogenous domain border strength scale with the occupancy level of architectural protein binding sites, suggesting co-binding by architectural proteins underlies the functional potential of these loci. Analyses in mouse and human stem cells suggest that clustering of architectural proteins is a general feature of genome organization, and conserved architectural protein binding sites may underlie the tissue-invariant nature of topologically associating domains observed in mammals. Conclusions We identify a spectrum of architectural protein occupancy that scales with the topological structure of chromosomes and the regulatory potential of these elements. Whereas high occupancy architectural protein binding sites associate with robust partitioning of topologically associating domains and robust insulator function, low occupancy sites appear reserved for gene-specific regulation within topological domains. PMID:24981874

On-chip copper-dielectric interference filters for manufacturing of ambient light and proximity CMOS sensors.

PubMed

Frey, Laurent; Masarotto, Lilian; D'Aillon, Patrick Gros; Pellé, Catherine; Armand, Marilyn; Marty, Michel; Jamin-Mornet, Clémence; Lhostis, Sandrine; Le Briz, Olivier

2014-07-10

Filter technologies implemented on CMOS image sensors for spectrally selective applications often use a combination of on-chip organic resists and an external substrate with multilayer dielectric coatings. The photopic-like and near-infrared bandpass filtering functions respectively required by ambient light sensing and user proximity detection through time-of-flight can be fully integrated on chip with multilayer metal-dielectric filters. Copper, silicon nitride, and silicon oxide are the materials selected for a technological proof-of-concept on functional wafers, due to their immediate availability in front-end semiconductor fabs. Filter optical designs are optimized with respect to specific performance criteria, and the robustness of the designs regarding process errors are evaluated for industrialization purposes.

Diversity of multilayer networks and its impact on collaborating epidemics

NASA Astrophysics Data System (ADS)

Min, Yong; Hu, Jiaren; Wang, Weihong; Ge, Ying; Chang, Jie; Jin, Xiaogang

2014-12-01

Interacting epidemics on diverse multilayer networks are increasingly important in modeling and analyzing the diffusion processes of real complex systems. A viral agent spreading on one layer of a multilayer network can interact with its counterparts by promoting (cooperative interaction), suppressing (competitive interaction), or inducing (collaborating interaction) its diffusion on other layers. Collaborating interaction displays different patterns: (i) random collaboration, where intralayer or interlayer induction has the same probability; (ii) concentrating collaboration, where consecutive intralayer induction is guaranteed with a probability of 1; and (iii) cascading collaboration, where consecutive intralayer induction is banned with a probability of 0. In this paper, we develop a top-bottom framework that uses only two distributions, the overlaid degree distribution and edge-type distribution, to model collaborating epidemics on multilayer networks. We then state the response of three collaborating patterns to structural diversity (evenness and difference of network layers). For viral agents with small transmissibility, we find that random collaboration is more effective in networks with higher diversity (high evenness and difference), while the concentrating pattern is more suitable in uneven networks. Interestingly, the cascading pattern requires a network with moderate difference and high evenness, and the moderately uneven coupling of multiple network layers can effectively increase robustness to resist cascading failure. With large transmissibility, however, we find that all collaborating patterns are more effective in high-diversity networks. Our work provides a systemic analysis of collaborating epidemics on multilayer networks. The results enhance our understanding of biotic and informative diffusion through multiple vectors.

Thermal coupon testing of Load-Bearing Multilayer Insulation

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Heckle, K. W.; Hurd, J.

2014-01-01

Advanced liquid hydrogen storage concepts being considered for long duration space travel incorporate refrigeration systems and cryocoolers to lower the heat load. Using a refrigeration loop to intercept the energy flowing through MLI to a liquid hydrogen tank at a temperature between the environment and the liquid hydrogen can lower the heat load on the propellant system by as much as 50%. However, the refrigeration loop requires structural integration into the MLI. Use of a more traditional concept of MLI underneath this refrigeration loop requires that a structural system be put in place to support the loop. Such structures, even when thermally optimized, present a relatively large parasitic heat load into the tank. Through NASA small business innovation research funding, Quest Thermal Group and Ball Aerospace have been developing a structural MLI based insulation system. These systems are designed with discrete polymeric spacers between reflective layers instead of either dacron or silk netting. The spacers (or posts) have an intrinsic structural capability that is beyond that of just supporting the internal insulation mechanical loads. This new MLI variant called Load Bearing MLI (LB-MLI) has been developed specifically for the application of supporting thermal shields within the insulation system. Test articles (coupons) of the new LB-MLI product were fabricated for thermal performance testing using liquid nitrogen at Kennedy Space Center (KSC) and using cryocooler based calorimetry at Florida State University. The test results and analysis are presented. Thermal models developed for correlation with the thermal testing results both at KSC and testing that was performed at Florida State University are also discussed.

Robust antiferromagnetic spin waves across the metal-insulator transition in hole-doped BaMn 2 As 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramazanoglu, M.; Sapkota, A.; Pandey, Abhishek

BaMn 2 As 2 is an antiferromagnetic insulator where a metal-insulator transition occurs with hole doping via the substitution of Ba with K. The metal-insulator transition causes only a small suppression of the Néel temperature (T N) and the ordered moment, suggesting that doped holes interact weakly with the Mn spin system. Powder inelastic neutron scattering measurements were performed on three different samples of Ba 1 - xK xMn 2 As 2 with x = 0 , 0.125, and 0.25 to study the effect of hole doping and metallization on the spin dynamics. We compare the neutron intensities to amore » linear spin-wave theory approximation to the J 1 $-$ J 2 $-$ J c Heisenberg model. Hole doping is found to introduce only minor modifications to the exchange energies and spin gap. Lastly, the changes observed in the exchange constants are consistent with the small drop of T N with doping.« less

Robust antiferromagnetic spin waves across the metal-insulator transition in hole-doped BaMn 2 As 2

DOE PAGES

Ramazanoglu, M.; Sapkota, A.; Pandey, Abhishek; ...

2017-06-01

BaMn 2 As 2 is an antiferromagnetic insulator where a metal-insulator transition occurs with hole doping via the substitution of Ba with K. The metal-insulator transition causes only a small suppression of the Néel temperature (T N) and the ordered moment, suggesting that doped holes interact weakly with the Mn spin system. Powder inelastic neutron scattering measurements were performed on three different samples of Ba 1 - xK xMn 2 As 2 with x = 0 , 0.125, and 0.25 to study the effect of hole doping and metallization on the spin dynamics. We compare the neutron intensities to amore » linear spin-wave theory approximation to the J 1 $-$ J 2 $-$ J c Heisenberg model. Hole doping is found to introduce only minor modifications to the exchange energies and spin gap. Lastly, the changes observed in the exchange constants are consistent with the small drop of T N with doping.« less

Measurement of Two-Phase Flow and Heat Transfer Parameters using Infrared Thermometry

NASA Technical Reports Server (NTRS)

Kim, Tae-Hoon; Kommer, Eric; Dessiatoun, Serguei; Kim, Jungho

2012-01-01

A novel technique to measure heat transfer and liquid film thickness distributions over relatively large areas for two-phase flow and heat transfer phenomena using infrared (IR)thermometry is described. IR thermometry is an established technology that can be used to measure temperatures when optical access to the surface is available in the wavelengths of interest. In this work, a midwave IR camera (3.6-5.1 microns) is used to determine the temperature distribution within a multilayer consisting of a silicon substrate coated with a thin insulator. Since silicon is largely transparent to IR radiation, the temperature of the inner and outer walls of the multilayer can be measured by coating selected areas with a thin, IR opaque film. If the fluid used is also partially transparent to IR, the flow can be visualized and the liquid film thickness can be measured. The theoretical basis for the technique is given along with a description of the test apparatus and data reduction procedure. The technique is demonstrated by determining the heat transfer coefficient distributions produced by droplet evaporation and flow boiling heat transfer.

Quantifying MLI Thermal Conduction in Cryogenic Applications from Experimental Data

NASA Astrophysics Data System (ADS)

Ross, R. G., Jr.

2015-12-01

Multilayer Insulation (MLI) uses stacks of low-emittance metalized sheets combined with low-conduction spacer features to greatly reduce the heat transfer to cryogenic applications from higher temperature surrounds. However, as the hot-side temperature decreases from room temperature to cryogenic temperatures, the level of radiant heat transfer drops as the fourth power of the temperature, while the heat transfer by conduction only falls off linearly. This results in cryogenic MLI being dominated by conduction, a quantity that is extremely sensitive to MLI blanket construction and very poorly quantified in the literature. To develop useful quantitative data on cryogenic blanket conduction, multilayer nonlinear heat transfer models are used to analyze extensive heat transfer data measured by Lockheed Palo Alto on their cryogenic dewar MLI and measured by JPL on their spacecraft MLI. The data-fitting aspect of the modeling allows the radiative and conductive thermal properties of the tested blankets to be explicitly quantified. Results are presented showing that MLI conductance varies by a factor of 600 between spacecraft MLI and Lockheed's best cryogenic MLI.

Features of electronic and lattice mechanisms of transboundary heat transfer in multilayer nanolaminate TiAlN/Ag coatings.

PubMed

Kovalev, A I; Wainstein, D L; Vakhrushev, V O; Gago, R; Soldera, F; Endrino, J L; Fox-Rabinovich, G S; Veldhuis, S

2017-12-06

Plasmon resonance heterogeneities were identified and studied along Ag and TiAlN layers within a multilayer stack in nanolaminate TiAlN/Ag coatings. For this purpose, a high-resolution plasmon microscopy was used. The plasmons intensity, energy, and depth of interface plasmon-polariton penetration were studied by scanning reflected electron energy loss spectroscopy. The heat conductivity of such metal-insulator-metal (MIM) nanolaminate coatings was measured by laser reflectometry. Dependencies of thermal conductivity coefficient of coatings, MIM interfaces, and resistivity of Ag layers as a function of the Ag-TiAlN bilayer thickness were calculated on the basis of experimental data. The contribution of plasmon resonance confinement to the abnormal lower thermal conductivity in the MIM metamaterial with Ag layer thickness below 25 nm is discussed. In particular, the results highlight the relevant role of different heat transfer mechanisms between MI and IM interfaces: asymmetry of plasmon-polariton interactions on upper and lower boundaries of Ag layer and asymmetry of LA and TA phonons propagation through interfaces.

Intermetallic Al-, Fe-, Co- and Ni-Based Thermal Barrier Coatings Prepared by Cold Spray for Applications on Low Heat Rejection Diesel Engines

NASA Astrophysics Data System (ADS)

Leshchinsky, E.; Sobiesiak, A.; Maev, R.

2018-02-01

Conventional thermal barrier coating (TBC) systems consist of a duplex structure with a metallic bond coat and a ceramic heat insulating topcoat. They possess the desired low thermal conductivity, but at the same time they are very brittle and sensitive to thermal shock and thermal cycling due to the inherently low coefficient of thermal expansion. Recent research activities are focused on the developing of multilayer TBC structures obtained using cold spraying and following annealing. Aluminum intermetallics have demonstrated thermal and mechanical properties that allow them to be used as the alternative TBC materials, while the intermetallic layers can be additionally optimized to achieve superior thermal physical properties. One example is the six layer TBC structure in which cold sprayed Al-based intermetallics are synthesized by annealing in nitrogen atmosphere. These multilayer coating systems demonstrated an improved thermal fatigue capability as compared to conventional ceramic TBC. The microstructures and properties of the coatings were characterized by SEM, EDS and mechanical tests to define the TBC material properties and intermetallic formation mechanisms.

An explicit asymptotic preserving low Froude scheme for the multilayer shallow water model with density stratification

NASA Astrophysics Data System (ADS)

Couderc, F.; Duran, A.; Vila, J.-P.

2017-08-01

We present an explicit scheme for a two-dimensional multilayer shallow water model with density stratification, for general meshes and collocated variables. The proposed strategy is based on a regularized model where the transport velocity in the advective fluxes is shifted proportionally to the pressure potential gradient. Using a similar strategy for the potential forces, we show the stability of the method in the sense of a discrete dissipation of the mechanical energy, in general multilayer and non-linear frames. These results are obtained at first-order in space and time and extended using a second-order MUSCL extension in space and a Heun's method in time. With the objective of minimizing the diffusive losses in realistic contexts, sufficient conditions are exhibited on the regularizing terms to ensure the scheme's linear stability at first and second-order in time and space. The other main result stands in the consistency with respect to the asymptotics reached at small and large time scales in low Froude regimes, which governs large-scale oceanic circulation. Additionally, robustness and well-balanced results for motionless steady states are also ensured. These stability properties tend to provide a very robust and efficient approach, easy to implement and particularly well suited for large-scale simulations. Some numerical experiments are proposed to highlight the scheme efficiency: an experiment of fast gravitational modes, a smooth surface wave propagation, an initial propagating surface water elevation jump considering a non-trivial topography, and a last experiment of slow Rossby modes simulating the displacement of a baroclinic vortex subject to the Coriolis force.

