Development of improved pyroelectric detectors. Measurements of pyroelectric material characteristics and FET characteristics

NASA Technical Reports Server (NTRS)

Weiner, S.; Beerman, H. P.; Schwarz, F. C.

1990-01-01

Research was undertaken to improve the detectivity of the pyroelectric detector with the ultimate goal of operation at or near the temperature-noise limit. Two general areas of investigation were undertaken: (1) to improve responsivity through the use of new materials; and (2) to reduce noise through improved field effect transistor characteristics, and improved electroding of the pyroelectric material. FET's are being obtained from various manufacturers, evaulated, and selected units tested for evaluation of characteristics critical to their use as preamplifiers with pyroelectric detectors.

Pyroelectric response in crystalline hafnium zirconium oxide (Hf 1- x Zr x O 2 ) thin films

DOE PAGES

Smith, S. W.; Kitahara, A. R.; Rodriguez, M. A.; ...

2017-02-13

Pyroelectric coefficients were measured for 20 nm thick crystalline hafnium zirconium oxide (Hf 1-xZr xO 2) thin films across a composition range of 0 ≤ x ≤ 1. Pyroelectric currents were collected near room temperature under zero applied bias and a sinusoidal oscillating temperature profile to separate the influence of non-pyroelectric currents. The pyroelectric coefficient was observed to correlate with zirconium content, increased orthorhombic/tetragonal phase content, and maximum polarization response. The largest measured absolute value was 48 μCm -2K -1 for a composition with x = 0.64, while no pyroelectric response was measured for compositions which displayed no remanent polarizationmore » (x = 0, 0.91, 1).« less

Accounting for the various contributions to pyroelectricity in lead zirconate titanate thin films

NASA Astrophysics Data System (ADS)

Hanrahan, B.; Espinal, Y.; Neville, C.; Rudy, R.; Rivas, M.; Smith, A.; Kesim, M. T.; Alpay, S. P.

2018-03-01

An understanding of the pyroelectric coefficient and particularly its relationship with the applied electric field is critical to predicting the device performance for infrared imaging, energy harvesting, and solid-state cooling devices. In this work, we compare direct measurements of the pyroelectric effect under pulsed heating to the indirect extraction of the pyroelectric coefficient from adiabatic hysteresis loops and predictions from Landau-Devonshire theory for PbZr0.52Ti0.48O3 (PZT 52/48) on platinized silicon substrates. The differences between these measurements are explained through a series of careful measurements that quantify the magnitude and direction of the secondary and field-induced pyroelectric effects. The indirect measurement is shown to be up to 25% of the direct measurement at high fields, while the direct measurements and theoretical predictions converge at high fields as the film approaches a mono-domain state. These measurements highlight the importance of directly measuring the pyroelectric response in thin films, where non-intrinsic effects can be a significant proportion of the total observed pyroelectricity. Material and operating conditions are also discussed which could simultaneously maximize all contributions to pyroelectricity.

Modified lead titanate thin films for pyroelectric infrared detectors on gold electrodes

NASA Astrophysics Data System (ADS)

Ahmed, Moinuddin; Butler, Donald P.

2015-07-01

Pyroelectric infrared detectors provide the advantage of both a wide spectral response and dynamic range, which also has enabled systems to be developed with reduced size, weight and power consumption. This paper demonstrates the deposition of lead zirconium titanate (PZT) and lead calcium titanate (PCT) thin films for uncooled pyroelectric detectors with the utilization of gold electrodes. The modified lead titanate thin films were deposited by pulsed laser deposition on gold electrodes. The PZT and PCT thins films deposited and annealed at temperatures of 650 °C and 550 °C respectively demonstrated the best pyroelectric performance in this work. The thin films displayed a pyroelectric effect that increased with temperature. Poling of the thin films was carried out for a fixed time periods and fixed dc bias voltages at elevated temperature in order to increase the pyroelectric coefficient by establishing a spontaneous polarization of the thin films. Poling caused the pyroelectric current to increase one order of magnitude.

The Electronic Structure and Secondary Pyroelectric Properties of Lithium Tetraborate

PubMed Central

Adamiv, Volodymyr.T.; Burak, Yaroslav.V.; Wooten, David. J.; McClory, John; Petrosky, James; Ketsman, Ihor; Xiao, Jie; Losovyj, Yaroslav B.; Dowben, Peter A.

2010-01-01

We review the pyroelectric properties and electronic structure of Li2B4O7(110) and Li2B4O7(100) surfaces. There is evidence for a pyroelectric current along the [110] direction of stoichiometric Li2B4O7 so that the pyroelectric coefficient is nonzero but roughly 103 smaller than along the [001] direction of spontaneous polarization. Abrupt decreases in the pyroelectric coefficient along the [110] direction can be correlated with anomalies in the elastic stiffness C33D contributing to the concept that the pyroelectric coefficient is not simply a vector but has qualities of a tensor, as expected. The time dependent surface photovoltaic charging suggests that surface charging is dependent on crystal orientation and doping, as well as temperature. PMID:28883341

Temperature field analysis for PZT pyroelectric cells for thermal energy harvesting.

PubMed

Hsiao, Chun-Ching; Ciou, Jing-Chih; Siao, An-Shen; Lee, Chi-Yuan

2011-01-01

This paper proposes the idea of etching PZT to improve the temperature variation rate of a thicker PZT sheet in order to enhance the energy conversion efficiency when used as pyroelectric cells. A partially covered electrode was proven to display a higher output response than a fully covered electrode did. A mesh top electrode monitored the temperature variation rate and the electrode area. The mesh electrode width affected the distribution of the temperature variation rate in a thinner pyroelectric material. However, a pyroelectric cell with a thicker pyroelectric material was beneficial in generating electricity pyroelectrically. The PZT sheet was further etched to produce deeper cavities and a smaller electrode width to induce lateral temperature gradients on the sidewalls of cavities under homogeneous heat irradiation, enhancing the temperature variation rate.

Temperature Field Analysis for PZT Pyroelectric Cells for Thermal Energy Harvesting

PubMed Central

Hsiao, Chun-Ching; Ciou, Jing-Chih; Siao, An-Shen; Lee, Chi-Yuan

2011-01-01

This paper proposes the idea of etching PZT to improve the temperature variation rate of a thicker PZT sheet in order to enhance the energy conversion efficiency when used as pyroelectric cells. A partially covered electrode was proven to display a higher output response than a fully covered electrode did. A mesh top electrode monitored the temperature variation rate and the electrode area. The mesh electrode width affected the distribution of the temperature variation rate in a thinner pyroelectric material. However, a pyroelectric cell with a thicker pyroelectric material was beneficial in generating electricity pyroelectrically. The PZT sheet was further etched to produce deeper cavities and a smaller electrode width to induce lateral temperature gradients on the sidewalls of cavities under homogeneous heat irradiation, enhancing the temperature variation rate. PMID:22346652

Development of improved pyroelectric detectors; Literature survey of pyroelectric materials and their characteristics

NASA Technical Reports Server (NTRS)

Weiner, S.; Beerman, H. P.

1971-01-01

The object of this program is to improve the detectivity of the pyroelectric detector with the ultimate goal of operation at or near the temperature-noise limit. Two general areas of investigation are undertaken. The first is to improve responsivity through the use of new materials. The second is directed toward reduction of noise and will be effected with improved field effect transistor characteristics, and improved electroding of the pyroelectric material. The search for new materials has begun with a review of the literature on pyroelectric materials in several languages. The compiled data includes an extensive list of references. From this, several materials have already been selected for investigation. FETs are being obtained from various manufacturers, evaluated, and selected units will be tested with pyroelectric elements as complete detectors.

Design of the flame detector based on pyroelectric infrared sensor

NASA Astrophysics Data System (ADS)

Liu, Yang; Yu, Benhua; Dong, Lei; Li, Kai

2017-10-01

As a fire detection device, flame detector has the advantages of short reaction time and long distance. Based on pyroelectric infrared sensor working principle, the passive pyroelectric infrared alarm system is designed, which is mainly used for safety of tunnel to detect whether fire occurred or not. Modelling and Simulation of the pyroelectric Detector Using Labview. An attempt was made to obtain a simple test platform of a pyroelectric detector which would make an excellent basis for the analysis of its dynamic behaviour. After many experiments, This system has sensitive response, high anti-interference ability and safe and reliable performance.

The flexoelectric effect associated size dependent pyroelectricity in solid dielectrics

NASA Astrophysics Data System (ADS)

Bai, Gang; Liu, Zhiguo; Xie, Qiyun; Guo, Yanyan; Li, Wei; Yan, Xiaobing

2015-09-01

A phenomenological thermodynamic theory is used to investigate the effect of strain gradient on the pyroelectric effect in centrosymmetric dielectric solids. Direct pyroelectricity can exist as external mechanical stress is applied to non-pyroelectric dielectrics with shapes such as truncated pyramids, due to elastic strain gradient induced flexoelectric polarization. Effective pyroelectric coefficient was analyzed in truncated pyramids. It is found to be controlled by size, ambient temperature, stress, and aspect ratio and depends mainly on temperature sensitivity of flexoelectric coefficient (TSFC) and strain gradient of the truncated pyramids dielectric solids. These results show that the pyroelectric property of Ba0.67Sr0.33TiO3 above Tc similar to PZT and other lead-based ferroelectrics can be obtained. This feature might widely broaden the selection of materials for infrared detectors with preferable properties.

Fast response pyroelectric detector-preamplifier assembled device

NASA Astrophysics Data System (ADS)

Bai, PiJi; Tai, Yunjian; Liu, Huiping

2008-03-01

The pyroelectric detector is wide used for its simple structure and high performance to price ratio. It has been used in thermal detecting, infrared spectrum and laser testing. When the pyroelectric detector was applied in practice, fast reponse speed is need. For improving the response speed of the pyroelectric detector some specific technology has been used in the preamplifier schematic. High sense and fast response character of the pyroelectric detector-preamplifier assembled device had been achieved. When the device is applied in acute concussion condition, it must survive from the acute concussion condition testing. For it reliability some specific technology was used in the device fabricating procedure. At last the performance parameter testing result and simulation application condition result given in this paper show the performance of the pyroelectric detector-preamplifier assembled device had achieved the advance goal.

Potassium dihydrogen phosphate and potassium tantalate niobate pyroelectric materials and far-infrared detectors

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

Baumann, Hilary Beatrix

1993-10-01

This thesis discusses characterization of two ferroelectric materials and the fabrication of bolometers. Potassium tantalate niobate (KTN) and potassium dihydrogen phosphate (KDP) are chosen because they can be optimized for operation near 100K. Chap. 2 reviews the physics underlying pyroelectric materials and its subclass of ferroelectric materials. Aspects of pyroelectric detection are discussed in Chap. 3 including measurement circuit, noise sources, and effects of materials properties on pyroelectric response. Chap. 4 discusses materials selection and specific characteristics of KTN and KDP; Chap. 5 describes materials preparation; and Chap. 6 presents detector configuration and a thermal analysis of the pyroelectric detector.more » Electrical techniques used to characterize the materials and devices and results are discussed in Chap. 7 followed by conclusions on feasibility of KDP and KTN pyroelectric detectors in Chap. 8.« less

The pyroelectric behavior of lead free ferroelectric ceramics in thermally stimulated depolarization current measurements

NASA Astrophysics Data System (ADS)

González-Abreu, Y.; Peláiz-Barranco, A.; Garcia-Wong, A. C.; Guerra, J. D. S.

2012-06-01

The present paper shows a detailed analysis on the thermally stimulated processes in barium modified SrBi2Nb2O9 ferroelectric bi-layered perovskite, which is one of the most promising candidates for non-volatile random access memory applications because of its excellent fatigue-resistant properties. A numerical method is used to separate the real pyroelectric current from the other thermally stimulated processes. A discharge due to the space-charge injected during the poling process, the pyroelectric response, and a conductive process are discussed in a wide temperature range from ferroelectric to paraelectric phase. The pyroelectric response is separated from the other components to evaluate the polarization behavior and some pyroelectric parameters. The remanent polarization, the pyroelectric coefficient, and the merit figure are evaluated, which show good results.

Pyroelectric Energy Harvesting: Model and Experiments

DTIC Science & Technology

2016-05-01

consisting of a current source for the pyroelectric current, a dielectric capacitor for the adiabatic charging and discharging, and optionally a resistor to...polarization) in a piezoelectric material. To extract work from the pyroelectric effect, the material acts as the dielectric in a capacitor that is...amplifier was chosen for the setup. The pyroelectric element is commonly modeled as a dielectric capacitor and a current source in parallel, as seen in

Uncooled thin film pyroelectric IR detector with aerogel thermal isolation

DOEpatents

Ruffner, Judith A.; Bullington, Jeff A.; Clem, Paul G.; Warren, William L.; Brinker, C. Jeffrey; Tuttle, Bruce A.; Schwartz, Robert W.

1999-01-01

A monolithic infrared detector structure which allows integration of pyroelectric thin films atop low thermal conductivity aerogel thin films. The structure comprises, from bottom to top, a substrate, an aerogel insulating layer, a lower electrode, a pyroelectric layer, and an upper electrode layer capped by a blacking layer. The aerogel can offer thermal conductivity less than that of air, while providing a much stronger monolithic alternative to cantilevered or suspended air-gap structures for pyroelectric thin film pixel arrays. Pb(Zr.sub.0.4 Ti.sub.0.6)O.sub.3 thin films deposited on these structures displayed viable pyroelectric properties, while processed at 550.degree. C.

Pyroelectric property of SrTiO3/Si ferroelectric-semiconductor heterojunctions near room temperature

NASA Astrophysics Data System (ADS)

Bai, Gang; Wu, Dongmei; Xie, Qiyun; Guo, Yanyan; Li, Wei; Deng, Licheng; Liu, Zhiguo

2015-12-01

A nonlinear thermodynamic formalism is developed to calculate the pyroelectric property of epitaxial single domain SrTiO3/Si heterojunctions by taking into account the thermal expansion misfit strain at different temperatures. It has been demonstrated that the crucial role was played by the contribution associated with the structure order parameter arising from the rotations of oxygen octahedral on pyroelectricity. A dramatic decrease in the pyroelectric coefficient due to the strong coupling between the polarization and the structure order parameter is found at ferroelectric TF1-TF2 phase transition. At the same time, the thermal expansion mismatch between film and substrate is also found to provide an additional weak decrease of pyroelectricity. The analytic relationship of the out-of-plane pyroelectric coefficient and dielectric constant of ferroelectric phases by considering the thermal expansion of thin films and substrates has been determined for the first time. Our research provides another avenue for the investigation of the pyroelectric effects of ferroic thin films, especially, such as antiferroelectric and multiferroic materials having two or more order parameters.

Pyroelectricity in globular protein lysozyme films

NASA Astrophysics Data System (ADS)

Stapleton, A.; Noor, M. R.; Haq, E. U.; Silien, C.; Soulimane, T.; Tofail, S. A. M.

2018-03-01

Pyroelectricity is the ability of certain non-centrosymmetric materials to generate an electric charge in response to a change in temperature and finds use in a range of applications from burglar alarms to thermal imaging. Some biological materials also exhibit pyroelectricity but the examples of the effect are limited to fibrous proteins, polypeptides, and tissues and organs of animals and plants. Here, we report pyroelectricity in polycrystalline aggregate films of lysozyme, a globular protein.

Pyroelectric response mechanism of barium strontium titanate ceramics in dielectric bolometer mode: The underlying essence of the enhancing effect of direct current bias field

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

Mao, Chaoliang; Cao, Sheng; Yan, Shiguang

Pyroelectric response mechanism of Ba{sub 0.70}Sr{sub 0.30}TiO{sub 3} ceramics under dielectric bolometer (DB) mode was investigated by dielectric and pyroelectric properties measurement. The variations of total, intrinsic, and induced pyroelectric coefficients (p{sub tot}, p{sub int}, p{sub ind}) with temperatures and bias fields were analyzed. p{sub int} plays the dominant role to p{sub tot} through most of the temperature range and p{sub ind} will be slightly higher than p{sub int} above T{sub 0}. The essence of the enhancing effect of DC bias field on pyroelectric coefficient can be attributed to the high value of p{sub int}. This mechanism is useful formore » the pyroelectric materials (DB mode) applications.« less

Research on the Multiple Factors Influencing Human Identification Based on Pyroelectric Infrared Sensors

PubMed Central

Lou, Ping; Hu, Jianmin

2018-01-01

Analysis of the multiple factors affecting human identification ability based on pyroelectric infrared technology is a complex problem. First, we examine various sensed pyroelectric waveforms of the human body thermal infrared signal and reveal a mechanism for affecting human identification. Then, we find that the mechanism is decided by the distance, human target, pyroelectric infrared (PIR) sensor, the body type, human moving velocity, signal modulation mask, and Fresnel lens. The mapping relationship between the sensed waveform and multiple influencing factors is established, and a group of mathematical models are deduced which fuse the macro factors and micro factors. Finally, the experimental results show the macro-factors indirectly affect the recognition ability of human based on the pyroelectric technology. At the same time, the correctness and effectiveness of the mathematical models is also verified, which make it easier to obtain more pyroelectric infrared information about the human body for discriminating human targets. PMID:29462908

Neutron interrogation systems using pyroelectric crystals and methods of preparation thereof

DOEpatents

Tang, Vincent; Meyer, Glenn A.; Falabella, Steven; Guethlein, Gary; Rusnak, Brian; Sampayan, Stephen; Spadaccini, Christopher M.; Wang, Li-Fang; Harris, John; Morse, Jeff

2017-08-01

According to one embodiment, an apparatus includes a pyroelectric crystal, a deuterated or tritiated target, an ion source, and a common support coupled to the pyroelectric crystal, the deuterated or tritiated target, and the ion source. In another embodiment, a method includes producing a voltage of negative polarity on a surface of a deuterated or tritiated target in response to a temperature change of a pyroelectric crystal, pulsing a deuterium ion source to produce a deuterium ion beam, accelerating the deuterium ion beam to the deuterated or tritiated target to produce a neutron beam, and directing the ion beam onto the deuterated or tritiated target to make neutrons using a voltage of the pyroelectric crystal and/or an HGI surrounding the pyroelectric crystal. The directionality of the neutron beam is controlled by changing the accelerating voltage of the system. Other apparatuses and methods are presented as well.

Polymer-Ceramic Composite Materials for Pyroelectric Infrared Detectors: An Overview

NASA Technical Reports Server (NTRS)

Aggarwal, M. D; Currie, J. R.; Penn, B. G.; Batra, A. K.; Lal, R. B.

2007-01-01

Ferroelectrics:Polymer composites can be considered an established substitute for conventional electroceramics and ferroelectric polymers. The composites have a unique blend of polymeric properties such as mechanical flexibility, high strength, formability, and low cost, with the high electro-active properties of ceramic materials. They have attracted considerable interest because of their potential use in pyroelectric infrared detecting devices and piezoelectric transducers. These flexible sensors and transducers may eventually be useful for their health monitoring applications for NASA crew launch vehicles and crew exploration vehicles being developed. In the light of many technologically important applications in this field, it is worthwhile to present an overview of the pyroelectric infrared detector theory, models to predict dielectric behavior and pyroelectric coefficient, and the concept of connectivity and fabrication techniques of biphasic composites. An elaborate review of Pyroelectric-Polymer composite materials investigated to date for their potential use in pyroelectric infrared detectors is presented.

Pyroelectric conversion in space: A conceptual design study

NASA Technical Reports Server (NTRS)

Olsen, R. B.

1983-01-01

Pyroelectric conversion is potentially a very lightweight means of providing electrical power generation in space. Two conceptualized systems approaches for the direct conversion of heat (from sunlight) into electrical energy using the pyroelectric effect of a new class of polar polymers were evaluated. Both of the approaches involved large area thin sheets of plastic which are thermally cycled by radiative input and output of thermal energy. The systems studied are expected to eventually achieve efficiencies of the order of 8% and may deliver as much as one half kilowatt per kilogram. In addition to potentially very high specific power, the pyroelectric conversion approaches outlined appear to offer low cost per watt in the form of an easily deployed, flexible, strong, electrically ""self-healing'', and high voltage sheet. This study assessed several potential problems such as plasma interactions and radiation degradation and suggests approaches to overcome them. The fundamental technological issues for space pyroelectric conversion are: (1) demonstration of the conversion cycle with the proposed class of polymers, (2) achievement of improved dielectric strength of the material, (3) demonstration of acceptable plasma power losses for low altitude, and (4) establishment of reasonable lifetime for the pyroelectric material in the space environment. Recommendations include an experimental demonstration of the pyroelectric conversion cycle followed by studies to improve the dielectric strength of the polymer and basic studies to discover additional pyroelectric materials.

Pyroelectric detector arrays

NASA Technical Reports Server (NTRS)

Fripp, A. L.; Robertson, J. B.; Breckenridge, R. (Inventor)

1982-01-01

A pyroelectric detector array and the method for using it are described. A series of holes formed through a silicon dioxide layer on the surface of a silicon substrate forms the mounting fixture for the pyroelectric detector array. A series of nontouching strips of indium are formed around the holes to make contact with the backside electrodes and form the output terminals for individual detectors. A pyroelectric detector strip with front and back electrodes, respectively, is mounted over the strips. Biasing resistors are formed on the surface of the silicon dioxide layer and connected to the strips. A metallized pad formed on the surface of layer is connected to each of the biasing resistors and to the film to provide the ground for the pyroelectric detector array.

Pyroelectric Materials for Uncooled Infrared Detectors: Processing, Properties, and Applications

NASA Technical Reports Server (NTRS)

Aggarwal, M. D.; Batra, A. K.; Guggilla, P.; Edwards, M. E.; Penn, B. G.; Currie, J. R., Jr.

2010-01-01

Uncooled pyroelectric detectors find applications in diverse and wide areas such as industrial production; automotive; aerospace applications for satellite-borne ozone sensors assembled with an infrared spectrometer; health care; space exploration; imaging systems for ships, cars, and aircraft; and military and security surveillance systems. These detectors are the prime candidates for NASA s thermal infrared detector requirements. In this Technical Memorandum, the physical phenomena underlying the operation and advantages of pyroelectric infrared detectors is introduced. A list and applications of important ferroelectrics is given, which is a subclass of pyroelectrics. The basic concepts of processing of important pyroelectrics in various forms are described: single crystal growth, ceramic processing, polymer-composites preparation, and thin- and thick-film fabrications. The present status of materials and their characteristics and detectors figures-of-merit are presented in detail. In the end, the unique techniques demonstrated for improving/enhancing the performance of pyroelectric detectors are illustrated. Emphasis is placed on recent advances and emerging technologies such as thin-film array devices and novel single crystal sensors.

Pyroelectric Ceramics for Infrared Detection Applications

NASA Technical Reports Server (NTRS)

Guggilla, Padmaja; Batra, A. K.; Currie, J. R.; Aggarwal, M. D.; Penn, B.; Lal, R. B.

2004-01-01

Pyroelectric and dielectric properties of modified PZT and PZ have been studied for their use in infrared detectors. Various material figure-of-merits for their use in infrared detector are calculated including when the pyroelectric element is placed on heat-sink condition. The results are compared with exiting candidate materials.

Thermally stimulated processes in samarium-modified lead titanate ferroelectric ceramics

NASA Astrophysics Data System (ADS)

Peláiz-Barranco, A.; García-Wong, A. C.; González-Abreu, Y.; Gagou, Y.; Saint-Grégoire, P.

2013-08-01

The thermally stimulated processes in a samarium-modified lead titanate ferroelectric system are analyzed from the thermally stimulated depolarization discharge current. The discharge due to the space charge injected during the poling process, the pyroelectric response and a conduction process related to oxygen vacancies are evaluated considering a theoretical decomposition by using a numerical method. The pyroelectric response is separated from other components to evaluate the polarization behavior and some pyroelectric parameters. High remanent polarization, pyroelectric coefficient and merit figure values are obtained at room temperature.

All-fiber pyroelectric nanogenerator

NASA Astrophysics Data System (ADS)

Ghosh, Sujoy Kumar; Xie, Mengying; Bowen, Christopher Rhys; Mandal, Dipankar

2018-04-01

An all-fiber pyroelectric nanogenerator (PyNG) is fabricated where both the active pyroelectric component and the electrodes were composed of fiber. The pyroelectric component was made with randomly organized electrospun PVDF nano-fibers possessing ferroelectric β- and γ-phases. The PyNG possess higher level of sensitivity which can detect very low level of temperature fluctuation, as, low as, 2 K. In addition, the thermal energy harvesting ability of the PyNG under several temperature variations and cycling frequencies paves the way for next generation thermal sensor and self-powered flexible micro-electronics.

Experiments to demonstrate piezoelectric and pyroelectric effects

NASA Astrophysics Data System (ADS)

Erhart, Jiří

2013-07-01

Piezoelectric and pyroelectric materials are used in many current applications. The purpose of this paper is to explain the basic properties of pyroelectric and piezoelectric effects and demonstrate them in simple experiments. Pyroelectricity is presented on lead zirconium titanate (PZT) ceramics as an electric charge generated by the temperature change. The direct piezoelectric effect is demonstrated by the electric charge generated from the bending of the piezoelectric ceramic membrane or from the gas igniter. The converse piezoelectric effect is presented in the experiments by the deflection of the bending piezoelectric element (piezoelectric bimorph).

Pyroelectricity in Polycrystalline Ferroelectrics

NASA Astrophysics Data System (ADS)

Jiménez, R.; Jiménez, B.

The first reference to pyroelectric effect is by Theophrastus in 314 BC, who noted that tourmaline becomes charged because it attracted bits of straw and ash when heated. Tourmaline's properties were reintroduced in Europe in 1707 by Johann George Schmidt, who also noted the attractive properties of the mineral when heated. Pyroelectricity was first described by Louis Lemery in 1717. In 1747, Linnaeus first related the phenomenon to electricity, although this was not proven until 1756 by Franz Ulrich Thodor Aepinus. In 1824, Sir David Brewster gave the effect the name it has today. William Thomson in 1878 and Voight in 1897 helped develop a theory for the processes behind pyroelectricity. Pierre Curie and his brother, Jacques Curie, studied pyroelectricity in the 1880s, leading to their discovery of some of the mechanisms behind piezoelectricity.

High-frequency thermal-electrical cycles for pyroelectric energy conversion

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

Bhatia, Bikram; Damodaran, Anoop R.; Cho, Hanna

2014-11-21

We report thermal to electrical energy conversion from a 150 nm thick BaTiO{sub 3} film using pyroelectric cycles at 1 kHz. A microfabricated platform enables temperature and electric field control with temporal resolution near 1 μs. The rapid electric field changes as high as 11 × 10{sup 5 }kV/cm-s, and temperature change rates as high as 6 × 10{sup 5 }K/s allow exploration of pyroelectric cycles in a previously unexplored operating regime. We investigated the effect of phase difference between electric field and temperature cycles, and electric field and temperature change rates on the electrical energy generated from thermal-electrical cycles based on the pyroelectric Ericsson cycle. Complete thermodynamic cyclesmore » are possible up to the highest cycle rates tested here, and the energy density varies significantly with phase shifts between temperature and electric field waveforms. This work could facilitate the design and operation of pyroelectric cycles at high cycle rates, and aid in the design of new pyroelectric systems.« less

Noise effect on performance of IR PVDF pyroelectric detector

NASA Astrophysics Data System (ADS)

Abdullah, K. Al; Batal, M. Anwar; Hamdan, Rawad; Khalil, Toni; Salame, Chafic

2018-05-01

The spin-casting and casting technology were used to make IR pyroelectric PVDF detectors, where the operational amplifier, TC75S63TU, is used to amplify pyroelectrical signal. The pyroelectric coefficient is measured by charge integration method, which is 23 µC/m2K. The voltage responsivity and noise equivalent power depending on the dielectric constant, specific conductivity and loss tangent, which are measured at various frequencies, is estimated where changing of detector capacitance and resistor with frequency is taken into account. Maximum voltage responsivity was for detector thickness d=116.05 µm at chopping frequency (f=0.8Hz). Influence of thermal, Johnson and amplifier noises on output voltage are studied. At frequencies (<1kHz), Johnson noise dominates whereas at frequencies (>1kHz), amplifier voltage noise dominates. The thinner detector, the lower noise affects on output voltage. The optimal signal to noise ratio (SNR) of pyroelectrical detector is for thickness d=30.1 µm at frequency f=20Hz. The reducing electrode area decreases slightly total noise at low frequency and enhances slightly SNR of pyroelectrical detector.

Pyroelectricity of silicon-doped hafnium oxide thin films

NASA Astrophysics Data System (ADS)

Jachalke, Sven; Schenk, Tony; Park, Min Hyuk; Schroeder, Uwe; Mikolajick, Thomas; Stöcker, Hartmut; Mehner, Erik; Meyer, Dirk C.

2018-04-01

Ferroelectricity in hafnium oxide thin films is known to be induced by various doping elements and in solid-solution with zirconia. While a wealth of studies is focused on their basic ferroelectric properties and memory applications, thorough studies of the related pyroelectric properties and their application potential are only rarely found. This work investigates the impact of Si doping on the phase composition and ferro- as well as pyroelectric properties of thin film capacitors. Dynamic hysteresis measurements and the field-free Sharp-Garn method were used to correlate the reported orthorhombic phase fractions with the remanent polarization and pyroelectric coefficient. Maximum values of 8.21 µC cm-2 and -46.2 µC K-1 m-2 for remanent polarization and pyroelectric coefficient were found for a Si content of 2.0 at%, respectively. Moreover, temperature-dependent measurements reveal nearly constant values for the pyroelectric coefficient and remanent polarization over the temperature range of 0 ° C to 170 ° C , which make the material a promising candidate for IR sensor and energy conversion applications beyond the commonly discussed use in memory applications.

Pyroelectricity as a possible mechanism for cell membrane permeabilization.

PubMed

García-Sánchez, Tomás; Muscat, Adeline; Leray, Isabelle; Mir, Lluis M

2018-02-01

The effects of pyroelectricity on cell membrane permeability had never been explored. Pyroelectricity consists in the generation of an electric field in the surface of some materials when a change in temperature is produced. In the present study, tourmaline microparticles, which are known to display pyroelectrical properties, were subjected to different changes in temperature upon exposure to cells in order to induce an electric field at their surface. Then, the changes in the permeability of the cell membrane to a cytotoxic agent (bleomycin) were assessed by a cloning efficacy test. An increase in the permeability of the cell membrane was only detected when tourmaline was subjected to a change in temperature. This suggests that the apparition of an induced pyroelectrical electric field on the material could actually be involved in the observed enhancement of the cell membrane permeability as a result of cell electropermeabilization. Copyright © 2017 Elsevier B.V. All rights reserved.

Active Pyroelectric Infrared Detector

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J. (Inventor); Zalameda, Joseph N. (Inventor); Mina, Joseph M. (Inventor)

1995-01-01

A noncontact pyroelectric infrared detector is described. A pyroelectric film that also has piezoelectric properties is held in place so that it is free to vibrate. It is electrically stimulated to vibrate at a resonance frequency. The vibrating film forms part of a balanced bridge circuit. As thermal radiation impinges on the film the pyroelectric effect causes the resonance frequency to change, thereby unbalancing the bridge circuit. A differential amplifier tracks the change in voltage across the bridge. The resulting voltage signal is further processed by a bandpass filter and a precision rectifier. The device allows for DC or static temperature measurements without the use of a mechanical chopping device.

Improving Pyroelectric Energy Harvesting Using a Sandblast Etching Technique

PubMed Central

Hsiao, Chun-Ching; Siao, An-Shen

2013-01-01

Large amounts of low-grade heat are emitted by various industries and exhausted into the environment. This heat energy can be used as a free source for pyroelectric power generation. A three-dimensional pattern helps to improve the temperature variation rates in pyroelectric elements by means of lateral temperature gradients induced on the sidewalls of the responsive elements. A novel method using sandblast etching is successfully applied in fabricating the complex pattern of a vortex-like electrode. Both experiment and simulation show that the proposed design of the vortex-like electrode improved the electrical output of the pyroelectric cells and enhanced the efficiency of pyroelectric harvesting converters. A three-dimensional finite element model is generated by commercial software for solving the transient temperature fields and exploring the temperature variation rate in the PZT pyroelectric cells with various designs. The vortex-like type has a larger temperature variation rate than the fully covered type, by about 53.9%.The measured electrical output of the vortex-like electrode exhibits an obvious increase in the generated charge and the measured current, as compared to the fully covered electrode, by of about 47.1% and 53.1%, respectively. PMID:24025557

[Study on the application of pyroelectric infrared sensor to safety protection system].

PubMed

Wang, Song-de; Zhang, Shuan-ji; Zhu, Xiao-long; Yang, Jie-hui

2006-11-01

Using the infrared ray of human body, which is received and magnified by pyroelectric infrared sensor to form a certain voltage control signal, and using the control signal to trigger a voice recording-reproducing circuit, a pyroelectric infrared detector voice device with auto-control function designed. The circuit adopted new pyroelectric infrared detector assembly and voice recording-reproducing assembly. When someone is present in the detectable range of the pyroelectric infrared detector, first, the pyroelectric infrared sensor will transform the incepted radiation energy to a electric signal, which is then magnified and compared by an inside circuit, and an output control signal, touches off the voice recording-reproducing assembly with the reproducer sending out a beforehand transcribed caution voice to wise the man who does not know well the surrounding condition that the frontage is a danger zone and should not be approched. With the design of integrated structures, the distance-warning device has the advantages of strong anti-jamming ability, low temperature resistance, working stability and use-convenience, and it can be suitably installed and used in several locations which may endanger person safety, such as substation, high voltage switch panel, electric transformer, etc.

Optimization and improvement of thermal energy harvesting by using pyroelectric materials

NASA Astrophysics Data System (ADS)

El Fatnani, Fatima Zahra; Guyomar, Daniel; Mazroui, M.'hammed; Belhora, Fouad; Boughaleb, Yahia

2016-06-01

We deal with the thermal energy which is one of the ambient energy sources surely exploitable, but it has not been much interest as the mechanical energy. In this paper, our aim is to use thermal energy and show that it's an important source for producing the electrical energy through pyroelectric effect which is the property of some dielectric materials to show a spontaneous electrical polarization versus temperature. In this context, we present a concept to harvest a thermal energy using infrared rays and pyroelectric effect. The pyroelectric material used in this work can generate an electrical voltage when it subjected to a temperature change which will be ensured by the use of infrared lamp. Our experimental results show that the electrical voltage, current and harvested power increased significantly when increasing the area of the pyroelectric element. The experimental results show also that with this simple concept we harvested a heavy amount value of power which will certainly be useful in an extensive range of applications, including sensors and infrared detection. These results shed light on the thermoelectric energy conversion by Ceramic lead zirconate titanate (PZT) buzzer having the pyroelectric property.

THz QCL-Based Cryogen-Free Spectrometer for in Situ Trace Gas Sensing

PubMed Central

Consolino, Luigi; Bartalini, Saverio; Beere, Harvey E.; Ritchie, David A.; Vitiello, Miriam Serena; De Natale, Paolo

2013-01-01

We report on a set of high-sensitivity terahertz spectroscopy experiments making use of QCLs to detect rotational molecular transitions in the far-infrared. We demonstrate that using a compact and transportable cryogen-free setup, based on a quantum cascade laser in a closed-cycle Stirling cryostat, and pyroelectric detectors, a considerable improvement in sensitivity can be obtained by implementing a wavelength modulation spectroscopy technique. Indeed, we show that the sensitivity of methanol vapour detection can be improved by a factor ≈ 4 with respect to standard direct absorption approaches, offering perspectives for high sensitivity detection of a number of chemical compounds across the far-infrared spectral range. PMID:23478601

THz QCL-based cryogen-free spectrometer for in situ trace gas sensing.

PubMed

Consolino, Luigi; Bartalini, Saverio; Beere, Harvey E; Ritchie, David A; Vitiello, Miriam Serena; De Natale, Paolo

2013-03-11

We report on a set of high-sensitivity terahertz spectroscopy experiments making use of QCLs to detect rotational molecular transitions in the far-infrared. We demonstrate that using a compact and transportable cryogen-free setup, based on a quantum cascade laser in a closed-cycle Stirling cryostat, and pyroelectric detectors, a considerable improvement in sensitivity can be obtained by implementing a wavelength modulation spectroscopy technique. Indeed, we show that the sensitivity of methanol vapour detection can be improved by a factor ≈ 4 with respect to standard direct absorption approaches, offering perspectives for high sensitivity detection of a number of chemical compounds across the far-infrared spectral range.

Pyroelectric response of perovskite heterostructures incorporating conductive oxide electrodes

NASA Astrophysics Data System (ADS)

Tipton, Charles Wesley, IV

2000-10-01

The use of imaging technologies has become pervasive in many applications as the demand for situational awareness information has increased over the last decade. No better example of the integration of these technologies can be found than that of infrared or thermal imaging. This dissertation, in the field of thermal imaging, has been motivated by the desire to advance the technology of uncooled, thin-film pyroelectric sensors and focuses on the materials and structures from which the detector elements will be built. This work provides a detailed study of the pyroelectric response of the La-Sr-Co-O/Pb-La-Zr-Ti-O/La-Sr-Co-O (LPL) structure. The LPL structure was chosen based on the needs of thin film detectors, the unique properties of the conductive oxide La-Sr-Co-O (LSCO), and the broad applicability of the Pb-La-Zr-Ti-O (PLZT) material system. Epitaxial heterostructures were grown by pulsed laser deposition on single-crystal oxide substrates. Using the oxygen pressure during cooling and heating of the LSCO layer as a key variable, we have been able to produce structures that have a pronounced internal field in the as-grown state. In these capacitors, where the bottom electrode has a large concentration of oxygen vacancies, we have discovered very large pyroelectric responses that are 10 to 30 times larger than expected of PLZT-based pyroelectric materials (typical values are 20 to 40 nCcm-2K -1). The enhanced pyroelectric responses are very repeatable, stable over time, and distinctly different from responses attributed to thermally stimulated currents. Detailed positron annihilation spectroscopy measurements reveal that there is indeed an oxygen concentration gradient across the capacitor. Based on the results of this study, I will present an analysis of the enhanced pyroelectric response. Although the enhanced response has been correlated with high concentrations of oxygen vacancies in the PLZT film and LSCO electrodes, the mechanism by which the large pyroelectric currents are generated is not yet known. It is likely, however, that a sub-lattice of oxygen and lead vacancies forms the enhanced dipoles and that due to the highly defective nature of the lattice, has a large effective pyroelectric coefficient.

Assembly and evaluation of a pyroelectric detector bonded to vertically aligned multiwalled carbon nanotubes over thin silicon.

PubMed

Theocharous, E; Theocharous, S P; Lehman, J H

2013-11-20

A novel pyroelectric detector consisting of a vertically aligned nanotube array on thin silicon (VANTA/Si) bonded to a 60 μm thick crystal of LiTaO₃ has been fabricated. The performance of the VANTA/Si-coated pyroelectric detector was evaluated using National Physical Laboratory's (NPL's) detector-characterization facilities. The relative spectral responsivity of the detector was found to be spectrally flat in the 0.8-24 μm wavelength range, in agreement with directional-hemispherical reflectance measurements of witness samples of the VANTA. The spatial uniformity of response of the test detector exhibited good uniformity, although the nonuniformity increased with increasing modulation frequency. The nonuniformity may be assigned either to the dimensions of the VANTA or the continuity of the bond between the VANTA/Si coating and the pyroelectric crystal substrate. The test detector exhibited a small superlinear response, which is similar to that of pyroelectric detectors coated with good quality gold-black coatings.

Infrared responsivity of a pyroelectric detector with a single-wall carbon nanotube coating.

PubMed

Theocharous, E; Engtrakul, C; Dillon, A C; Lehman, J

2008-08-01

The performance of a 10 mm diameter pyroelectric detector coated with a single-wall carbon nanotube (SWCNT) was evaluated in the 0.8 to 20 microm wavelength range. The relative spectral responsivity of this detector exhibits significant fluctuations over the wavelength range examined. This is consistent with independent absorbance measurements, which show that SWCNTs exhibit selective absorption bands in the visible and near-infrared. The performance of the detector in terms of noise equivalent power and detectivity in wavelength regions of high coating absorptivity was comparable with gold-black-coated pyroelectric detectors based on 50 microm thick LiTaO(3) crystals. The response of this detector was shown to be nonlinear for DC equivalent photocurrents >10(-9) A, and its spatial uniformity of response was comparable with other pyroelectric detectors utilizing gold-black coatings. The nonuniform spectral responsivity exhibited by the SWCNT-coated detector is expected to severely restrict the use of SWCNTs as black coatings for thermal detectors. However, the deposition of SWCNT coatings on a pyroelectric crystal followed by the study of the prominence of the spectral features in the relative spectral responsivity of the resultant pyroelectric detectors is shown to provide an effective method for quantifying the impurity content in SWCNT samples.

Pyroelectric detector arrays

NASA Technical Reports Server (NTRS)

Fripp, A. L.; Robertson, J. B.; Breckenridge, R. A. (Inventor)

1982-01-01

A pryoelectric detector array and the method for making it are described. A series of holes formed through a silicon dioxide layer on the surface of a silicon substrate forms the mounting fixture for the pyroelectric detector array. A series of nontouching strips of indium are formed around the holes to make contact with the backside electrodes and form the output terminals for individual detectors. A pyroelectric detector strip with front and back electrodes, respectively, is mounted over the strip. Biasing resistors are formed on the surface of the silicon dioxide layer and connected to the strips. A metallized pad formed on the surface of the layer is connected to each of the biasing resistors and to the film to provide the ground for the pyroelectric detector array.

Pyroelectric Ceramics as Temperature Sensors for Energy System Applications

NASA Astrophysics Data System (ADS)

Silva, Jorge Luis

Temperature is continuously monitored in energy systems to ensure safe operation temperatures, increase efficiency and avoid high emissions. Most of energy systems operate at high temperature and harsh environments to achieve higher efficiencies, therefore temperature sensing devices that can operate under these conditions are highly desired. The interest has increased in temperature sensors capable to operate and in harsh environments and temperature sensors capable to transmit thermal information wirelessly. One of the solutions for developing harsh environment sensors is to use ceramic materials, especially functional ceramics such as pyroelectrics. Pyroelectric ceramics could be used to develop active sensors for both temperature and pressure due to their capabilities in coupling energy among mechanical, thermal, and electrical domains. In this study, two different pyroelectric materials were used to develop two different temperature sensors systems. First, a high temperature sensor was developed using a lithium niobate (LiNbO3) pyroelectric ceramic. With its Curie temperature of 1210 °C, lithium niobate is capable to maintain its pyroelectric properties at high temperature making it ideal for temperature sensing at high temperature applications. Lithium niobate has been studied previously in the attempt to use its pyroelectric current as the sensing mechanism to measure temperatures up to 500 °C. Pyroelectric coefficient of lithium niobate is a function of temperature as reported in a previous study, therefore a dynamic technique is utilized to measure the pyroelectric coefficient of the lithium niobate used in this study. The pyroelectric coefficient was successfully measured up to 500 °C with coefficients ranging from -8.5 x 10 -5 C/m2 °C at room temperature to -23.70 x 10 -5 C/m2 °C at 500 °C. The lithium niobate sensor was then tested at higher temperatures: 220 °C, 280 °C, 410 °C and 500 °C with 4.31 %, 2.1 %, 0.4 % and 0.6 % deviation respectively when compared with thermocouple measurements. The second phase of this study focused on developing a wireless temperature sensor with lead zirconate titanate (PZT) as the pyroelectric material. This wireless temperature sensor consists of generating current by the PZT when exposed to a rate of temperature change with time, which was conducted to a built electromagnet to produce a magnetic field. The magnetic field was captured wirelessly with a milligaussmeter at a certain distance. Pyroelectric property of PZT (-40x10-5 C/m2 °C at 25 °C) is higher than that of the lithium niobate (-8.5x10-5 C/m2 °C at 25 °C), which was necessary to be able to generate the necessary pyroelectric current to make magnetic field detectable by the milligaussmeter. The electromagnet body was 3D printed with ABS material and surrounded with winding wire material. Before attempting a wireless temperature measurement, several attempts to measure the magnetic field at different distances away from the electromagnet were done. At the applied heating rates, the milligaussmeter was able to measure magnetic field up to 1.27 cm away from the electromagnet edge. A PZT sensor with a thickness of 0.1 cm was tested for use in the wireless temperature measurement configuration. For more accurate wireless temperature measurements, a similar pyroelectric coefficient measurement technique as used in phase one was done. The pyroelectric coefficient was found to increase from -40x10 -5 C/m2 °C to -71.84x10-5 C/m 2 °C from 25 °C to 122 °C, respectively. The PZT sensor was then tested for wireless temperature measurement at a distance of 1.27 cm at set temperatures of 100 °C, 150 °C, and 200 °C, and showed a maximum 10.47 % deviation when compared to thermocouple reading. In order to increase the distance that the wireless temperature sensor can read, a ferromagnetic material was placed inside the electromagnet. The sensor was tested for wireless temperature measurement at 1.27 cm, 2.54 cm and 3.81 cm with a maximum deviation of 13.4 %.

A strategy for high specific power pyroelectric energy harvesting from a fluid source

NASA Astrophysics Data System (ADS)

Maheux, E.; Hrebtov, M. Yu.; Sukhorukov, G.; Kozyulin, N. N.; Bobrov, M. S.; Dobroselsky, K. G.; Chikishev, L. M.; Dulin, V. M.; Yudin, P. V.

2017-12-01

Conversion of waste heat into usable electricity is now one of the important strategies for saving natural resources and minimizing impact on the environment. In contrast to Seebeck devices, utilizing a temperature gradient, pyroelectric scavengers use temporal temperature oscillations. Here, optimal strategies for pyroelectric energy harvesting are theoretically investigated from the point of view of non-stationary heat exchange for the application-relevant case of harvesting with a pyroelectric lamella from a fluid heat source. It is shown that for a fixed lamella thickness by choosing appropriate phase shift between the temperature oscillations and the voltage on the pyroelectric lamella, one can effectively operate at high frequencies and achieve a two to three-fold increase in specific power with respect to the classical Olsen cycle. A further increase in specific power is achieved by thinning down the lamella. For devices with a thickness down to a few hundreds of nanometers, specific power linearly increases with the inverse thickness. Further scaling down of the device is hampered with the heat exchange in the boundary layer. Our simulations for a representative pyroelectric Pb(Zr0,5Ti0,5)O3 predict harvestable powers of the order of kW/kg for a device with a thickness in the range from 100 nm to 1 μm, operating at hundreds of Hz.

Study of the growth and pyroelectric properties of TGS crystals doped with aniline-family dipolar molecules

NASA Astrophysics Data System (ADS)

Zhang, Kecong; Song, Jiancheng; Wang, Min; Fang, Changshui; Lu, Mengkai

1987-04-01

TGS crystals doped with aniline-family dipolar molecules (aniline, 2-aminobenzoic acid, 3-aminobenzoic acid, 3-aminobenzene-sulphonic acid, 4-aminobenzenesulphonic acid and 4-nitroraniline) have been grown by the slow-cooling solution method. The influence of these dopants on the growth habits, crystal morphology pyroelectric properties, and structure parameters of TGS crystals has been systematically investigated. The effects of the domain structure of the seed crystal on the pyroelectric properties of the doped crystals have been studied. It is found that the spontaneous polarization (P), pyroelectric coefficient (lambda), and internal bias field of the doped crystals are slightly higher than those of the pure TGS, and the larger the dipole moment of the dopant molecule, the higher the P and lambda of the doped TGS crystal.

Pyroelectric effect in tryglicyne sulphate single crystals - Differential measurement method

NASA Astrophysics Data System (ADS)

Trybus, M.

2018-06-01

A simple mathematical model of the pyroelectric phenomenon was used to explain the electric response of the TGS (triglycine sulphate) samples in the linear heating process in ferroelectric and paraelectric phases. Experimental verification of mathematical model was realized. TGS single crystals were grown and four electrode samples were fabricated. Differential measurements of the pyroelectric response of two different regions of the samples were performed and the results were compared with data obtained from the model. Experimental results are in good agreement with model calculations.

Absolute linearity measurements on a gold-black-coated deuterated L-alanine-doped triglycine sulfate pyroelectric detector.

PubMed

Theocharous, E

2008-07-20

The nonlinearity characteristics of a commercially available deuterated L-alanine-doped triglycine sulfate (DLATGS) pyroelectric detector were experimentally investigated at high levels of illumination using the National Physical Laboratory detector linearity characterization facility. The detector was shown to exhibit a superlinear response at high levels of illumination. Moreover, the linearity factor was shown to depend on the area of the spot on the detector active area being illuminated, i.e., the incident irradiance. Possible reasons for the observed behavior are proposed and discussed. The temperature coefficient of the response of the DLATGS pyroelectric detector was measured and found to be higher than +2.5% degrees C(-1). This large and positive temperature coefficient of response is the most likely cause of the superlinear behavior of the DLATGS pyroelectric detector.

Graphene Ink Laminate Structures on Poly(vinylidene difluoride) (PVDF) for Pyroelectric Thermal Energy Harvesting and Waste Heat Recovery.

PubMed

Zabek, Daniel; Seunarine, Kris; Spacie, Chris; Bowen, Chris

2017-03-15

Thermal energy can be effectively converted into electricity using pyroelectrics, which act as small scale power generator and energy harvesters providing nanowatts to milliwatts of electrical power. In this paper, a novel pyroelectric harvester based on free-standing poly(vinylidene difluoride) (PVDF) was manufactured that exploits the high thermal radiation absorbance of a screen printed graphene ink electrode structure to facilitate the conversion of the available thermal radiation energy into electrical energy. The use of interconnected graphene nanoplatelets (GNPs) as an electrode enable high thermal radiation absorbance and high electrical conductivity along with the ease of deposition using a screen print technique. For the asymmetric structure, the pyroelectric open-circuit voltage and closed-circuit current were measured, and the harvested electrical energy was stored in an external capacitor. For the graphene ink/PVDF/aluminum system the closed circuit pyroelectric current improves by 7.5 times, the open circuit voltage by 3.4 times, and the harvested energy by 25 times compared to a standard aluminum/PVDF/aluminum system electrode design, with a peak energy density of 1.13 μJ/cm 3 . For the pyroelectric device employed in this work, a complete manufacturing process and device characterization of these structures are reported along with the thermal conductivity of the graphene ink. The material combination presented here provides a new approach for delivering smart materials and structures, wireless technologies, and Internet of Things (IoT) devices.

Development of an ultra-compact mid-infrared attenuated total reflectance spectrophotometer

NASA Astrophysics Data System (ADS)

Kim, Dong Soo; Lee, Tae-Ro; Yoon, Gilwon

2014-07-01

Mid-infrared spectroscopy has been an important tool widely used for qualitative analysis in various fields. However, portable or personal use is size and cost prohibitive for either Fourier transform infrared or attenuated total reflectance (ATR) spectrophotometers. In this study, we developed an ultra-compact ATR spectrophotometer whose frequency band was 5.5-11.0 μm. We used miniature components, such as a light source fabricated by semiconductor technology, a linear variable filter, and a pyro-electric array detector. There were no moving parts. Optimal design based on two light sources, a zippered configuration of the array detector and ATR optics could produce absorption spectra that might be used for qualitative analysis. A microprocessor synchronized the pulsed light sources and detector, and all the signals were processed digitally. The size was 13.5×8.5×3.5 cm3 and the weight was 300 grams. Due to its low cost, our spectrophotometer can replace many online monitoring devices. Another application could be for a u-healthcare system installed in the bathroom or attached to a smartphone for monitoring substances in body fluids.

Direct Measurement of Pyroelectric and Electrocaloric Effects in Thin Films

NASA Astrophysics Data System (ADS)

Pandya, Shishir; Wilbur, Joshua D.; Bhatia, Bikram; Damodaran, Anoop R.; Monachon, Christian; Dasgupta, Arvind; King, William P.; Dames, Chris; Martin, Lane W.

2017-03-01

An understanding of polarization-heat interactions in pyroelectric and electrocaloric thin-film materials requires that the electrothermal response is reliably characterized. While most work, particularly in electrocalorics, has relied on indirect measurement protocols, here we report a direct technique for measuring both pyroelectric and electrocaloric effects in epitaxial ferroelectric thin films. We demonstrate an electrothermal test platform where localized high-frequency (approximately 1 kHz) periodic heating and highly sensitive thin-film resistance thermometry allow the direct measurement of pyrocurrents (<10 pA ) and electrocaloric temperature changes (<2 mK ) using the "2-omega" and an adapted "3-omega" technique, respectively. Frequency-domain, phase-sensitive detection permits the extraction of the pyrocurrent from the total current, which is often convoluted by thermally-stimulated currents. The wide-frequency-range measurements employed in this study further show the effect of secondary contributions to pyroelectricity due to the mechanical constraints of the substrate. Similarly, measurement of the electrocaloric effect on the same device in the frequency domain (at approximately 100 kHz) allows for the decoupling of Joule heating from the electrocaloric effect. Using one-dimensional, analytical heat-transport models, the transient temperature profile of the heterostructure is characterized to extract pyroelectric and electrocaloric coefficients.

Piezoelectric and pyroelectric properties of DL-alanine and L-lysine amino-acid polymer nanofibres

NASA Astrophysics Data System (ADS)

de Matos Gomes, Etelvina; Viseu, Teresa; Belsley, Michael; Almeida, Bernardo; Costa, Maria Margarida R.; Rodrigues, Vitor H.; Isakov, Dmitry

2018-04-01

The piezoelectric and pyroelectric properties of electrospun polyethylene oxide nanofibres embedded with polar amino acids DL-alanine and L-lysine hemihydrate are reported. A high pyroelectric coefficient of 150 μC m‑2 K‑1 was measured for L-lysine hemihydrate and piezoelectric current densities up to 7 μA m‑2 were obtained for the nanofibres. The study reveals a potential for polymer amino-acid nanofibres to be used as biocompatible energy harvesters for autonomous circuit applications like in implantable electronics.

Piezoelectric and pyroelectric properties of PZT/P(VDF-TrFE) composites with constituent phases poled in parallel or antiparallel directions.

PubMed

Ng, K L; Chan, H L; Choy, C L

2000-01-01

Composites of lead zirconate titanate (PZT) powder dispersed in a vinylidene fluoride-trifluoroethylene copolymer [P(VDF-TrFE)] matrix have been prepared by compression molding. Three groups of polarized samples have been prepared by poling: only the ceramic phase, the ceramic and polymer phases in parallel directions, and the two phases in antiparallel directions. The measured permittivities of the unpoled composites are consistent with the predictions of the Bruggeman model. The changes in the pyroelectric and piezoelectric coefficients of the poled composites with increasing ceramic volume fraction can be described by modified linear mixture rules. When the ceramic and copolymer phases are poled in the same direction, their pyroelectric activities reinforce while their piezoelectric activities partially cancel. However, when the ceramic and copolymer phases are poled in opposite directions, their piezoelectric activities reinforce while their pyroelectric activities partially cancel.

Pyroelectric response of lead zirconate titanate thin films on silicon: Effect of thermal stresses

NASA Astrophysics Data System (ADS)

Kesim, M. T.; Zhang, J.; Trolier-McKinstry, S.; Mantese, J. V.; Whatmore, R. W.; Alpay, S. P.

2013-11-01

Ferroelectric lead zirconate titanate [Pb(ZrxTi1-xO)3, (PZT x:1-x)] has received considerable interest for applications related to uncooled infrared devices due to its large pyroelectric figures of merit near room temperature, and the fact that such devices are inherently ac coupled, allowing for simplified image post processing. For ferroelectric films made by industry-standard deposition techniques, stresses develop in the PZT layer upon cooling from the processing/growth temperature due to thermal mismatch between the film and the substrate. In this study, we use a non-linear thermodynamic model to investigate the pyroelectric properties of polycrystalline PZT thin films for five different compositions (PZT 40:60, PZT 30:70, PZT 20:80, PZT 10:90, PZT 0:100) on silicon as a function of processing temperature (25-800 °C). It is shown that the in-plane thermal stresses in PZT thin films alter the out-of-plane polarization and the ferroelectric phase transformation temperature, with profound effect on the pyroelectric properties. PZT 30:70 is found to have the largest pyroelectric coefficient (0.042 μC cm-2 °C-1, comparable to bulk values) at a growth temperature of 550 °C; typical to what is currently used for many deposition processes. Our results indicate that it is possible to optimize the pyroelectric response of PZT thin films by adjusting the Ti composition and the processing temperature, thereby, enabling the tailoring of material properties for optimization relative to a specific deposition process.

Digital holographic characterization of liquid microlenses array fabricated in electrode-less configuration

NASA Astrophysics Data System (ADS)

Miccio, L.; Vespini, V.; Grilli, S.; Paturzo, M.; Finizio, A.; De Nicola, S.; Ferraro, P.

2009-06-01

We show how thin liquid film on polar dielectric substrate can form an array of liquid micro-lenses. The effect is driven by the pyroelectric effect leading to a new concept in electro-wetting (EW). EW is a viable method for actuation of liquids in microfluidic systems and requires the design and fabrication of complex electrodes for suitable actuation of liquids. When compared to conventional electrowetting devices, the pyroelectric effect allowed to have an electrode-less and circuitless configuration. In our case the surface electric charge induced by the thermal stimulus is able to pattern selectively the surface wettability according to geometry of the ferroelectric domains micro-engineered into the lithium niobate crystal. We show that different geometries of liquid microlenses can be obtained showing also a tuneability of the focal lenses down to 1.6 mm. Thousand of liquid microlenses, each with 100 μm diameter, can be formed and actuated. Also different geometries such as hemi-cylindrical and toroidal liquid structures can be easily obtained. By means of a digital holography method, an accurate characterization of the micro-lenses curvature is performed and presented. The preliminary results concerning the imaging capability of the micro-lens array are also reported. Microlens array can find application in medical stereo-endoscopy, imaging, telecommunication and optical data storage too.

Effect of space exposure on pyroelectric infrared detectors

NASA Technical Reports Server (NTRS)

Robertson, James B.; Clark, Ivan O.

1991-01-01

Twenty pyroelectric type infrared detectors were flown onboard the Long Duration Exposure Facility (LDEF). The detector chips were of three different pyroelectric materials: lithium-tantalate, strontium-barium-niobate, and triglycine-sulfide. The experiment was passive; no measurements were taken during the flight. Performance of the detectors was measured before and after flight. Postflight measurements revealed that detectors made of lithium-tantalate and strontium-barium-niobate suffered no measureable loss in performance. Detectors made of triglycine-sulfide suffered complete loss of performance, but so did the control samples of the same material. Repoling of the triglycine-sulfide failed to revive the detectors.

Pyroelectricity Assisted Infrared-Laser Desorption Ionization (PAI-LDI) for Atmospheric Pressure Mass Spectrometry

NASA Astrophysics Data System (ADS)

Li, Yanyan; Ma, Xiaoxiao; Wei, Zhenwei; Gong, Xiaoyun; Yang, Chengdui; Zhang, Sichun; Zhang, Xinrong

2015-08-01

A new atmospheric pressure ionization method termed pyroelectricity-assisted infrared laser desorption ionization (PAI-LDI) was developed in this study. The pyroelectric material served as both sample target plate and enhancing ionization substrate, and an IR laser with wavelength of 1064 nm was employed to realize direct desorption and ionization of the analytes. The mass spectra of various compounds obtained on pyroelectric material were compared with those of other substrates. For the five standard substances tested in this work, LiNbO3 substrate produced the highest ion yield and the signal intensity was about 10 times higher than that when copper was used as substrate. For 1-adamantylamine, as low as 20 pg (132.2 fmol) was successfully detected. The active ingredient in (Compound Paracetamol and 1-Adamantylamine Hydrochloride Capsules), 1-adamantylamine, can be sensitively detected at an amount as low as 150 pg, when the medicine stock solution was diluted with urine. Monosaccharide and oligosaccharides in Allium Cepa L. juice was also successfully identified with PAI-LDI. The method did not require matrix-assisted external high voltage or other extra facility-assisted set-ups for desorption/ionization. This study suggested exciting application prospect of pyroelectric materials in matrix- and electricity-free atmospheric pressure mass spectrometry research.

Pyroelectric Energy Scavenging Techniques for Self-Powered Nuclear Reactor Wireless Sensor Networks

DOE PAGES

Hunter, Scott Robert; Lavrik, Nickolay V; Datskos, Panos G; ...