A quantized microwave quadrupole insulator with topologically protected corner states

NASA Astrophysics Data System (ADS)

Peterson, Christopher W.; Benalcazar, Wladimir A.; Hughes, Taylor L.; Bahl, Gaurav

2018-03-01

The theory of electric polarization in crystals defines the dipole moment of an insulator in terms of a Berry phase (geometric phase) associated with its electronic ground state. This concept not only solves the long-standing puzzle of how to calculate dipole moments in crystals, but also explains topological band structures in insulators and superconductors, including the quantum anomalous Hall insulator and the quantum spin Hall insulator, as well as quantized adiabatic pumping processes. A recent theoretical study has extended the Berry phase framework to also account for higher electric multipole moments, revealing the existence of higher-order topological phases that have not previously been observed. Here we demonstrate experimentally a member of this predicted class of materials—a quantized quadrupole topological insulator—produced using a gigahertz-frequency reconfigurable microwave circuit. We confirm the non-trivial topological phase using spectroscopic measurements and by identifying corner states that result from the bulk topology. In addition, we test the critical prediction that these corner states are protected by the topology of the bulk, and are not due to surface artefacts, by deforming the edges of the crystal lattice from the topological to the trivial regime. Our results provide conclusive evidence of a unique form of robustness against disorder and deformation, which is characteristic of higher-order topological insulators.

Materials Development and Spin Transport Study of Magnetic Insulator Based Heterostructures

NASA Astrophysics Data System (ADS)

Tang, Chi

The subfield of magnetic insulator (MI) based spintronics is playing a substantial role in modern solid state physics research. Spin current in the MI is propagated in spin wave with a much longer decay length than spin-polarized carriers in conducting ferromagnet. In the MI-based hetereostructures, the adjacent non-magnetic materials can be magnetized in proximity of MI. Therefore, it is a promising system to study exotic transport phenomena such as quantum Anomalous Hall effect in topological insulator and graphene. Rare-earth Iron garnet (ReIG), a class of magnetic insulators with large electronic bandgap and high Curie temperature, stands out among various magnetic insulator materials and have attracted a great deal of attention in recent magnetic insulator based spintronics research. The first chapter of this dissertation gives a brief introduction to the spintronics research by introducing some essential concepts in the spintronics field and the most recent spin transport phenomena. The second chapter of this dissertation summarizes my work in the materials development of ReIG ferrimagnetic insulators, including exquisite control of high quality ultra-flat yttrium iron garnet (YIG) thin films with extremely low magnetic damping and engineering of strain induced robust perpendicular magnetic anisotropy in thulium iron garnet (TIG) and Bi-doped YIG films. The last chapter of this dissertation shows a systematic study in various ReIG based heterostructures, mainly divided into groups: ReIG (YIG & TIG)/heavy metal bilayers (Pd & Pt) and ReIG (YIG & TIG)/Dirac systems (graphene & topological insulator). The magneto-transport study disentangles the contribution from a spin current origin and proximity induced magnetism. Furthermore, the demonstration in the proximity coupling induced high-temperature ferromagnetic phase in low-dimensional Dirac systems, i.e. graphene and topological insulator surface states, provides new possibilities in the future spintronics applications. The modulation on the spin dynamics of magnetic insulator layer by topological insulator surface states is investigated at last, further confirming the superb properties of such magnetic insulator based spintronics systems.

Robust Thermal Control of Propulsion Lines for Space Missions

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep

2011-01-01

A document discusses an approach to insulating propulsion lines for spacecraft. In spacecraft that have propulsion lines that are located externally with open bus architecture, the lines are typically insulated by Multi Layer Insulation (MLI) blankets. MLI on propulsion lines tends to have large and somewhat random variances in its heat loss properties (effective emittance) from one location to the next, which makes it an un-robust approach to control propulsion line temperatures. The approach described here consists of a clamshell design in which the inner surface of the shell is coated with low-emissivity aluminized Kapton tape, and the outer surface is covered with black tape. This clamshell completely encloses the propulsion line. The line itself is covered with its heater, which in turn, is covered completely with black tape. This approach would be low in heater power needs because even though the outer surface of the prop line (and its heater) is covered with black tape as well as the outer surface of the clamshell, the inner surface of the clamshell is covered with low-emissivity aluminized Kapton tape. Hence, the heat loss from the line will be small and comparable to the MLI based one. In terms of contamination changing the radiative properties of surfaces, since the clamshell s inner surface is always protected during handling and is only installed after all the work on the prop line has been completed, the controlling surface, which is the clamshell s inner surface, is always in pristine condition. This proposed design allows for a much more deterministic and predictable design using a very simple and implementable approach for thermal control. It also uses low heater power and is robust to handling and contamination during and after implementation.

A charging study of ACTS using NASCAP

NASA Technical Reports Server (NTRS)

Herr, Joel L.

1991-01-01

The NASA Charging Analyzer Program (NASCAP) computer code is a three dimensional finite element charging code designed to analyze spacecraft charging in the magnetosphere. Because of the characteristics of this problem, NASCAP can use an quasi-static approach to provide a spacecraft designer with an understanding of how a specific spacecraft will interact with a geomagnetic substorm. The results of the simulation can help designers evaluate the probability and location of arc discharges of charged surfaces on the spacecraft. A charging study of NASA's Advanced Communication Technology Satellite (ACTS) using NASCAP is reported. The results show that the ACTS metalized multilayer insulating blanket design should provide good electrostatic discharge control.

Cassidy during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009322 (27 July 2009) --- Astronauts Tom Marshburn (left) and Christopher Cassidy, both STS-127 mission specialists, participate in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and Cassidy secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Dewar technology study

NASA Technical Reports Server (NTRS)

Davis, W.

1975-01-01

The development of a Dewar system for handling liquid helium under weightless conditions is described. Porous plug designs for the prevention of superfluid creep out of the dewar through the vent line were evaluated. For the purpose of designing a neck to provide a transition from the cold cavity to the outside, the loads carried by the neck and equipment supports were studied. Temperature, pressure, and mass flow instrumentation for monitoring Dewar performance were also evaluated. In addition, multilayer blankets consisting of aluminized Mylar separated by Dacron net sheets were designed to insulate the pressure vessel. The dewar system is suggested for use with the star tracking telescope aboard the relativity satellite.

Study on the Weak Stress in Flexural MEMS Cantilever

NASA Astrophysics Data System (ADS)

Ge, Yuetao; Ren, Yan

2018-03-01

In order to design a better piezoresistive MEMS cantilever beam, especially for cantilever beams that will detect weak forces or will be subjected to weak forces, this paper uses study on the weak stress in flexural MEMS cantilever. The sensor design structure, divided into protective layer, piezoresistive layer, support layer. The protective layer is responsible for protecting the piezoresistive layer so that the varistor is insulated from the outside; the piezoresistive layer is used to make the varistor; the support layer forms the main part of the cantilever beam, the majority of the cantilever beam. This paper has some value for cantilever multilayer structure design and cantilever beam size design.

An evaluation of Orbital Workshop passive thermal control surfaces

NASA Technical Reports Server (NTRS)

Daniels, D. J.; Kawano, P. I.; Sieker, W. D.; Walters, D. E.; Witherspoon, G. F.; Grunditz, D. W.

1974-01-01

The optical properties of selected Orbital Workshop thermal control surfaces are discussed from the time of their installation through the end of the Skylab missions. The surfaces considered are the goldized Kapton tape on the habitation area sidewall, the S-13G white paint on the Workshop aft skirt, and the multilayer insulation system on the forward dome of the habitation area. A quantitative assessment of the effects of exposure to the ascent and orbital environments is made including the effects of rocket exhaust plume contamination. Although optical property degradation of the external surfaces was noted, satisfactory thermal performance was maintained throughout the Skylab missions.

Thermal design of the IUE hydrazine auxiliary propulsion system. [International Ultraviolet Explorer

NASA Technical Reports Server (NTRS)

Skladany, J. T.; Kelly, W. H.

1977-01-01

The International Ultraviolet Explorer is a large astronomical observatory scheduled to be placed in a three-axis stabilized synchronous orbit in the fourth quarter of 1977. The Hydrazine Auxiliary Propulsion System (HAPS) must perform a number of spacecraft maneuvers to achieve a successful mission. This paper describes the thermal design which accomplishes temperature control between 5 and 65 C for all orbital conditions by utilizing multilayer insulation and commandable component heaters. A primary design criteria was the minimization of spacecraft power by the selective use of the solar environment. The thermal design was carefully assessed and verified in both spacecraft thermal balance and subsystem solar simulation testing.

Design Factors for Applying Cryogen Storage and Delivery Technology to Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Millis, Marc G.

1996-01-01

Thermodynamic Vent System (TVS) and Multilayer Insulation (MLI) technology, originally developed for long term storage of cryogen propellants in microgravity, is ideally suited for propellant storage and delivery systems for solar thermal propulsion. With this technology the heat-induced pressure rise in the tank provides the propellant delivery pressure without the need for an auxiliary pressurant system, and propellant delivery is used to remove the excess heat to control tank pressure. The factors to consider in designing such a balanced system, are presented. An example of a minimum system design is presented along with examples of laboratory-tested hardware.

Thermal Properties of Double-Aluminized Kapton at Low Temperatures

NASA Technical Reports Server (NTRS)

Tuttle, J.; DiPirro, M.; Canavan, E.; Hait, T.

2007-01-01

Double-aluminized kapton (DAK) is commonly used in multi-layer insulation blankets in cryogenic systems. NASA plans to use individual DAK sheets in lightweight deployable shields for satellites carrying instruments. A set of these shields will reflect away thermal radiation from the sun, the earth, and the instrument's warm side and allow the instrument's cold side to radiate its own heat to deep space. In order to optimally design such a shield system, it is important to understand the thermal characteristics of DAK down to low temperatures. We describe experiments which measured the thermal conductivity and electrical resistivity down to 4 Kelvin and the emissivity down to 10 Kelvin.

Small-Scale Mechanical Characterization of Space-Exposed Fluorinated Ethylene Propylene Recovered from the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Jones, J. S.; Sharon, J. A.; Mohammed, J.; Hemker, K. J.

2012-01-01

Multi-layer insulation panels from the Hubble Space Telescope have been recovered after 19.1 years of on-orbit service and micro-tensile experiments have been performed to characterize the effect of space exposure on the mechanical response of the outermost layer. This outer layer, 127 m thick fluorinated ethylene propylene with a 100 nm thick vapor deposited aluminum reflective coating, maintained significant tensile ductility but exhibited a degradation of strength that scales with severity of space exposure. This change in properties is attributed to damage from incident solar flux, atomic oxygen damage, and thermal cycling.

Numerical modeling of interaction in the dynamic system "gas-structure" with harmonic motion of the piston in the variable section pipe

NASA Astrophysics Data System (ADS)

Butymova, L. N.; Modorskii, V. Ya.; Petrov, V. Yu.

2016-10-01

The Helmholtz resonator is an instrument to create low-frequency natural oscillations whose wavelength is substantially larger than the dimensions of the resonator itself. Some modern insulating materials are a set of Helmholtz resonators made in the form of a multilayer composite structure with a layer of cells between the carrier layers. The cells have an outlet hole drilled in the support layer. Improving effectiveness of such structures in terms of noise reduction is an urgent task [1 - 7]. It is found that the resonator with a throat of higher surface roughness damps noise more effectively.

Analysis of International Space Station Vehicle Materials Exposed on Materials International Space Station Experiment from 2001 to 2011

NASA Technical Reports Server (NTRS)

Finckenor, M. M.; Golden, J. L.; Kravchenko, M.

2013-01-01

Since August 2001, the Materials on International Space Station Experiment (MISSE) has provided data on a variety of materials and spacecraft components, including samples chosen to provide sustaining engineering and life extension data for the International Space Station vehicle itself. This Technical Publication is by no means a complete set of MISSE data but does provide changes in solar absorptance, infrared emittance, and visual appearance due to atomic oxygen, ultraviolet radiation, and thermal cycling in vacuum. Conversion coatings, anodizes, thermal control coatings with organic and inorganic binders, multilayer insulation components, optical materials, and part markings are discussed.

Mechanically Robust, Stretchable Solar Absorbers with Submicron-Thick Multilayer Sheets for Wearable and Energy Applications.