2014-11-01

Recent advances in technologies for harvesting waste thermal energy from ambient environments present an opportunity to implement truly wireless sensor nodes in nuclear power plants. These sensors could continue to operate during extended station blackouts and during periods when operation of the plant s internal power distribution system has been disrupted. The energy required to power the wireless sensors must be generated using energy harvesting techniques from locally available energy sources, and the energy consumption within the sensor circuitry must therefore be low to minimize power and hence the size requirements of the energy harvester. Harvesting electrical energy from thermalmore » energy sources can be achieved using pyroelectric or thermoelectric conversion techniques. Recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics in self powered wireless sensor applications and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, is outlined. This paper outlines the modeling of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-to-electrical energy conversion devices.« less

Pyroelectric Energy Scavenging Techniques for Self-Powered Nuclear Reactor Wireless Sensor Networks

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

Hunter, Scott Robert; Lavrik, Nickolay V; Datskos, Panos G

Recent advances in technologies for harvesting waste thermal energy from ambient environments present an opportunity to implement truly wireless sensor nodes in nuclear power plants. These sensors could continue to operate during extended station blackouts and during periods when operation of the plant s internal power distribution system has been disrupted. The energy required to power the wireless sensors must be generated using energy harvesting techniques from locally available energy sources, and the energy consumption within the sensor circuitry must therefore be low to minimize power and hence the size requirements of the energy harvester. Harvesting electrical energy from thermalmore » energy sources can be achieved using pyroelectric or thermoelectric conversion techniques. Recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics in self powered wireless sensor applications and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, is outlined. This paper outlines the modeling of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-to-electrical energy conversion devices.« less

Enhanced pyroelectric and piezoelectric properties of PZT with aligned porosity for energy harvesting applications† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7ta00967d Click here for additional data file.

PubMed Central

Zhang, Yan; Xie, Mengying; Roscow, James; Bao, Yinxiang; Zhou, Kechao

2017-01-01

This paper demonstrates the significant benefits of exploiting highly aligned porosity in piezoelectric and pyroelectric materials for improved energy harvesting performance. Porous lead zirconate (PZT) ceramics with aligned pore channels and varying fractions of porosity were manufactured in a water-based suspension using freeze-casting. The aligned porous PZT ceramics were characterized in detail for both piezoelectric and pyroelectric properties and their energy harvesting performance figures of merit were assessed parallel and perpendicular to the freezing direction. As a result of the introduction of porosity into the ceramic microstructure, high piezoelectric and pyroelectric harvesting figures of merits were achieved for porous freeze-cast PZT compared to dense PZT due to the reduced permittivity and volume specific heat capacity. Experimental results were compared to parallel and series analytical models with good agreement and the PZT with porosity aligned parallel to the freezing direction exhibited the highest piezoelectric and pyroelectric harvesting response; this was a result of the enhanced interconnectivity of the ferroelectric material along the poling direction and reduced fraction of unpoled material that leads to a higher polarization. A complete thermal energy harvesting system, composed of a parallel-aligned PZT harvester element and an AC/DC converter, was successfully demonstrated by charging a storage capacitor. The maximum energy density generated by the 60 vol% porous parallel-connected PZT when subjected to thermal oscillations was 1653 μJ cm–3, which was 374% higher than that of the dense PZT with an energy density of 446 μJ cm–3. The results are beneficial for the design and manufacture of high performance porous pyroelectric and piezoelectric materials in devices for energy harvesting and sensor applications. PMID:28580142

Enhanced pyroelectric and piezoelectric properties of PZT with aligned porosity for energy harvesting applications.

PubMed

Zhang, Yan; Xie, Mengying; Roscow, James; Bao, Yinxiang; Zhou, Kechao; Zhang, Dou; Bowen, Chris R

2017-04-14

This paper demonstrates the significant benefits of exploiting highly aligned porosity in piezoelectric and pyroelectric materials for improved energy harvesting performance. Porous lead zirconate (PZT) ceramics with aligned pore channels and varying fractions of porosity were manufactured in a water-based suspension using freeze-casting. The aligned porous PZT ceramics were characterized in detail for both piezoelectric and pyroelectric properties and their energy harvesting performance figures of merit were assessed parallel and perpendicular to the freezing direction. As a result of the introduction of porosity into the ceramic microstructure, high piezoelectric and pyroelectric harvesting figures of merits were achieved for porous freeze-cast PZT compared to dense PZT due to the reduced permittivity and volume specific heat capacity. Experimental results were compared to parallel and series analytical models with good agreement and the PZT with porosity aligned parallel to the freezing direction exhibited the highest piezoelectric and pyroelectric harvesting response; this was a result of the enhanced interconnectivity of the ferroelectric material along the poling direction and reduced fraction of unpoled material that leads to a higher polarization. A complete thermal energy harvesting system, composed of a parallel-aligned PZT harvester element and an AC/DC converter, was successfully demonstrated by charging a storage capacitor. The maximum energy density generated by the 60 vol% porous parallel-connected PZT when subjected to thermal oscillations was 1653 μJ cm -3 , which was 374% higher than that of the dense PZT with an energy density of 446 μJ cm -3 . The results are beneficial for the design and manufacture of high performance porous pyroelectric and piezoelectric materials in devices for energy harvesting and sensor applications.

Preparation and Characterization of BaTiO3-PbZrTiO3 Coating for Pyroelectric Energy Harvesting

NASA Astrophysics Data System (ADS)

Raghavendra, R. M.; Praneeth, K. P. S. S.; Dutta, Soma

2017-01-01

Harvesting energy from waste heat is a promising field of research as there are significant energy recovery opportunities from various waste thermal energy sources. The present study reports pyroelectric energy harvesting using thick film prepared from a (x)BaTiO3-(1 - x)PbZr0.52Ti0.48O3 (BT-PZT) solid solution. The developed BT-PZT system is engineered to tune the ferro to paraelectric phase transition temperature of it in-between the phase transition temperature of BaTiO3 (393 K) and PbZrTiO3 (573 K) with higher pyroelectric figure-of-merit (FOM). The temperature-dependent dielectric behavior of the material has revealed the ferro- to paraelectric phase transition at 427 K with a maximum dielectric constant of 755. The room-temperature (298 K) pyroelectric coefficient (Pi) of the material was obtained as 738.63 μC/m2K which has yielded a significantly high FOM of 1745.8 J m-3 K-2. The enhancement in pyroelectric property is attributed to the morphotopic phase transition between tetragonal and rhombohedral PZT phases in the BT-PZT system. The developed BT-PZT system is capable of generating a power output of 1.3 mW/m2 near the Curie temperature with a constant rate (0.11 K/s) of heating. A signal conditioning circuit has been developed to rectify the time-varying current and voltage signals obtained from the harvester during heating cycles. The output voltage generated by the pyroelectric harvester has been stored in a capacitor for powering wearable electronics.

Pyroelectric effect and lattice thermal conductivity of InN/GaN heterostructures

NASA Astrophysics Data System (ADS)

Hansdah, Gopal; Sahoo, Bijay Kumar

2018-06-01

The built-in-polarization (BIP) of InN/GaN heterostructures enhances Debye temperature, phonon mean free path and thermal conductivity of the heterostructure at room temperature. The variation of thermal conductivities (kp: including polarization mechanism and k: without polarization mechanism) with temperature predicts the existence of a transition temperature (Tp) between primary and secondary pyroelectric effect. Below Tp, kp is lower than k; while above Tp, kp is significantly contributed from BIP mechanism due to thermal expansion. A thermodynamic theory has been proposed to explain the result. The room temperature thermal conductivity of InN/GaN heterostructure with and without polarization is respectively 32 and 48 W m-1 K-1. The temperature Tp and room temperature pyroelectric coefficient of InN has been predicted as 120 K and -8.425 μC m-2 K-1, respectively which are in line with prior literature studies. This study suggests that thermal conductivity measurement in InN/GaN heterostructures can help to understand the role of phonons in pyroelectricity.

Properties of reactively sputtered AlxNy thin films for pyroelectric detectors

NASA Astrophysics Data System (ADS)

Calvano, Nicholas; Chrostoski, Philip; Voshell, Andrew; Braithwaite, Keesean; Rana, Mukti

2017-08-01

Uncooled infrared detectors are utilized in various radiometric devices and cameras because of their low cost, light weight and performance. A pyroelectric detector is a class of uncooled infrared detector whose polarization changes with change in temperature. Infrared radiation from objects falls on top of the sensing layer of the pyroelectric detector and the absorbed radiation causes the temperature of the sensing layer to change. This work describes the deposition and characterization of AlxNy thin films for using them as pyroelectric detector's sensing material. To test the sensitivity of infrared detection or pyroelectric effect of AlxNy thin films, capacitors of various sizes were fabricated. The diameter of the electrodes for capacitor used during testing of the device was 1100 μm while the distances between these two electrodes was 1100 μm. On a 3-inch diameter cleaned silicon wafer, 100 nm thick AlxNy thin films were deposited by radio frequency (RF) sputtering from an Al target in Ar: N2 environment. On top of this, a 100-nm thick Au layer was deposited and lifted off by using conventional photo lithography to form the electrodes of capacitors. All the layers were deposited by RF sputtering at room temperature. The thin film samples were annealed at 700 °C in N2 environment for 10 minutes. X-ray diffraction showed the films are poly-crystalline with peaks in (100), (002) and (101) directions. When the temperature varied between 303 K to 353 K, the pyroelectric coefficient was increased from 8.60 × 10-9 C/m2K to 3.76 × 10-8C/m2K with a room temperature pyroelectric coefficient value of 8.60×10-9C/m2K. The non-annealed films were found to be transparent between the wavelengths of 600 nm to 3000 nm. The refraction coefficient was found to be varied between 2.0 and 2.2 while the extinction coefficient was found to be zero. The optical bandgap determined using Tauc's equation was 1.65 eV.

Lightweight biometric detection system for human classification using pyroelectric infrared detectors.

PubMed

Burchett, John; Shankar, Mohan; Hamza, A Ben; Guenther, Bob D; Pitsianis, Nikos; Brady, David J

2006-05-01

We use pyroelectric detectors that are differential in nature to detect motion in humans by their heat emissions. Coded Fresnel lens arrays create boundaries that help to localize humans in space as well as to classify the nature of their motion. We design and implement a low-cost biometric tracking system by using off-the-shelf components. We demonstrate two classification methods by using data gathered from sensor clusters of dual-element pyroelectric detectors with coded Fresnel lens arrays. We propose two algorithms for person identification, a more generalized spectral clustering method and a more rigorous example that uses principal component regression to perform a blind classification.

Roto-flexoelectric coupling impact on the phase diagrams and pyroelectricity of thin SrTiO 3 films

DOE PAGES

Morozovska, Anna N.; Eliseev, Eugene A.; Bravina, Svetlana L.; ...

2012-09-20

The influence of the flexoelectric and rotostriction coupling on the phase diagrams of ferroelastic-quantum paraelectric SrTiO 3 films was studied using Landau-Ginzburg-Devonshire (LGD) theory. We calculated the phase diagrams in coordinates temperature - film thickness for different epitaxial misfit strains. Tensile misfit strains stimulate appearance of the spontaneous out-of-plane structural order parameter (displacement vector of an appropriate oxygen atom from its cubic position) in the structural phase. For compressive misfit strains are stimulated because of the spontaneous in-plane structural order parameter. Furthermore, gradients of the structural order parameter components, which inevitably exist in the vicinity of film surfaces due tomore » the termination and symmetry breaking, induce improper polarization and pyroelectric response via the flexoelectric and rotostriction coupling mechanism. Flexoelectric and rotostriction coupling results in the roto-flexoelectric field that is antisymmetric inside the film, small in the central part of the film, where the gradients of the structural parameter are small, and maximal near the surfaces, where the gradients of the structural parameter are highest. The field induces improper polarization and pyroelectric response. Penetration depths of the improper phases (both polar and structural) can reach several nm from the film surfaces. An improper pyroelectric response of thin films is high enough to be registered with planar-type electrode configurations by conventional pyroelectric methods.« less

Photothermal Spectroscopy Using a Pyroelectric Thin Film Detector.

DTIC Science & Technology

1983-09-16

FRD-fi34 291 PHOTOTHERNAL SPECTROSCOPYIJ SING A PYROELECTRIC THIN- I/IT, F FILM DETECTOR(J) INTERNATIONAL BUSINESS MACHINES CORP I SAN JOSE CALIF SAN...Coufal N01-1C01 9, PERFORMING3 ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK International Business Machines Corp. AE OKUI UBR San Jose

Modeling of a honeycomb-shaped pyroelectric energy harvester for human body heat harvesting

NASA Astrophysics Data System (ADS)

Kim, Myoung-Soo; Jo, Sung-Eun; Ahn, Hye-Rin; Kim, Yong-Jun

2015-06-01

Pyroelectric conversion can be used for thermal energy harvesting in lieu of thermoelectric conversion. In the case of human body energy harvesting, the general pyroelectric energy harvester (PEH) cannot be applied because the weak body heat can hardly penetrate the protecting layer to reach the pyroelectric material. This paper presents the realization of a honeycomb-shaped PEH (H-PEH) and a modeling method of the electrode and hole areas. The fabricated H-PEH successfully generated electrical energy using human body heat. The H-PEH with a 1:1.5 electrode-and-hole area ratio showed the best performance. To verify the human energy harvesting, we evaluated the characteristics of conventional PEH and H-PEH when body heat was used as a heat source. The maximum power of the H-PEH was 0.06 and 0.16 μW at wind velocities of 2 and 4 m s-1, respectively. These output power values of the H-PEH were 200 and 224% larger than those of the PEH, respectively, according to the wind velocity.

The theory and design of piezoelectric/pyroelectric polymer film sensors for biomedical engineering applications.

PubMed

Brown, L F

1989-01-01

The unique properties of piezoelectric/pyroelectric polymers offer many new opportunities for biomedical engineering sensor applications. Since their discovery nearly 20 years ago, the polymer films have been used for many novel switching and sensor applications. Despite the prodigious exposure from many recent publications describing piezo film applications, methods of sensor fabrication and circuit interfacing still elude most engineers. This paper is presented as a tutorial guide to applying piezo polymers to biomedical engineering applications. A review of the fundamentals of piezoelectricity/pyroelectricity in piezo polymers is first presented. Their material properties are contrasted with piezoelectric ceramic materials. Some advantages and disadvantages of the films for biomedical sensors are discussed. Specific details on the fabrication of piezo film sensors are presented. Methods are described for forming, cutting, and mounting film sensors, and making lead connections. A brief discussion of equivalent circuit models for the design and simulation of piezoelectric/pyroelectric sensors is included, as well as common circuit interface techniques. Finally, several sources are recommended for further information on a variety of biomedical sensor applications.

Spontaneous Polarization in Bio-organic Materials Studied by Scanning Pyroelectric Microscopy (SPEM) and Second Harmonic Generation Microscopy (SHGM)

NASA Astrophysics Data System (ADS)

Putzeys, T.; Wübbenhorst, M.; van der Veen, M. A.

2015-06-01

Bio-organic materials such as bones, teeth, and tendon generally show nonlinear optical (Masters and So in Handbook of Biomedical Nonlinear Optical Microscopy, 2008), pyro- and piezoelectric (Fukada and Yasuda in J Phys Soc Jpn 12:1158, 1957) properties, implying a permanent polarization, the presence of which can be rationalized by describing the growth of the sample and the creation of a polar axis according to Markov's theory of stochastic processes (Hulliger in Biophys J 84:3501, 2003; Batagiannis et al. in Curr Opin Solid State Mater Sci 17:107, 2010). Two proven, versatile techniques for probing spontaneous polarization distributions in solids are scanning pyroelectric microscopy (SPEM) and second harmonic generation microscopy (SHGM). The combination of pyroelectric scanning with SHG-microscopy in a single experimental setup leading to complementary pyroelectric and nonlinear optical data is demonstrated, providing us with a more complete image of the polarization in organic materials. Crystals consisting of a known polar and hyperpolarizable material, CNS (4-chloro-4-nitrostilbene) are used as a reference sample, to verify the functionality of the setup, with both SPEM and SHGM images revealing the same polarization domain information. In contrast, feline and human nails exhibit a pyroelectric response, but a second harmonic response is absent for both keratin containing materials, implying that there may be symmetry-allowed SHG, but with very inefficient second harmonophores. This new approach to polarity detection provides additional information on the polar and hyperpolar nature in a variety of (bio) materials.

Electrostatic force microscopy as a broadly applicable method for characterizing pyroelectric materials.

PubMed

Martin-Olmos, Cristina; Stieg, Adam Z; Gimzewski, James K

2012-06-15

A general method based on the combination of electrostatic force microscopy with thermal cycling of the substrate holder is presented for direct, nanoscale characterization of the pyroelectric effect in a range of materials and sample configurations using commercial atomic force microscope systems. To provide an example of its broad applicability, the technique was applied to the examination of natural tourmaline gemstones. The method was validated using thermal cycles similar to those experienced in ambient conditions, where the induced pyroelectric response produced localized electrostatic surface charges whose magnitude demonstrated a correlation with the iron content and heat dissipation of each gemstone variety. In addition, the surface charge was shown to persist even at thermal equilibrium. This behavior is attributed to constant, stochastic cooling of the gemstone surface through turbulent contact with the surrounding air and indicates a potential utility for energy harvesting in applications including environmental sensors and personal electronics. In contrast to previously reported methods, ours has a capacity to carry out such precise nanoscale measurements with little or no restriction on the sample of interest, and represents a powerful new tool for the characterization of pyroelectric materials and devices.

Electrostatic force microscopy as a broadly applicable method for characterizing pyroelectric materials

NASA Astrophysics Data System (ADS)

Martin-Olmos, Cristina; Stieg, Adam Z.; Gimzewski, James K.

2012-06-01

A general method based on the combination of electrostatic force microscopy with thermal cycling of the substrate holder is presented for direct, nanoscale characterization of the pyroelectric effect in a range of materials and sample configurations using commercial atomic force microscope systems. To provide an example of its broad applicability, the technique was applied to the examination of natural tourmaline gemstones. The method was validated using thermal cycles similar to those experienced in ambient conditions, where the induced pyroelectric response produced localized electrostatic surface charges whose magnitude demonstrated a correlation with the iron content and heat dissipation of each gemstone variety. In addition, the surface charge was shown to persist even at thermal equilibrium. This behavior is attributed to constant, stochastic cooling of the gemstone surface through turbulent contact with the surrounding air and indicates a potential utility for energy harvesting in applications including environmental sensors and personal electronics. In contrast to previously reported methods, ours has a capacity to carry out such precise nanoscale measurements with little or no restriction on the sample of interest, and represents a powerful new tool for the characterization of pyroelectric materials and devices.

3D-Printing of inverted pyramid suspending architecture for pyroelectric infrared detectors with inhibited microphonic effect

NASA Astrophysics Data System (ADS)

Xu, Qing; Zhao, Xiangyong; Li, Xiaobing; Deng, Hao; Yan, Hong; Yang, Linrong; Di, Wenning; Luo, Haosu; Neumann, Norbert

2016-05-01

A sensitive chip with ultralow dielectric loss based on Mn doped PMNT (71/29) has been proposed for high-end pyroelectric devices. The dielectric loss at 1 kHz is 0.005%, one order lower than the minimum value reported so far. The detective figure of merit (Fd) is up to 92.6 × 10-5 Pa-1/2 at 1 kHz and 53.5 × 10-5 Pa-1/2 at 10 Hz, respectively. In addition, an inverted pyramid suspending architecture for supporting the sensitive chip has been designed and manufactured by 3D printing technology. The combination of this sensitive chip and the proposed suspending architecture largely enhances the performance of the pyroelectric detectors. The responsivity and specific detectivity are 669,811 V/W and 3.32 × 109 cm Hz1/2/W at 10 Hz, respectively, 1.9 times and 1.5 times higher than those of the highest values in literature. Furthermore, the microphonic effect can be largely inhibited according to the theoretical and experimental analysis. This architecture will have promising applications in high-end and stable pyroelectric infrared detectors.

Note: Development of target changeable palm-top pyroelectric x-ray tube

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

Imashuku, Susumu; Kawai, Jun

2012-01-15

A target changeable palm-top size x-ray tube was realized using pyroelectric crystal and detachable vacuum flanges. The target metals can be exchanged easily by attaching them on the brass stage with carbon tape. When silver and titanium palates (area: 10 mm{sup 2}) were used as targets, silver L{alpha} and titanium K lines were clearly observed by bombarding electrons on the targets for 90 s. The intensities were the same or higher than those of previously reported pyroelectric x-ray tubes. Chromium, iron, nickel, copper, and zinc K lines in the x-ray tube (stainless steel and brass) disappeared by replacing the brassmore » stage and the stainless steel vacuum flange with a carbon stage and a glass tube, respectively.« less

Recent advances in laser-driven neutron sources

NASA Astrophysics Data System (ADS)

Alejo, A.; Ahmed, H.; Green, A.; Mirfayzi, S. R.; Borghesi, M.; Kar, S.

2016-11-01

Due to the limited number and high cost of large-scale neutron facilities, there has been a growing interest in compact accelerator-driven sources. In this context, several potential schemes of laser-driven neutron sources are being intensively studied employing laser-accelerated electron and ion beams. In addition to the potential of delivering neutron beams with high brilliance, directionality and ultra-short burst duration, a laser-driven neutron source would offer further advantages in terms of cost-effectiveness, compactness and radiation confinement by closed-coupled experiments. Some of the recent advances in this field are discussed, showing improvements in the directionality and flux of the laser-driven neutron beams.

Systematic Study of Pyroelectricity. Light Scattering and Pyroelectricity in Ferroelectrics

DTIC Science & Technology

1976-04-01

6 compares the experimental X(Z:)X spectrum near 430 cm with the prediction of Eq. (2) to which a slowly varying background has been...Molecular field theory, Triglycine sulfate, Potassium niobate, Raman scattering, vidicons 20. ABSTRACT (Continue on reverie tide II neceeeary and...ray and neutron scattering studies and which provides the starting point for the generalized molecular field theory of ferroelectricity proposed

Improved detectivity of pyroelectric detectors

NASA Technical Reports Server (NTRS)

Marshall, D. E.; Gelpey, J. C.; Marciniec, J. W.; Chiang, A. M.; Maciolek, R. B.

1978-01-01

High detectivity single-element SBN pyroelectric detectors were fabricated. The theory and technology developments related to improved detector performance were identified and formulated. Improved methods of material characterization, thinning, mounting, blackening and amplifier matching are discussed. Detectors with detectivities of 1.3 x 10 to the 9th power square root of Hz/watt at 1 Hz are reported. Factors limiting performance and recommendations for future work are discussed.

Characterisation and Modelling of Meshed Electrodes on Free Standing Polyvilylidene Difluoride (PVDF) Films for Enhanced Pyroelectric Energy Harvesting.

PubMed

Zabek, Daniel; Taylor, John; Bowen, Chris

2016-09-05

Flexible pyroelectric energy generators provide unique features for harvesting temperature fluctuations which can be effectively enhanced using meshed electrodes that improve thermal conduction, convection and radiation into the pyroelectric. In this paper, thermal radiation energy is continuously harvested with pyroelectric free standing Polyvilylidene Difluoride (PVDF) films over a large number of heat heat cycles using a novel micro-sized symmetrical patterned meshed electrode. It is shown that, for the meshed electrode geometries considered in this work, the polarisation-field (P-E), current-field (I-E) characteristics and device capacitance are unaffected since the fringing fields were generally small; this is verified using numerical simulations and comparison with experimental measurements. The use of meshed electrodes has been shown to significantly improve both the open circuit voltage (16 V to 59 V) and closed-circuit current (9 nA to 32 nA). The pyroelectric alternating current (AC) is rectified for direct current (DC) storage and 30% reduction in capacitor charging time is achieved by using the optimum meshed electrodes. The use of meshed electrodes on ferroelectric materials provides an innovative route to improve their performance in applications such as wearable devices, novel flexible sensors and large scale pyroelectric energy harvesters.hese instructions give you guidelines for preparing papers for IEEE Transactions and Journals. Use this document as a template if you are using Microsoft Word 6.0 or later. Otherwise, use this document as an instruction set. The electronic file of your paper will be formatted further at IEEE. Paper titles should be written in uppercase and lowercase letters, not all uppercase. Avoid writing long formulas with subscripts in the title; short formulas that identify the elements are fine (e.g., "Nd-Fe-B"). Do not write "(Invited)" in the title. Full names of authors are preferred in the author field, but are not required. Put a space between authors' initials. Define all symbols used in the abstract. Do not cite references in the abstract. Do not delete the blank line immediately above the abstract; it sets the footnote at the bottom of this column.

Growth of 4-(dimethylamino) benzaldehyde doped triglycine sulphate single crystals and its characterization

NASA Astrophysics Data System (ADS)

Rai, Chitharanjan; Sreenivas, K.; Dharmaprakash, S. M.

2009-11-01

Single crystals of triglycine sulphate (TGS) doped with 1 mol% of 4-(dimethylamino) benzaldehyde (DB) have been grown from aqueous solution at ambient temperature by slow evaporation technique. The effect of dopant on the crystal growth and dielectric, pyroelectric and mechanical properties of TGS crystal have been investigated. X-ray powder diffraction pattern for pure and doped TGS was collected to determine the lattice parameters. FTIR spectra were employed to confirm the presence of 4-(dimethylamino) benzaldehyde in TGS crystal, qualitatively. The dielectric permittivity has been studied as a function of temperature by cooling the sample at a rate of 1 °C/min. An increase in the Curie temperature Tc=51 °C (for pure TGS, Tc=48.5 °C) and decrease in maximum permittivity has been observed for doped TGS when compared to pure TGS crystal. Pyroelectric studies on doped TGS were carried out to determine pyroelectric coefficient. The Vickers's hardness of the doped TGS crystals along (0 1 0) face is higher than that of pure TGS crystal for the same face. Domain patterns on b-cut plates were observed using scanning electron microscope. The low dielectric constant, higher pyroelectric coefficient and higher value of hardness suggest that doped TGS crystals could be a potential material for IR detectors.

Improved Ambient Pressure Pyroelectric Ion Source

NASA Technical Reports Server (NTRS)

Beegle, Luther W.; Kim, Hugh I.; Kanik, Isik; Ryu, Ernest K.; Beckett, Brett

2011-01-01

The detection of volatile vapors of unknown species in a complex field environment is required in many different applications. Mass spectroscopic techniques require subsystems including an ionization unit and sample transport mechanism. All of these subsystems must have low mass, small volume, low power, and be rugged. A volatile molecular detector, an ambient pressure pyroelectric ion source (APPIS) that met these requirements, was recently reported by Caltech researchers to be used in in situ environments.

Functional Cementitious Composites for Pyroelectric Applications

NASA Astrophysics Data System (ADS)

Srikanth, K. S.; Patel, Satyanarayan; Vaish, Rahul

2018-04-01

We have synthesized Ba0.85Ca0.15Zr0.10Ti0.88Sn0.02O3 (BCZT-Sn)-cement composites. They were prepared as BCZT-Sn to cement ratios of 90-10% and 85-15% by weight. The larger fraction of BCZT-Sn ceramic was used to minimize the losses in the composites. The open circuit voltage was found to be 0.75 V, 0.56 V and 0.4 V for pure, 10% and 15% cement composites, respectively. The voltage and current were also measured across resistances of 1 and 3 MΩ, and the obtained voltages were lower for composites compared to pure BCZT-Sn. Nonetheless, they remain promising candidates over traditional pyroelectric materials for device applications owing to their advantages, such as (1) these composites can be made without any sintering process and (2) they can be made in any shape and size. We also studied relative permittivity, which influences performance of pyroelectric devices.

Ferroelectriclike and pyroelectric behavior of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

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

Shri Prakash, B.; Varma, K. B. R.

2007-02-19

A ferroelectriclike hysteresis loop was obtained at room temperature for CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) ceramic. The remnant polarization and coercive field for 1100 deg. C/5 h sintered CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics were 0.063 {mu}C/cm{sup 2} and 195 V/cm, respectively. Remnant polarization increased while the coercive field decreased with increase in sintering temperature/duration, implying that these were microstructural dependent. The observation of the hysteresis loop for CCTO ceramic was corroborated by its pyroelectric behavior, and the pyroelectric current at room temperature was -0.0028 nA. These findings were attributed to the presence of mixed-valent Ti ions, apart from off centermore » displacement of Ti ions in TiO{sub 6} octahedra.« less

Light-induced pyroelectric effect as an effective approach for ultrafast ultraviolet nanosensing

NASA Astrophysics Data System (ADS)

Wang, Zhaona; Yu, Ruomeng; Pan, Caofeng; Li, Zhaoling; Yang, Jin; Yi, Fang; Wang, Zhong Lin

2015-09-01

Zinc oxide is potentially a useful material for ultraviolet detectors; however, a relatively long response time hinders practical implementation. Here by designing and fabricating a self-powered ZnO/perovskite-heterostructured ultraviolet photodetector, the pyroelectric effect, induced in wurtzite ZnO nanowires on ultraviolet illumination, has been utilized as an effective approach for high-performance photon sensing. The response time is improved from 5.4 s to 53 μs at the rising edge, and 8.9 s to 63 μs at the falling edge, with an enhancement of five orders in magnitudes. The specific detectivity and the responsivity are both enhanced by 322%. This work provides a novel design to achieve ultrafast ultraviolet sensing at room temperature via light-self-induced pyroelectric effect. The newly designed ultrafast self-powered ultraviolet nanosensors may find promising applications in ultrafast optics, nonlinear optics, optothermal detections, computational memories and biocompatible optoelectronic probes.

Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates and Method Relating Thereto

NASA Technical Reports Server (NTRS)

Simpson, Joycelyn O. (Inventor); St.Claire, Terry L. (Inventor)

2002-01-01

A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared, This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers, acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors. in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches. adjustable fresnel lenses, speakers, tactile sensors, weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 100 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrates; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates

NASA Technical Reports Server (NTRS)

Simpson, Joycely O. (Inventor); St.Clair, Terry L. (Inventor)

1999-01-01

A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers. acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors, in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors. weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 1000 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

Porous Ba0.85Ca0.15Zr0.1Ti0.9O3 Ceramics for Pyroelectric Applications

NASA Astrophysics Data System (ADS)

Sharma, Moolchand; Singh, V. P.; Singh, Shatrughan; Azad, Puneet; Ilahi, Bouraoui; Madhar, Niyaz Ahamad

2018-05-01

Porous Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ferroelectric ceramics were fabricated using a solid-state reaction consisting of BCZT and poly(methyl methacrylate)(PMMA) (2%, 4%, 8% and 10% by wt.%) as a pore former. By increasing the PMMA content from 0% to 10%, porosity increased from 8% to 29%. It was found that the dielectric constant (ɛ r ) decreased and the dielectric loss (tanδ) increased with increasing porosity. At 29% porosity, ɛ r of the BCZT was found to decrease more, from 3481 to 1117 at 5 kHz and at room temperature. The dielectric constant and volume-specific heat capacity decreased with the increase in porosity which ultimately improved the pyroelectric figure-of-merits (FOMs). Further, the pyroelectric FOMs were estimated and found to be improved at optimum porosity.