PubMed

Lee, Hye Jin; Jung, Dae-Han; Kil, Tae-Hyeon; Kim, Sang Hyeon; Lee, Ki-Suk; Baek, Seung-Hyub; Choi, Won Jun; Baik, Jeong Min

2017-05-31

A facile method to fabricate a mechanically robust, stretchable solar absorber for stretchable heat generation and an enhanced thermoelectric generator (TEG) is demonstrated. This strategy is very simple: it uses a multilayer film made of titanium and magnesium fluoride optimized by a two-dimensional finite element frequency-domain simulation, followed by the application of mechanical stresses such as bending and stretching to the film. This process produces many microsized sheets with submicron thickness (∼500 nm), showing great adhesion to any substrates such as fabrics and polydimethylsiloxane. It exhibits a quite high light absorption of approximately 85% over a wavelength range of 0.2-4.0 μm. Under 1 sun illumination, the solar absorber on various stretchable substrates increased the substrate temperature to approximately 60 °C, irrespective of various mechanical stresses such as bending, stretching, rubbing, and even washing. The TEG with the absorber on the top surface also showed an enhanced output power of 60%, compared with that without the absorber. With an incident solar radiation flux of 38.3 kW/m 2 , the output power significantly increased to 24 mW/cm 2 because of the increase in the surface temperature to 141 °C.

Orbital Magnetization of Quantum Spin Hall Insulator Nanoparticles.

PubMed

Potasz, P; Fernández-Rossier, J

2015-09-09

Both spin and orbital degrees of freedom contribute to the magnetic moment of isolated atoms. However, when inserted in crystals, atomic orbital moments are quenched because of the lack of rotational symmetry that protects them when isolated. Thus, the dominant contribution to the magnetization of magnetic materials comes from electronic spin. Here we show that nanoislands of quantum spin Hall insulators can host robust orbital edge magnetism whenever their highest occupied Kramers doublet is singly occupied, upgrading the spin edge current into a charge current. The resulting orbital magnetization scales linearly with size, outweighing the spin contribution for islands of a few nm in size. This linear scaling is specific of the Dirac edge states and very different from Schrodinger electrons in quantum rings. By modeling Bi(111) flakes, whose edge states have been recently observed, we show that orbital magnetization is robust with respect to disorder, thermal agitation, shape of the island, and crystallographic direction of the edges, reflecting its topological protection.

Encapsulated silicene: A robust large-gap topological insulator

DOE PAGES

Kou, Liangzhi; Ma, Yandong; Yan, Binghai; ...

2015-08-20

The quantum spin Hall (QSH) effect predicted in silicene has raised exciting prospects of new device applications compatible with current microelectronic technology. Efforts to explore this novel phenomenon, however, have been impeded by fundamental challenges imposed by silicene’s small topologically nontrivial band gap and fragile electronic properties susceptible to environmental degradation effects. Here we propose a strategy to circumvent these challenges by encapsulating silicene between transition-metal dichalcogenides (TMDCs) layers. First-principles calculations show that such encapsulated silicene exhibit a two-orders-of-magnitude enhancement in its nontrivial band gap, which is driven by the strong spin–orbit coupling effect in TMDCs via the proximity effect.more » Moreover, the cladding TMDCs layers also shield silicene from environmental gases that are detrimental to the QSH state in free-standing silicene. In conclusion, the encapsulated silicene represents a novel two-dimensional topological insulator with a robust nontrivial band gap suitable for room-temperature applications, which has significant implications for innovative QSH device design and fabrication.« less

Analyses of Hubble Space Telescope Aluminized-Teflon Insulation Retrieved After 19 Years of Space Exposure

NASA Technical Reports Server (NTRS)

deGroh, Kim K.; Waters, Deborah L.; Mohammed, Jelila S.; Perry, Bruce A.; Banks, Bruce A.

2012-01-01

Since its launch in April 1990, the Hubble Space Telescope (HST) has made many important observations from its vantage point in low Earth orbit (LEO). However, as seen during five servicing missions, the outer layer of multilayer insulation (MLI) has become successively more embrittled and has cracked in many areas. In May 2009, during the 5th servicing mission (called SM4), two MLI blankets were replaced with new insulation pieces and the space-exposed MLI blankets were retrieved for degradation analyses by teams at NASA Glenn Research Center (GRC) and NASA Goddard Space Flight Center (GSFC). The MLI blankets were from Equipment Bay 8, which received direct sunlight, and Equipment Bay 5, which received grazing sunlight. Each blanket contained a range of unique regions based on environmental exposure and/or physical appearance. The retrieved MLI blanket s aluminized-Teflon (DuPont) fluorinated ethylene propylene (Al-FEP) outer layers have been analyzed for changes in optical, physical, and mechanical properties, along with space induced chemical and morphological changes. When compared to pristine material, the analyses have shown how the Al-FEP was severely affected by the space environment. This paper reviews tensile properties, solar absorptance, thermal emittance, x-ray photoelectron spectroscopy (XPS) data and atomic oxygen erosion values of the retrieved HST blankets after 19 years of space exposure.

Spectroscopic Identification of the Au-C Bond Formation upon Electroreduction of an Aryl Diazonium Salt on Gold.

PubMed

Guo, Limin; Ma, Lipo; Zhang, Yelong; Cheng, Xun; Xu, Ye; Wang, Jin; Wang, Erkang; Peng, Zhangquan

2016-11-08

Electroreduction of aryl diazonium salts on gold can produce organic films that are more robust than their analogous self-assembled monolayers formed from chemical adsorption of organic thiols on gold. However, whether the enhanced stability is due to the Au-C bond formation remains debated. In this work, we report the electroreduction of an aryl diazonium salt of 4,4'-disulfanediyldibenzenediazonium on gold forming a multilayer of Au-(Ar-S-S-Ar) n , which can be further degraded to a monolayer of Au-Ar-S - by electrochemical cleavage of the S-S moieties within the multilayer. By conducting an in situ surface-enhanced Raman spectroscopic study of both the multilayer formation/degradation and the monolayer reduction/oxidation processes, coupled to density functional theory calculations, we provide compelling evidence that an Au-C bond does form upon electroreduction of aryl diazonium salts on gold and that the enhanced stability of the electrografted organic films is due to the Au-C bond being intrinsically stronger than the Au-S bond for a given phenylthiolate compound by ca. 0.4 eV.

CRYogenic Orbital TEstbed Ground Test Article Thermal Analysis

NASA Technical Reports Server (NTRS)

Piryk, David; Schallhorn, Paul; Walls, Laurie; Stopnitzky, Benny; Rhys, Noah; Wollen, Mark

2012-01-01

The purpose of this study was to anchor thermal and fluid system models to CRYOTE ground test data. The CRYOTE ground test artide was jointly developed by Innovative Engineering Solutions, United Launch Alliance and NASA KSC. The test article was constructed out of a titanium alloy tank, Sapphire 77 composite skin (similar to G10), an external secondary payload adapter ring, thermal vent system, multi layer insulation and various data acquisition instrumentation. In efforts to understand heat loads throughout this system, the GTA (filled with liquid nitrogen for safety purposes) was subjected to a series of tests in a vacuum chamber at Marshall Space Flight Center. By anchoring analytical models against test data, higher fidelity thermal environment predictions can be made for future flight articles which would eventually demonstrate critical cryogenic fluid management technologies such as system chilldown, transfer, pressure control and long term storage. Significant factors that influenced heat loads included radiative environments, multi-layer insulation performance, tank fill levels and pressures and even contact conductance coefficients. This report demonstrates how analytical thermal/fluid networks were established and includes supporting rationale for specific thermal responses.

The Thermal Hogan - A Means of Surviving the Lunar Night

NASA Technical Reports Server (NTRS)

Fruitwala, Neelay; Ungar, Eugene; Cornwell, John

2013-01-01

document describes the Thermal Hogan, a new shelter concept that would be used on the Moon to moderate the extreme nighttime temperatures, allowing survival of equipment with minimal heater power. It is lightweight, has few mechanical parts, and would be relatively easy to deploy on the Moon. The Lunar Hogan has two parts: an insulated shelter and a thermal mass. The shelter is constructed of multilayer insulation (MLI) draped over a structural framework. Entry and egress are accomplished either by raising the structure or via a door constructed of the same MLI material as the shelter. The thermal mass can be manufactured from locally available materials, either by piling substantially sized rocks to a depth of 0.25 meter, or by filling a 0.25-meter-deep conductive honeycomb-like structure with lunar dust. For ease of transport, the structural framework and honeycomb can be collapsible. The door can be opened by pushing on it in either direction. Gravity would cause it to close and it could be sealed via magnetic strips on the doorframe.

Design and Operation of a Calorimeter for Advanced Multilayer Insulation Testing

NASA Technical Reports Server (NTRS)

Chato, David J.; Johnson, Wesley L.; Van Dresar, Neil

2016-01-01

A calorimeter has been constructed to accurately measure insulation performance with a nominal 90K outer boundary and a 20K inner boundary. Unique features of this design include use of mechanical cryocoolers instead of cryogens and measurement of the heat load with a calibrated heat conduction rod. The calorimeter is operational and has completed its first test series. The initial test series was designed to look for differences in performance between a single layer of aluminum foil and a sheet of double aluminized Mylar (DAM). Although it has been speculated that the aluminum foil would perform better, since the aluminum coating on the Mylar might not be thick enough to stop the transmission of long wave length infrared radiation, our testing showed a higher heat load for the aluminum foil than the DAM. The aluminum foil showed a heat load of 132 mW at an 87 K outer temperature and 152 mW at a 107K outer temperature, whereas the DAM showed a heat load of 66 mW at an 88 K outer temperature and 81 mW at 108 K.

Design and Operation of a Calorimeter for Advanced Multilayer Insulation Testing

NASA Technical Reports Server (NTRS)

Chato, David; Johnson, Wesley; Dresar, Neil Van

2016-01-01

A calorimeter has been constructed to accurately measure insulation performance with a nominal 90K cold outer boundary and a 20K inner boundary. Unique features of this design include use of mechanical cryocoolers instead cryogens and measurement of the heat load with a calibrated rod to serve as a conduction path. The calorimeter is operational and has completed its first test series. The initial test series was designed to look for differences in performance between a single layer of aluminum foil and a sheet of double aluminized mylar (DAM). Although it has been speculated that the aluminum foil would perform better, since the mylar coating might not thick enough to stop the transmission of long wave length infrared radiation, our testing showed a higher heat load for the aluminum foil than the DAM. The aluminum foil showed a heat load of 132 mW at an 87 K outer temperature and 152 mW at a 107K outer temperature. Whereas the DAM showed a heat load of 66 mW at an 88 K outer temperature and 81 mW at 108 K.

All-Aluminum Thin Film Transistor Fabrication at Room Temperature.

PubMed

Yao, Rihui; Zheng, Zeke; Zeng, Yong; Liu, Xianzhe; Ning, Honglong; Hu, Shiben; Tao, Ruiqiang; Chen, Jianqiu; Cai, Wei; Xu, Miao; Wang, Lei; Lan, Linfeng; Peng, Junbiao

2017-02-23

Bottom-gate all-aluminum thin film transistors with multi conductor/insulator nanometer heterojunction were investigated in this article. Alumina (Al₂O₃) insulating layer was deposited on the surface of aluminum doping zinc oxide (AZO) conductive layer, as one AZO/Al₂O₃ heterojunction unit. The measurements of transmittance electronic microscopy (TEM) and X-ray reflectivity (XRR) revealed the smooth interfaces between ~2.2-nm-thick Al₂O₃ layers and ~2.7-nm-thick AZO layers. The devices were entirely composited by aluminiferous materials, that is, their gate and source/drain electrodes were respectively fabricated by aluminum neodymium alloy (Al:Nd) and pure Al, with Al₂O₃/AZO multilayered channel and AlO x :Nd gate dielectric layer. As a result, the all-aluminum TFT with two Al₂O₃/AZO heterojunction units exhibited a mobility of 2.47 cm²/V·s and an I on / I off ratio of 10⁶. All processes were carried out at room temperature, which created new possibilities for green displays industry by allowing for the devices fabricated on plastic-like substrates or papers, mainly using no toxic/rare materials.

Spin-orbit torque induced magnetization switching in heavy metal/ferromagnet multilayers with bilayer of heavy metals

NASA Astrophysics Data System (ADS)

Bekele, Zelalem Abebe; Meng, Kangkang; Zhao, Bing; Wu, Yong; Miao, Jun; Xu, Xiaoguang; Jiang, Yong

2017-08-01

Symmetry breaking provides new insight into the physics of spin-orbit torque (SOT) and the switching without a magnetic field could lead to significant impact. In this work, we demonstrate the robust zero-field SOT switching of a perpendicular ferromagnet (FM) layer where the symmetry is broken by a bilayer of heavy metals (HMs) with the strong spin-orbit coupling (SOC). We observed the change of coercivity value by 31% after inserting Co2FeAl in the multilayer structure. These two HM layers (Ta and Pt) are used to strengthen the SOC by linear combination. With different angles between the magnetization and the current (i.e. parallel and anti-parallel), the structures show different switching behaviors such as clockwise or counterclockwise.

Modelling the Flow Stress of Alloy 316L using a Multi-Layered Feed Forward Neural Network with Bayesian Regularization

NASA Astrophysics Data System (ADS)

Abiriand Bhekisipho Twala, Olufunminiyi

2017-08-01

In this paper, a multilayer feedforward neural network with Bayesian regularization constitutive model is developed for alloy 316L during high strain rate and high temperature plastic deformation. The input variables are strain rate, temperature and strain while the output value is the flow stress of the material. The results show that the use of Bayesian regularized technique reduces the potential of overfitting and overtraining. The prediction quality of the model is thereby improved. The model predictions are in good agreement with experimental measurements. The measurement data used for the network training and model comparison were taken from relevant literature. The developed model is robust as it can be generalized to deformation conditions slightly below or above the training dataset.

Using parallel evolutionary development for a biologically-inspired computer vision system for mobile robots.

PubMed

Wright, Cameron H G; Barrett, Steven F; Pack, Daniel J

2005-01-01

We describe a new approach to attacking the problem of robust computer vision for mobile robots. The overall strategy is to mimic the biological evolution of animal vision systems. Our basic imaging sensor is based upon the eye of the common house fly, Musca domestica. The computational algorithms are a mix of traditional image processing, subspace techniques, and multilayer neural networks.

Ambient Dried Aerogels

NASA Technical Reports Server (NTRS)

Jones, Steven M.; Paik, Jong-Ah

2013-01-01

A method has been developed for creating aerogel using normal pressure and ambient temperatures. All spacecraft, satellites, and landers require the use of thermal insulation due to the extreme environments encountered in space and on extraterrestrial bodies. Ambient dried aerogels introduce the possibility of using aerogel as thermal insulation in a wide variety of instances where supercritically dried aerogels cannot be used. More specifically, thermoelectric devices can use ambient dried aerogel, where the advantages are in situ production using the cast-in ability of an aerogel. Previously, aerogels required supercritical conditions (high temperature and high pressure) to be dried. Ambient dried aerogels can be dried at room temperature and pressure. This allows many materials, such as plastics and certain metal alloys that cannot survive supercritical conditions, to be directly immersed in liquid aerogel precursor and then encapsulated in the final, dried aerogel. Additionally, the metalized Mylar films that could not survive the previous methods of making aerogels can survive the ambient drying technique, thus making multilayer insulation (MLI) materials possible. This results in lighter insulation material as well. Because this innovation does not require high-temperature or high-pressure drying, ambient dried aerogels are much less expensive to produce. The equipment needed to conduct supercritical drying costs many tens of thousands of dollars, and has associated running expenses for power, pressurized gasses, and maintenance. The ambient drying process also expands the size of the pieces of aerogel that can be made because a high-temperature, high-pressure system typically has internal dimensions of up to 30 cm in diameter and 60 cm in height. In the case of this innovation, the only limitation on the size of the aerogels produced would be in the ability of the solvent in the wet gel to escape from the gel network.

Review of Current State of the Art and Key Design Issues With Potential Solutions for Liquid Hydrogen Cryogenic Storage Tank Structures for Aircraft Applications

NASA Technical Reports Server (NTRS)

Mital, Subodh K.; Gyekenyesi, John Z.; Arnold, Steven M.; Sullivan, Roy M.; Manderscheid, Jane M.; Murthy, Pappu L. N.

2006-01-01

Due to its high specific energy content, liquid hydrogen (LH2) is emerging as an alternative fuel for future aircraft. As a result, there is a need for hydrogen tank storage systems, for these aircraft applications, that are expected to provide sufficient capacity for flight durations ranging from a few minutes to several days. It is understood that the development of a large, lightweight, reusable cryogenic liquid storage tank is crucial to meet the goals of and supply power to hydrogen-fueled aircraft, especially for long flight durations. This report provides an annotated review (including the results of an extensive literature review) of the current state of the art of cryogenic tank materials, structural designs, and insulation systems along with the identification of key challenges with the intent of developing a lightweight and long-term storage system for LH2. The broad classes of insulation systems reviewed include foams (including advanced aerogels) and multilayer insulation (MLI) systems with vacuum. The MLI systems show promise for long-term applications. Structural configurations evaluated include single- and double-wall constructions, including sandwich construction. Potential wall material candidates are monolithic metals as well as polymer matrix composites and discontinuously reinforced metal matrix composites. For short-duration flight applications, simple tank designs may suffice. Alternatively, for longer duration flight applications, a double-wall construction with a vacuum-based insulation system appears to be the most optimum design. The current trends in liner material development are reviewed in the case that a liner is required to minimize or eliminate the loss of hydrogen fuel through permeation.

Fabrication of large area woodpile structure in polymer

NASA Astrophysics Data System (ADS)

Gupta, Jaya Prakash; Dutta, Neilanjan; Yao, Peng; Sharkawy, Ahmed S.; Prather, Dennis W.

2009-02-01

A fabrication process of three-dimensional Woodpile photonic crystals based on multilayer photolithography from commercially available photo resist SU8 have been demonstrated. A 6-layer, 2 mm × 2mm woodpile has been fabricated. Different factors that influence the spin thickness on multiple resist application have been studied. The fabrication method used removes, the problem of intermixing, and is more repeatable and robust than the multilayer fabrication techniques for three dimensional photonic crystal structures that have been previously reported. Each layer is developed before next layer photo resist spin, instead of developing the whole structure in the final step as used in multilayer process. The desired thickness for each layer is achieved by the calibration of spin speed and use of different photo resist compositions. Deep UV exposure confinement has been the defining parameter in this process. Layer uniformity for every layer is independent of the previous developed layers and depends on the photo resist planarizing capability, spin parameters and baking conditions. The intermixing problem, which results from the previous layers left uncrossed linked photo resist, is completely removed in this process as the previous layers are fully developed, avoiding any intermixing between the newly spun and previous layers. Also this process gives the freedom to redo every spin any number of times without affecting the previously made structure, which is not possible in other multilayer process where intermediate developing is not performed.

All-Organic High-Performance Piezoelectric Nanogenerator with Multilayer Assembled Electrospun Nanofiber Mats for Self-Powered Multifunctional Sensors.

PubMed

Maity, Kuntal; Mandal, Dipankar

2018-05-30

Rapid development of wearable electronics, piezoelectric nanogenerator (PNG), has been paid a special attention because of its sustainable and accessible energy generation. In this context, we present a simple yet highly efficient design strategy to enhance the output performance of an all-organic PNG (OPNG) based on multilayer assembled electrospun poly(vinylidene fluoride) (PVDF) nanofiber (NF) mats where vapor-phase polymerized poly(3,4-ethylenedioxythiophene)-coated PVDF NFs are assembled as electrodes and neat PVDF NFs are utilized as an active component. In addition to the multilayer assembly, electrode compatibility and durability remain a challenging task to mitigate the primary requirements of wearable electronics. A multilayer networked three-dimensional structure integrated with a compatible electrode thereby provides enhanced output voltage and current (e.g., open-circuit voltage, V oc ≈ 48 V, and short-circuit current, I sc ≈ 6 μA, upon 8.3 kPa of the applied stress amplitude) with superior piezoelectric energy conversion efficiency of 66% compared to the single-mat device. Besides, OPNG also shows ultrasensitivity toward human movements such as foot strikes and walking. The weight measurement mapping is critically explored by principal component analysis that may have enormous applications in medical diagnosis to smart packaging industries. More importantly, fatigue test under continuous mechanical impact (over 6 months) shows great promise as a robust wearable mechanical energy harvester.

Disorder effects in topological states: Brief review of the recent developments

NASA Astrophysics Data System (ADS)

Wu, Binglan; Song, Juntao; Zhou, Jiaojiao; Jiang, Hua

2016-11-01

Disorder inevitably exists in realistic samples, manifesting itself in various exotic properties for the topological states. In this paper, we summarize and briefly review the work completed over the last few years, including our own, regarding recent developments in several topics about disorder effects in topological states. For weak disorder, the robustness of topological states is demonstrated, especially for both quantum spin Hall states with Z 2 = 1 and size induced nontrivial topological insulators with Z 2 = 0. For moderate disorder, by increasing the randomness of both the impurity distribution and the impurity induced potential, the topological insulator states can be created from normal metallic or insulating states. These phenomena and their mechanisms are summarized. For strong disorder, the disorder causes a metal-insulator transition. Due to their topological nature, the phase diagrams are much richer in topological state systems. Finally, the trends in these areas of disorder research are discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374219, 11474085, and 11534001) and the Natural Science Foundation of Jiangsu Province, China (Grant No BK20160007).

Integrated Electrical Wire Insulation Repair System

NASA Technical Reports Server (NTRS)

Williams, Martha; Jolley, Scott; Gibson, Tracy; Parks, Steven

2013-01-01

An integrated system tool will allow a technician to easily and quickly repair damaged high-performance electrical wire insulation in the field. Low-melt polyimides have been developed that can be processed into thin films that work well in the repair of damaged polyimide or fluoropolymer insulated electrical wiring. Such thin films can be used in wire insulation repairs by affixing a film of this low-melt polyimide to the damaged wire, and heating the film to effect melting, flow, and cure of the film. The resulting repair is robust, lightweight, and small in volume. The heating of this repair film is accomplished with the use of a common electrical soldering tool that has been modified with a special head or tip that can accommodate the size of wire being repaired. This repair method can furthermore be simplified for the repair technician by providing replaceable or disposable soldering tool heads that have repair film already "loaded" and ready for use. The soldering tool heating device can also be equipped with a battery power supply that will allow its use in areas where plug-in current is not available

Persistent Hall voltages across thin planar charged quantum rings on the surface of a topological insulator

NASA Astrophysics Data System (ADS)

Durganandini, P.

2015-03-01

We consider thin planar charged quantum rings on the surface of a three dimensional topological insulator coated with a thin ferromagnetic layer. We show theoretically, that when the ring is threaded by a magnetic field, then, due to the Aharanov-Bohm effect, there are not only the well known circulating persistent currents in the ring but also oscillating persistent Hall voltages across the thin ring. Such oscillating persistent Hall voltages arise due to the topological magneto-electric effect associated with the axion electrodynamics exhibited by the surface electronic states of the three dimensional topological insulator when time reversal symmetry is broken. We further generalize to the case of dipole currents and show that analogous Hall dipole voltages arise. We also discuss the robustness of the effect and suggest possible experimental realizations in quantum rings made of semiconductor heterostructures. Such experiments could also provide new ways of observing the predicted topological magneto-electric effect in three dimensional topological insulators with time reversal symmetry breaking. I thank BCUD, Pune University, Pune for financial support through research grant.

Measuring the lateral charge-carrier mobility in metal-insulator-semiconductor capacitors via Kelvin-probe.

PubMed

Milotti, Valeria; Pietsch, Manuel; Strunk, Karl-Philipp; Melzer, Christian

2018-01-01

We report a Kelvin-probe method to investigate the lateral charge-transport properties of semiconductors, most notably the charge-carrier mobility. The method is based on successive charging and discharging of a pre-biased metal-insulator-semiconductor stack by an alternating voltage applied to one edge of a laterally confined semiconductor layer. The charge carriers spreading along the insulator-semiconductor interface are directly measured by a Kelvin-probe, following the time evolution of the surface potential. A model is presented, describing the device response for arbitrary applied biases allowing the extraction of the lateral charge-carrier mobility from experimentally measured surface potentials. The method is tested using the organic semiconductor poly(3-hexylthiophene), and the extracted mobilities are validated through current voltage measurements on respective field-effect transistors. Our widely applicable approach enables robust measurements of the lateral charge-carrier mobility in semiconductors with weak impact from the utilized contact materials.

Measuring the lateral charge-carrier mobility in metal-insulator-semiconductor capacitors via Kelvin-probe

NASA Astrophysics Data System (ADS)

Milotti, Valeria; Pietsch, Manuel; Strunk, Karl-Philipp; Melzer, Christian

2018-01-01

We report a Kelvin-probe method to investigate the lateral charge-transport properties of semiconductors, most notably the charge-carrier mobility. The method is based on successive charging and discharging of a pre-biased metal-insulator-semiconductor stack by an alternating voltage applied to one edge of a laterally confined semiconductor layer. The charge carriers spreading along the insulator-semiconductor interface are directly measured by a Kelvin-probe, following the time evolution of the surface potential. A model is presented, describing the device response for arbitrary applied biases allowing the extraction of the lateral charge-carrier mobility from experimentally measured surface potentials. The method is tested using the organic semiconductor poly(3-hexylthiophene), and the extracted mobilities are validated through current voltage measurements on respective field-effect transistors. Our widely applicable approach enables robust measurements of the lateral charge-carrier mobility in semiconductors with weak impact from the utilized contact materials.