Nanotubes, nanorods and nanowires having piezoelectric and/or pyroelectric properties and devices manufactured therefrom

DOEpatents

Russell, Thomas P [Amherst, MA; Lutkenhaus, Jodie [Wethersfield, CT

2012-05-15

Disclosed herein is a device comprising a pair of electrodes; and a nanotube, a nanorod and/or a nanowire; the nanotube, nanorod and/or nanowire comprising a piezoelectric and/or pyroelectric polymeric composition; the pair of electrodes being in electrical communication with opposing surfaces of the nanotube, nanorod and/or a nanowire; the pair of electrodes being perpendicular to a longitudinal axis of the nanotube, nanorod and/or a nanowire.

Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates and Method Relating Thereto

NASA Technical Reports Server (NTRS)

Simpson, Joycelyn O. (Inventor); St.Clair, Terry L. (Inventor)

1995-01-01

Production of an electric voltage in response to mechanical excitation (piezoelectricity) or thermal excitation (pyroelectricity) requires a material to have a preferred dipole orientation in its structure. This preferred orientation or polarization occurs naturally in some crystals such as quartz and can be induced into some ceramic and polymeric materials by application of strong electric or mechanical fields. For some materials, a combination of mechanical and electrical orientation is necessary to completely polarize the material. The only commercially available piezoelectric polymer is poly(vinylidene fluoride) (PVF2). However, this polymer has material and process limitations which prohibit its use in numerous device applications where thermal stability is a requirement. By the present invention, thermally stable, piezoelectric and pyroelectric polymeric substrates were prepared from polymers having a softening temperature greater than 1000C. A metal electrode material is deposited onto the polymer substrate and several electrical leads are attached to it. The polymer substrate is heated in a low dielectric medium to enhance molecular mobility of the polymer chains. A voltage is then applied to the polymer substrate inducing polarization. The voltage is then maintained while the polymer substrate is cooled 'freezing in' the molecular orientation. The novelty of the invention resides in the process of preparing the piezoelectric and pyroelectric polymeric substrate. The nonobviousness of the invention is found in heating the polymeric substrate in a low dielectric medium while applying a voltage.

Effect of Li doping on the electric and pyroelectric properties of ZnO thin films

NASA Astrophysics Data System (ADS)

Trinca, L. M.; Galca, A. C.; Boni, A. G.; Botea, M.; Pintilie, L.

2018-01-01

Un-doped ZnO (UDZO) and Li-doped ZnO (LZO) polycrystalline thin films were grown on platinized silicon by pulsed laser deposition (PLD). The electrical properties were investigated on as-grown and annealed UDZO and LZO films with capacitor configuration, using top and bottom platinum electrodes. In the case of the as-grown films it was found that the introduction of Li increases the resistivity of ZnO and induces butterfly shape in the C-V characteristic, suggesting ferroelectric-like behavior in LZO films. The properties of LZO samples does not significantly changes after thermal annealing while the properties of UDZO samples show significant changes upon annealing, manifested in a butterfly shape of the C-V characteristic and resistive-like switching. However, the butterfly shape disappears if long delay time is used in the C-V measurement, the characteristic remaining non-linear. Pyroelectric signal could be measured only on annealed films. Comparing the UDZO results with those obtained in the case of Li:ZnO, it was found that the pyroelectric properties are considerably enhanced by Li doping, leading to pyroelectric signal with about one order of magnitude larger at low modulation frequencies than for un-doped samples. Although the results of this study hint towards a ferroelectric-like behavior of Li doped ZnO, the presence of real ferroelectricity in this material remains controversial.

Flexible Pb(Zr0.52Ti0.48)O3 Films for a Hybrid Piezoelectric-Pyroelectric Nanogenerator under Harsh Environments.

PubMed

Ko, Young Joon; Kim, Dong Yeong; Won, Sung Sik; Ahn, Chang Won; Kim, Ill Won; Kingon, Angus I; Kim, Seung-Hyun; Ko, Jae-Hyeon; Jung, Jong Hoon

2016-03-01

In spite of extremely high piezoelectric and pyroelectric coefficients, there are few reports on flexible ferroelectric perovskite film based nanogenerators (NGs). Here, we report the successful growth of a flexible Pb(Zr0.52Ti0.48)O3 (PZT) film and its application to hybrid piezoelectric-pyroelectric NG. A highly flexible Ni-Cr metal foil substrate with a conductive LaNiO3 bottom electrode enables the growth of flexible PZT film having high piezoelectric (140 pC/N) and pyroelectric (50 nC/cm(2)K) coefficients at room temperature. The flexible PZT-based NG effectively scavenges mechanical vibration and thermal fluctuation from sources ranging from the human body to the surroundings such as wind. Furthermore, it stably generates electric current even at elevated temperatures of 100 °C, relative humidity of 70%, and pH of 13 by virtue of its high Curie temperature and strong resistance for water and base. As proof of power generation under harsh environments, we demonstrate the generation of extremely high current at the exhaust pipe of a car, where hot CO and CO2 gases are rapidly expelled to air. This work expands the application of flexible PZT film-based NG for the scavenging mechanical vibration and thermal fluctuation energies even at extreme conditions.

Tunable liquid microlens array driven by pyroelectric effect: full interferometric characterization

NASA Astrophysics Data System (ADS)

Miccio, Lisa; Grilli, Simonetta; Vespini, Veronica; Ferraro, Pietro

2008-09-01

Liquid lenses with adjustable focal length are of great interest in the field of microfluidic devices. They are, usually, realized by electrowetting effect after electrodes patterning on a hydrofobic substrate. Applications are possible in many fields ranging from commercial products such as digital cameras to biological cell sorting. We realized an open array of liquid lenses with adjustable focal length without electrode patterning. We used a z-cut Lithium Niobate crystal (LN) as substrate and few microliters of an oily substance to obtain the droplets array. The spontaneous polarization of LN crystals is reversed by the electric field poling process, thus enabling the realization of periodically poled LN (PPLN) crystals. The substrate consists of a two-dimensional square array of reversed domains with a period around 200 μm. Each domain presents an hexagonal geometry due to the crystal structure. PPLN is first covered by a thin and homogeneous layer of the above mentioned liquid and therefore its temperature is changed by means of a digitally controlled hot plate. During heating and cooling process there is a rearrangement of the liquid layer until it reaches the final topography. Lenses formation is due to the superficial tension changing at the liquid-solid interface by means of the pyroelectric effect. Such effect allows to create a two-dimensional lens pattern of tunable focal length without electrodes. The temporal evolution of both shape and focal length lenses are quantitatively measured by Digital Holographic Microscopy. Array imaging properties and quantitative analysis of the lenses features and aberrations are presented.

Modeling of Firn Compaction for Estimating Ice-Sheet Mass Change from Observed Ice-Sheet Elevation Change

NASA Technical Reports Server (NTRS)

Li, Jun; Zwally, H. Jay

2011-01-01

Changes in ice-sheet surface elevation are caused by a combination of ice-dynamic imbalance, ablation, temporal variations in accumulation rate, firn compaction and underlying bedrock motion. Thus, deriving the rate of ice-sheet mass change from measured surface elevation change requires information on the rate of firn compaction and bedrock motion, which do not involve changes in mass, and requires an appropriate firn density to associate with elevation changes induced by recent accumulation rate variability. We use a 25 year record of surface temperature and a parameterization for accumulation change as a function of temperature to drive a firn compaction model. We apply this formulation to ICESat measurements of surface elevation change at three locations on the Greenland ice sheet in order to separate the accumulation-driven changes from the ice-dynamic/ablation-driven changes, and thus to derive the corresponding mass change. Our calculated densities for the accumulation-driven changes range from 410 to 610 kg/cu m, which along with 900 kg/cu m for the dynamic/ablation-driven changes gives average densities ranging from 680 to 790 kg/cu m. We show that using an average (or "effective") density to convert elevation change to mass change is not valid where the accumulation and the dynamic elevation changes are of opposite sign.

Applications of Piezoelectric and Pyroelectric Thin Films: Opportunities for Langmuir-Blodgett Technology.

DTIC Science & Technology

1984-12-31

LII IH"L 5 B 1.4 1111.6 MICROCOPY RESOLUTION TEST CHART SECURITY CLASSIFICATION OF THIS PAGE (MS’ien Dare Itere d) RED DSTUC ONS REPORT ...DOCUMENTATION PAGE BEFORE COMPLETIG FORM R NUMER . GOVT ACCESSION NO 5. RECIPIENT’S CATALOG iUMBER • TR-09 4. TITLE ( nd Subttle) S. TYPE OF REPORT A PERIOD...COVERELs Applications of Piezoelectric and Pyroelectric Technical Report -Interim Thin Films: Opportunities for Langmuir-Blodgett Technology 6. PERFORMING

Systematic Study of Pyroelectricity. Applications of Pyroelectric Materials.

DTIC Science & Technology

1979-07-01

those now in use are not likely to be found within the well-known families of ferroelectrics (e.g. perovskites or triglycine sulfate derivatives) or by...renewal of interest in this approach , it would appear not to be applicable to a large class of ferroelectrics, including the perovskites , where the...neutron scattering experiments6 on BaTiO 3 , KTaO3 , IKTa Nb 0 (KTN), and SrTiO Additional evidence for disorder in the X l-x 3 perovskites nas been

UV scale calibration transfer from an improved pyroelectric detector standard to field UV-A meters and 365 nm excitation sources

NASA Astrophysics Data System (ADS)

Eppeldauer, G. P.; Podobedov, V. B.; Cooksey, C. C.

2017-05-01

Calibration of the emitted radiation from UV sources peaking at 365 nm, is necessary to perform the ASTM required 1 mW/cm2 minimum irradiance in certain military material (ships, airplanes etc) tests. These UV "black lights" are applied for crack-recognition using fluorescent liquid penetrant inspection. At present, these nondestructive tests are performed using Hg-lamps. Lack of a proper standard and the different spectral responsivities of the available UV meters cause significant measurement errors even if the same UV-365 source is measured. A pyroelectric radiometer standard with spectrally flat (constant) response in the UV-VIS range has been developed to solve the problem. The response curve of this standard determined from spectral reflectance measurement, is converted into spectral irradiance responsivity with <0.5% (k=2) uncertainty as a result of using an absolute tie point from a Si-trap detector traceable to the primary standard cryogenic radiometer. The flat pyroelectric radiometer standard can be used to perform uniform integrated irradiance measurements from all kinds of UV sources (with different peaks and distributions) without using any source standard. Using this broadband calibration method, yearly spectral calibrations for the reference UV (LED) sources and irradiance meters is not needed. Field UV sources and meters can be calibrated against the pyroelectric radiometer standard for broadband (integrated) irradiance and integrated responsivity. Using the broadband measurement procedure, the UV measurements give uniform results with significantly decreased uncertainties.

Pyroelectric Applications of the VDF-TrFE Copolymer

NASA Technical Reports Server (NTRS)

Simonne, J. J.; Bauer, Ph.; Audaire, L.; Bauer, F.

1995-01-01

VDF/TrFe pyroelectric sensors have now definitely reached the level of a product. Based on a bidimensional staring array, it can be considered as a whole system with a monolithic technology processed on a silicon substrate provided with the integrated read out circuit. The paper will describe the main procedure dealing with the elaboration of a 32 x 32 focal plane array developed, in the context of the PROMETHEUS PROCHIP European Program (EUREKA), as a passive infrared obstacle detection applied to automotive. Additional experimental data suggest that this microsystem could operate in space environment.

Method of Evaluating the Thermal Stability of the Pyroelectric Properties of Polyvinylidene Fluoride Effects of Poling Temperature and Field

DTIC Science & Technology

1982-06-01

Stability of th Technical Report No. 18 Pyroelectric Properties of Po.iyvinylidene Fluoride Effects of Poling Temperature and Field 4’ p."ORING or6. RePORT... poled polyvinyylidene •=•- fluoride films has been meesured while the teMseratire was varied at a constant rate of ", 5 OC/min. fromn roan...influenced in a reproducible mLnner by the poling vari.- ables especiall the poliN teoperature. The measuremwnt is therefore (Cont.) DD , O൙ 1473

Pyroelectric, piezoelectric, and photoeffects in hydroxyapatite thin films on silicon

NASA Astrophysics Data System (ADS)

Lang, S. B.; Tofail, S. A. M.; Gandhi, A. A.; Gregor, M.; Wolf-Brandstetter, C.; Kost, J.; Bauer, S.; Krause, M.

2011-03-01

Hydroxyapatite (HA) is the major component of bone and is used in artificial form in many biomedical applications. It was once believed to have a centrosymmetric crystal structure. In theoretical and experimental studies published in 2005, it was shown to have a monoclinic P21 structure. In the work reported here, 500 nm films of HA were spin-coated on silicon wafers. The materials were not poled. They had a nonuniform polarization distribution and exhibited pyroelectricity, piezoelectricity, and photoeffects. Structures of this type may have a number of technological applications.

Reversible pyroelectric and photogalvanic current in epitaxial Pb(Zr0.52Ti0.48)O3 thin films

NASA Astrophysics Data System (ADS)

Lee, J.; Esayan, S.; Prohaska, J.; Safari, A.

1994-01-01

The pyroelectric and photogalvanic effects have been studied in epitaxial Pb(Zr0.52Ti0.48)O3 (PZT) thin films. Photoinduced currents, which were completely reversible by electrical voltage, were observed. The photoinduced currents exhibited transient and steady state components. The transient component, in turn, consisted of two components with fast (<1 s) and slow (˜hours) relaxation times. The mechanisms of the photoinduced currents in PZT films and their possible applications in nondestructive readout ferroelectric memory are discussed.

A pyroelectric thermal imaging system for use in medical diagnosis.

PubMed

Black, C M; Clark, R P; Darton, K; Goff, M R; Norman, T D; Spikes, H A

1990-07-01

The value of infra-red thermography in a number of pathologies, notably rheumatology and vascular diseases, is becoming well established. However, the high cost of thermal scanners and the associated image processing computers has been a limitation to the widespread availability of this technique to the clinical community. This paper describes a relatively inexpensive thermographic system based on a pyroelectric vidicon scanner and a microcomputer. Software has been written with particular reference to the use of thermography in rheumatoid arthritis and vasospastic conditions such as Raynaud's phenomenon.

Systematic evaluation of a secondary method for measuring diagnostic-level medical ultrasound transducer output power based on a large-area pyroelectric sensor

NASA Astrophysics Data System (ADS)

Zeqiri, B.; Žauhar, G.; Rajagopal, S.; Pounder, A.

2012-06-01

A systematic study of the application of a novel pyroelectric technique to the measurement of diagnostic-level medical ultrasound output power is described. The method exploits the pyroelectric properties of a 0.028 mm thick membrane of polyvinylidene fluoride (PVDF), backed by an acoustic absorber whose ultrasonic absorption coefficient approaches 1000 dB cm-1 at 3 MHz. When exposed to an ultrasonic field, absorption of ultrasound adjacent to the PVDF-absorber interface results in heating and the generation of a pyroelectric output voltage across gold electrodes deposited on the membrane. For a sensor large enough to intercept the whole of the acoustic beam, the output voltage can be calibrated for the measurement of acoustic output power. A number of key performance properties of the method have been investigated. The technique is very sensitive, with a power to voltage conversion factor of typically 0.23 V W-1. The frequency response of a particular embodiment of the sensor in which acoustic power reflected at the absorber-PVDF interface is subsequently returned to the pyroelectric membrane to be absorbed, has been evaluated over the frequency range 1.5 MHz to 10 MHz. This has shown the frequency response to be flat to within ±4%, above 2.5 MHz. Below this frequency, the sensitivity falls by 20% at 1.5 MHz. Linearity of the technique has been demonstrated to within ±1.6% for applied acoustic power levels from 1 mW up to 120 mW. A number of other studies targeted at assessing the achievable measurement uncertainties are presented. These involve: the effects of soaking, the influence of the angle of incidence of the acoustic beam, measurement repeatability and sensitivity to transducer positioning. Additionally, over the range 20 °C to 30 °C, the rate of change in sensitivity with ambient temperature has been shown to be +0.5% °C-1. Implications of the work for the development of a sensitive, traceable, portable, secondary method of ultrasound output power measurement, appropriate for clinical diagnostic ultrasound systems, are discussed.

Relativistic klystron driven compact high gradient accelerator as an injector to an X-ray synchrotron radiation ring

DOEpatents

Yu, David U. L.

1990-01-01

A compact high gradient accelerator driven by a relativistic klystron is utilized to inject high energy electrons into an X-ray synchrotron radiation ring. The high gradients provided by the relativistic klystron enables accelerator structure to be much shorter (typically 3 meters) than conventional injectors. This in turn enables manufacturers which utilize high energy, high intensity X-rays to produce various devices, such as computer chips, to do so on a cost effective basis.

Structural Transition and Electrical Properties of (1 - x)(Na0.4K0.1Bi0.5)TiO3- xSrTiO3 Lead-Free Piezoceramics

NASA Astrophysics Data System (ADS)

Liu, Xing; Zhai, Jiwei; Shen, Bo; Li, Feng; Li, Peng

2017-10-01

(1 - x)(Na0.4K0.1Bi0.5)TiO3- xSrTiO3 (NKBT- xST) ceramics with x = 0 mol.%, 3 mol.%, and 5 mol.% (0ST, 3ST, and 5ST) have been prepared by a conventional solid-state reaction method and their ferroelectric, electrostrictive, and pyroelectric properties investigated. Addition of ST considerably disrupted the long-range ferroelectric order of NKBT- xST ceramics, and the 5ST ceramic exhibited ergodic relaxor phase structure. T FR shifted to near or below room temperature for 5ST ceramic, accompanied by a significant decline of ferroelectricity and enhanced strain. As the temperature approached T FR, the NKBT- xST ceramics exhibited predominantly electrostrictive effect, and the 5ST ceramic presented relatively high electrostrictive coefficient Q 33 of 0.0193 m4/C2. High pyroelectric response was observed for 0ST, 3ST, and 5ST ceramics in the vicinity of T FR due to the large polarization release during the ferroelectric-relaxor structural transition. The 5ST ceramic exhibited high and frequency-insensitive (100 Hz to 10 kHz) room-temperature pyroelectric properties with pyroelectric coefficient p of 656 μC m-2 K-1 and figures of merit F i, F v, and F d reaching 233 pm/V, 0.013 m2/C, and 7.61 μPa-1/2, respectively, indicating that 5ST ceramic is a promising candidate to replace PZT-based ceramics.

Dielectric constant tunability at microwave frequencies and pyroelectric behavior of lead-free submicrometer-structured (Bi0.5Na0.5)1-xBaxTiO3 ferroelectric ceramics.

PubMed

Martínez, Félix L; Hinojosa, Juan; Doménech, Ginés; Fernández-Luque, Francisco J; Zapata, Juan; Ruiz, Ramon; Pardo, Lorena

2013-08-01

In this article, we show that the dielectric constant of lead-free ferroelectric ceramics based on the solid solution (1-x)(Bi(0.5)Na(0.5))TiO(3)-xBaTiO(3), with compositions at or near the morphotropic phase boundary (MPB), can be tuned by a local applied electric field. Two compositions have been studied, one at the MPB, with x = 0.06 (BNBT6), and another one nearer the BNT side of the phase diagram, with x = 0.04 (BNBT4). The tunability of the dielectric constant is measured at microwave frequencies between 100 MHz and 3 GHz by a nonresonant method and simultaneously applying a dc electric field. As expected, the tunability is higher for the composition at the MPB (BNBT6), reaching a maximum value of 60% for an electric field of 900 V/cm, compared with the composition below this boundary (BNBT4), which saturates at 40% for an electric field of 640 V/cm. The high tunability in both cases is attributed to the fine grain and high density of the samples, which have a submicrometer homogeneous grain structure with grain size of the order of a few hundred nanometers. Such properties make these ceramics attractive for microwave tunable devices. Finally, we have tested these ceramics for their application as infrared pyroelectric detectors and we have found that the pyroelectric figure of merit is comparable to traditional lead-containing pyroelectrics.

Demonstration of a non-contact x-ray source using an inductively heated pyroelectric accelerator

NASA Astrophysics Data System (ADS)

Klopfer, Michael; Satchouk, Vladimir; Cao, Anh; Wolowiec, Thomas; Alivov, Yahya; Molloi, Sabee

2015-04-01

X-ray emission from pyroelectric sources can be produced through non-contact thermal cycling using induction heating. In this study, we demonstrated a proof of concept non-contact x-ray source powered via induction heating. An induction heater operating at 62.5 kHz provided a total of 6.5 W of delivered peak thermal power with 140 V DC of driving voltage. The heat was applied to a ferrous substrate mechanically coupled to a cubic 1 cm3 Lithium Niobate (LiNbO3) pyroelectric crystal maintained in a 3-12 mTorr vacuum. The maximum temperature reached was 175 °C in 86 s of heating. The cooling cycle began immediately after heating and was provided by passive radiative cooling. The total combined cycle time was 250 s. x-ray photons were produced and analyzed in both heating and cooling phases. Maximum photon energies of 59 keV and 55 keV were observed during heating and cooling, respectively. Non-contact devices such as this, may find applications in cancer therapy (brachytherapy), non-destructive testing, medical imaging, and physics education fields.

Graphene-based mid-infrared room-temperature pyroelectric bolometers with ultrahigh temperature coefficient of resistance.

PubMed

Sassi, U; Parret, R; Nanot, S; Bruna, M; Borini, S; De Fazio, D; Zhao, Z; Lidorikis, E; Koppens, F H L; Ferrari, A C; Colli, A

2017-01-31

There is a growing number of applications demanding highly sensitive photodetectors in the mid-infrared. Thermal photodetectors, such as bolometers, have emerged as the technology of choice, because they do not need cooling. The performance of a bolometer is linked to its temperature coefficient of resistance (TCR, ∼2-4% K -1 for state-of-the-art materials). Graphene is ideally suited for optoelectronic applications, with a variety of reported photodetectors ranging from visible to THz frequencies. For the mid-infrared, graphene-based detectors with TCRs ∼4-11% K -1 have been demonstrated. Here we present an uncooled, mid-infrared photodetector, where the pyroelectric response of a LiNbO 3 crystal is transduced with high gain (up to 200) into resistivity modulation for graphene. This is achieved by fabricating a floating metallic structure that concentrates the pyroelectric charge on the top-gate capacitor of the graphene channel, leading to TCRs up to 900% K -1 , and the ability to resolve temperature variations down to 15 μK.

Great enhancement of pyroelectric properties for Ba{sub 0.65}Sr{sub 0.35}TiO{sub 3} films on Pt-Si substrates by inserting a self-buffered layer

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

Wu, C. G.; Li, Y. R.; Zhu, J.

2009-02-15

(100)-Ba{sub 0.65}Sr{sub 0.35}TiO{sub 3} (BST) films were deposited on Pt/Ti/SiO{sub 2}/Si substrates using a low-temperature self-buffered layer. X-ray diffraction and atomic force microscope investigations show that the microstructure of BST films strongly depends on surface morphology of annealed self-buffered layer. The mechanism of nucleus formation and the growth initiation of BST films on self-buffered layers were proposed. It was found that the pyroelectric properties of BST films can be greatly enhanced. The pyroelectric coefficient and material merit figure of (100)-BST films are 1.16x10{sup 4} {mu}C m{sup -2} K{sup -1} and 2.18x10{sup -4} Pa{sup -1/2}, respectively. The detectivity of 9.4x10{sup 7}more » cm Hz{sup 1/2} W{sup -1} was obtained in the (100)-BST film capacitors thermally isolated by 500 nm SiO{sub 2} films.« less

Applications of compact accelerator-driven neutron sources: An updated assessment from the perspective of materials research in Italy

DOE PAGES

Andreani, C.; Anderson, I. S.; Carpenter, J. M.; ...

2014-12-24

In 2005 the International Atomic Energy Agency (IAEA) in Vienna published a report [1] on ‘Development Opportunities of Small and Medium Scale Accelerator Driven Neutron Sources’ which summarized the prospect of smaller sources in supporting the large spallation neutron sources for materials characterization and instrumentation, a theme advocated by Bauer, Clausen, Mank, and Mulhauser in previous publications [2-4]. In 2010 the Union for Compact Accelerator-driven Neutron Sources (UCANS) was established [5], galvanizing cross-disciplinary collaborations on new source and neutronics development and expanded applications based on both slow-neutron scattering and other neutron-matter interactions of neutron energies ranging from 10⁻⁶ to 10²more » MeV [6]. Here, we first cover the recent development of ongoing and prospective projects of compact accelerator-driven neutron sources (CANS) but concentrate on prospective accelerators currently proposed in Italy. Two active R&D topics, irradiation effects on electronics and cultural heritage studies, are chosen to illustrate the impact of state-of-the-art CANS on these programs with respect to the characteristics and complementarity of the accelerator and neutronics systems as well as instrumentation development.« less

Photopyroelectric response of PTCa∕PEEK composite.

PubMed

Estevam, Giuliano Pierre; de Melo, Washington Luiz Barros; Sakamoto, Walter Katsumi

2011-02-01

A pyroelectric composite made of calcium modified lead titanate ceramic and polyether-ether-ketone high performance polymer was obtained in the film form by hot pressing the ceramic/polymer mixture into the desired composition. After polarization with a suitable electric field, a ceramic composite film (60% vol.) exhibited a pyroelectric figure of merit three times higher than that of a lead zirconate titanate ceramic. The material was used as infrared radiation sensor. The voltage responsivity decreases with the inverse of the frequency showing the same behavior of the thermally thick sensor. The reproducibility of the sensor responses was observed.

Liquid micro-lens array activated by selective electrowetting on lithium niobate substrates.

PubMed

Grilli, S; Miccio, L; Vespini, V; Finizio, A; De Nicola, S; Ferraro, Pietro

2008-05-26

Lens effect was obtained in an open microfluidic system by using a thin layer of liquid on a polar electric crystal like LiNbO3. An array of liquid micro-lenses was generated by electrowetting effect in pyroelectric periodically poled crystals. Compared to conventional electrowetting devices, the pyroelectric effect allowed to have an electrode-less and circuit-less configuration. An interferometric technique was used to characterize the curvature of the micro-lenses and the corresponding results are presented and discussed. The preliminary results concerning the imaging capability of the micro-lens array are also reported.

Intelligent lightening system of urban and rural road traffic based on pyroelectric infrared detector

NASA Astrophysics Data System (ADS)

Miao, Man-Xiang

2007-12-01

By using the photo-voltage characteristics of pyroelectric infrared detector to fulfill signal acquisition, the detecting signal is processed with the core of a single chip microprocessor AT89C51. AT89C51 controls the CAN bus controller SJA1000/transceiver 82C250 to structure CAN bus communication system to transmit data through serial interface MAX232 connected with PC. The intelligent lightening system of urban and rural road traffic was carried out. In this paper, its construction and part's methods of hardware and software design were introduced in detail.

Detection of long wavelength infrared at moderate temperatures

NASA Technical Reports Server (NTRS)

Tredwell, T. J.

1977-01-01

Technical approaches for the advanced development of 8-12 micrometer detectors operating at elevated temperatures were defined. The theoretical limits to performance of 8-12 micrometer quantum detectors (photoconductive and photovoltaic) and thermal detectors (pyroelectrics, bolometers etc). An analytic model of signal and noise in both quantum detectors and pyroelectric detectors was developed and candidate materials for both detector types were identified and examined. The present status of both quantum and thermal detectors was assessed as well as the parameters limiting operating temperature and detectivity. The areas of research and development likely to lead to detector performance near the theoretical limit are identified.

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Thermally induced optical damage to barium-sodium niobate crystals

NASA Astrophysics Data System (ADS)

Baryshev, S. A.; Goncharova, I. F.; Konvisar, P. G.; Kuznetsov, V. A.

1990-06-01

Thermally induced optical damage (TIOD) was observed in undoped barium-sodium niobate (BSN) crystals as a result of changes in their temperature. This damage was deduced from the behavior of YAG:Nd3+ laser radiation when a BSN crystal was inserted in the resonator and also using a helium-neon laser probe beam. The experimental results were satisfactorily explained by the familiar pyroelectric model of TIOD and, in the crystals studied, an inhomogeneity of the conductivity rather than an inhomogeneity of the pyroelectric constant played the main role.

The value of balanced growth for transportation.

DOT National Transportation Integrated Search

2014-12-01

The Ohio Balanced Growth Program is a voluntary, locally-driven, incentive-driven program which aims to encourage : compact, nodal development patterns. The Ohio Department of Transportation provided support for this research to evaluate : potential ...

Compaction-Driven Evolution of Pluto's Rocky Core: Implications for Water-Rock Interactions

NASA Astrophysics Data System (ADS)

Gabasova, L. R.; Tobie, G.; Choblet, G.

2018-05-01

We model the compaction of Pluto's rocky core after accretion and explore the potential for hydrothermal circulation within the porous layer, as well as examine its effect on core cooling and the persistence of a liquid internal ocean.

Spontaneous polarization and pyroelectric effect in the improper ferroelectrics-ferroelastics Gd2(MoO4)3 and Tb2(MoO4)3 at low temperatures

NASA Astrophysics Data System (ADS)

Matyjasik, S.; Shaldin, Yu. V.

2013-11-01

The experimental variations in the spontaneous polarization ΔPs(T) and pyroelectric coefficient γs(T) for Gd2(MoO4)3 (GMO) and Tb2(MoO4)3 (TMO) at low temperatures reported here differ from those for intrinsic ferroelectrics. A fundamental difference is found in the repolarization behavior of samples of GMO and TMO at fixed temperatures of 300 and 4.2 K. While the single domain formation temperature essentially has no effect on the measurements for TMO, a fundamental difference is observed in the case of GMO: single domain formation in the latter at 4.2 K leads to an order of magnitude increase in ΔPs at T > 85 K and distinct anomalies are observed in γs(T), at one of which the pyroelectric coefficient reaches a record peak of 3 × 10-4 C/(m2.K) at T = 25 K. At T = 200 K the pyroelectric coefficients equal -1.45 and -1.8 in units of 10-6 C/(m2.K). Based on these results and taking published data on the rotational structural transformation in the (001) plane and symmetry considerations into account, we propose a crystal physical model for GMO-type improper ferroelectrics consisting of four mesotetrahedra, each of which is made up of three different types (a, b, c) of MoO4 coordination tetrahedra. The physical significance of the pseudodeviator coefficient Q12*, which initiates the phase transition at T > 433 K from one non-centrally symmetric phase (mm2) into another (4¯2m), is discussed in terms of this model.