Room-Temperature Spin-Orbit Torque Switching Induced by a Topological Insulator

NASA Astrophysics Data System (ADS)

Han, Jiahao; Richardella, A.; Siddiqui, Saima A.; Finley, Joseph; Samarth, N.; Liu, Luqiao

2017-08-01

The strongly spin-momentum coupled electronic states in topological insulators (TI) have been extensively pursued to realize efficient magnetic switching. However, previous studies show a large discrepancy of the charge-spin conversion efficiency. Moreover, current-induced magnetic switching with TI can only be observed at cryogenic temperatures. We report spin-orbit torque switching in a TI-ferrimagnet heterostructure with perpendicular magnetic anisotropy at room temperature. The obtained effective spin Hall angle of TI is substantially larger than the previously studied heavy metals. Our results demonstrate robust charge-spin conversion in TI and provide a direct avenue towards applicable TI-based spintronic devices.

Evaluation of the Anisotropic Radiative Conductivity of a Low-Density Carbon Fiber Material from Realistic Microscale Imaging

NASA Technical Reports Server (NTRS)

Nouri, Nima; Panerai, Francesco; Tagavi, Kaveh A.; Mansour, Nagi N.; Martin, Alexandre

2015-01-01

The radiative heat transfer inside a low-density carbon fiber insulator is analyzed using a three-dimensional direct simulation model. A robust procedure is presented for the numerical calculation of the geometric configuration factor to compute the radiative energy exchange processes among the small discretized surface areas of the fibrous material. The methodology is applied to a polygonal mesh of a fibrous insulator obtained from three-dimensional microscale imaging of the real material. The anisotropic values of the radiative conductivity are calculated for that geometry. The results yield both directional and thermal dependence of the radiative conductivity.

Exfoliated BN shell-based high-frequency magnetic core-shell materials.

PubMed

Zhang, Wei; Patel, Ketan; Ren, Shenqiang

2017-09-14

The miniaturization of electric machines demands high frequency magnetic materials with large magnetic-flux density and low energy loss to achieve a decreased dimension of high rotational speed motors. Herein, we report a solution-processed high frequency magnetic composite (containing a nanometal FeCo core and a boron nitride (BN) shell) that simultaneously exhibits high electrical resistivity and magnetic permeability. The frequency dependent complex initial permeability and the mechanical robustness of nanocomposites are intensely dependent on the content of BN insulating phase. The results shown here suggest that insulating magnetic nanocomposites have potential for application in next-generation high-frequency electric machines with large electrical resistivity and permeability.

NASA Tech Briefs, May 2007

NASA Technical Reports Server (NTRS)

2007-01-01

Topics include: Noise-Canceling Helmet Audio System; Program Analyzes Spacecraft/Ground Radio Links; Two-Way Communication Using RFID Equipment and Techniques; Six-Message Electromechanical Display System; Scanning Terahertz Heterodyne Imaging Systems; Master Clock and Time-Signal-Distribution System; Synchronous Phase-Resolving Flash Range Imaging; Integrated Radial Probe Transition From MMIC to Waveguide; Bar-Code System for a Microbiological Laboratory; MMIC Amplifier Produces Gain of 10 dB at 235 GHz; Mapping Nearby Terrain in 3D by Use of a Grid of Laser Spots; Digital Beam Deflectors Based Partly on Liquid Crystals; Narrow-Band WGM Optical Filters With Tunable FSRs; Better Finite-Element Analysis of Composite Shell Structures; Computing Spacecraft-Pointing Vectors for Limb Tracking; Enhanced Master Controller Unit Tester; Rover Graphical Simulator; Increasing Durability of Flame-Sprayed Strain Gauges; Multifunctional, High-Temperature Nanocomposites; Multilayer Impregnated Fibrous Thermal Insulation Tiles; Radiation-Shielding Polymer/Soil Composites; Film/Adhesive Processing Module for Fiber-Placement Processing of Composites; Fabrication of Submillimeter Axisymmetric Optical Components; Electrochemical Disposal of Hydrazines in Water; Statistical Model of Evaporating Multicomponent Fuel Drops; Resistively Heated SiC Nozzle for Generating Molecular Beams; Compact Packaging of Photonic Millimeter-Wave Receiver; Diffractive Combiner of Single-Mode Pump Laser-Diode Beams; Wide-Band, High-Quantum-Efficiency Photodetector; A Robustly Stabilizing Model Predictive Control Algorithm; Modeling Evaporation of Drops of Different Kerosenes; Development of Vapor-Phase Catalytic Ammonia Removal System; Several Developments in Space Tethers; Design Concept for a Nuclear Reactor-Powered Mars Rover; Formation-Initialization Algorithm for N Spacecraft; and DNSs of Multicomponent Gaseous and Drop-Laden Mixing Layers Achieving Transition to Turbulence.

Comparison of Observed Beta Cloth Interactions with Simulated and Actual Space Environment

NASA Technical Reports Server (NTRS)

Kamenetzy, R. R.; Finckenor, M. M.

1999-01-01

A common component of multilayer insulation blankets is beta cloth, a woven fiberglass cloth impregnated with Teflon(TM). It is planned for extensive use on the International Space Station. The Environmental Etl'ects Group of the Marshall Space Flight Center Materials, Processing, and Manufacturing Department has investigated the impact of atomic oxygen (AO) and ultraviolet (UV) radiation on the optical properties of plain and aluminized beta cloth. both in the laboratory and as part of long-duration flight experiments. These investigations indicate that beta cloth is susceptible to darkening in the presence of UV radiation, dependent on the additives used. AO interactions resulted in bleaching of the beta cloth.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolotov, V. V.; Knyazev, E. V.; Ponomareva, I. V.

The oxidation of mesoporous silicon in a double-layer “macroporous silicon–mesoporous silicon” structure is studied. The morphology and dielectric properties of the buried insulating layer are investigated using electron microscopy, ellipsometry, and electrical measurements. Specific defects (so-called spikes) are revealed between the oxidized macropore walls in macroporous silicon and the oxidation crossing fronts in mesoporous silicon. It is found that, at an initial porosity of mesoporous silicon of 60%, three-stage thermal oxidation leads to the formation of buried silicon-dioxide layers with an electric-field breakdown strength of E{sub br} ~ 10{sup 4}–10{sup 5} V/cm. Multilayered “porous silicon-on-insulator” structures are shown to bemore » promising for integrated chemical micro- and nanosensors.« less

Cassidy and Marshburn during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009342 (27 July 2009) --- Astronauts Tom Marshburn (foreground) and Christopher Cassidy, both STS-127 mission specialists, participate in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and Cassidy secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009315 (27 July 2009) --- Astronaut Christopher Cassidy, STS-127 mission specialist, participates in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Cassidy and astronaut Tom Marshburn (out of frame), mission specialist, secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy and Marshburn during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009312 (27 July 2009) --- Astronauts Tom Marshburn (left) and Christopher Cassidy, both STS-127 mission specialists, participate in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and Cassidy secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy and Marshburn during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009317 (27 July 2009) --- Astronauts Tom Marshburn (left) and Christopher Cassidy, both STS-127 mission specialists, participate in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and Cassidy secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy and Marshburn during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009329 (27 July 2009) --- Astronauts Christopher Cassidy and Tom Marshburn (partially out of frame at left), both STS-127 mission specialists, participate in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and Cassidy secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy and Marshburn during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009323 (27 July 2009) --- Astronauts Tom Marshburn (foreground) and Christopher Cassidy, both STS-127 mission specialists, participate in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and Cassidy secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Marshburn during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009303 (27 July 2009) --- Astronaut Tom Marshburn, STS-127 mission specialist, participates in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and astronaut Christopher Cassidy (out of frame), mission specialist, secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy and Marshburn during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009363 (27 July 2009) --- Astronauts Tom Marshburn (foreground) and Christopher Cassidy, both STS-127 mission specialists, participate in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and Cassidy secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy and Marshburn during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009372 (27 July 2009) --- Astronauts Tom Marshburn (left) and Christopher Cassidy, both STS-127 mission specialists, participate in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and Cassidy secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

iss020e025085

NASA Image and Video Library

2009-07-27

ISS020-E-025085 (27 July 2009) --- Astronaut Christopher Cassidy, STS-127 mission specialist, participates in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Cassidy and astronaut Tom Marshburn (out of frame), mission specialist, secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of ?get ahead? tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009248 (27 July 2009) --- Astronaut Christopher Cassidy, STS-127 mission specialist, participates in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Cassidy and astronaut Tom Marshburn (out of frame), mission specialist, secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009347 (27 July 2009) --- Astronaut Christopher Cassidy, STS-127 mission specialist, participates in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Cassidy and astronaut Tom Marshburn (out of frame), mission specialist, secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Cassidy and Marshburn during EVA-5

NASA Image and Video Library

2009-07-27

S127-E-009371 (27 July 2009) --- Astronauts Tom Marshburn (left) and Christopher Cassidy, both STS-127 mission specialists, participate in the mission's fifth and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the four-hour, 54-minute spacewalk, Marshburn and Cassidy secured multi-layer insulation around the Special Purpose Dexterous Manipulator known as Dextre, split out power channels for two space station Control Moment Gyroscopes, installed video cameras on the front and back of the new Japanese Exposed Facility and performed a number of “get ahead” tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.

Design of the Coordinate Transformation Function for Cylindrical Acoustic Cloaks with a Quantity of Discrete Layers

NASA Astrophysics Data System (ADS)

Cai, Li; Wen, Ji-Hong; Yu, Dian-Long; Lu, Zhi-Miao; Wen, Xi-Sen

2014-09-01

Acoustic cloak based on coordinate transformation is of great topical interest and has promise in potential applications such as sound transparency and insulation. The frequency response of acoustic cloaks with a quantity of discrete homogeneous layers is analyzed by the acoustic scattering theory. The effect of coordinate transformation function on the acoustic total scattering cross section is discussed to achieve low scattering with only a few layers of anisotropic metamaterials. Also, the physics of acoustic wave interaction with the interfaces between the discrete layers inside the cloak shell is discussed. These results provide a better way of designing a multilayered acoustic cloak with fewer layers.

Analysis of selected materials flown on interior locations of the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

Smith, H. A.; Nelson, K. M.; Eash, D.; Pippin, H. G.

1994-01-01

This report documents the post-flight condition of selected hardware taken from interior locations on the Long Duration Exposure Facility (LDEF). This hardware was generally in excellent condition. Outgassing data is presented for heat shrink tubing and fiberglass composite shims. Variation in total mass loss (TML) values for heat shrink tubing were correlated with location. Nylon grommets were evaluated for mechanical integrity; slight embrittlement was observed for flight specimens. Multi-layer insulation blankets, wire bundles, and paints in non-exposed interior locations were all in visibly good condition. Silicon-containing contaminant films were observed on silver-coated hex nuts at the space- and Earth-end interior locations.

Wide gap Chern Mott insulating phases achieved by design

NASA Astrophysics Data System (ADS)

Guo, Hongli; Gangopadhyay, Shruba; Koeksal, Okan; Pentcheva, Rossitza; Pickett, Warren E.

Chern insulators are exciting both as a novel electronic phase and for their novel and potentially useful boundary transport properties. Honeycomb lattices occupied by heavy transition metal ions,have been proposed by Okamoto and coworkers as Chern insulators, but finding a concrete example has been challenging due to an assortment of broken symmetry phases that thwart the topological character. Building on accumulated knowledge of the behavior of the 3 d series, we tune spin-orbit and interaction strength together with strain to design two Chern insulator systems (one with Ru, one with Os) with bandgaps up to 130 meV and Chern numbers calC = - 1 and calC = 2 . We find, in this class, that a trade-off between larger spin-orbit coupling and strong interactions leads to a larger gap, whereas the stronger SOC correlates with the larger magnitude of the Hall conductivity. Symmetry lowering in the course of structural relaxation hampers retaining QAH character, as pointed out previously. Fortunately there is only mild structural symmetry breaking of the bilayer in these robust Chern phases.Recent (111) growth of insulating, magnetic phases in closely related materials with this orientation supports the likelihood that synthesis and exploitation will follow. Supported partially by the NSF DMREF program.

Tailoring Materials for Mottronics: Excess Oxygen Doping of a Prototypical Mott Insulator.

PubMed

Scheiderer, Philipp; Schmitt, Matthias; Gabel, Judith; Zapf, Michael; Stübinger, Martin; Schütz, Philipp; Dudy, Lenart; Schlueter, Christoph; Lee, Tien-Lin; Sing, Michael; Claessen, Ralph

2018-05-07

The Mott transistor is a paradigm for a new class of electronic devices-often referred to by the term Mottronics-which are based on charge correlations between the electrons. Since correlation-induced insulating phases of most oxide compounds are usually very robust, new methods have to be developed to push such materials right to the boundary to the metallic phase in order to enable the metal-insulator transition to be switched by electric gating. Here, it is demonstrated that thin films of the prototypical Mott insulator LaTiO 3 grown by pulsed laser deposition under oxygen atmosphere are readily tuned by excess oxygen doping across the line of the band-filling controlled Mott transition in the electronic phase diagram. The detected insulator to metal transition is characterized by a strong change in resistivity of several orders of magnitude. The use of suitable substrates and capping layers to inhibit oxygen diffusion facilitates full control of the oxygen content and renders the films stable against exposure to ambient conditions. These achievements represent a significant advancement in control and tuning of the electronic properties of LaTiO 3+ x thin films making it a promising channel material in future Mottronic devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultra High Voltage Propellant Isolators and Insulators for JIMO Ion Thrusters

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Gaier, James R.; Hung, Ching-Cheh; Walters, Patty A.; Sechkar, Ed; Panko, Scott; Kamiotis, Christina A.

2004-01-01

Within NASA's Project Prometheus, high specific impulse ion thrusters for electric propulsion of spacecraft for the proposed Jupiter Icy Moon Orbiter (JIMO) mission to three of Jupiter's moons: Callisto, Ganymede and Europa will require high voltage operation to meet mission propulsion. The anticipated approx.6,500 volt net ion energy will require electrical insulation and propellant isolation which must exceed that used successfully by the NASA Solar Electric Propulsion Technology Readiness (NSTAR) Deep Space 1 mission thruster by a factor of approx.6. Xenon propellant isolator prototypes that operate at near one atmosphere and prototypes that operate at low pressures (<100 Torr) have been designed and are being tested for suitability to the JIMO mission requirements. Propellant isolators must be durable to Paschen breakdown, sputter contamination, high temperature, and high voltage while operating for factors longer duration than for the Deep Space 1 Mission. Insulators used to mount the thrusters as well as those needed to support the ion optics have also been designed and are under evaluation. Isolator and insulator concepts, design issues, design guidelines, fabrication considerations and performance issues are presented. The objective of the investigation was to identify candidate isolators and insulators that are sufficiently robust to perform durably and reliably during the proposed JIMO mission.

A study on metallic thermal protection system panel for Reusable Launch Vehicle

NASA Astrophysics Data System (ADS)

Caogen, Yao; Hongjun, Lü; Zhonghua, Jia; Xinchao, Jia; Yan, Lu; Haigang, Li

2008-07-01

A Ni-based superalloy honeycomb thermal protection system (TPS) panel has been fabricated. And a curved Ni-based superalloy honeycomb sandwich has also been fabricated. The preliminary thermal insulation results of a fabricated Ni-based superalloy honeycomb TPS panel (the areal density of this panel is 6.7 kg /m2 and total height is 32 mm) indicate that the maximum temperature of the lower surfaces of the panel is lower than 150∘ C when the temperature of outer surface is held at 650∘ C for 30 min. The flatwise tensile strength and compressive properties of a fabricated Ni-based superalloy honeycomb sandwich coupon was studied at room temperature. A multilayered coating has been developed on the surface of the superalloy honeycomb TPS panel for environmental protection and thermal control. The oxidation weight-change results show that the weight change of the Ni-based superalloy honeycomb sandwich with the oxidation resistant coating is extremely small at 1100∘ C in air for 10 h. The emittance layer of the multilayered coating imparts an emittance in excess of 0.85 during exposure at 850∘ C, which was at least 14% greater than that of the substrate with oxidation resistant alone.

Implosion of multilayered cylindrical targets driven by intense heavy ion beams.

PubMed

Piriz, A R; Portugues, R F; Tahir, N A; Hoffmann, D H H

2002-11-01

An analytical model for the implosion of a multilayered cylindrical target driven by an intense heavy ion beam has been developed. The target is composed of a cylinder of frozen hydrogen or deuterium, which is enclosed in a thick shell of solid lead. This target has been designed for future high-energy-density matter experiments to be carried out at the Gesellschaft für Schwerionenforschung, Darmstadt. The model describes the implosion dynamics including the motion of the incident shock and the first reflected shock and allows for calculation of the physical conditions of the hydrogen at stagnation. The model predicts that the conditions of the compressed hydrogen are not sensitive to significant variations in target and beam parameters. These predictions are confirmed by one-dimensional numerical simulations and thus allow for a robust target design.

High- T c superconductivity at the interface between the CaCuO 2 and SrTiO 3 insulating oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Di Castro, D.; Cantoni, C.; Ridolfi, F.

2015-09-28

At interfaces between complex oxides it is possible to generate electronic systems with unusual electronic properties, which are not present in the isolated oxides. One important example is the appearance of superconductivity at the interface between insulating oxides, although, until now, with very low T c. We report the occurrence of high T c superconductivity in the bilayer CaCuO 2/SrTiO 3, where both the constituent oxides are insulating. In order to obtain a superconducting state, the CaCuO 2/SrTiO 3 interface must be realized between the Ca plane of CaCuO 2 and the TiO 2 plane of SrTiO 3. Only inmore » this case can oxygen ions be incorporated in the interface Ca plane, acting as apical oxygen for Cu and providing holes to the CuO 2 planes. In addition, a detailed hole doping spatial profile can be obtained by scanning transmission electron microscopy and electron-energy-loss spectroscopy at the O K edge, clearly showing that the (super)conductivity is confined to about 1–2 CaCuO 2 unit cells close to the interface with SrTiO 3. The results obtained for the CaCuO 2/SrTiO 3 interface can be extended to multilayered high T c cuprates, contributing to explaining the dependence of T c on the number of CuO 2 planes in these systems.« less

Density matrix renormalization group study of a three-orbital Hubbard model with spin-orbit coupling in one dimension

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaushal, Nitin; Herbrych, Jacek W.; Nocera, Alberto

Using the density matrix renormalization group technique we study the effect of spin-orbit coupling on a three-orbital Hubbard model in the (t 2g) 4 sector and in one dimension. Fixing the Hund coupling to a robust value compatible with some multiorbital materials, we present the phase diagram varying the Hubbard U and spin-orbit coupling λ, at zero temperature. Our results are shown to be qualitatively similar to those recently reported using the dynamical mean-field theory in higher dimensions, providing a robust basis to approximate many-body techniques. Among many results, we observe an interesting transition from an orbital-selective Mott phase tomore » an excitonic insulator with increasing λ at intermediate U. In the strong U coupling limit, we find a nonmagnetic insulator with an effective angular momentum <(J eff) 2>≠0 near the excitonic phase, smoothly connected to the <(J eff) 2>=0 regime. In conclusion, we also provide a list of quasi-one-dimensional materials where the physics discussed in this paper could be realized.« less

Density matrix renormalization group study of a three-orbital Hubbard model with spin-orbit coupling in one dimension

NASA Astrophysics Data System (ADS)

Kaushal, Nitin; Herbrych, Jacek; Nocera, Alberto; Alvarez, Gonzalo; Moreo, Adriana; Reboredo, F. A.; Dagotto, Elbio

2017-10-01

Using the density matrix renormalization group technique we study the effect of spin-orbit coupling on a three-orbital Hubbard model in the (t2g) 4 sector and in one dimension. Fixing the Hund coupling to a robust value compatible with some multiorbital materials, we present the phase diagram varying the Hubbard U and spin-orbit coupling λ , at zero temperature. Our results are shown to be qualitatively similar to those recently reported using the dynamical mean-field theory in higher dimensions, providing a robust basis to approximate many-body techniques. Among many results, we observe an interesting transition from an orbital-selective Mott phase to an excitonic insulator with increasing λ at intermediate U . In the strong U coupling limit, we find a nonmagnetic insulator with an effective angular momentum 〈(Jeff)2〉≠0 near the excitonic phase, smoothly connected to the 〈(Jeff)2〉=0 regime. We also provide a list of quasi-one-dimensional materials where the physics discussed in this paper could be realized.

Density matrix renormalization group study of a three-orbital Hubbard model with spin-orbit coupling in one dimension

DOE PAGES

Kaushal, Nitin; Herbrych, Jacek W.; Nocera, Alberto; ...

2017-10-09

Using the density matrix renormalization group technique we study the effect of spin-orbit coupling on a three-orbital Hubbard model in the (t 2g) 4 sector and in one dimension. Fixing the Hund coupling to a robust value compatible with some multiorbital materials, we present the phase diagram varying the Hubbard U and spin-orbit coupling λ, at zero temperature. Our results are shown to be qualitatively similar to those recently reported using the dynamical mean-field theory in higher dimensions, providing a robust basis to approximate many-body techniques. Among many results, we observe an interesting transition from an orbital-selective Mott phase tomore » an excitonic insulator with increasing λ at intermediate U. In the strong U coupling limit, we find a nonmagnetic insulator with an effective angular momentum <(J eff) 2>≠0 near the excitonic phase, smoothly connected to the <(J eff) 2>=0 regime. In conclusion, we also provide a list of quasi-one-dimensional materials where the physics discussed in this paper could be realized.« less

Electrical transport measurements of thin film samples under high hydrostatic pressure

NASA Astrophysics Data System (ADS)

Zabaleta, J.; Parks, S. C.; Baum, B.; Teker, A.; Syassen, K.; Mannhart, J.

2017-03-01

We present a method to perform electrical measurements of epitaxial films and heterostructures a few nanometers thick under high hydrostatic pressures in a diamond anvil cell (DAC). Hydrostatic pressure offers the possibility to tune the rich landscape of properties shown by epitaxial heterostructures, systems in which the combination of different materials, performed with atomic precision, can give rise to properties not present in their individual constituents. Measuring electrical conductivity under hydrostatic pressure in these systems requires a robust method that can address all the challenges: the preparation of the sample with side length and thickness that fits in the DAC setup, a contacting method compatible with liquid media, a gasket insulation that resists high forces, as well as an accurate procedure to place the sample in the pressure chamber. We prove the robustness of the method described by measuring the resistance of a two dimensional electron system buried at the interface between two insulating oxides under hydrostatic conditions up to ˜5 GPa. The setup remains intact until ˜10 GPa, where large pressure gradients affect the two dimensional conductivity.

Electrical transport measurements of thin film samples under high hydrostatic pressure.

PubMed

Zabaleta, J; Parks, S C; Baum, B; Teker, A; Syassen, K; Mannhart, J

2017-03-01

We present a method to perform electrical measurements of epitaxial films and heterostructures a few nanometers thick under high hydrostatic pressures in a diamond anvil cell (DAC). Hydrostatic pressure offers the possibility to tune the rich landscape of properties shown by epitaxial heterostructures, systems in which the combination of different materials, performed with atomic precision, can give rise to properties not present in their individual constituents. Measuring electrical conductivity under hydrostatic pressure in these systems requires a robust method that can address all the challenges: the preparation of the sample with side length and thickness that fits in the DAC setup, a contacting method compatible with liquid media, a gasket insulation that resists high forces, as well as an accurate procedure to place the sample in the pressure chamber. We prove the robustness of the method described by measuring the resistance of a two dimensional electron system buried at the interface between two insulating oxides under hydrostatic conditions up to ∼5 GPa. The setup remains intact until ∼10 GPa, where large pressure gradients affect the two dimensional conductivity.

Depth profiling of mechanical degradation of PV backsheets after UV exposure

NASA Astrophysics Data System (ADS)

Gu, Xiaohong; Krommenhoek, Peter J.; Lin, Chiao-Chi; Yu, Li-Chieh; Nguyen, Tinh; Watson, Stephanie S.

2015-09-01

Polymeric multilayer backsheets protect the photovoltaic modules from damage of moisture and ultraviolet (UV) while providing electrical insulation. Due to the multilayer structures, the properties of the inner layers of the backsheets, including their interfaces, during weathering are not well known. In this study, a commercial type of PPE (polyethylene terephthalate (PET)/PET/ethylene vinyl acetate (EVA)) backsheet films was selected as a model system for a depth profiling study of mechanical properties of a backsheet film during UV exposure. The NIST SPHERE (Simulated Photodegradation via High Energy Radiant Exposure) was used for the accelerated laboratory exposure of the materials with UV at 85°C and two relative humidities (RH) of 5 % (dry) and 60 % (humid). Cryomicrotomy was used to obtain cross-sectional PPE samples. Mechanical depth profiling of the cross-sections of aged and unaged samples was conducted by nanoindentation, and a peak-force based quantitative nanomechanical atomic force microscopy (QNM-AFM) mapping techniquewas used to investigate the microstructure and adhesion properties of the adhesive tie layers. The nanoindentation results show the stiffening of the elastic modulus in the PET outer and pigmented EVA layers. From QNM-AFM, the microstructures and adhesion properties of the adhesive layers between PET outer and core layers and between PET core and EVA inner layers are revealed and found to degrade significantly after aging under humidity environment. The results from mechanical depth profiling of the PPE backsheet are further related to the previous chemical depth profiling of the same material, providing new insights into the effects of accelerated UV and humidity on the degradation of multilayer backsheet.