High performance Bi0.5Na0.5TiO3-BiAlO3-K0.5Na0.5NbO3 lead-free pyroelectric ceramics for thermal detectors

NASA Astrophysics Data System (ADS)

Liu, Zhen; Ren, Weijun; Peng, Ping; Guo, Shaobo; Lu, Teng; Liu, Yun; Dong, Xianlin; Wang, Genshui

2018-04-01

Both high pyroelectric properties and good temperature stability of ferroelectric materials are desirable when used for applications in infrared thermal detectors. In this work, we report lead-free ternary 0.97(0.99Bi0.5Na0.5TiO3-0.01BiAlO3)-0.03K0.5Na0.5NbO3 (BNT-BA-KNN) ceramics, which not only exhibits a large pyroelectric coefficient (p ˜ 3.7 × 10-8 C cm-2 K-1) and figures of merit (Fi, Fv, and Fd) but also shows excellent thermal stable properties. At room temperature, Fi, Fv, and Fd are determined as high as 1.32 × 10-10 m/V, 2.89 × 10-2 m2/C, and 1.15 × 10-5 Pa-1/2 at 1 kHz and 1.32 × 10-10 m/V, 2.70 × 10-2 m2/C, and 1.09 × 10-5 Pa-1/2 at 20 Hz, respectively. During the temperature range of RT to 85 °C, the achieved p, Fi, Fv, and Fd do not vary too much. The high depolarization temperature and the undispersed ferroelectric-ergodic relaxor phase transition with a sharp pyroelectric coefficient peak value of ˜400 × 10-8 C cm-2 K-1 are suggested to be responsible for this thermal stability, which ensures reliable actual operation. The results reveal the BNT-BA-KNN ceramics as promising lead-free candidates for infrared thermal detector applications.

Widely tunable Fabry-Perot filter based MWIR and LWIR microspectrometers

NASA Astrophysics Data System (ADS)

Ebermann, Martin; Neumann, Norbert; Hiller, Karla; Gittler, Elvira; Meinig, Marco; Kurth, Steffen

2012-06-01

As is generally known, miniature infrared spectrometers have great potential, e. g. for process and environmental analytics or in medical applications. Many efforts are being made to shrink conventional spectrometers, such as FTIR or grating based devices. A more rigorous approach for miniaturization is the use of MEMS technologies. Based on an established design for the MWIR new MEMS Fabry-Perot filters and sensors with expanded spectral ranges in the LWIR have been developed. The range 5.5 - 8 μm is particularly suited for the analysis of liquids. A dual-band sensor, which can be simultaneously tuned from 4 - 5 μm and 8 - 11 μm for the measurement of anesthetics and carbon dioxide has also been developed. A new material system is used to reduce internal stress in the reflector layer stack. Good results in terms of finesse (<= 60) and transmittance (<= 80 %) could be demonstrated. The hybrid integration of the filter in a pyroelectric detector results in very compact, robust and cost effective microspectrometers. FP filters with two moveable reflectors instead of only one reduce significantly the acceleration sensitivity and actuation voltage.

Mechanical compaction directly modulates the dynamics of bile canaliculi formation.

PubMed

Wang, Yan; Toh, Yi-Chin; Li, Qiushi; Nugraha, Bramasta; Zheng, Baixue; Lu, Thong Beng; Gao, Yi; Ng, Mary Mah Lee; Yu, Hanry

2013-02-01

Homeostatic pressure-driven compaction is a ubiquitous mechanical force in multicellular organisms and is proposed to be important in the maintenance of multicellular tissue integrity and function. Previous cell-free biochemical models have demonstrated that there are cross-talks between compaction forces and tissue structural functions, such as cell-cell adhesion. However, its involvement in physiological tissue function has yet to be directly demonstrated. Here, we use the bile canaliculus (BC) as a physiological example of a multicellular functional structure in the liver, and employ a novel 3D microfluidic hepatocyte culture system to provide an unprecedented opportunity to experimentally modulate the compaction states of primary hepatocyte aggregates in a 3D physiological-mimicking environment. Mechanical compaction alters the physical attributes of the hepatocyte aggregates, including cell shape, cell packing density and cell-cell contact area, but does not impair the hepatocytes' remodeling and functional capabilities. Characterization of structural and functional polarity shows that BC formation in compact hepatocyte aggregates is accelerated to as early as 12 hours post-seeding; whereas non-compact control requires 48 hours for functional BC formation. Further dynamic immunofluorescence imaging and gene expression profiling reveal that compaction accelerated BC formation is accompanied by changes in actin cytoskeleton remodeling dynamics and transcriptional levels of hepatic nuclear factor 4α and Annexin A2. Our report not only provides a novel strategy of modeling BC formation for in vitro hepatology research, but also shows a first instance that homeostatic pressure-driven compaction force is directly coupled to the higher-order multicellular functions.

Preliminary Results from Pyroelectric Crystal Accelerator

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

Anderson, Tom; Edwards, Ronald; Bright, Kevin

The Nuclear Science and Engineering Research Center (NSERC), a Defense Threat Reduction Agency (DTRA) office located at the United States Military Academy (USMA), sponsors and manages cadet and faculty research in support of DTRA objectives. Cadets in the Department of Physics and Nuclear Engineering at USMA are using pyroelectric crystals to ionize and accelerate residual gas trapped inside a vacuum system. A system using two lithium tantalate crystals with associated diagnostics was designed and is now operational. X-ray energies of approximately 150 keV have been achieved. Future work will focus on developing a portable neutron generator using the D-D nuclearmore » fusion process.« less

Electrical performances of pyroelectric bimetallic strip heat engines describing a Stirling cycle

NASA Astrophysics Data System (ADS)

Arnaud, A.; Boughaleb, J.; Monfray, S.; Boeuf, F.; Cugat, O.; Skotnicki, T.

2015-12-01

This paper deals with the analytical modeling of pyroelectric bimetallic strip heat engines. These devices are designed to exploit the snap-through of a thermo-mechanically bistable membrane to transform a part of the heat flowing through the membrane into mechanical energy and to convert it into electric energy by means of a piezoelectric layer deposited on the surface of the bistable membrane. In this paper, we describe the properties of these heat engines in the case when they complete a Stirling cycle, and we evaluate the performances (available energy, Carnot efficiency...) of these harvesters at the macro- and micro-scale.

Real-time, T-ray imaging using a sub-terahertz gyrotron

NASA Astrophysics Data System (ADS)

Han, Seong-Tae; Torrezan, Antonio C.; Sirigiri, Jagadishwar R.; Shapiro, Michael A.; Temkin, Richard J.

2012-06-01

We demonstrated real-time, active, T-ray imaging using a 0.46 THz gyrotron capable of producing 16 W in continuous wave operation and a pyroelectric array camera with 124-by-124 pixels. An expanded Gaussian beam from the gyrotron was used to maintain the power density above the detection level of the pyroelectric array over the area of the irradiated object. Real-time imaging at a video rate of 48 Hz was achieved through the use of the built-in chopper of the camera. Potential applications include fast scanning for security purposes and for quality control of dry or frozen foods.

Experimental demonstration of a compact epithermal neutron source based on a high power laser

NASA Astrophysics Data System (ADS)

Mirfayzi, S. R.; Alejo, A.; Ahmed, H.; Raspino, D.; Ansell, S.; Wilson, L. A.; Armstrong, C.; Butler, N. M. H.; Clarke, R. J.; Higginson, A.; Kelleher, J.; Murphy, C. D.; Notley, M.; Rusby, D. R.; Schooneveld, E.; Borghesi, M.; McKenna, P.; Rhodes, N. J.; Neely, D.; Brenner, C. M.; Kar, S.

2017-07-01

Epithermal neutrons from pulsed-spallation sources have revolutionised neutron science allowing scientists to acquire new insight into the structure and properties of matter. Here, we demonstrate that laser driven fast (˜MeV) neutrons can be efficiently moderated to epithermal energies with intrinsically short burst durations. In a proof-of-principle experiment using a 100 TW laser, a significant epithermal neutron flux of the order of 105 n/sr/pulse in the energy range of 0.5-300 eV was measured, produced by a compact moderator deployed downstream of the laser-driven fast neutron source. The moderator used in the campaign was specifically designed, by the help of MCNPX simulations, for an efficient and directional moderation of the fast neutron spectrum produced by a laser driven source.

Special issue on compact x-ray sources

NASA Astrophysics Data System (ADS)

Hooker, Simon; Midorikawa, Katsumi; Rosenzweig, James

2014-04-01

Journal of Physics B: Atomic, Molecular and Optical Physics is delighted to announce a forthcoming special issue on compact x-ray sources, to appear in the winter of 2014, and invites you to submit a paper. The potential for high-brilliance x- and gamma-ray sources driven by advanced, compact accelerators has gained increasing attention in recent years. These novel sources—sometimes dubbed 'fifth generation sources'—will build on the revolutionary advance of the x-ray free-electron laser (FEL). New radiation sources of this type have widespread applications, including in ultra-fast imaging, diagnostic and therapeutic medicine, and studies of matter under extreme conditions. Rapid advances in compact accelerators and in FEL techniques make this an opportune moment to consider the opportunities which could be realized by bringing these two fields together. Further, the successful development of compact radiation sources driven by compact accelerators will be a significant milestone on the road to the development of high-gradient colliders able to operate at the frontiers of particle physics. Thus the time is right to publish a peer-reviewed collection of contributions concerning the state-of-the-art in: advanced and novel acceleration techniques; sophisticated physics at the frontier of FELs; and the underlying and enabling techniques of high brightness electron beam physics. Interdisciplinary research connecting two or more of these fields is also increasingly represented, as exemplified by entirely new concepts such as plasma based electron beam sources, and coherent imaging with fs-class electron beams. We hope that in producing this special edition of Journal of Physics B: Atomic, Molecular and Optical Physics (iopscience.iop.org/0953-4075/) we may help further a challenging mission and ongoing intellectual adventure: the harnessing of newly emergent, compact advanced accelerators to the creation of new, agile light sources with unprecedented capabilities. New schemes for compact accelerators: laser- and beam-driven plasma accelerators; dielectric laser accelerators; THz accelerators. Latest results for compact accelerators. Target design and staging of advanced accelerators. Advanced injection and phase space manipulation techniques. Novel diagnostics: single-shot measurement of sub-fs bunch duration; measurement of ultra-low emittance. Generation and characterization of incoherent radiation: betatron and undulator radiation; Thomson/Compton scattering sources, novel THz sources. Generation and characterization of coherent radiation. Novel FEL simulation techniques. Advances in simulations of novel accelerators: simulations of injection and acceleration processes; simulations of coherent and incoherent radiation sources; start-to-end simulations of fifth generation light sources. Novel undulator schemes. Novel laser drivers for laser-driven accelerators: high-repetition rate laser systems; high wall-plug efficiency systems. Applications of compact accelerators: imaging; radiography; medical applications; electron diffraction and microscopy. Please submit your article by 15 May 2014 (expected web publication: winter 2014); submissions received after this date will be considered for the journal, but may not be included in the special issue.

Understanding and Mitigating Reservoir Compaction: an Experimental Study on Sand Aggregates

NASA Astrophysics Data System (ADS)

Schimmel, M.; Hangx, S.; Spiers, C. J.

2016-12-01

Fossil fuels continue to provide a source for energy, fuels for transport and chemicals for everyday items. However, adverse effects of decades of hydrocarbons production are increasingly impacting society and the environment. Production-driven reduction in reservoir pore pressure leads to a poro-elastic response of the reservoir, and in many occasions to time-dependent compaction (creep) of the reservoir. In turn, reservoir compaction may lead to surface subsidence and could potentially result in induced (micro)seismicity. To predict and mitigate the impact of fluid extraction, we need to understand production-driven reservoir compaction in highly porous siliciclastic rocks and explore potential mitigation strategies, for example, by using compaction-inhibiting injection fluids. As a first step, we investigate the effect of chemical environment on the compaction behaviour of sand aggregates, comparable to poorly consolidated, highly porous sandstones. The sand samples consist of loose aggregates of Beaujean quartz sand, sieved into a grainsize fraction of 180-212 µm. Uniaxial compaction experiments are performed at an axial stress of 35 MPa and temperature of 80°C, mimicking conditions of reservoirs buried at three kilometres depth. The chemical environment during creep is either vacuum-dry or CO2-dry, or fluid-saturated, with fluids consisting of distilled water, acid solution (CO2-saturated water), alkaline solution (pH 9), aluminium solution (pH 3) and solution with surfactants (i.e., AMP). Preliminary results show that compaction of quartz sand aggregates is promoted in a wet environment compared to a dry environment. It is inferred that deformation is controlled by subcritical crack growth when dry and stress corrosion cracking when wet, both resulting in grain failure and subsequent grain rearrangement. Fluids inhibiting these processes, have the potential to inhibit aggregate compaction.

High-explosive driven crowbar switch

DOEpatents

Dike, Robert S.; Kewish, Jr., Ralph W.

1976-01-13

The disclosure relates to a compact explosive driven switch for use as a low resistance, low inductance crowbar switch. A high-explosive charge extrudes a deformable conductive metallic plate through a polyethylene insulating layer to achieve a hard current contact with a supportive annular conductor.

Enhanced thermal and pyroelectric properties in 0-3 TGS:PVDF composites doped with graphene for infrared application

NASA Astrophysics Data System (ADS)

Feng, Xiaodong; Wang, Minqiang; Li, Le; Yang, Zhi; Cao, Minghui; Cheng, Z.-Y.

Pyroelectric composites of triglycine sulfate (TGS)-polyvinylidene difluoride (PVDF) doped with graphene are studied. It is found that the graphene can effectively improve the polling efficiency and thermal property of the composites so that the infrared detective performance can be significantly improved. For example, by adding about 0.83 wt.% of graphene, the infrared detective property can be improved by more than 30%. It is also found that the size of the graphene plays a critical role on the property improvement. For example, the small-sized graphene prepared by ultrasonic exfoliation (UE) method is more effective than the big-sized graphene prepared by electrochemical exfoliation (EE) method.

Nonlinear pyroelectric energy harvesting from relaxor single crystals.

PubMed

Khodayari, Akram; Pruvost, Sebastien; Sebald, Gael; Guyomar, Daniel; Mohammadi, Saber

2009-04-01

Energy harvesting from temperature variations in a Pb(Zn(1/3)Nb(2/3))(0.955)Ti(0.045)O(3) single crystal was studied and evaluated using the Ericsson thermodynamic cycle. The efficiency of this cycle related to Carnot cycle is 100 times higher than direct pyroelectric energy harvesting, and it can be as high as 5.5% for a 10 degrees C temperature variation and 2 kV/mm electric field. The amount of harvested energy for a 60 degrees C temperature variation and 2 kV/mm electric field is 242.7 mJ x cm(-3). The influence of ferroelectric phase transitions on the energy harvesting performance is discussed and illustrated with experimental results.

Investigating Thermal Parameters of PVDF Sensor in the Front Pyroelectric Configuration

NASA Astrophysics Data System (ADS)

Noroozi, Monir; Zakaria, Azmi; Husin, Mohd Shahril; Moksin, Mohd Maarof; Wahab, Zaidan Abd

2013-11-01

A metalized PVDF pyroelectric (PE) sensor was used as an optically opaque sensor and in a thermally thick regime for both sensor and sample, instead of a very thick sensor in the conventional front PE configuration. From the frequency dependence measurements, the normalized amplitude and phase signal were independently analyzed to obtain the thermal effusivity of the sensor. The differential normalized amplitude measured with water as a substrate was analyzed to determine the sensor thermal diffusivity. The PVDF thermal diffusivity and thermal effusivity agree with literature values. Then, from the known thermal parameters of the sensor, the thermal effusivity of a standard liquid sample, glycerol, and other liquids were obtained by the similar procedure.

Real-time human versus animal classification using pyro-electric sensor array and Hidden Markov Model

NASA Astrophysics Data System (ADS)

Hossen, Jakir; Jacobs, Eddie L.; Chari, Srikant

2014-03-01

In this paper, we propose a real-time human versus animal classification technique using a pyro-electric sensor array and Hidden Markov Model. The technique starts with the variational energy functional level set segmentation technique to separate the object from background. After segmentation, we convert the segmented object to a signal by considering column-wise pixel values and then finding the wavelet coefficients of the signal. HMMs are trained to statistically model the wavelet features of individuals through an expectation-maximization learning process. Human versus animal classifications are made by evaluating a set of new wavelet feature data against the trained HMMs using the maximum-likelihood criterion. Human and animal data acquired-using a pyro-electric sensor in different terrains are used for performance evaluation of the algorithms. Failures of the computationally effective SURF feature based approach that we develop in our previous research are because of distorted images produced when the object runs very fast or if the temperature difference between target and background is not sufficient to accurately profile the object. We show that wavelet based HMMs work well for handling some of the distorted profiles in the data set. Further, HMM achieves improved classification rate over the SURF algorithm with almost the same computational time.

Interferometric characterization of pyroelectrically activated micro-arrays of liquid lenses in lithium niobate crystals

NASA Astrophysics Data System (ADS)

Grilli, S.; Miccio, L.; Vespini, V.; Ferraro, P.

2008-08-01

In recent years a wide variety of liquid based optical elements have been conceived, designed and fabricated even for commercial products like digital cameras. The impressive development of microfluidic systems in conjunction with optics has led to the creation of a completely new field of investigation named optofludics. Among other things, the optofluidic area deals with the investigation and the realization of liquid micro-lenses. Different methods and configurations have been proposed in literature to achieve liquid variable micro-lenses. This paper reports about the possibility to achieve lensing effect by a relatively easy to accomplish technique based on an open microfluidic system consisting of a tiny amount of appropriate liquid manipulated by the pyroelectric effect onto a periodically poled LiNbO3 substrate. Basically, an electrowetting process is performed to actuate the liquid film by using the surface charges generated pyroelectrically under temperature variation. The configuration is electrode-less compared to standard electrowetting systems, thus improving the device flexibility and easiness of fabrication. The curvature of the liquid lenses has been characterized by interferometric techniques based on the evaluation of the phase map through digital holography. The results showing the evolution of the lens curvature with the temperature variation will be presented and discussed.

Low cost space power generation

NASA Technical Reports Server (NTRS)

Olsen, Randall B.

1991-01-01

The success of this study has given a method of fabricating durable copolymer films without size limitations. Previously, only compression molded samples were durable enough to generate electrical energy. The strengthened specimens are very long lived materials. The lifetime was enhanced at least a factor of 1,300 in full pyroelectric conversion cycle experiments compared with extruded, non-strengthened film. The new techniques proved so successful that the lifetime of the resultant copolymer samples was not fully characterized. The lifetime of these new materials is so long that accelerated tests were devised to probe their durability. After a total of more than 67 million high voltage electrical cycles at 100 C, the electrical properties of a copolymer sample remained stable. The test was terminated without any detectable degradation to allow for other experiments. One must be cautious in extrapolating to power cycle performance, but 67 million electrical cycles correspond to 2 years of pyroelectric cycling at 1 Hz. In another series of experiments at reduced temperature and electrical stress, a specimen survived over one-third of a billion electrical cycles during nearly three months of continuous testing. The radiation-limited lifetimes of the copolymer were shown to range from several years to millions of years for most earth orbits. Thus, the pyroelectric copolymer has become a strong candidate for serious consideration for future spacecraft power supplies.

A compact model for electroosmotic flows in microfluidic devices

NASA Astrophysics Data System (ADS)

Qiao, R.; Aluru, N. R.

2002-09-01

A compact model to compute flow rate and pressure in microfluidic devices is presented. The microfluidic flow can be driven by either an applied electric field or a combined electric field and pressure gradient. A step change in the ζ-potential on a channel wall is treated by a pressure source in the compact model. The pressure source is obtained from the pressure Poisson equation and conservation of mass principle. In the proposed compact model, the complex fluidic network is simplified by an electrical circuit. The compact model can predict the flow rate, pressure distribution and other basic characteristics in microfluidic channels quickly with good accuracy when compared to detailed numerical simulation. Using the compact model, fluidic mixing and dispersion control are studied in a complex microfluidic network.

Tracking and recognition of multiple human targets moving in a wireless pyroelectric infrared sensor network.

PubMed

Xiong, Ji; Li, Fangmin; Zhao, Ning; Jiang, Na

2014-04-22

With characteristics of low-cost and easy deployment, the distributed wireless pyroelectric infrared sensor network has attracted extensive interest, which aims to make it an alternate infrared video sensor in thermal biometric applications for tracking and identifying human targets. In these applications, effectively processing signals collected from sensors and extracting the features of different human targets has become crucial. This paper proposes the application of empirical mode decomposition and the Hilbert-Huang transform to extract features of moving human targets both in the time domain and the frequency domain. Moreover, the support vector machine is selected as the classifier. The experimental results demonstrate that by using this method the identification rates of multiple moving human targets are around 90%.

Compact hohlraum configuration with parallel planar-wire-array x-ray sources at the 1.7-MA Zebra generator.

PubMed

Kantsyrev, V L; Chuvatin, A S; Rudakov, L I; Velikovich, A L; Shrestha, I K; Esaulov, A A; Safronova, A S; Shlyaptseva, V V; Osborne, G C; Astanovitsky, A L; Weller, M E; Stafford, A; Schultz, K A; Cooper, M C; Cuneo, M E; Jones, B; Vesey, R A

2014-12-01

A compact Z-pinch x-ray hohlraum design with parallel-driven x-ray sources is experimentally demonstrated in a configuration with a central target and tailored shine shields at a 1.7-MA Zebra generator. Driving in parallel two magnetically decoupled compact double-planar-wire Z pinches has demonstrated the generation of synchronized x-ray bursts that correlated well in time with x-ray emission from a central reemission target. Good agreement between simulated and measured hohlraum radiation temperature of the central target is shown. The advantages of compact hohlraum design applications for multi-MA facilities are discussed.

A Charge Sensitive Pre-Amplifier for Smart Point-of-Care Devices Employing Polymer Based Lab-on-a-Chip

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

Wang, Hanfeng; Britton, Charles; Quaiyum, Farhan

With increasing emphasis on implantable and portable medical devices, low-power, small-chip-area sensor readout system realized in lab-on-a-chip (LOC) platform is gaining more and more importance these days. The main building blocks of the LOC system include a front-end transducer that generates an electrical signal in response to the presence of an analyte of interest, signal processing electronics to process the signal to comply with a specific transmission protocol and a low-power transmitter, all realized in a single integrated circuit platform. Low power consumption and compactness of the components are essential requirements of the LOC system. This paper presents a novelmore » charge sensitive pre-amplifier developed in a standard 180-nm CMOS process suitable for implementing in an LOC platform. The pre-amplifier converts the charge generated by a pyroelectric transducer into a voltage signal, which provides a measurement of the temperature variation in biological fluids. The proposed design is capable of providing 0.8-mV/pC gain while consuming only 2.1 μW of power. Finally, the pre-amplifier composed of integrated components occupies an area of 0.038 mm 2.« less

A Charge Sensitive Pre-Amplifier for Smart Point-of-Care Devices Employing Polymer Based Lab-on-a-Chip

DOE PAGES

Wang, Hanfeng; Britton, Charles; Quaiyum, Farhan; ...

2018-01-01

With increasing emphasis on implantable and portable medical devices, low-power, small-chip-area sensor readout system realized in lab-on-a-chip (LOC) platform is gaining more and more importance these days. The main building blocks of the LOC system include a front-end transducer that generates an electrical signal in response to the presence of an analyte of interest, signal processing electronics to process the signal to comply with a specific transmission protocol and a low-power transmitter, all realized in a single integrated circuit platform. Low power consumption and compactness of the components are essential requirements of the LOC system. This paper presents a novelmore » charge sensitive pre-amplifier developed in a standard 180-nm CMOS process suitable for implementing in an LOC platform. The pre-amplifier converts the charge generated by a pyroelectric transducer into a voltage signal, which provides a measurement of the temperature variation in biological fluids. The proposed design is capable of providing 0.8-mV/pC gain while consuming only 2.1 μW of power. Finally, the pre-amplifier composed of integrated components occupies an area of 0.038 mm 2.« less

A hydrogeologic model of stratiform copper mineralization in the Midcontinent Rift System, Northern Michigan, USA

USGS Publications Warehouse

Swenson, J.B.; Person, M.; Raffensperger, Jeff P.; Cannon, W.F.; Woodruff, L.G.; Berndt, M.E.

2004-01-01

This paper presents a suite of two-dimensional mathematical models of basin-scale groundwater flow and heat transfer for the middle Proterozoic Midcontinent Rift System. The models were used to assess the hydrodynamic driving mechanisms responsible for main-stage stratiform copper mineralization of the basal Nonesuch Formation during the post-volcanic/pre-compressional phase of basin evolution. Results suggest that compaction of the basal aquifer (Copper Harbor Formation), in response to mechanical loading during deposition of the overlying Freda Sandstone, generated a pulse of marginward-directed, compaction-driven discharge of cupriferous brines from within the basal aquifer. The timing of this pulse is consistent with the radiometric dates for the timing of mineralization. Thinning of the basal aquifer near White Pine, Michigan, enhanced stratiform copper mineralization. Focused upward leakage of copper-laden brines into the lowermost facies of the pyrite-rich Nonesuch Formation resulted in copper sulfide mineralization in response to a change in oxidation state. Economic-grade mineralization within the White Pine ore district is a consequence of intense focusing of compaction-driven discharge, and corresponding amplification of leakage into the basal Nonesuch Formation, where the basal aquifer thins dramatically atop the Porcupine Mountains volcanic structure. Equilibrium geochemical modeling and mass-balance calculations support this conclusion. We also assessed whether topography and density-driven flow systems could have caused ore genesis at White Pine. Topography-driven flow associated with the Ottawan orogeny was discounted because it post-dates main-stage ore genesis and because recent seismic interpretations of basin inversion indicates that basin geometry would not be conductive to ore genesis. Density-driven flow systems did not produce focused discharge in the vicinity of the White Pine ore district.

Enhanced energy storage and pyroelectric properties of highly (100)-oriented (Pb1-x-yLaxCay)Ti1-x/4O3 thin films derived at low temperature

NASA Astrophysics Data System (ADS)

Zhu, Hanfei; Ma, Hongfang; Zhao, Yuyao

2018-05-01

Highly (100)-oriented (Pb1-x-yLaxCay)Ti1-x/4O3 (x = 0.15, y = 0.05; x = 0.1, y = 0.1; x = 0.05, y = 0.15) thin films were deposited on Pt/Ti/SiO2/Si substrates at a low temperature of 450 °C via a sol-gel route. It was found that all the (Pb1-x-yLaxCay)Ti1-x/4O3 thin films could be completely crystallized and the content of La/Ca showed a significant effect on the electrical properties of films. Among the three films, the (Pb1-x-yLaxCay)Ti1-x/4O3 (x = 0.1, y = 0.1) thin film exhibited the enhanced overall electrical properties, such as a low dielectric loss (tan ⁡ δ < 0.08) and leakage current (J ∼ 4.6 ×10-5 A/cm2), a high recoverable energy density (Wre ∼ 15 J/cm3), as well as a large pyroelectric coefficient (p ∼ 190 μC/m2K) and figure of merit (Fd‧∼ 77 μC /m2K). The findings suggest that the fabricated thin films with a good (100) orientation can be an attractive candidate for applications in Si-based energy storage and pyroelectric devices.

Compact and tunable focusing device for plasma wakefield acceleration

NASA Astrophysics Data System (ADS)

Pompili, R.; Anania, M. P.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Lollo, V.; Notargiacomo, A.; Picardi, L.; Ronsivalle, C.; Rosenzweig, J. B.; Shpakov, V.; Vannozzi, A.

2018-03-01

Plasma wakefield acceleration, either driven by ultra-short laser pulses or electron bunches, represents one of the most promising techniques able to overcome the limits of conventional RF technology and allows the development of compact accelerators. In the particle beam-driven scenario, ultra-short bunches with tiny spot sizes are required to enhance the accelerating gradient and preserve the emittance and energy spread of the accelerated bunch. To achieve such tight transverse beam sizes, a focusing system with short focal length is mandatory. Here we discuss the development of a compact and tunable system consisting of three small-bore permanent-magnet quadrupoles with 520 T/m field gradient. The device has been designed in view of the plasma acceleration experiments planned at the SPARC_LAB test-facility. Being the field gradient fixed, the focusing is adjusted by tuning the relative position of the three magnets with nanometer resolution. Details about its magnetic design, beam-dynamics simulations, and preliminary results are examined in the paper.

Tracking and Recognition of Multiple Human Targets Moving in a Wireless Pyroelectric Infrared Sensor Network

PubMed Central

Xiong, Ji; Li, Fangmin; Zhao, Ning; Jiang, Na

2014-01-01

With characteristics of low-cost and easy deployment, the distributed wireless pyroelectric infrared sensor network has attracted extensive interest, which aims to make it an alternate infrared video sensor in thermal biometric applications for tracking and identifying human targets. In these applications, effectively processing signals collected from sensors and extracting the features of different human targets has become crucial. This paper proposes the application of empirical mode decomposition and the Hilbert-Huang transform to extract features of moving human targets both in the time domain and the frequency domain. Moreover, the support vector machine is selected as the classifier. The experimental results demonstrate that by using this method the identification rates of multiple moving human targets are around 90%. PMID:24759117

FAST TRACK COMMUNICATION: Pyroxenes: a new class of multiferroics

NASA Astrophysics Data System (ADS)

Jodlauk, S.; Becker, P.; Mydosh, J. A.; Khomskii, D. I.; Lorenz, T.; Streltsov, S. V.; Hezel, D. C.; Bohatý, L.

2007-10-01

Pyroxenes with the general formula AMSi2O6 (A = mono- or divalent metal, M = di- or trivalent metal) are shown to be a new class of multiferroic materials. In particular, we have found so far that NaFeSi2O6 becomes ferroelectric in a magnetically ordered state below ~6 K. Similarly, magnetically driven ferroelectricity is also detected in the Li homologues, LiFeSi2O6 (TC~18 K) and LiCrSi2O6 (TC~11 K). In all these monoclinic systems the electric polarization can be strongly modified by magnetic fields. Measurements of magnetic susceptibility, pyroelectric current and dielectric constants (and their dependence on magnetic field) are performed using a natural crystal of aegirine (NaFeSi2O6) and synthetic crystals of LiFeSi2O6 and LiCrSi2O6 grown from melt solution. For NaFeSi2O6 a temperature versus magnetic field phase diagram is proposed. Exchange constants are computed on the basis of ab initio band structure calculations. The possibility of a spiral magnetic structure caused by frustration to be the reason for the origin of the multiferroic behaviour is discussed. We propose that other pyroxenes may also be multiferroic, and that the versatility of this family offers an exceptional opportunity to study general conditions for and mechanisms of magnetically driven ferroelectricity.