Laser engineered multilayer coating of biphasic calcium phosphate/titanium nanocomposite on metal substrates.

PubMed

Zhang, Martin Yi; Ye, Chang; Erasquin, Uriel Joseph; Huynh, Toan; Cai, Chengzhi; Cheng, Gary J

2011-02-01

In this work, laser coating of biphasic calcium phosphate/titanium (BCP/Ti) nanocomposite on Ti-6Al-4 V substrates was developed. A continuous wave neodymium-doped yttrium aluminium garnet (Nd:YAG) laser was used to form a robust multilayer of BCP/Ti nanocomposite starting from hydroxyapatite and titanium nanoparticles. In this process, low power coating is realized because of the strong laser-nanoparticle interaction and good sinterability of nanosized titanium. To guide the optimization of laser processing conditions for the coating process, a multiphysics model coupling electromagnetic module with heat transfer module was developed. This model was validated by laser coating experiments. Important features of the coated samples, including microstructures, chemical compositions, and interfacial bonding strength, were characterized. We found that a multilayer of BCP, consisting of 72% hydroxyapatite (HA) and 28% beta-tricalcium phosphate (β-TCP), and titanium nanocomposite was formed on Ti-6Al-4 V substrates. Significantly, the coating/substrate interfacial bonding strength was found to be two times higher than that of the commercial plasma sprayed coatings. Preliminary cell culture studies showed that the resultant BCP/Ti nanocomposite coating supported the adhesion and proliferation of osteoblast-like UMR-106 cells.

Micro-Vibration Measurements on Thermally Loaded Multi-Layer Insulation Samples in Vacuum

NASA Technical Reports Server (NTRS)

Deutsch, Georg; Grillenbeck, Anton

2008-01-01

Some scientific missions require to an extreme extent the absence of any on-board microvibration. Recent projects dedicated to measuring the Earth's gravity field and modeling the geoid with extremely high accuracy are examples. Their missions demand for extremely low micro-vibration environment on orbit for: (1) Not disturbing the measurement of earth gravity effects with the installed gradiometer or (2) Even not damaging the very high sensitive instruments. Based on evidence from ongoing missions multi-layer insulation (MLI) type thermal control blankets have been identified as a structural element of spacecrafts which might deform under temperature variations being caused by varying solar irradiation in orbit. Any such deformation exerts tiny forces which may cause small reactions resulting in micro-vibrations, in particular by exciting the spacecraft eigenmodes. The principle of the test set-up for the micro-vibration test was as follows. A real side wall panel of the spacecraft (size about 0.25 m2) was low-frequency suspended in a thermal vacuum chamber. On the one side of this panel, the MLI samples were fixed by using the standard methods. In front of the MLI, an IR-rig was installed which provided actively controlled IR-radiation power of about 6 kW/m2 in order to heat the MLI surface. The cooling was passive using the shroud temperature at a chamber pressure <1E-5mbar. The resulting micro-vibrations due to MLI motion in the heating and the cooling phase were measured via seismic accelerometers which were rigidly mounted to the panel. Video recording was used to correlate micro-vibration events to any visual MLI motion. Different MLI sample types were subjected to various thermal cycles in a temperature range between -60 C to +80 C. In this paper, the experience on these micro-vibration measurements will be presented and the conclusions for future applications will be discussed

Macroscopic Quantum Tunneling in Superconducting Junctions of β-Ag2Se Topological Insulator Nanowire.

PubMed

Kim, Jihwan; Kim, Bum-Kyu; Kim, Hong-Seok; Hwang, Ahreum; Kim, Bongsoo; Doh, Yong-Joo

2017-11-08

We report on the fabrication and electrical transport properties of superconducting junctions made of β-Ag 2 Se topological insulator (TI) nanowires in contact with Al superconducting electrodes. The temperature dependence of the critical current indicates that the superconducting junction belongs to a short and diffusive junction regime. As a characteristic feature of the narrow junction, the critical current decreases monotonously with increasing magnetic field. The stochastic distribution of the switching current exhibits the macroscopic quantum tunneling behavior, which is robust up to T = 0.8 K. Our observations indicate that the TI nanowire-based Josephson junctions can be a promising building block for the development of nanohybrid superconducting quantum bits.

Topological crystalline magnets: Symmetry-protected topological phases of fermions

DOE PAGES

Watanabe, Haruki; Fu, Liang

2017-02-27

Here, we introduce a novel class of interaction-enabled topological crystalline insulators in two- and three-dimensional electronic systems, which we call “topological crystalline magnet.” It is protected by the product of the time-reversal symmetry T and a mirror symmetry or a rotation symmetry R. A topological crystalline magnet exhibits two intriguing features: (i) it cannot be adiabatically connected to any Slater insulator and (ii) the edge state is robust against coupling electrons to the edge. These features are protected by the anomalous symmetry transformation property ( RT) 2 = -1 of the edge state. Finally, an anisotropic response to the externalmore » magnetic field can be an experimental signature.« less

Topological crystalline magnets: Symmetry-protected topological phases of fermions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watanabe, Haruki; Fu, Liang

Here, we introduce a novel class of interaction-enabled topological crystalline insulators in two- and three-dimensional electronic systems, which we call “topological crystalline magnet.” It is protected by the product of the time-reversal symmetry T and a mirror symmetry or a rotation symmetry R. A topological crystalline magnet exhibits two intriguing features: (i) it cannot be adiabatically connected to any Slater insulator and (ii) the edge state is robust against coupling electrons to the edge. These features are protected by the anomalous symmetry transformation property ( RT) 2 = -1 of the edge state. Finally, an anisotropic response to the externalmore » magnetic field can be an experimental signature.« less

Lieb polariton topological insulators

NASA Astrophysics Data System (ADS)

Li, Chunyan; Ye, Fangwei; Chen, Xianfeng; Kartashov, Yaroslav V.; Ferrando, Albert; Torner, Lluis; Skryabin, Dmitry V.

2018-02-01

We predict that the interplay between the spin-orbit coupling, stemming from the transverse electric-transverse magnetic energy splitting, and the Zeeman effect in semiconductor microcavities supporting exciton-polariton quasiparticles, results in the appearance of unidirectional linear topological edge states when the top microcavity mirror is patterned to form a truncated dislocated Lieb lattice of cylindrical pillars. Periodic nonlinear edge states are found to emerge from the linear ones. They are strongly localized across the interface and they are remarkably robust in comparison to their counterparts in honeycomb lattices. Such robustness makes possible the existence of nested unidirectional dark solitons that move steadily along the lattice edge.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smylie, M. P.; Willa, K.; Claus, H.

We present resistivity and magnetization measurements on proton-irradiated crystals demonstrating that the superconducting state in the doped topological insulator Nb xBi 2Se 3 (x = 0.25) is surprisingly robust against disorder-induced electron scattering. The superconducting transition temperature Tc decreases without indication of saturation with increasing defect concentration, and the corresponding scattering rates far surpass expectations based on conventional theory. The low-temperature variation of the London penetration depth Δλ(T) follows a power law [Δλ(T)~T 2] indicating the presence of symmetry-protected point nodes. Lastly, our results are consistent with the proposed robust nematic E u pairing state in this material.

Aerogel Insulation Applications for Liquid Hydrogen Launch Vehicle Tanks

NASA Technical Reports Server (NTRS)

Fesmire, J. E.; Sass, J.

2007-01-01

Aerogel based insulation systems for ambient pressure environments were developed for liquid hydrogen (LH2) tank applications. Solutions to thermal insulation problems were demonstrated for the Space Shuttle External Tank (ET) through extensive testing at the Cryogenics Test Laboratory. Demonstration testing was performed using a 1/10th scale ET LH2 intertank unit and liquid helium as the coolant to provide the 20 K cold boundary temperature. Cryopumping tests in the range of 20K were performed using both constant mass and constant pressure methods. Long-duration tests (up to 10 hours) showed that the nitrogen mass taken up inside the intertank is reduced by a factor of nearly three for the aerogel insulated case as compared to the un-insulated (bare metal flight configuration) case. Test results including thermal stabilization, heat transfer effectiveness, and cryopumping confirm that the aerogel system eliminates free liquid nitrogen within the intertank. Physisorption (or adsorption) of liquid nitrogen within the fine pore structure of aerogel materials was also investigated. Results of a mass uptake method show that the sorption ratio (liquid nitrogen to aerogel beads) is about 62 percent by volume. A novel liquid nitrogen production method of testing the liquid nitrogen physical adsorption capacity of aerogel beads was also performed to more closely approximate the actual launch vehicle cooldown and thermal stabilization effects within the aerogel material. The extraordinary insulating effectiveness of the aerogel material shows that cryopumping is not an open-cell mass transport issue but is strictly driven by thermal communication between warm and cold surfaces. The new aerogel insulation technology is useful to solve heat transfer problem areas and to augment existing thermal protection systems on launch vehicles. Examples are given and potential benefits for producing launch systems that are more reliable, robust, reusable, and efficient are outlined.

In-Situ Wire Damage Detection System

NASA Technical Reports Server (NTRS)

Williams, Martha; Roberson, Luke; Tate, Lanetra; Smith, Trent; Gibson, Tracy; Medelius, Pedro; Jolley, Scott

2012-01-01

An In-Situ Wire Damage Detection System (ISWDDS) has been developed that is capable of detecting damage to a wire insulation, or a wire conductor, or to both. The system will allow for realtime, continuous monitoring of wiring health/integrity and reduce the number of false negatives and false positives while being smaller, lighter in weight, and more robust than current systems. The technology allows for improved safety and significant reduction in maintenance hours for aircraft, space vehicles, satellites, and other critical high-performance wiring systems for industries such as energy production and mining. The integrated ISWDDS is comprised of two main components: (1) a wire with an innermost core conductor, an inner insulation film, a conductive layer or inherently conductive polymer (ICP) covering the inner insulation film, an outermost insulation jacket; and (2) smart connectors and electronics capable of producing and detecting electronic signals, and a central processing unit (CPU) for data collection and analysis. The wire is constructed by applying the inner insulation films to the conductor, followed by the outer insulation jacket. The conductive layer or ICP is on the outer surface of the inner insulation film. One or more wires are connected to the CPU using the smart connectors, and up to 64 wires can be monitored in real-time. The ISWDDS uses time domain reflectometry for damage detection. A fast-risetime pulse is injected into either the core conductor or conductive layer and referenced against the other conductor, producing transmission line behavior. If either conductor is damaged, then the signal is reflected. By knowing the speed of propagation of the pulse, and the time it takes to reflect, one can calculate the distance to and location of the damage.

IUS materials outgassing condensation effects on sensitive spacecraft surfaces

NASA Technical Reports Server (NTRS)

Mullen, C. R.; Shaw, C. G.; Crutcher, E. R.

1982-01-01

Four materials used on the inertial upper state (IUS) were subjected to vacuum conditions and heated to near-operational temperatures (93 to 316 C), releasing volatile materials. A fraction of the volatile materials were collected on 25 C solar cells, optical solar reflectors (OSR's) or aluminized Mylar. The contaminated surfaces were exposed to 26 equivalent sun hours of simulated solar ultraviolet (UV) radiation. Measurements of contamination deposit mass, structure, reflectance and effects on solar cell power output were made before and after UV irradiation. Standard total mass loss - volatile condensible materials (TML - VCM) tests were also performed. A 2500 A thick contaminant layer produced by EPDM rubber motor-case insulation outgassing increased the solar absorptance of the OSR's from 0.07 to 0.14, and to 0.18 after UV exposure. An 83,000 A layer caused an increase from 0.07 to 0.21, and then the 0.46 after UV exposure. The Kevlar-epoxy motor-case material outgassing condensation raised the absorptance from 0.07 to 0.13, but UV had no effect. Outgassing from multilayer insulation and carbon-carbon nozzle materials did not affect the solar absorptance of the OSR's.

Glass-mica composite: a new structural thermal-insulating material for building applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Low, N.M.P.