Pyroelectric IR sensor arrays for fall detection in the older population

NASA Astrophysics Data System (ADS)

Sixsmith, A.; Johnson, N.; Whatmore, R.

2005-09-01

Uncooled pyroelectric sensor arrays have been studied over many years for their uses in thermal imaging applications. These arrays will only detect changes in IR flux and so systems based upon them are very good at detecting movements of people in the scene without sensing the background, if they are used in staring mode. Relatively-low element count arrays (16 x 16) can be used for a variety of people sensing applications, including people counting (for safety applications), queue monitoring etc. With appropriate signal processing such systems can be also be used for the detection of particular events such as a person falling over. There is a considerable need for automatic fall detection amongst older people, but there are important limitations to some of the current and emerging technologies available for this. Simple sensors, such as 1 or 2 element pyroelectric infra-red sensors provide crude data that is difficult to interpret; the use of devices worn on the person, such as wrist communicator and motion detectors have potential, but are reliant on the person being able and willing to wear the device; video cameras may be seen as intrusive and require considerable human resources to monitor activity while machine-interpretation of camera images is complex and may be difficult in this application area. The use of a pyroelectric thermal array sensor was seen to have a number of potential benefits. The sensor is wall-mounted and does not require the user to wear a device. It enables detailed analysis of a subject's motion to be achieved locally, within the detector, using only a modest processor. This is possible due to the relative ease with which data from the sensor can be interpreted relative to the data generated by alternative sensors such as video devices. In addition to the cost-effectiveness of this solution, it was felt that the lack of detail in the low-level data, together with the elimination of the need to transmit data outside the detector, would help to avert feelings intrusiveness on the part of the end-user.The main benefits of this type of technology would be for older people who spend time alone in unsupervised environments. This would include people living alone in ordinary housing or in sheltered accommodation (apartment complexes for older people with local warden) and non-communal areas in residential/nursing home environments (e.g. bedrooms and ensuite bathrooms and toilets). This paper will review the development of the array, the pyroelectric ceramic material upon which it is based and the system capabilities. It will present results from the Framework 5 SIMBAD project, which used the system to monitor the movements of elderly people over a considerable period of time.

Laser experiments to simulate coronal mass ejection driven magnetospheres and astrophysical plasma winds on compact magnetized stars

NASA Astrophysics Data System (ADS)

Horton, W.; Ditmire, T.; Zakharov, Yu. P.

2010-06-01

Laboratory experiments using a plasma wind generated by laser-target interaction are proposed to investigate the creation of a shock in front of the magnetosphere and the dynamo mechanism for creating plasma currents and voltages. Preliminary experiments are shown where measurements of the electron density gradients surrounding the obstacles are recorded to infer the plasma winds. The proposed experiments are relevant to understanding the electron acceleration mechanisms taking place in shock-driven magnetic dipole confined plasmas surrounding compact magnetized stars and planets. Exploratory experiments have been published [P. Brady, T. Ditmire, W. Horton, et al., Phys. Plasmas 16, 043112 (2009)] with the one Joule Yoga laser and centimeter sized permanent magnets.

Development of a compact, rf-driven, pulsed ion source for neutron generation

NASA Astrophysics Data System (ADS)

Perkins, L. T.; Celata, C.; Lee, Y.; Leung, K. N.; Picard, D. S.; Vilaithong, R.; Williams, M. D.; Wutte, D.

1997-02-01

Lawrence Berkeley National Laboratory is currently developing a compact, sealed-accelerator-tube neutron generator capable of producing a neutron flux in the range of 109 to 1010 D-T neutrons per second. The ion source, a miniaturized variation of earlier radio-frequency (rf)-driven multicusp ion sources, is designed to fit within a ˜5 cm diameter borehole. Typical operating parameters include repetition rates up to 100 pps, with pulse widths between 10 and 80 μs (limited only by the available rf power supply) and source pressures as low as ˜5 mTorr. In this configuration, peak extractable hydrogen current densities exceeding 1180 mA/cm2 with H1+ yields over 94% having been achieved.

Compact and low-cost THz QTDS system.

PubMed

Probst, Thorsten; Rehn, Arno; Koch, Martin

2015-08-24

We present a terahertz quasi time domain spectroscopy (QTDS) system setup which is improved regarding cost and compactness. The diode laser is mounted directly onto the optical delay line, making the optical setup more compact. The system is operated using a Raspberry Pi and an additional sound card. This combination replaces the desktop/laptop computer, the lock-in-amplifier, the stage controller and the signal generator. We examined not only a commercially available stepper motor driven delay line, but also the repurposed internal mechanics from a DVD drive. We characterize the performance of the new system concept.

Study on data acquisition system for living environmental information for biofication of living spaces

NASA Astrophysics Data System (ADS)

Shimoyama, Norihisa; Mita, Akira

2008-03-01

In Japan's rapidly aging society, the number of elderly people living alone increases every year. Theses elderly people require more and more to maintain as independent a life as possible in their own homes. It is necessary to make living spaces that assist in providing safe and comfortable lives. "Biofication of Living Spaces" is proposed with the concept of creating save and pleasant living environments. It implies learning from biological systems, and applying to living spaces features such as high adaptability and excellent tolerance to environmental changes. As a first step towards realizing "Biofied Spaces", a system for acquisition and storing information must be developed. This system is similar to the five human senses. The information acquired includes environmental information such as temperature, human behavior, psychological state and location of furniture. This study addresses human behavior as it is the most important factor in design of a living space. In the present study, pyroelectric infrared sensors were chosen for human behavior recognition. The pyroelectric infrared sensor is advantageous in that it has no limitation on the number of sensors put in a single space because sensors do not interfere with each other. Wavelet analysis was applied to the output time histories of the pyroelectric infrared sensors. The system successfully classified walking patterns with 99.5% accuracy of walking direction (from right or left) and 85.7% accuracy of distance for 440 patterns pre-learned and an accuracy of over 80% accuracy of walking direction for 720 non-learned patterns.

The dynamic ejecta of compact object mergers and eccentric collisions.

PubMed

Rosswog, Stephan

2013-06-13

Compact object mergers eject neutron-rich matter in a number of ways: by the dynamical ejection mediated by gravitational torques, as neutrino-driven winds, and probably also a good fraction of the resulting accretion disc finally becomes unbound by a combination of viscous and nuclear processes. If compact binary mergers indeed produce gamma-ray bursts, there should also be an interaction region where an ultra-relativistic outflow interacts with the neutrino-driven wind and produces moderately relativistic ejecta. Each type of ejecta has different physical properties, and therefore plays a different role for nucleosynthesis and for the electromagnetic (EM) transients that go along with compact object encounters. Here, we focus on the dynamic ejecta and present results for over 30 hydrodynamical simulations of both gravitational wave-driven mergers and parabolic encounters as they may occur in globular clusters. We find that mergers eject approximately 1 per cent of a Solar mass of extremely neutron-rich material. The exact amount, as well as the ejection velocity, depends on the involved masses with asymmetric systems ejecting more material at higher velocities. This material undergoes a robust r-process and both ejecta amount and abundance pattern are consistent with neutron star mergers being a major source of the 'heavy' (A>130) r-process isotopes. Parabolic collisions, especially those between neutron stars and black holes, eject substantially larger amounts of mass, and therefore cannot occur frequently without overproducing gala- ctic r-process matter. We also discuss the EM transients that are powered by radioactive decays within the ejecta ('macronovae'), and the radio flares that emerge when the ejecta dissipate their large kinetic energies in the ambient medium.

Coordination-Driven Syntheses of Compact Supramolecular Metallacycles toward Extended Metallo-organic Stacked Supramolecular Assemblies.

PubMed

Lescop, Christophe

2017-04-18

One important concept associated with supramolecular chemistry is supramolecular self-assembly, which deals with the way discrete individual components interact via intermolecular interactions in order to build, upon their spontaneous association, high order functional assemblies. The accumulation of these very simple and localized noncovalent interactions (such as H-bonding, dipole-dipole, hydrophobic/hydrophilic, van der Waals, π-π, π-CH, etc.) is ubiquitous in the complexity of natural systems (such as DNA, proteins, membranes, micelles, etc.). It can also be transposed to the directed synthesis of intricate artificial scaffolds, which have anticipated geometries and properties. Among the synthetic strategies based on this concept, coordination-driven supramolecular chemistry uses the robust, reversible, and directional metal-to-ligand coordinative bond to build discrete metallo-supramolecular architectures. Within the last two decades, coordination-driven supramolecular chemistry has proved to be one of the most powerful contemporary synthetic approaches and has provided a significant number of increasingly complex supramolecular assemblies, which have predetermined sizes and geometries. While much focus has been devoted to architectures bearing internal cavities for host-guest chemistry or to generate specific reactivity, particular attention can also be paid to compact supramolecular assemblies given that their specific structures are characterized by peculiar synthetic guiding rules as well as by alternative long-range self-assembling properties. This Account describes how a preassembled Cu I bimetallic clip bearing short intermetallic distances can be used as a U-shaped molecular clip to give general and versatile access to a large variety of original compact supramolecular metallacycles. When this Cu I precursor is reacted with various cyano-capped ditopic linkers that have increasing lengths and complexities, specific effects guiding the selective and straightforward syntheses of such compact supramolecular objects are highlighted. Whereas a subtle compromise between the length of the ditopic linkers and the steric bulk of the molecular clip appears to be a purely stereogeometric preliminary parameter to master, lateral interlinker interactions (π-π stacking interactions or aurophilic interactions depending on the nature of the internal cores of the linkers) can circumvent these constraints regardless of the length of the linkers and allow the selective formation of new compact supramolecular structures. Generally, such derivatives presented a strong tendency to self-assemble in the solid state due to inter-supramolecule interactions. This approach thus opens a new door toward molecular materials having an attractive solid state structure for potential applications related to charge carrier mobility and luminescence properties. These compact supramolecular assemblies can therefore be considered as original secondary binding units directing the predictive preparation of such extended networks. The on-purpose design of original building blocks bearing specific cores allowed the formation of new compact supramolecular metallacycles such as "U-shaped" π-stacked assemblies or "pseudodouble paracyclophanes". Similarly, the control of the secondary structure of one-dimensional coordination polymers alternating π-stacked compact supramolecular metallacycles was also conducted. The results that are discussed in this Account illustrate how the rational design of both preassembled polymetallic precursors bearing short intermetallic distances and ditopic linkers able to induce cumulative lateral weak interactions can implement the general synthetic guiding rules of coordination driven supramolecular chemistry. This opens perspectives to use such compact supramolecular assemblies as secondary building blocks for the design of long-range organized functional molecular materials that have predictable architectures and targeted properties.

Irradiation-driven Mass Transfer Cycles in Compact Binaries

NASA Astrophysics Data System (ADS)

Büning, A.; Ritter, H.

2005-08-01

We elaborate on the analytical model of Ritter, Zhang, & Kolb (2000) which describes the basic physics of irradiation-driven mass transfer cycles in semi-detached compact binary systems. In particular, we take into account a contribution to the thermal relaxation of the donor star which is unrelated to irradiation and which was neglected in previous studies. We present results of simulations of the evolution of compact binaries undergoing mass transfer cycles, in particular also of systems with a nuclear evolved donor star. These computations have been carried out with a stellar evolution code which computes mass transfer implicitly and models irradiation of the donor star in a point source approximation, thereby allowing for much more realistic simulations than were hitherto possible. We find that low-mass X-ray binaries (LMXBs) and cataclysmic variables (CVs) with orbital periods ⪉ 6hr can undergo mass transfer cycles only for low angular momentum loss rates. CVs containing a giant donor or one near the terminal age main sequence are more stable than previously thought, but can possibly also undergo mass transfer cycles.

Impact Compaction of a Granular Material

NASA Astrophysics Data System (ADS)

Fenton, Gregg; Asay, Blaine; Todd, Steve; Grady, Dennis

2017-06-01

The dynamic behavior of granular materials has importance to a variety of engineering applications. Although, the mechanical behavior of granular materials have been studied extensively for several decades, the dynamic behavior of these materials remains poorly understood. High-quality experimental data are needed to improve our general understanding of granular material compaction physics. This paper describes how an instrumented plunger impact system can be used to measure the compaction process for granular materials at high and controlled strain rates and subsequently used for computational modelling. The experimental technique relies on a gas-gun driven plunger system to generate a compaction wave through a volume of granular material. This volume of material has been redundantly instrumented along the bed length to track the progression of the compaction wave, and the piston displacement is measured with Photon Doppler Velocimetry (PDV). Using the gathered experimental data along with the initial material tap density, a granular material equation of state can be determined.

A compact and continuously driven supersonic plasma and neutral source.

PubMed

Asai, T; Itagaki, H; Numasawa, H; Terashima, Y; Hirano, Y; Hirose, A

2010-10-01

A compact and repetitively driven plasma source has been developed by utilizing a magnetized coaxial plasma gun (MCPG) for diagnostics requiring deep penetration of a large amount of neutral flux. The system consists of a MCPG 95mm in length with a DN16 ConFlat connection port and an insulated gate bipolar transistor (IGBT) inverter power unit. The power supply consists of an array of eight IGBT units and is able to switch the discharge on and off at up to 10 kV and 600 A with a maximum repetitive frequency of 10 kHz. Multiple short duration discharge pulses maximize acceleration efficiency of the plasmoid. In the case of a 10 kHz operating frequency, helium-plasmoids in the velocity range of 20 km/s can be achieved.

Proton-induced Nuclear Reactions Using Compact High-Contrast High-Intensity Laser

NASA Astrophysics Data System (ADS)

Ogura, Koichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Yogo, Akifumi; Nishiuchi, Mamiko; Orimo, Satoshi; Sagisaka, Akito; Pirozhkov, Alexander; Mori, Michiaki; Kiriyama, Hiromitsu; Kanazawa, Shuhei; Kondo, Shunji; Nakai, Yoshiki; Shimoura, Takuya; Tanoue, Manabu; Akutsu, Atsushi; Motomura, Tomohiro; Okada, Hajime; Kimura, Toyoaki; Oishi, Yuji; Nayuki, Takuya; Fujii, Takashi; Nemoto, Koshichi; Daido, Hiroyuki

2009-06-01

A multi-MeV proton beam driven by a compact laser with an intensity of ˜1020 W/cm2 is used to induce the nuclear reaction 11B(p,n)11C. The total activity of 11C produced after 60 shots of laser irradiation is found to be 11.1+/-0.4 Bq. The possibility of thin layer activation (TLA) analysis using a high-intensity ultrashort-pulse laser is discussed.

Compact scanning transmission x-ray microscope at the photon factory

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

Takeichi, Yasuo, E-mail: yasuo.takeichi@kek.jp; Inami, Nobuhito; Ono, Kanta

We report the design and performance of a compact scanning transmission X-ray microscope developed at the Photon Factory. Piezo-driven linear stages are used as coarse stages of the microscope to realize excellent compactness, mobility, and vibrational and thermal stability. An X-ray beam with an intensity of ∼10{sup 7} photons/s was focused to a diameter of ∼40 nm at the sample. At the soft X-ray undulator beamline used with the microscope, a wide range of photon energies (250–1600 eV) is available. The microscope has been used to research energy materials and in environmental sciences.

Application of pyroelectric crystal and ionic liquid to the production of metal compounds

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

Imashuku, Susumu; Imanishi, Akira; Kawai, Jun

2013-04-19

Zinc fluoride (ZnF{sub 2}) was deposited on a silicon substrate by changing temperature of a pyroelectric crystal of LiTaO{sub 3} on which ionic liquid (EMI-Tf{sub 2}N) containing zinc ions was dripped at 1 Pa. ZnF{sub 2} was also obtained by bombarding argon ions on EMI-Tf{sub 2}N containing zinc ions. From these results, it is concluded that EMI-Tf{sub 2}N containing zinc ions on the LiTaO{sub 3} crystal was evaporated on the silicon substrate by changing temperature of the LiTaO{sub 3} crystal in vacuum and that the evaporated EMI-Tf{sub 2}N containing metal zinc ions was decomposed to ZnF{sub 2} by the bombardmentmore » of electrons accelerated by the electric field between the LiTaO{sub 3} crystal and the silicon substrate.« less

Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

PubMed Central

Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

2013-01-01

Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics. PMID:23884324

Continuous-wave terahertz digital holography by use of a pyroelectric array camera.

PubMed

Ding, Sheng-Hui; Li, Qi; Li, Yun-Da; Wang, Qi

2011-06-01

Terahertz (THz) digital holography is realized based on a 2.52 THz far-IR gas laser and a commercial 124 × 124 pyroelectric array camera. Off-axis THz holograms are obtained by recording interference patterns between light passing through the sample and the reference wave. A numerical reconstruction process is performed to obtain the field distribution at the object surface. Different targets were imaged to test the system's imaging capability. Compared with THz focal plane images, the image quality of the reconstructed images are improved a lot. The results show that the system's imaging resolution can reach at least 0.4 mm. The system also has the potential for real-time imaging application. This study confirms that digital holography is a promising technique for real-time, high-resolution THz imaging, which has extensive application prospects. © 2011 Optical Society of America

Micro-optical foundry: 3D lithography by freezing liquid instabilities at nanoscale

NASA Astrophysics Data System (ADS)

Grilli, S.; Coppola, S.; Vespini, V.; Merola, F.; Finizio, A.; Ferraro, P.

2012-06-01

The pyroelectric functionality of a Lithium Niobate (LN) substrate is used for non-contact manipulation of polymeric material. In this work we introduced a novel approach for fabricating a wide variety of soft solid-like microstructures, thus leading to a new concept in 3D lithography. A relatively easy to accomplish technique has been demonstrated for curing different transient stages of polymer fluids by rapid cross-linking of PDMS. The method is twofold innovative thanks to the electrode-less configuration and to the rapid formation of a wide variety of 3D solid-like structures by exploiting polymer instabilities. This new and unique technique is named "pyro-electrohydrodynamic (PEHD) lithography", meaning the generation of structures by using forces produced by electric fields generated by the pyroelectric effect. The fabrication of polymer wires, needles, pillars, cones, or microspheres is reported, and practical proofs of their use in photonics are presented.

Effect of the out-of-plane stress on the properties of epitaxial SrTiO3 films with nano-pillar array on Si-substrate

NASA Astrophysics Data System (ADS)

Bai, Gang; Xie, Qiyun; Liu, Zhiguo; Wu, Dongmei

2015-08-01

A nonlinear thermodynamic formalism has been proposed to calculate the physical properties of the epitaxial SrTiO3 films containing vertical nano-pillar array on Si-substrate. The out-of-plane stress induced by the mismatch between film and nano-pillars provides an effective way to tune the physical properties of ferroelectric SrTiO3 films. Tensile out-of-plane stress raises the phase transition temperature and increases the out-of-plane polarization, but decreases the out-of-plane dielectric constant below Curie temperature, pyroelectric coefficient, and piezoelectric coefficient. These results showed that by properly controlling the out-of-plane stress, the out-of-plane stress induced paraelectric-ferroelectric phase transformation will appear near room temperature. Excellent dielectric, pyroelectric, piezoelectric properties of these SrTiO3 films similar to PZT and other lead-based ferroelectrics can be expected.

Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

NASA Astrophysics Data System (ADS)

Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

2013-07-01

Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics.

Ferroelectric polarization in nanocrystalline hydroxyapatite thin films on silicon.

PubMed

Lang, S B; Tofail, S A M; Kholkin, A L; Wojtaś, M; Gregor, M; Gandhi, A A; Wang, Y; Bauer, S; Krause, M; Plecenik, A

2013-01-01

Hydroxyapatite nanocrystals in natural form are a major component of bone--a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics.

Zero-Power Radio Device.

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

Brocato, Robert W.

This report describes an unpowered radio receiver capable of detecting and responding to weak signals transmit ted from comparatively long distances . This radio receiver offers key advantages over a short range zero - power radio receiver previously described in SAND2004 - 4610, A Zero - Power Radio Receiver . The device described here can be fabricated as an integrated circuit for use in portable wireless devices, as a wake - up circuit, or a s a stand - alone receiver operating in conjunction with identification decoders or other electroni cs. It builds on key sub - components developed atmore » Sandia National Laboratories over many years. It uses surface acoustic wave (SAW) filter technology. It uses custom component design to enable the efficient use of small aperture antennas. This device uses a key component, the pyroelectric demodulator , covered by Sandia owned U.S. Patent 7397301, Pyroelectric Demodulating Detector [1] . This device is also described in Sandia owned U.S. Patent 97266446, Zero Power Receiver [2].« less

Enhancement in ferroelectric, pyroelectric and photoluminescence properties in dye doped TGS crystals

NASA Astrophysics Data System (ADS)

Sinha, Nidhi; Goel, Neeti; Singh, B. K.; Gupta, M. K.; Kumar, Binay

2012-06-01

Pure and dye doped (0.1 and 0.2 mol%) Triglycine Sulfate (TGS) single crystals were grown by slow evaporation technique. A pyramidal coloring pattern, along with XRD and FT-IR studies confirmed the dye doping. Decrease in dielectric constant and increase in Curie temperature (Tc) were observed with increasing doping concentration. Low absorption cut off (231 nm) and high optical transparency (>90%) resulting in large band gap was observed in UV-VIS studies. In addition, strong hyper-luminescent emission bands at 350 and 375 nm were observed in which the relative intensity were found to be reversed as a result of doping. In P-E hysteresis loop studies, a higher curie temperature and an improved and more uniform figure of merit over a large region of the ferroelectric phase were observed. The improved dielectric, optical and ferroelectric/pyroelectric properties make the dye doped TGS crystals better candidate for various opto- and piezo-electronics applications.

Method of Making Thermally Stable, Piezoelectric and Proelectric Polymeric Substrates

NASA Technical Reports Server (NTRS)

Simpson, Joycelyn O. (Inventor); St.Clair, Terry L. (Inventor)

1999-01-01

A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers, acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors. in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors, weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 100 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium: applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

Complete diagnostics of pyroactive structures for smart systems of optoelectronics

NASA Astrophysics Data System (ADS)

Bravina, Svetlana L.; Morozovsky, Nicholas V.

1998-04-01

The results of study of pyroelectric phenomena in ferroelectric materials for evidence of the possibility to embody the functions promising for creation of smart systems for optoelectronic applications are presented. Designing such systems requires the development of methods for non- destructive complete diagnostics preferably by developing the self-diagnostic ability inherent in materials with the features of smart/intelligent ones. The complex method of complete non-destructive qualification of pyroactive materials based on the method of dynamic photopyroelectric effect allows the determination of pyroelectric, piezoelectric, ferroelectric, dielectric and thermophysical characteristics. The measuring system which allows the study of these characteristics and also memory effects, switching effects, fatigue and degradation process, self-repair process and others is presented. Sample pyroactive system with increased intelligence, such as systems with built-in adaptive controllable domain structure promising for functional optics are developed and peculiarities of their characterization are discussed.

Short range ferromagnetic, magneto-electric, and magneto-dielectric effect in ceramic Co{sub 3}TeO{sub 6}

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

Singh, Harishchandra, E-mail: singh85harish@gmail.com, E-mail: singh85harish@rrcat.gov.in; Ghosh, Haranath; Indus Synchrotrons Utilization Division, Raja Ramanna Center for Advanced Technology, Indore 452013

2016-01-28

We report observation of magneto-electric and magneto-dielectric couplings along with short range ferromagnetic order in ceramic Cobalt Tellurate (Co{sub 3}TeO{sub 6}, CTO) using magnetic, structural, dielectric, pyroelectric, and polarization studies. DC magnetization along with dielectric constant measurements indicate a coupling between magnetic order and electrical polarization. A strong anomaly in the dielectric constant at ∼17.4 K in zero magnetic field indicates spontaneous electric polarization, consistent with a recent neutron diffraction study. Observation of weak short range ferromagnetic order at lower temperatures is attributed to the Griffiths-like ferromagnetism. Furthermore, magnetic field dependence of the ferroelectric transition follows earlier theoretical predictions, applicable tomore » single crystal CTO. Finally, combined dielectric, pyroelectric, and polarization measurements suggest that the ground state of CTO may possess spontaneous symmetry breaking in the absence of magnetic field.« less

Section 1: Interfacial reactions and grain growth in ferroelectric SrBi{sub 2}Ta{sub 2}O (SBT) thin films on Si substrates

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

Dickerson, B.D.; Zhang, X.; Desu, S.B.

1997-04-01

Much of the cost of traditional infrared cameras based on narrow-bandgap photoelectric semiconductors comes from the cryogenic cooling systems required to achieve high detectivity. Detectivity is inversely proportional to noise. Generation-recombination noise in photoelectric detectors increases roughly exponentially with temperature, but thermal noise in photoelectric detectors increases only linearly with temperature. Therefore `thermal detectors perform far better at room temperature than 8-14 {mu}m photon detectors.` Although potentially more affordable, uncooled pyroelectric cameras are less sensitive than cryogenic photoelectric cameras. One way to improve the sensitivity to cost ratio is to deposit ferroelectric pixels with good electrical properties directly on mass-produced,more » image-processing chips. `Good` properties include a strong temperature dependence of the remanent polarization, P{sub r}, or the relative dielectric constant, {epsilon}{sub r}, for sensitive operation in pyroelectric or dielectric mode, respectively, below or above the Curie temperature, which is 320 C for SBT. When incident infrared radiation is chopped, small oscillations in pixel temperature produce pyroelectric or dielectric alternating currents. The sensitivity of ferroelectric thermal detectors depends strongly on pixel microstructure, since P{sub r} and {epsilon}{sub r} increase with grain size during annealing. To manufacture SBT pixels on Si chips, acceptable SBT grain growth must be achieved at the lowest possible oxygen annealing temperature, to avoid damaging the Si chip below. Therefore current technical progress describes how grain size, reaction layer thickness, and electrical properties develop during the annealing of SBT pixels deposited on Si.« less

How to Make Eccentricity Cycles in Stratigraphy: the Role of Compaction

NASA Astrophysics Data System (ADS)

Liu, W.; Hinnov, L.; Wu, H.; Pas, D.

2017-12-01

Milankovitch cycles from astronomically driven climate variations have been demonstrated as preserved in cyclostratigraphy throughout geologic time. These stratigraphic cycles have been identified in many types of proxies, e.g., gamma ray, magnetic susceptibility, oxygen isotopes, carbonate content, grayscale, etc. However, the commonly prominent spectral power of orbital eccentricity cycles in stratigraphy is paradoxical to insolation, which is dominated by precession index power. How is the spectral power transferred from precession to eccentricity in stratigraphy? Nonlinear sedimentation and bioturbation have long been identified as players in this transference. Here, we propose that in the absence of bioturbation differential compaction can generate the transference. Using insolation time series, we trace the steps by which insolation is transformed into stratigraphy, and how differential compaction of lithology acts to transfer spectral power from precession to eccentricity. Differential compaction is applied to unique values of insolation, which is assumed to control the type of deposited sediment. High compaction is applied to muds, and progressively lower compaction is applied to silts and sands, or carbonate. Linear differential compaction promotes eccentricity spectral power, but nonlinear differential compaction elevates eccentricity spectral power to dominance and precession spectral power to near collapse as is often observed in real stratigraphy. Keywords: differential compaction, cyclostratigraphy, insolation, eccentricity

Passive and active plasma deceleration for the compact disposal of electron beams

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

Bonatto, A., E-mail: abonatto@lbl.gov; CAPES Foundation, Ministry of Education of Brazil, Brasília, DF 700040-020; Schroeder, C. B.

2015-08-15

Plasma-based decelerating schemes are investigated as compact alternatives for the disposal of high-energy beams (beam dumps). Analytical solutions for the energy loss of electron beams propagating in passive and active (laser-driven) schemes are derived. These solutions, along with numerical modeling, are used to investigate the evolution of the electron distribution, including energy chirp and total beam energy. In the active beam dump scheme, a laser-driver allows a more homogeneous beam energy extraction and drastically reduces the energy chirp observed in the passive scheme. These concepts could benefit applications requiring overall compactness, such as transportable light sources, or facilities operating atmore » high beam power.« less

Measured temperature and pressure dependence of compressional (Vp) and shear (Vs) wave speeds in compacted, polycrystalline ice lh

USGS Publications Warehouse

Helgerud, M.B.; Waite, W.F.; Kirby, S.H.; Nur, A.

2003-01-01

We report on laboratory measurements of compressional- and shear-wave speeds in a compacted, polycrystalline ice-Ih sample. The sample was made from triply distilled water that had been frozen into single crystal ice, ground into small grains, and sieved to extract the 180–250 µm diameter fraction. Porosity was eliminated from the sample by compacting the granular ice between a hydraulically driven piston and a fixed end plug, both containing shear-wave transducers. Based on simultaneous compressional- and shear-wave-speed measurements, we calculated Poisson's ratio and compressional-wave, bulk, and shear moduli from –20 to –5°C and 22 to 33 MPa.

Zero-power receiver

DOEpatents

Brocato, Robert W.

2016-10-04

An unpowered signal receiver and a method for signal reception detects and responds to very weak signals using pyroelectric devices as impedance transformers and/or demodulators. In some embodiments, surface acoustic wave devices (SAW) are also used. Illustrative embodiments include satellite and long distance terrestrial communications applications.

Sealing ability of lateral compaction and tapered single cone gutta-percha techniques in root canals prepared with stainless steel and rotary nickel titanium instruments.

PubMed

Koçak, Mustafa M; Darendeliler-Yaman, Sis

2012-07-01

The aim of this study was to evaluate the sealing ability of lateral compaction and tapered single cone gutta-percha techniques in root canals prepared with stainless steel and rotary nickel titanium root canal instruments by fluid filtration method. The root canals were prepared with stainless steel (SS) and nickel titanium (NiTi) instruments. The canals prepared with SS were obturated with lateral compaction technique using .02 tapered cones and the canals prepared with NiTi instruments were obturated with lateral compaction technique using .02 tapered cones or 06 tapered single cones. The amount of leakage was evaluated by fluid filtration model. The results were statistically analyzed with one-way ANOVA. The group prepared with NiTi instruments and filled with lateral compaction technique showed significantly less coronal leakage than the group prepared with SS instruments and filled with lateral compaction technique (p<0.05). There was no statistically difference between apical leakages of groups (p>0.05). Obturation with lateral compaction of gutta-percha provides a superior coronal seal whilst canal instrumentation with engine-driven NiTi files reduces the extent of microleakage in root canals when compared with stainless steel hand instruments. Tapered single cone technique was comparable with lateral compaction technique because of easier application. Key words:Apical leakage, coronal leakage, lateral compaction technique, single cone technique.