1981-12-01

Homogeneous, rigid glass-mica composites have been synthesized from mixtures of Canadian natural mica flakes of the phlogopite type and ground glass powders prepared from recycled soda-lime waste glasses by a simple sintering process. By means of selection of compositions and processing techniques, composites can be fabricated into products that exhibit a celular structure, a highly densified structure, and multilayer and sandwich structures. The cellular structure composite has a thermal conductivity in the range of 0.165 to 0.230 W/m /sup 0/C when measured over the temperature range 25 to 180/sup 0/C, and a compressive strength of about 0.874 MPa; the highlymore » densified composite, on the other hand, has a thermal conductivity in the range of 0.155 to 0.330 W/m /sup 0/C, a compressive strength in excess of 40 MPa, and an instantaneous coefficient of thermal expansion of 5.8 X 10/sup -6///sup 0/C at 100/sup 0/C. These glass-mica composites exhibit qualities such as insulating efficiency, safety, mechanical strength, and durability that are suitable for engineering applications in building structures or other systems.« less

Thermal performance of a customized multilayer insulation (MLI)

NASA Technical Reports Server (NTRS)

Leonhard, K. E.

1976-01-01

The thermal performance of a LH2 tank on a shroudless vehicle was investigated. The 1.52 m (60 in) tank was insulated with 2 MLI blankets consisting of 18 double aluminized Mylar radiation shields and 19 silk net spacers. The temperature of outer space was simulated by using a cryoshroud which was maintained at near liquid hydrogen temperature. The heating effects of a payload were simulated by utilizing a thermal payload simulator (TPS) viewing the tank. The test program consisted of three major test categories: (1) null testing, (2) thermal performance testing of the tank installed MLI system, and (3) thermal testing of a customized MLI configuration. TPS surface temperatures during the null test were maintained at near hydrogen temperature and during test categories 2 and 3 at 289 K (520R). The heat flow rate through the tank installed MLI at a tank/TPS spacing of 0.457 m was 1.204 watts with no MLI on the TPS and 0.059 watts through the customized MLI with three blankets on the TPS. Reducing the tank/TPS spacing from 0.457 m to 0.152 m the heat flow through the customized MLI increased by 10 percent.

Wider-Opening Dewar Flasks for Cryogenic Storage

NASA Technical Reports Server (NTRS)

Ruemmele, Warren P.; Manry, John; Stafford, Kristin; Bue, Grant; Krejci, John; Evernden, Bent

2010-01-01

Dewar flasks have been proposed as containers for relatively long-term (25 days) storage of perishable scientific samples or other perishable objects at a temperature of 175 C. The refrigeration would be maintained through slow boiling of liquid nitrogen (LN2). For the purposes of the application for which these containers were proposed, (1) the neck openings of commercial off-the-shelf (COTS) Dewar flasks are too small for most NASA samples; (2) the round shapes of the COTS containers give rise to unacceptably low efficiency of packing in rectangular cargo compartments; and (3) the COTS containers include metal structures that are too thermally conductive, such that they cannot, without exceeding size and weight limits, hold enough LN2 for the required long-term-storage. In comparison with COTS Dewar flasks, the proposed containers would be rectangular, yet would satisfy the long-term storage requirement without exceeding size and weight limits; would have larger neck openings; and would have greater sample volumes, leading to a packing efficiency of about double the sample volume as a fraction of total volume. The proposed containers would be made partly of aerospace- type composite materials and would include vacuum walls, multilayer insulation, and aerogel insulation.

All-Aluminum Thin Film Transistor Fabrication at Room Temperature

PubMed Central

Yao, Rihui; Zheng, Zeke; Zeng, Yong; Liu, Xianzhe; Ning, Honglong; Hu, Shiben; Tao, Ruiqiang; Chen, Jianqiu; Cai, Wei; Xu, Miao; Wang, Lei; Lan, Linfeng; Peng, Junbiao

2017-01-01

Bottom-gate all-aluminum thin film transistors with multi conductor/insulator nanometer heterojunction were investigated in this article. Alumina (Al2O3) insulating layer was deposited on the surface of aluminum doping zinc oxide (AZO) conductive layer, as one AZO/Al2O3 heterojunction unit. The measurements of transmittance electronic microscopy (TEM) and X-ray reflectivity (XRR) revealed the smooth interfaces between ~2.2-nm-thick Al2O3 layers and ~2.7-nm-thick AZO layers. The devices were entirely composited by aluminiferous materials, that is, their gate and source/drain electrodes were respectively fabricated by aluminum neodymium alloy (Al:Nd) and pure Al, with Al2O3/AZO multilayered channel and AlOx:Nd gate dielectric layer. As a result, the all-aluminum TFT with two Al2O3/AZO heterojunction units exhibited a mobility of 2.47 cm2/V·s and an Ion/Ioff ratio of 106. All processes were carried out at room temperature, which created new possibilities for green displays industry by allowing for the devices fabricated on plastic-like substrates or papers, mainly using no toxic/rare materials. PMID:28772579

Superconducting Cable Termination

DOEpatents

Sinha, Uday K.; Tolbert, Jerry

2005-08-30

Disclosed is a termination that connects high temperature superconducting (HTS) cable immersed in pressurized liquid nitrogen to high voltage and neutral (shield) external bushings at ambient temperature and pressure. The termination consists of a splice between the HTS power (inner) and shield (outer) conductors and concentric copper pipes which are the conductors in the termination. There is also a transition from the dielectric tape insulator used in the HTS cable to the insulators used between and around the copper pipe conductors in the termination. At the warm end of the termination the copper pipes are connected via copper braided straps to the conventional warm external bushings which have low thermal stresses. This termination allows for a natural temperature gradient in the copper pipe conductors inside the termination which enables the controlled flashing of the pressurized liquid coolant (nitrogen) to the gaseous state. Thus the entire termination is near the coolant supply pressure and the high voltage and shield cold bushings, a highly stressed component used in most HTS cables, are eliminated. A sliding seal allows for cable contraction as it is cooled from room temperature to ˜72-82 K. Seals, static vacuum, and multi-layer superinsulation minimize radial heat leak to the environment.

Simulated Solar Flare X-Ray and Thermal Cycling Durability Evaluation of Hubble Space Telescope Thermal Control Candidate Replacement Materials

NASA Technical Reports Server (NTRS)

deGroh, Kim K.; Banks, Bruce A.; Sechkar, Edward A.; Scheiman, David A.

1998-01-01

During the Hubble Space Telescope (HST) second servicing mission (SM2), astronauts noticed that the multilayer insulation (MLI) covering the telescope was damaged. Large pieces of the outer layer of MLI (aluminized Teflon fluorinated ethylene propylene (Al-FEP)) were torn in several locations around the telescope. A piece of curled up Al-FEP was retrieved by the astronauts and was found to be severely embrittled, as witnessed by ground testing. Goddard Space Flight Center (GSFC) organized a HST MLI Failure Review Board (FRB) to determine the damage mechanism of FEP in the HST environment, and to recommend replacement insulation material to be installed on HST during the third servicing mission (SM3) in 1999. Candidate thermal control replacement materials were chosen by the FRB and tested for environmental durability under various exposures and durations. This paper describes durability testing of candidate materials which were exposed to charged particle radiation, simulated solar flare x-ray radiation and thermal cycling under load. Samples were evaluated for changes in solar absorptance and tear resistance. Descriptions of environmental exposures and durability evaluations of these materials are presented.

Self-consistent performance modeling for dual band MIS UV photodetectors based on Si/SiO2 multilayer structure.

PubMed

Rostami, A; Leilaeioun, M; Golmmohamadi, S; Rasooli Saghai, H

2012-06-01

In this paper, we present a self-consistent theoretical model for a metal-insulator semiconductor (MIS) dual band ultraviolet (UV) photodetector with a modified structure implying an arbitrarily defined insulating potential barrier as its active region. Utilizing our proposed model, the dark and photocurrent density-voltage (J-V) characteristics of MIS UV photodetectors with multi-quantum wells of silicon (MQWs) are calculated. We demonstrate that dark current is reduced in the suggested structure, because the electron-tunneling probability becomes unity at energies coincident with the peak detection wavelength. This is due to the resonant tunneling and decreases at energies that are significantly smaller than this optimum value. In consequence, the number of carriers contributing to the dark current, which have a broad energy distribution at high temperatures, will decrease. It is also shown that the designed structure could detect two individual UV wavelengths, simultaneously. The width of each Si quantum well has been considered at around 1.2 nm, in order to observe these two absorption peaks in the middle and near UV regions of photon spectrum (about 365 nm, 175 nm).

Final Design and Experimental Validation of the Thermal Performance of the LHC Lattice Cryostats

NASA Astrophysics Data System (ADS)

Bourcey, N.; Capatina, O.; Parma, V.; Poncet, A.; Rohmig, P.; Serio, L.; Skoczen, B.; Tock, J.-P.; Williams, L. R.

2004-06-01

The recent commissioning and operation of the LHC String 2 have given a first experimental validation of the global thermal performance of the LHC lattice cryostat at nominal cryogenic conditions. The cryostat designed to minimize the heat inleak from ambient temperature, houses under vacuum and thermally protects the cold mass, which contains the LHC twin-aperture superconducting magnets operating at 1.9 K in superfluid helium. Mechanical components linking the cold mass to the vacuum vessel, such as support posts and insulation vacuum barriers are designed with efficient thermalisations for heat interception to minimise heat conduction. Heat inleak by radiation is reduced by employing multilayer insulation (MLI) wrapped around the cold mass and around an aluminium thermal shield cooled to about 60 K. Measurements of the total helium vaporization rate in String 2 gives, after substraction of supplementary heat loads and end effects, an estimate of the total thermal load to a standard LHC cell (107 m) including two Short Straight Sections and six dipole cryomagnets. Temperature sensors installed at critical locations provide a temperature mapping which allows validation of the calculated and estimated thermal performance of the cryostat components, including efficiency of the heat interceptions.

LHC interaction region quadrupole cryostat design

NASA Astrophysics Data System (ADS)

Nicol, T. H.; Darve, Ch.; Huang, Y.; Page, T. M.

2002-05-01

The cryostat of a Large Hadron Collider (LHC) Interaction Region (IR) quadrupole magnet consists of all components of the inner triplet except the magnet assembly itself. It serves to support the magnet accurately and reliably within the vacuum vessel, to house all required cryogenic piping, and to insulate the cold mass from heat radiated and conducted from the environment. It must function reliably during storage, shipping and handling, normal magnet operation, quenches, and seismic excitations, and must be able to be manufactured at low cost. The major components of the cryostat are the vacuum vessel, thermal shield, multi-layer insulation system, cryogenic piping, and suspension system. The overall design of a cryostat for superconducting accelerator magnets requires consideration of fluid flow, proper selection of materials for their thermal and structural performance at both ambient and operating temperature, and knowledge of the environment to which the magnets will be subjected over the course of their expected operating lifetime. This paper describes the current LHC IR inner triplet quadrupole magnet cryostats being designed and manufactured at Fermilab as part of the US-LHC collaboration, and includes discussions on the structural and thermal considerations involved in the development of each of the major systems.

Electromagnetic waves in a topological insulator thin film stack: helicon-like wave mode and photonic band structure.

PubMed

Inoue, Jun-ichi

2013-09-09

We theoretically explore the electromagnetic modes specific to a topological insulator superlattice in which topological and conventional insulator thin films are stacked periodically. In particular, we obtain analytic formulas for low energy mode that corresponds to a helicon wave, as well as those for photonic bands. We illustrate that the system can be modeled as a stack of quantum Hall layers whose conductivity tensors alternately change signs, and then we analyze the photonic band structures. This subject is a natural extension of a previous study by Tselis et al., which took into consideration a stack of identical quantum Hall layers but their discussion was limited into a low energy mode. Thus we provide analytic formulas for photonic bands and compare their features between the two systems. Our central findings in the topological insulator superlattice are that a low energy mode corresponding to a helicon wave has linear dispersion instead of the conventional quadratic form, and that a robust gapless photonic band appears although the system considered has spacial periodicity. In addition, we demonstrate that the photonic bands agree with the numerically calculated transmission spectra.

Fast and accurate metrology of multi-layered ceramic materials by an automated boundary detection algorithm developed for optical coherence tomography data

PubMed Central

Ekberg, Peter; Su, Rong; Chang, Ernest W.; Yun, Seok Hyun; Mattsson, Lars

2014-01-01

Optical coherence tomography (OCT) is useful for materials defect analysis and inspection with the additional possibility of quantitative dimensional metrology. Here, we present an automated image-processing algorithm for OCT analysis of roll-to-roll multilayers in 3D manufacturing of advanced ceramics. It has the advantage of avoiding filtering and preset modeling, and will, thus, introduce a simplification. The algorithm is validated for its capability of measuring the thickness of ceramic layers, extracting the boundaries of embedded features with irregular shapes, and detecting the geometric deformations. The accuracy of the algorithm is very high, and the reliability is better than 1 µm when evaluating with the OCT images using the same gauge block step height reference. The method may be suitable for industrial applications to the rapid inspection of manufactured samples with high accuracy and robustness. PMID:24562018