Emphysema diagnosis using X-ray dark-field imaging at a laser-driven compact synchrotron light source

PubMed Central

Schleede, Simone; Meinel, Felix G.; Bech, Martin; Herzen, Julia; Achterhold, Klaus; Potdevin, Guillaume; Malecki, Andreas; Adam-Neumair, Silvia; Thieme, Sven F.; Bamberg, Fabian; Nikolaou, Konstantin; Bohla, Alexander; Yildirim, Ali Ö.; Loewen, Roderick; Gifford, Martin; Ruth, Ronald; Eickelberg, Oliver; Reiser, Maximilian; Pfeiffer, Franz

2012-01-01

In early stages of various pulmonary diseases, such as emphysema and fibrosis, the change in X-ray attenuation is not detectable with absorption-based radiography. To monitor the morphological changes that the alveoli network undergoes in the progression of these diseases, we propose using the dark-field signal, which is related to small-angle scattering in the sample. Combined with the absorption-based image, the dark-field signal enables better discrimination between healthy and emphysematous lung tissue in a mouse model. All measurements have been performed at 36 keV using a monochromatic laser-driven miniature synchrotron X-ray source (Compact Light Source). In this paper we present grating-based dark-field images of emphysematous vs. healthy lung tissue, where the strong dependence of the dark-field signal on mean alveolar size leads to improved diagnosis of emphysema in lung radiographs. PMID:23074250

New shielding material development for compact accelerator-driven neutron source

NASA Astrophysics Data System (ADS)

Hu, Guang; Hu, Huasi; Wang, Sheng; Han, Hetong; Otake, Y.; Pan, Ziheng; Taketani, A.; Ota, H.; Hashiguchi, Takao; Yan, Mingfei

2017-04-01

The Compact Accelerator-driven Neutron Source (CANS), especially the transportable neutron source is longing for high effectiveness shielding material. For this reason, new shielding material is researched in this investigation. The component of shielding material is designed and many samples are manufactured. Then the attenuation detection experiments were carried out. In the detections, the dead time of the detector appeases when the proton beam is too strong. To grasp the linear range and nonlinear range of the detector, two currents of proton are employed in Pb attenuation detections. The transmission ratio of new shielding material, polyethylene (PE), PE + Pb, BPE + Pb is detected under suitable current of proton. Since the results of experimental neutrons and γ-rays appear as together, the MCNP and PHITS simulations are applied to assisting the analysis. The new shielding material could reduce of the weight and volume compared with BPE + Pb and PE + Pb.

Research opportunities with compact accelerator-driven neutron sources

NASA Astrophysics Data System (ADS)

Anderson, I. S.; Andreani, C.; Carpenter, J. M.; Festa, G.; Gorini, G.; Loong, C.-K.; Senesi, R.

2016-10-01

Since the discovery of the neutron in 1932 neutron beams have been used in a very broad range of applications, As an aging fleet of nuclear reactor sources is retired the use of compact accelerator-driven neutron sources (CANS) is becoming more prevalent. CANS are playing a significant and expanding role in research and development in science and engineering, as well as in education and training. In the realm of multidisciplinary applications, CANS offer opportunities over a wide range of technical utilization, from interrogation of civil structures to medical therapy to cultural heritage study. This paper aims to provide the first comprehensive overview of the history, current status of operation, and ongoing development of CANS worldwide. The basic physics and engineering regarding neutron production by accelerators, target-moderator systems, and beam line instrumentation are introduced, followed by an extensive discussion of various evolving applications currently exploited at CANS.

Development of a Compact, Efficient Cooling Pump for Space Suit Life Support Systems

NASA Technical Reports Server (NTRS)

van Boeyen, Roger; Reeh, Jonathan; Trevino, Luis

2009-01-01

A compact, low-power electrochemically-driven fluid cooling pump is currently being developed by Lynntech, Inc. With no electric motor and minimal lightweight components, the pump is significantly lighter than conventional rotodynamic and displacement pumps. Reliability and robustness is achieved with the absence of rotating or moving components (apart from the bellows). By employing sulfonated polystyrene-based proton exchange membranes, rather than conventional Nafion membranes, a significant reduction in the actuator power consumption was demonstrated. Lynntech also demonstrated that these membranes possess the necessary mechanical strength, durability, and temperature range for long life space operation. The preliminary design for a Phase II prototype pump compares very favorably to the fluid cooling pumps currently used in space suit primary life support systems (PLSSs). Characteristics of the electrochemically-driven pump are described and the benefits of the technology as a replacement for electric motor pumps in mechanically pumped single-phase fluid loops is discussed.

Ferroic Shape Memory Materials & Piezo:Pyro-Electric Oriented Recrystallized Glasses.

DTIC Science & Technology

1986-07-01

microcope hot stage. The direction of crystallization was parallel to the direction of temperature gradient. The crystalline phases in the glass...may increase or decrease with temperature. Several compounds show a sign reversal in the pyroelectric coefficients, going from positive to negative

Investigation of synthetic spider silk crystallinity and alignment via electrothermal, pyroelectric, literature XRD, and tensile techniques.

PubMed

Munro, Troy; Putzeys, Tristan; Copeland, Cameron G; Xing, Changhu; Lewis, Randolph V; Ban, Heng; Glorieux, Christ; Wubbenhorst, Michael

2017-04-01

The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the N. clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by XRD data. The results show that stretching and passage through liquid baths induce crystal formation and axial alignment in synthetic fibers, but with different structural organization than natural silks. Furthermore, an increase in thermal diffusivity and elastic modulus is observed with decreasing fiber diameter, trending towards properties of natural fiber. This effect seems to be related to silk fibers being subjected to a radial gradient during production.

Investigation of synthetic spider silk crystallinity and alignment via electrothermal, pyroelectric, literature XRD, and tensile techniques

PubMed Central

Munro, Troy; Putzeys, Tristan; Copeland, Cameron G.; Xing, Changhu; Lewis, Randolph V; Ban, Heng; Glorieux, Christ; Wubbenhorst, Michael

2018-01-01

The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the N. clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by XRD data. The results show that stretching and passage through liquid baths induce crystal formation and axial alignment in synthetic fibers, but with different structural organization than natural silks. Furthermore, an increase in thermal diffusivity and elastic modulus is observed with decreasing fiber diameter, trending towards properties of natural fiber. This effect seems to be related to silk fibers being subjected to a radial gradient during production. PMID:29430211

EMD-Based Symbolic Dynamic Analysis for the Recognition of Human and Nonhuman Pyroelectric Infrared Signals.

PubMed

Zhao, Jiaduo; Gong, Weiguo; Tang, Yuzhen; Li, Weihong

2016-01-20

In this paper, we propose an effective human and nonhuman pyroelectric infrared (PIR) signal recognition method to reduce PIR detector false alarms. First, using the mathematical model of the PIR detector, we analyze the physical characteristics of the human and nonhuman PIR signals; second, based on the analysis results, we propose an empirical mode decomposition (EMD)-based symbolic dynamic analysis method for the recognition of human and nonhuman PIR signals. In the proposed method, first, we extract the detailed features of a PIR signal into five symbol sequences using an EMD-based symbolization method, then, we generate five feature descriptors for each PIR signal through constructing five probabilistic finite state automata with the symbol sequences. Finally, we use a weighted voting classification strategy to classify the PIR signals with their feature descriptors. Comparative experiments show that the proposed method can effectively classify the human and nonhuman PIR signals and reduce PIR detector's false alarms.

Photovoltaic-Pyroelectric Coupled Effect Induced Electricity for Self-Powered Photodetector System.

PubMed

Ma, Nan; Zhang, Kewei; Yang, Ya

2017-12-01

Ferroelectric materials have demonstrated novel photovoltaic effect to scavenge solar energy. However, most of the ferroelectric materials with wide bandgaps (2.7-4 eV) suffer from low power conversion efficiency of less than 0.5% due to absorbing only 8-20% of solar spectrum. Instead of harvesting solar energy, these ferroelectric materials can be well suited for photodetector applications, especially for sensing near-UV irradiations. Here, a ferroelectric BaTiO 3 film-based photodetector is demonstrated that can be operated without using any external power source and a fast sensing of 405 nm light illumination is enabled. As compared with photovoltaic effect, both the responsivity and the specific detectivity of the photodetector can be dramatically enhanced by larger than 260% due to the light-induced photovoltaic-pyroelectric coupled effect. A self-powered photodetector array system can be utilized to achieve spatially resolved light intensity detection by recording the output voltage signals as a mapping figure. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of improved lithium tantalate pyroelectric detectors

NASA Technical Reports Server (NTRS)

Byer, N. E.; Vanderjagt, A.; Holton, W.

1978-01-01

A program was undertaken to increase the detectivity of LiTaO3 pyroelectric detectors to meet a performance requirement of D star (500 K, 15 Hz)=4x10 to the 9th power cm Hz1/2W-1. Emphasis was placed on reduction of the thermal conductance of the detector element to its surroundings, thinning the detector wafer to a thickness less than 3 micrometers, and increasing the absorptivity of the standard metallic film coatings. During the program, thermal conductance was reduced 41 percent through the use of reticulated (slotted) structures. Self-supported detector wafers less than 2 micrometers thick were fabricated. Multiple layer coatings, including an AR coating, with 16 percent more absorptance, were designed and fabricated. Later refinements in the multilayer design program have absorptivities of 75-80 percent, but detectors with these coatings had to be more than 2 micrometers thick because of a mismatch in the thermal expansion coefficients with LiTaO3.

Laser or charged-particle-beam fusion reactor with direct electric generation by magnetic flux compression

DOEpatents

Lasche, G.P.

1983-09-29

The invention is a laser or particle-beam-driven fusion reactor system which takes maximum advantage of both the very short pulsed nature of the energy release of inertial confinement fusion (ICF) and the very small volumes within which the thermonuclear burn takes place. The pulsed nature of ICF permits dynamic direct energy conversion schemes such as magnetohydrodynamic (MHD) generation and magnetic flux compression; the small volumes permit very compact blanket geometries. By fully exploiting these characteristics of ICF, it is possible to design a fusion reactor with exceptionally high power density, high net electric efficiency, and low neutron-induced radioactivity. The invention includes a compact blanket design and method and apparatus for obtaining energy utilizing the compact blanket.

Non-Dispersive Infrared Sensor for Online Condition Monitoring of Gearbox Oil.

PubMed

Rauscher, Markus S; Tremmel, Anton J; Schardt, Michael; Koch, Alexander W

2017-02-18

The condition of lubricating oil used in automotive and industrial gearboxes must be controlled in order to guarantee optimum performance and prevent damage to machinery parts. In normal practice, this is done by regular oil change intervals and routine laboratory analysis, both of which involve considerable operating costs. In this paper, we present a compact and robust optical sensor that can be installed in the lubrication circuit to provide quasi-continuous information about the condition of the oil. The measuring principle is based on non-dispersive infrared spectroscopy. The implemented sensor setup consists of an optical measurement cell, two thin-film infrared emitters, and two four-channel pyroelectric detectors equipped with optical bandpass filters. We present a method based on multivariate partial least squares regression to select appropriate optical bandpass filters for monitoring the oxidation, water content, and acid number of the oil. We perform a ray tracing analysis to analyze and correct the influence of the light path in the optical setup on the optical parameters of the bandpass filters. The measurement values acquired with the sensor for three different gearbox oil types show high correlation with laboratory reference data for the oxidation, water content, and acid number. The presented sensor can thus be a useful supplementary tool for the online condition monitoring of lubricants when integrated into a gearbox oil circuit.

Non-Dispersive Infrared Sensor for Online Condition Monitoring of Gearbox Oil

PubMed Central

Rauscher, Markus S.; Tremmel, Anton J.; Schardt, Michael; Koch, Alexander W.

2017-01-01

The condition of lubricating oil used in automotive and industrial gearboxes must be controlled in order to guarantee optimum performance and prevent damage to machinery parts. In normal practice, this is done by regular oil change intervals and routine laboratory analysis, both of which involve considerable operating costs. In this paper, we present a compact and robust optical sensor that can be installed in the lubrication circuit to provide quasi-continuous information about the condition of the oil. The measuring principle is based on non-dispersive infrared spectroscopy. The implemented sensor setup consists of an optical measurement cell, two thin-film infrared emitters, and two four-channel pyroelectric detectors equipped with optical bandpass filters. We present a method based on multivariate partial least squares regression to select appropriate optical bandpass filters for monitoring the oxidation, water content, and acid number of the oil. We perform a ray tracing analysis to analyze and correct the influence of the light path in the optical setup on the optical parameters of the bandpass filters. The measurement values acquired with the sensor for three different gearbox oil types show high correlation with laboratory reference data for the oxidation, water content, and acid number. The presented sensor can thus be a useful supplementary tool for the online condition monitoring of lubricants when integrated into a gearbox oil circuit. PMID:28218701

Manifestations of dynamo driven large-scale magnetic field in accretion disks of compact objects

NASA Technical Reports Server (NTRS)

Chagelishvili, G. D.; Chanishvili, R. G.; Lominadze, J. G.; Sokhadze, Z. A.

1991-01-01

A turbulent dynamo nonlinear theory of turbulence was developed that shows that in the compact objects of accretion disks, the generated large-scale magnetic field (when the generation takes place) has a practically toroidal configuration. Its energy density can be much higher than turbulent pulsations energy density, and it becomes comparable with the thermal energy density of the medium. On this basis, the manifestations to which the large-scale magnetic field can lead at the accretion onto black holes and gravimagnetic rotators, respectively, are presented.

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

Sokollik, T.; Leemans, W. P.; University of California, Berkeley, California 94720

We present experimental results on a tape-drive based plasma mirror which could be used for a compact coupling of a laser beam into a staged laser driven electron accelerator. This novel kind of plasma mirror is suitable for high repetition rates and for high number of laser shots.

Quasi-regenerative mode locking in a compact all-polarisation-maintaining-fibre laser

NASA Astrophysics Data System (ADS)

Nyushkov, B. N.; Ivanenko, A. V.; Kobtsev, S. M.; Pivtsov, V. S.; Farnosov, S. A.; Pokasov, P. V.; Korel, I. I.

2017-12-01

A novel technique of mode locking in erbium-doped all-polarisation-maintaining-fibre laser has been developed and preliminary investigated. The proposed quasi-regenerative technique combines the advantages of conventional active mode locking (when an intracavity modulator is driven by an independent RF oscillator) and regenerative mode locking (when a modulator is driven by an intermode beat signal from the laser itself). This scheme is based on intracavity intensity modulation driven by an RF oscillator being phase-locked to the actual intermode frequency of the laser. It features also possibilities of operation at multiple frequencies and harmonic mode-locking operation.

Current driven wiggler

NASA Astrophysics Data System (ADS)

Tournes, C.; Aucouturier, J.; Arnaud, B.; Brasile, J. P.; Convert, G.; Simon, M.

1992-07-01

A current-driven wiggler is the cornerstone of an innovative, compact, high-efficiency, transportable tunable free-electron laser (FEL), the feasibility of which is currently being evaluated by Thomson-CSF. The salient advantages are: compactness of the FEL, along with the possibility to accelerate the beam through several successive passes through the accelerating section (the number of passes being defined by the final wavelength of the radiation; i.e. visible, MWIR, LWIR); the wiggler can be turned off and be transparent to the beam until the last pass. Wiggler periodicities as small as 5 mm can be achieved, hence contributing to FEL compactness. To achieve overall efficiencies in the range of 10% at visible wavelengths, not only the wiggler periodicity must be variable, but the strength of the magnetic field of each period can be adjusted separately and fine-tuned versus time during the macropulse, so as to take into account the growing contribution of the wave energy in the cavity to the total ponderomotive force. The salient theoretical point of this design is the optimization of the parameters defining each period of the wiggler for each micropacket of the macropulse. The salient technology point is the mechanical and thermal design of the wiggler which allows the required high currents to achieve magnetic fields up to 2T.

An Ultrasonic Compactor for Oil and Gas Exploration

NASA Astrophysics Data System (ADS)

Feeney, Andrew; Sikaneta, Sakalima; Harkness, Patrick; Lucas, Margaret

The Badger Explorer is a rig-less oil and gas exploration tool which drills into the subsea environment to collect geological data. Drill spoil is transported from the front end of the system to the rear, where the material is compacted. Motivated by the need to develop a highly efficient compaction system, an ultrasonic compactor for application with granular geological materials encountered in subsea environments is designed and fabricated as part of this study. The finite element method is used to design a compactor configuration suitable for subsea exploration, consisting of a vibrating ultrasonic horn called a resonant compactor head, which operates in a longitudinal mode at 20 kHz, driven by a Langevin piezoelectric transducer. A simplified version of the compactor is also designed, due to its ease of incorporating in a lab-based experimental rig, in order to demonstrate enhanced compaction using ultrasonics. Numerical analysis of this simplified compactor system is supported with experimental characterisation using laser Doppler vibrometry. Compaction testing is then conducted on granular geological material, showing that compaction can be enhanced through the use of an ultrasonic compactor.

Laser Transmissometer, Installation, Alignment and Instruction Manual.

DTIC Science & Technology

1978-07-01

detector lens LI, which focuses the energy onto detector Dl, a pyroelectric long wavelength detector. The S2 radiation is reflected by BS5 to lens L2 and...Instruction Manual for Series TWO-10 YAG-TWOTM Lasers (Serial 162 and Above) General Photonics Inc. Operating and Maintenance Manual Hughes Helion Neon

Composite Pyroelectric Materials.

DTIC Science & Technology

1979-06-30

in hydtochloric acid .. The wax negative is reinvested with a PZT slip (43 volume% PZT, 53% 1120, 4% poly (vinyl alcohol)). Ultrasonics PZT-501A with an...Laboratory are also acknowledged with gratitude. This work was sponsored by the Department of Defense through contracts N00014-78-C-0291 and HDA 903-78

Vacuum compatible, high-speed, 2-D mirror tilt stage

DOEpatents

Denham; Paul E.

2007-09-25

A compact and vacuum compatible magnetic-coil driven tiltable stage that is equipped with a high efficiency reflective coating can be employed as a scanner in EUV applications. The drive electronics for the scanner is fully in situ programmable and rapidly switchable.

Improved Merge Valve

NASA Technical Reports Server (NTRS)

George-Falvy, Dez

1992-01-01

Circumferential design combines compactness and efficiency. In remotely controlled valve, flow in tributary duct along circumference of primary duct merged with flow in primary duct. Flow in tributary duct regulated by variable throat nuzzle driven by worm gear. Design leak-proof, and most components easily fabricated on lathe.

INTO THE LAIR: GRAVITATIONAL-WAVE SIGNATURES OF DARK MATTER

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

Macedo, Caio F. B.; Cardoso, Vitor; Crispino, Luis C. B.

The nature and properties of dark matter (DM) are both outstanding issues in physics. Besides clustering in halos, the universal character of gravity implies that self-gravitating compact DM configurations-predicted by various models-might be spread throughout the universe. Their astrophysical signature can be used to probe fundamental particle physics, or to test alternative descriptions of compact objects in active galactic nuclei. Here, we discuss the most promising dissection tool of such configurations: the inspiral of a compact stellar-size object and consequent gravitational-wave (GW) emission. The inward motion of this ''test probe'' encodes unique information about the nature of the supermassive configuration.more » When the probe travels through some compact region we show, within a Newtonian approximation, that the quasi-adiabatic inspiral is mainly driven by DM accretion and by dynamical friction, rather than by radiation reaction. When accretion dominates, the frequency and amplitude of the GW signal produced during the latest stages of the inspiral are nearly constant. In the exterior region we study a model in which the inspiral is driven by GW and scalar-wave emission, described at a fully relativistic level. Resonances in the energy flux appear whenever the orbital frequency matches the effective mass of the DM particle, corresponding to the excitation of the central object's quasinormal frequencies. Unexpectedly, these resonances can lead to large dephasing with respect to standard inspiral templates, to such an extent as to prevent detection with matched filtering techniques. We discuss some observational consequences of these effects for GW detection.« less

Compact Starburst Galaxies with Fast Outflows: Spatially Resolved Stellar Mass Profiles

NASA Astrophysics Data System (ADS)

Gottlieb, Sophia; Diamond-Stanic, Aleksandar; Lipscomb, Charles; Ohene, Senyo; Rines, Josh; Moustakas, John; Sell, Paul; Tremonti, Christy; Coil, Alison; Rudnick, Gregory; Hickox, Ryan C.; Geach, James; Kepley, Amanda

2018-01-01

Powerful galactic winds driven by stellar feedback and black hole accretion are thought to play an important role in regulating star formation in galaxies. In particular, strong stellar feedback from supernovae, stellar winds, radiation pressure, and cosmic rays is required by simulations of star-forming galaxies to prevent the vast majority of baryons from cooling and collapsing to form stars. However, it remains unclear whether these stellar processes play a significant role in expelling gas and shutting down star formation in massive progenitors of quiescent galaxies. What are the limits of stellar feedback? We present multi-band photometry with HST/WFC3 (F475W, F814W, F160W) for a dozen compact starburst galaxies at z~0.6 with half-light radii that suggest incredibly large central escape velocities. These massive galaxies are driving fast (>1000 km/s) outflows that have been previously attributed to stellar feedback associated with the compact (r~100 pc) starburst. But how compact is the stellar mass? In the context of the stellar feedback hypothesis, it is unclear whether these fast outflows are being driven at velocities comparable to the escape velocity of an incredibly dense stellar system (as predicted by some models of radiation-pressure winds) or at velocities that exceed the central escape velocity by large factor. Our spatially resolved measurements with HST show that the stellar mass is more extended than the light, and this requires that the physical mechanism responsible for driving the winds must be able to launch gas at velocities that are factors of 5-10 beyond the central escape velocity.

Compact plasma Pockels cell for TIL of SGIII laser facility

NASA Astrophysics Data System (ADS)

Zhang, Xiongjun; Wu, Dengsheng; Lin, Doughui; Yu, Haiwu; Zhang, Jun

2008-01-01

Compact plasma Pockel's cells (PPC) with 70mm aperture driven by one-pulse process have been constructed for technical integration line (TIL) of SGIII laser facility. The experimental results indicate that the working range of gas pressure is wide, and the delay of gas breakdown is steady. Measurements of the optical performance show static transmittance of 93.1%, static extinction ratio of 3900, and average switching efficiency of 99.7%. Eight compact PPCs are used for the second-stage integrating experiments of TIL. By using of parallel driving technology, one driver can work for four PPCs. An analyzer of optical switch is replaced with Brewster-angle Nd-glass slabs in amplifier. Two years application results show that the PPCs can effectively minimize the growth of parasitic-oscillation, and have a high reliability.

Battery driven 8 channel pulse height analyzer with compact, single gamma-peak display

DOEpatents

Morgan, John P.; Piper, Thomas C.

1991-01-01

The invention comprises a hand-held wand including an l.e.d. display and a aI photomultiplier tube encased in lead or other suitable gamma shielding material, and an electronics and battery back-pack package connected to the wand.

Rotatable prism for pan and tilt

NASA Technical Reports Server (NTRS)

Ball, W. B.

1980-01-01

Compact, inexpensive, motor-driven prisms change field of view of TV camera. Camera and prism rotate about lens axis to produce pan effect. Rotating prism around axis parallel to lens produces tilt. Size of drive unit and required clearance are little more than size of camera.

Compact beam transport system for free-electron lasers driven by a laser plasma accelerator

DOE PAGES

Liu, Tao; Zhang, Tong; Wang, Dong; ...

2017-02-01

Utilizing laser-driven plasma accelerators (LPAs) as a high-quality electron beam source is a promising approach to significantly downsize the x-ray free-electron laser (XFEL) facility. A multi-GeV LPA beam can be generated in several-centimeter acceleration distance, with a high peak current and a low transverse emittance, which will considerably benefit a compact FEL design. However, the large initial angular divergence and energy spread make it challenging to transport the beam and realize FEL radiation. In this paper, a novel design of beam transport system is proposed to maintain the superior features of the LPA beam and a transverse gradient undulator (TGU)more » is also adopted as an effective energy spread compensator to generate high-brilliance FEL radiation. As a result, theoretical analysis and numerical simulations are presented based on a demonstration experiment with an electron energy of 380 MeV and a radiation wavelength of 30 nm.« less

a Compact, Rf-Driven Pulsed Ion Source for Intense Neutron Generation

NASA Astrophysics Data System (ADS)

Perkins, L. T.; Celata, C. M.; Lee, Y.; Leung, K. N.; Picard, D. S.; Vilaithong, R.; Williams, M. D.; Wutte, D.

1997-05-01

Lawrence Berkeley National Laboratory is currently developing a compact, sealed-accelerator-tube neutron generator capable of producing a neutron flux in the range of 109 to 1010 D-T neutrons per second. The ion source, a miniaturized variation of earlier 2 MHz radio-frequency (rf)-driven multicusp ion sources, is designed to fit within a #197# 5 cm diameter borehole. Typical operating parameters include repetition rates up to 100 pps, with pulse widths between 10 and 80 us and source pressures as low as #197# 5 mTorr. In this configuration, peak extractable hydrogen current exceeding 35 mA from a 2 mm diameter aperture together with H1+ yields over 94% have been achieved. The required rf impedance matching network has been miniaturized to #197# 5 cm diameter. The accelerator column is a triode design using the IGUN ion optics codes and allows for electron suppression. Results from the testing of the integrated matching network-ion source-accelerator system will be presented.

Scale Model Test and Transient Analysis of Steam Injector Driven Passive Core Injection System for Innovative-Simplified Nuclear Power Plant

NASA Astrophysics Data System (ADS)

Ohmori, Shuichi; Narabayashi, Tadashi; Mori, Michitsugu

A steam injector (SI) is a simple, compact and passive pump and also acts as a high-performance direct-contact compact heater. This provides SI with capability to serve also as a direct-contact feed-water heater that heats up feed-water by using extracted steam from turbine. Our technology development aims to significantly simplify equipment and reduce physical quantities by applying "high-efficiency SI", which are applicable to a wide range of operation regimes beyond the performance and applicable range of existing SIs and enables unprecedented multistage and parallel operation, to the low-pressure feed-water heaters and emergency core cooling system of nuclear power plants, as well as achieve high inherent safety to prevent severe accidents by keeping the core covered with water (a severe accident-free concept). This paper describes the results of the scale model test, and the transient analysis of SI-driven passive core injection system (PCIS).

Development of compact explosively driven ferromagnetic seed source for helical magnetic flux compression generator

NASA Astrophysics Data System (ADS)

Liu, Peng; Zhang, He; Ma, Shaojie; Shi, Yunlei

2018-05-01

A compact explosively driven ferromagnetic generator (FMG) is developed for seed power source of helical magnetic flux compression generator (HMFCG). The mechanism of FMG is studied by establishing a magnetoelectric conversion model. Analytical calculations and numerical simulations are conducted on the magnetostatic field of open-circuit magnet in FMG. The calculation method for the magnet's cross-sectional magnetic flux is obtained. The pulse sources made of different materials and equipped with different initiation modes are experimentally explored. Besides, the dynamic coupling experiments of FMG and HMFCG are carried out. The results show that, N35 single-ended and double-ended initiating FMGs have an energy conversion efficiency ηt not less than 14.6% and 24.4%, respectively; FMG has an output pulse current not less than 4kA and an energy of about 3J on 320nH inductive load; HMFCG experiences energy gains of about 2-3 times. FMG and HMFCG can be coupled to form a full-blast electrical driving pulse source.

Systematic features of axisymmetric neutrino-driven core-collapse supernova models in multiple progenitors

NASA Astrophysics Data System (ADS)

Nakamura, Ko; Takiwaki, Tomoya; Kuroda, Takami; Kotake, Kei

2015-12-01

We present an overview of two-dimensional (2D) core-collapse supernova simulations employing a neutrino transport scheme by the isotropic diffusion source approximation. We study 101 solar-metallicity, 247 ultra metal-poor, and 30 zero-metal progenitors covering zero-age main sequence mass from 10.8 M⊙ to 75.0 M⊙. Using the 378 progenitors in total, we systematically investigate how the differences in the structures of these multiple progenitors impact the hydrodynamics evolution. By following a long-term evolution over 1.0 s after bounce, most of the computed models exhibit neutrino-driven revival of the stalled bounce shock at ˜200-800 ms postbounce, leading to the possibility of explosion. Pushing the boundaries of expectations in previous one-dimensional studies, our results confirm that the compactness parameter ξ that characterizes the structure of the progenitors is also a key in 2D to diagnosing the properties of neutrino-driven explosions. Models with high ξ undergo high ram pressure from the accreting matter onto the stalled shock, which affects the subsequent evolution of the shock expansion and the mass of the protoneutron star under the influence of neutrino-driven convection and the standing accretion-shock instability. We show that the accretion luminosity becomes higher for models with high ξ, which makes the growth rate of the diagnostic explosion energy higher and the synthesized nickel mass bigger. We find that these explosion characteristics tend to show a monotonic increase as a function of the compactness parameter ξ.

Micromechanical Prediction of the Effective Coefficients of Thermo-Piezoelectric Multiphase Composites

NASA Technical Reports Server (NTRS)

Aboudi, Jacob

1998-01-01

The micromechanical generalized method of cells model is employed for the prediction of the effective elastic, piezoelectric, dielectric, pyroelectric and thermal-expansion constants of multiphase composites with embedded piezoelectric materials. The predicted effective constants are compared with other micromechanical methods available in the literature and good agreements are obtained.

A microcalorimeter for measuring heat effects of electrochemical reactions with submonolayer conversions

NASA Astrophysics Data System (ADS)

Etzel, Kai D.; Bickel, Katrin R.; Schuster, Rolf

2010-03-01

We present a microcalorimeter for measuring heat effects during electrochemical reactions with conversions down to a few percent of a monolayer, referenced to the electrode's surface atoms. The design uses a thin pyroelectric polymer foil for temperature measurement at the backside of a thin electrode, similar to the concepts pioneered by the groups of D. A. King and Ch. T. Campbell for UHV adsorption microcalorimetry. To establish intimate thermal contact between electrode and sensor and utmost sensitivity, the free standing sensor and electrode foils are pressed together by air pressure, acting on the electrochemical cell. Pyroelectric temperature sensing is combined with pulsed electrochemistry, where the electrochemical heat is released on a time scale of about 10 ms, which is long enough for thermal equalization of the electrode-sensor assembly but short enough to avoid significant heat loss into electrolyte and cell compartment. As examples heat effects upon Ag deposition and dissolution as well as the electron transfer reaction of [Fe(CN)6]4-/[Fe(CN)6]3- are presented. The latter reaction was also employed for the calibration of the calorimeter.

Behavior of lanthanum containing barium stannate nanoparticles synthesized by cetyltriammonium bromide assisted wet chemistry route

NASA Astrophysics Data System (ADS)

Kumar, Astakala Anil; Kumar, Ashok; Quamara, J. K.

2018-02-01

In present study, we report dielectric, ferroelectric and pyroelectric behavior of pristine and La3+ containing barium stannate nanoparticles synthesized via wet chemical route involving cetyltriammonium bromide assisted thermal decomposition of binary precursors. The X-ray diffraction patterns of pristine and La3+ (2, 4 and 6 at%) doped BaSnO3 nanoparticles showed the formation of cubic perovskite phase. On substitution of Ba2+ lattice sites by La3+ at the La content of 6 at%, the sample exhibited fourfold increase in conductivity in comparison to pristine BaSnO3. Polarization hysteresis (P-E) curves of La containing barium stannate nanoparticles showed anti-ferroelectric behavior. The pyroelectric coefficient of pristine and La (2, 4 and 6 at%) containing BaSnO3 nanoparticles at 473 K were found to be 7.8, 11.6, 14.1 and 17.2 μCm-2K-1, respectively. Further, the responsivity and detectivity values were higher in comparison to the materials, such as AlN, GaN, CdS and ZnO.

Modulate chopper technique used in pyroelectric uncooled focal plane array thermal imager

NASA Astrophysics Data System (ADS)

He, Yuqing; Jin, Weiqi; Liu, Guangrong; Gao, Zhiyun; Wang, Xia; Wang, Lingxue

2002-09-01

Pyroelectric uncooled focal plane array (FPA) thermal imager has the advantages of low cost, small size, high responsibility and can work under room temperature, so it has great progress in recent years. As a matched technique, the modulate chopper has become one of the key techniques in uncooled FPA thermal imaging system. Now the Archimedes spiral cord chopper technique is mostly used. When it works, the chopper pushing scans the detector's pixel array, thus makes the pixels being exposed continuously. This paper simulates the shape of this kind of chopper, analyses the exposure time of the detector's every pixel, and also analyses the whole detector pixels' exposure sequence. From the analysis we can get the results: the parameter of Archimedes spiral cord, the detector's thermal time constant, the detector's geometrical dimension, the relative position of the detector to the chopper's spiral cord are the system's important parameters, they will affect the chopper's exposure efficiency and uniformity. We should design the chopper's relevant parameter according to the practical request to achieve the chopper's appropriate structure.

An Investigation on the Thermal Effusivity of Nanofluids Containing Al2O3 and CuO Nanoparticles

PubMed Central

Noroozi, Monir; Zakaria, Azmi; Moksin, Mohd Maarof; Wahab, Zaidan Abd

2012-01-01

The thermal effusivity of Al2O3 and CuO nanofluids in different base fluids, i.e., deionized water, ethylene glycol and olive oil were investigated. The nanofluids, nanoparticles dispersed in base fluids; were prepared by mixing Al2O3, CuO nanopowder and the base fluids using sonication with high-powered pulses to ensure a good uniform dispersion of nanoparticles in the base fluids. The morphology of the particles in the base fluids was investigated by transmission electron microscopy (TEM). In this study, a phase frequency scan of the front pyroelectric configuration technique, with a thermally thick PVDF pyroelectric sensor and sample, was used to measure the thermal effusivity of the prepared nanofluids. The experimental results of the thermal effusivity of the studied solvents (deionized water, ethylene glycol and olive oil) showed good agreement with literature values, and were reduced in the presence of nanoparticles. The thermal effusivity of the nanofluid was found to be particularly sensitive to its base fluid and the type of nanoparticles. PMID:22949865

An investigation on the thermal effusivity of nanofluids Containing Al(2)O(3) and CuO nanoparticles.

PubMed

Noroozi, Monir; Zakaria, Azmi; Moksin, Mohd Maarof; Wahab, Zaidan Abd

2012-01-01

The thermal effusivity of Al(2)O(3) and CuO nanofluids in different base fluids, i.e., deionized water, ethylene glycol and olive oil were investigated. The nanofluids, nanoparticles dispersed in base fluids; were prepared by mixing Al(2)O(3), CuO nanopowder and the base fluids using sonication with high-powered pulses to ensure a good uniform dispersion of nanoparticles in the base fluids. The morphology of the particles in the base fluids was investigated by transmission electron microscopy (TEM). In this study, a phase frequency scan of the front pyroelectric configuration technique, with a thermally thick PVDF pyroelectric sensor and sample, was used to measure the thermal effusivity of the prepared nanofluids. The experimental results of the thermal effusivity of the studied solvents (deionized water, ethylene glycol and olive oil) showed good agreement with literature values, and were reduced in the presence of nanoparticles. The thermal effusivity of the nanofluid was found to be particularly sensitive to its base fluid and the type of nanoparticles.

Thermally induced light-driven microfluidics using a MOEMS-based laser scanner for particle manipulation

NASA Astrophysics Data System (ADS)

Kremer, Matthias P.; Tortschanoff, Andreas

2014-03-01

One key challenge in the field of microfluidics and lab-on-a-chip experiments for biological or chemical applications is the remote manipulation of fluids, droplets and particles. These can be volume elements of reactants, particles coated with markers, cells or many others. Light-driven microfluidics is one way of accomplishing this challenge. In our work, we manipulated micrometre sized polystyrene beads in a microfluidic environment by inducing thermal flows. Therefore, the beads were held statically in an unstructured microfluidic chamber, containing a dyed watery solution. Inside this chamber, the beads were moved along arbitrary trajectories on a micrometre scale. The experiments were performed, using a MOEMS (micro-opto-electro-mechanical-systems)-based laser scanner with a variable focal length. This scanner system is integrated in a compact device, which is flexibly applicable to various microscope setups. The device utilizes a novel approach for varying the focal length, using an electrically tunable lens. A quasi statically driven MOEMS mirror is used for beam steering. The combination of a tunable lens and a dual axis micromirror makes the device very compact and robust and is capable of positioning the laser focus at any arbitrary location within a three dimensional working space. Hence, the developed device constitutes a valuable extension to manually executed microfluidic lab-on-chip experiments.

Hydrodynamic simulations of stellar wind disruption by a compact X-ray source

NASA Technical Reports Server (NTRS)

Blondin, John M.; Kallman, Timothy R.; Fryxell, Bruce A.; Taam, Ronald E.

1990-01-01

This paper presents two-dimensional numerical simulations of the gas flow in the orbital plane of a massive X-ray binary system, in which the mass accretion is fueled by a radiation-driven wind from an early-type companion star. These simulations are used to examine the role of the compact object (either a neutron star or a black hole) in disturbing the radiatively accelerating wind of the OB companion, with an emphasis on understanding the origin of the observed soft X-ray photoelectric absorption seen at late orbital phases in these systems. On the basis of these simulations, it is suggested that the phase-dependent photoelectric absorption seen in several of these systems can be explained by dense filaments of compressend gas formed in the nonsteady accreation bow shock and wake of the compact object.

Magnetic order and magnetoelectric properties of R2CoMn O6 perovskites (R =Ho , Tm, Yb, and Lu)

NASA Astrophysics Data System (ADS)

Blasco, J.; García-Muñoz, J. L.; García, J.; Subías, G.; Stankiewicz, J.; Rodríguez-Velamazán, J. A.; Ritter, C.

2017-07-01

We present a detailed study on the magnetic structure and magnetoelectric properties of several double perovskites R2CoMn O6 (R =Ho , Tm, Yb, and Lu). All of these samples show an almost perfect (˜94 %) ordering of C o2 + and M n4 + cations in the unit cell. Our research reveals that the magnetic ground state strongly depends on the R size. For samples with larger R (Ho and Tm), the ground state is formed by a ferromagnetic order (F type) of C o2 + and M n4 + moments, while R either remains mainly disordered (Ho) or is coupled antiferromagnetically (Tm) to the Co/Mn sublattice. For samples with smaller R (Yb or Lu), competitive interactions lead to the formation of an E -type arrangement for the C o2 + and M n4 + moments with a large amount of extended defects such as stacking faults. The Y b3 + is partly ordered at very low temperature. The latter samples undergo a metamagnetic transition from the E into the F type, which is coupled to a negative magnetodielectric effect. Actually, the real part of dielectric permittivity shows an anomaly at the magnetic transition for the samples exhibiting an E -type order. This anomaly is absent in samples with F -type order, and, accordingly, it vanishes coupled to the metamagnetic transition for R =Yb or Lu samples. At room temperature, the huge values of the dielectric constant reveal the presence of Maxwell-Wagner depletion layers. Pyroelectric measurements reveal a high polarization at low temperature, but the onset of pyroelectric current is neither correlated to the kind of magnetic ordering nor to the magnetic transition. Our study identified the pyroelectric current as thermally stimulated depolarization current and electric-field polarization curves show a linear behavior at low temperature. Therefore, no clear ferroelectric transition occurs in these compounds.

Access control violation prevention by low-cost infrared detection

NASA Astrophysics Data System (ADS)

Rimmer, Andrew N.

2004-09-01

A low cost 16x16 un-cooled pyroelectric detector array, allied with advanced tracking and detection algorithms, has enabled the development of a universal detector with a wide range of applications in people monitoring and homeland security. Violation of access control systems, whether controlled by proximity card, biometrics, swipe card or similar, may occur by 'tailgating' or 'piggybacking' where an 'approved' entrant with a valid entry card is accompanied by a closely spaced 'non-approved' entrant. The violation may be under duress, where the accompanying person is attempting to enter a secure facility by force or threat. Alternatively, the violation may be benign where staff members collude either through habit or lassitude, either with each other or with third parties, without considering the security consequences. Examples of the latter could include schools, hospitals or maternity homes. The 16x16 pyroelectric array is integrated into a detector or imaging system which incorporates data processing, target extraction and decision making algorithms. The algorithms apply interpolation to the array output, allowing a higher level of resolution than might otherwise be expected from such a low resolution array. The pyroelectric detection principle means that the detection will work in variable light conditions and even in complete darkness, if required. The algorithms can monitor the shape, form, temperature and number of persons in the scene and utilise this information to determine whether a violation has occurred or not. As people are seen as 'hot blobs' and are not individually recognisable, civil liberties are not infringed in the detection process. The output from the detector is a simple alarm signal which may act as input to the access control system as an alert or to trigger CCTV image display and storage. The applications for a tailgate detector can be demonstrated across many medium security applications where there are no physical means to prevent this type of security breach.

Trust and compactness in social network groups.

PubMed

De Meo, Pasquale; Ferrara, Emilio; Rosaci, Domenico; Sarné, Giuseppe M L

2015-02-01

Understanding the dynamics behind group formation and evolution in social networks is considered an instrumental milestone to better describe how individuals gather and form communities, how they enjoy and share the platform contents, how they are driven by their preferences/tastes, and how their behaviors are influenced by peers. In this context, the notion of compactness of a social group is particularly relevant. While the literature usually refers to compactness as a measure to merely determine how much members of a group are similar among each other, we argue that the mutual trustworthiness between the members should be considered as an important factor in defining such a term. In fact, trust has profound effects on the dynamics of group formation and their evolution: individuals are more likely to join with and stay in a group if they can trust other group members. In this paper, we propose a quantitative measure of group compactness that takes into account both the similarity and the trustworthiness among users, and we present an algorithm to optimize such a measure. We provide empirical results, obtained from the real social networks EPINIONS and CIAO, that compare our notion of compactness versus the traditional notion of user similarity, clearly proving the advantages of our approach.

Modelling, fabrication, and characterization for improved piezoelectric energy harvesters

NASA Astrophysics Data System (ADS)

Alomari, Almuatasim Ali

The ambitious goal of this dissertation is to contribute its share to the scientific researchers and academic community by demonstrate a versatile study on energy harvesting via smart materials. Smart materials are amongst the current production modes which generate clean and green energy. The advantages of smart materials include ferroelectric, piezoelectric, and pyroelectric ceramics and composites in materials science and technology of the 21 st century are inconceivable. Their most current applications include conventional sensors, actuators, batteries replacement, and switch. Further, Piezoelectricity is the accumulation of electrical charges as a result of applying mechanical stress on certain type of materials such as crystals, DNA, and protein, where pyro-electricity is the accumulation of electrical charges from ambient environment from temperature gauges or fluctuations. In an incessant effort to increase the performance of smart materials devices researchers in both academic and industrial communities in field of green energy have suggested many techniques and procedures to increase the power generation capability and enhance the bandwidth of thermal and vibration energy harvesters. In this study, the EulerBernoulli beam Theory, lumped parameter model (LPM), and chain matrix method were applied on various design and structure shape of smart materials to find the output electrical parameters. The modeling and simulation investigations are accomplished using MATLAB program and COMSOL Multiphysics software. A low-cost fabrication technique, of polyvinyl-dine difluoride (PVDF) with different amount of Lead Zirconate Titanate (PZT), Lead Magnesium Niobate-Lead Titanate (PMN-PT), and Multi-walled Carbon Nanotubes (MWCNT) are introduced in this study as well. Later, the (Paint/ PZT) fabricated nanocomposites was tested for dielectric constants over a wide frequency range at different temperatures. It was observed that the composites with higher concentrations of PZT nanocomposite have higher dielectric constants than well-known PVDF film. Finally, the performance of the piezoelectric and pyroelectric PMN-PT single crystal with a (67:33) composition grown in our laboratory using unimorph device structures was evaluated via modeling and experiments. The theoretical study was implemented based on a distributed parameter electromechanical model and the modelling procedure was approximated using the finite element analysis (FEA) to predict the electromechanical behavior of the harvesters. The maximum power density at a resonance frequency of 65 Hz and optimum resistance of 200 kO was 45 nW under a 0.5 g acceleration of vibration. By using pyroelectric effect along with the piezoelectric effect, the output voltage of the energy harvester was found to be enhanced at the optimum resistance and specific frequency values. It was noticed that the output voltage was increased monotonically with temperature-difference (DeltaT) and reaches up to 180% of its original value under difference temperature of 1.7 °C.

Mechanisms of differentiation in the Skaergaard magma chamber

NASA Astrophysics Data System (ADS)

Tegner, C.; Lesher, C. E.; Holness, M. B.; Jakobsen, J. K.; Salmonsen, L. P.; Humphreys, M. C. S.; Thy, P.

2012-04-01

The Skaergaard intrusion is a superb natural laboratory for studying mechanisms of magma chamber differentiation. The magnificent exposures and new systematic sample sets of rocks that solidified inwards from the roof, walls and floor of the chamber provide means to test the relative roles of crystal settling, diffusion, convection, liquid immiscibility and compaction in different regions of the chamber and in opposite positions relative to gravity. Examination of the melt inclusions and interstitial pockets has demonstrated that a large portion of intrusion crystallized from an emulsified magma chamber composed of immiscible silica- and iron-rich melts. The similarity of ratios of elements with opposite partitioning between the immiscible melts (e.g. P and Rb) in wall, floor and roof rocks, however, indicate that large-scale separation did not occur. Yet, on a smaller scale of metres to hundred of metres and close to the interface between the roof and floor rocks (the Sandwich Horizon), irregular layers and pods of granophyre hosted by extremely iron-rich cumulates point to some separation of the two liquid phases. Similar proportions of the primocryst (cumulus) minerals in roof, wall and floor rocks indicate that crystal settling was not an important mechanism. Likewise, the lack of fractionation of elements with different behavior indicate that diffusion and fluid-driven metasomatism played relatively minor roles. Compositional convection and/or compaction within the solidifying crystal mush boundary layer are likely the most important mechanisms. A correlation of low trapped liquid fractions (calculated from strongly incompatible elements) in floor rocks with high fractionation density (the density difference between the crystal framework and the liquid) indicate that compaction is the dominating process in expelling evolved liquid from the crystal mush layer. This is supported by high and variable trapped liquid contents in the roof rocks, where gravity-driven compaction will not work.

Magnetoelectric Energy Harvesting

DTIC Science & Technology

2014-11-20

materials to rotating or moving machinery , make it difficult to locate piezoelectric material devices in contact with the mechanical stress generator which...mechanical energy harvesting device and more particularly relates to such a device that has a magnetostrictive and piezoelectric component. (2...makes them a candidate as the active material in energy harvesting devices. By utilizing the direct piezoelectric (or pyroelectric) effect when

Concurrent Harvesting of Ambient Energy by Hybrid Nanogenerators for Wearable Self-Powered Systems and Active Remote Sensing.

PubMed

Zheng, Haiwu; Zi, Yunlong; He, Xu; Guo, Hengyu; Lai, Ying-Chih; Wang, Jie; Zhang, Steven L; Wu, Changsheng; Cheng, Gang; Wang, Zhong Lin

2018-05-02

Harvesting energy available from ambient environment is highly desirable for powering personal electronics and health applications. Due to natural process and human activities, steam can be produced by boilers, human perspiration, and the wind exists ubiquitously. In the outdoor environment, these two phenomena usually exist at the same place, which contain heat and mechanical energies simultaneously. However, previous studies have isolated them as separate sources of energy to harvest and hence failed to utilize them effectively. Herein, we present unique hybrid nanogenerators for individually/simultaneously harvesting thermal energy from water vapors and mechanical energy from intermittent wind blowing from the bottom side, which consist of a wind-driven triboelectric nanogenerator (TENG) and pyroelectric-piezoelectric nanogenerators (PPENGs). The output power of the PPENG and the TENG can be up to about 184.32 μW and 4.74 mW, respectively, indicating the TENG plays the dominant role. Our hybrid nanogenerators could provide different applications such as to power digital watch and enable self-powered sensing with wireless transmission. The device could also be further integrated into a face mask for potentially wearable applications. This work not only provides a promising approach for renewable energy harvesting but also enriches potential applications for self-powered systems and wireless sensors.

Laser-driven electron beam and radiation sources for basic, medical and industrial sciences.

PubMed

Nakajima, Kazuhisa

2015-01-01

To date active research on laser-driven plasma-based accelerators have achieved great progress on production of high-energy, high-quality electron and photon beams in a compact scale. Such laser plasma accelerators have been envisaged bringing a wide range of applications in basic, medical and industrial sciences. Here inheriting the groundbreaker's review article on "Laser Acceleration and its future" [Toshiki Tajima, (2010)],(1)) we would like to review recent progress of producing such electron beams due to relativistic laser-plasma interactions followed by laser wakefield acceleration and lead to the scaling formulas that are useful to design laser plasma accelerators with controllability of beam energy and charge. Lastly specific examples of such laser-driven electron/photon beam sources are illustrated.

Origins of structure in globular proteins.

PubMed Central

Chan, H S; Dill, K A

1990-01-01

The principal forces of protein folding--hydrophobicity and conformational entropy--are nonspecific. A long-standing puzzle has, therefore, been: What forces drive the formation of the specific internal architectures in globular proteins? We find that any self-avoiding flexible polymer molecule will develop large amounts of secondary structure, helices and parallel and antiparallel sheets, as it is driven to increasing compactness by any force of attraction among the chain monomers. Thus structure formation arises from the severity of steric constraints in compact polymers. This steric principle of organization can account for why short helices are stable in globular proteins, why there are parallel and anti-parallel sheets in proteins, and why weakly unfolded proteins have some secondary structure. On this basis, it should be possible to construct copolymers, not necessarily using amino acids, that can collapse to maximum compactness in incompatible solvents and that should then have structural organization resembling that of proteins. Images PMID:2385597

Compact pulse generators with soft ferromagnetic cores driven by gunpowder and explosive.

PubMed

Ben, Chi; He, Yong; Pan, Xuchao; Chen, Hong; He, Yuan

2015-12-01

Compact pulse generators which utilized soft ferromagnets as an initial energy carrier inside multi-turn coil and hard ferromagnets to provide the initial magnetic field outside the coil have been studied. Two methods of reducing the magnetic flux in the generators have been studied: (1) by igniting gunpowder to launch the core out of the generator, and (2) by detonating explosives that demagnetize the core. Several types of compact generators were explored to verify the feasibility. The generators with an 80-turn coil that utilize gunpowder were capable of producing pulses with amplitude 78.6 V and the full width at half maximum was 0.41 ms. The generators with a 37-turn coil that utilize explosive were capable of producing pulses with amplitude 1.41 kV and the full width at half maximum was 11.68 μs. These two methods were both successful, but produce voltage waveforms with significantly different characteristics.

A two-phase micromorphic model for compressible granular materials

NASA Astrophysics Data System (ADS)

Paolucci, Samuel; Li, Weiming; Powers, Joseph

2009-11-01

We introduce a new two-phase continuum model for compressible granular material based on micromorphic theory and treat it as a two-phase mixture with inner structure. By taking an appropriate number of moments of the local micro scale balance equations, the average phase balance equations result from a systematic averaging procedure. In addition to equations for mass, momentum and energy, the balance equations also include evolution equations for microinertia and microspin tensors. The latter equations combine to yield a general form of a compaction equation when the material is assumed to be isotropic. When non-linear and inertial effects are neglected, the generalized compaction equation reduces to that originally proposed by Bear and Nunziato. We use the generalized compaction equation to numerically model a mixture of granular high explosive and interstitial gas. One-dimensional shock tube and piston-driven solutions are presented and compared with experimental results and other known solutions.

Highly precise and compact ultrahigh vacuum rotary feedthrough.

PubMed

Aiura, Y; Kitano, K

2012-03-01

The precision and rigidity of compact ultrahigh vacuum (UHV) rotary feedthroughs were substantially improved by preparing and installing an optimal crossed roller bearing with mounting holes. Since there are mounting holes on both the outer and inner races, the bearing can be mounted directly to rotary and stationary stages without any fixing plates and housing. As a result, it is possible to increase the thickness of the bearing or the size of the rolling elements in the bearing without increasing the distance between the rotating and fixing International Conflat flanges of the UHV rotary feedthrough. Larger rolling elements enhance the rigidity of the UHV rotary feedthrough. Moreover, owing to the structure having integrated inner and outer races and mounting holes, the performance is almost entirely unaffected by the installation of the bearing, allowing for a precise optical encoder to be installed in the compact UHV rotary feedthrough. Using position feedback via a worm gear system driven by a stepper motor and a precise rotary encoder, the actual angle of the compact UHV rotary feedthrough can be controlled with extremely high precision.

Highly precise and compact ultrahigh vacuum rotary feedthrough

NASA Astrophysics Data System (ADS)

Aiura, Y.; Kitano, K.

2012-03-01

The precision and rigidity of compact ultrahigh vacuum (UHV) rotary feedthroughs were substantially improved by preparing and installing an optimal crossed roller bearing with mounting holes. Since there are mounting holes on both the outer and inner races, the bearing can be mounted directly to rotary and stationary stages without any fixing plates and housing. As a result, it is possible to increase the thickness of the bearing or the size of the rolling elements in the bearing without increasing the distance between the rotating and fixing International Conflat flanges of the UHV rotary feedthrough. Larger rolling elements enhance the rigidity of the UHV rotary feedthrough. Moreover, owing to the structure having integrated inner and outer races and mounting holes, the performance is almost entirely unaffected by the installation of the bearing, allowing for a precise optical encoder to be installed in the compact UHV rotary feedthrough. Using position feedback via a worm gear system driven by a stepper motor and a precise rotary encoder, the actual angle of the compact UHV rotary feedthrough can be controlled with extremely high precision.

Porosity and thermal collapse measurements of H2O, CH3OH, CO2, and H2O:CO2 ices.

PubMed

Isokoski, K; Bossa, J-B; Triemstra, T; Linnartz, H

2014-02-28

The majority of astronomical and laboratory based studies of interstellar ices have been focusing on ice constituents. Ice structure is a much less studied topic. Particularly the amount of porosity is an ongoing point of discussion. A porous ice offers more surface area than a compact ice, for reactions that are fully surface driven. In this paper we discuss the amount of compaction for four different ices--H2O, CH3OH, CO2 and mixed H2O : CO2 = 2 : 1--upon heating over an astronomically relevant temperature regime. Laser interference and Fourier transform infrared spectroscopy are used to confirm that for amorphous solid water the full signal loss of dangling OH bonds is not a proof for full compaction. These data are compared with the first compaction results for pure CH3OH, pure CO2 and mixed H2O : CO2 = 2 : 1 ice. Here we find that thermal segregation benefits from a higher degree of porosity.

Terahertz-driven linear electron acceleration

PubMed Central

Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.

2015-01-01

The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeV m−1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. These ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams. PMID:26439410

Terahertz-driven linear electron acceleration

DOE PAGES

Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; ...

2015-10-06

The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeVm -1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/protonmore » accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. As a result, these ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.« less

Dynamic loading and release in Johnson Space Center Lunar regolith simulant

NASA Astrophysics Data System (ADS)

Plesko, C. S.; Jensen, B. J.; Wescott, B. L.; Skinner McKee, T. E.

2011-10-01

The behavior of regolith under dynamic loading is important for the study of planetary evolution, impact cratering, and other topics. Here we present the initial results of explosively driven flier plate experiments and numerical models of compaction and release in samples of the JSC-1A Lunar regolith simulant.

Quantifying the AGN-driven outflows in ULIRGs (QUADROS) II: evidence for compact outflow regions from HST [OIII] imaging observations

NASA Astrophysics Data System (ADS)

Tadhunter, C.; Zaurín, J. Rodríguez; Rose, M.; Spence, R. A. W.; Batcheldor, D.; Berg, M. A.; Ramos Almeida, C.; Spoon, H. W. W.; Sparks, W.; Chiaberge, M.

2018-05-01

The true importance of the warm, AGN-driven outflows for the evolution of galaxies remains uncertain. Measurements of the radial extents of the outflows are key for quantifying their masses and kinetic powers, and also establishing whether the AGN outflows are galaxy-wide. Therefore, as part of a larger project to investigate the significance of warm, AGN-driven outflows in the most rapidly evolving galaxies in the local universe, here we present deep Hubble Space Telescope (HST) narrow-band [OIII]λ5007 observations of a complete sample of 8 nearby ULIRGs with optical AGN nuclei. Combined with the complementary information provided by our ground-based spectroscopy, the HST images show that the warm gas outflows are relatively compact for most of the objects in the sample: in three objects the outflow regions are barely resolved at the resolution of HST (0.065 < R[OIII] < 0.12 kpc); in a further four cases the outflows are spatially resolved but with flux weighted mean radii in the range 0.65 < R[OIII] < 1.2 kpc; and in only one object (Mrk273) is there clear evidence for a more extended outflow, with a maximum extent of R[OIII] ˜ 5 kpc. Overall, our observations show little evidence for the galaxy-wide outflows predicted by some models of AGN feedback.

A Compact and Low-Cost MEMS Loudspeaker for Digital Hearing Aids.

PubMed

Sang-Soo Je; Rivas, F; Diaz, R E; Jiuk Kwon; Jeonghwan Kim; Bakkaloglu, B; Kiaei, S; Junseok Chae

2009-10-01

A microelectromechanical-systems (MEMS)-based electromagnetically actuated loudspeaker to reduce form factor, cost, and power consumption, and increase energy efficiency in hearing-aid applications is presented. The MEMS loudspeaker has multilayer copper coils, an NiFe soft magnet on a thin polyimide diaphragm, and an NdFeB permanent magnet on the perimeter. The coil impedance is measured at 1.5 Omega, and the resonant frequency of the diaphragm is located far from the audio frequency range. The device is driven by a power-scalable, 0.25-mum complementary metal-oxide semiconductor class-D SigmaDelta amplifier stage. The class-D amplifier is formed by a differential H-bridge driven by a single bit, pulse-density-modulated SigmaDelta bitstream at a 1.2-MHz clock rate. The fabricated MEMS loudspeaker generates more than 0.8-mum displacement, equivalent to 106-dB sound pressure level (SPL), with 0.13-mW power consumption. Driven by the SigmaDelta class-D amplifier, the MEMS loudspeaker achieves measured 65-dB total harmonic distortion (THD) with a measurement uncertainty of less than 10%. Energy-efficient and cost-effective advanced hearing aids would benefit from further miniaturization via MEMS technology. The results from this study appear very promising for developing a compact, mass-producible, low-power loudspeaker with sufficient sound generation for hearing-aid applications.

Optimization of radiation shielding material aiming at compactness, lightweight, and low activation for a vehicle-mounted accelerator-driven D-T neutron source.

PubMed

Cai, Yao; Hu, Huasi; Lu, Shuangying; Jia, Qinggang

2018-05-01

To minimize the size and weight of a vehicle-mounted accelerator-driven D-T neutron source and protect workers from unnecessary irradiation after the equipment shutdown, a method to optimize radiation shielding material aiming at compactness, lightweight, and low activation for the fast neutrons was developed. The method employed genetic algorithm, combining MCNP and ORIGEN codes. A series of composite shielding material samples were obtained by the method step by step. The volume and weight needed to build a shield (assumed as a coaxial tapered cylinder) were adopted to compare the performance of the materials visually and conveniently. The results showed that the optimized materials have excellent performance in comparison with the conventional materials. The "MCNP6-ACT" method and the "rigorous two steps" (R2S) method were used to verify the activation grade of the shield irradiated by D-T neutrons. The types of radionuclide, the energy spectrum of corresponding decay gamma source, and the variation in decay gamma dose rate were also computed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparative study of disinfectants for use in low-cost gravity driven household water purifiers.

PubMed

Patil, Rajshree A; Kausley, Shankar B; Balkunde, Pradeep L; Malhotra, Chetan P

2013-09-01

Point-of-use (POU) gravity-driven household water purifiers have been proven to be a simple, low-cost and effective intervention for reducing the impact of waterborne diseases in developing countries. The goal of this study was to compare commonly used water disinfectants for their feasibility of adoption in low-cost POU water purifiers. The potency of each candidate disinfectant was evaluated by conducting a batch disinfection study for estimating the concentration of disinfectant needed to inactivate a given concentration of the bacterial strain Escherichia coli ATCC 11229. Based on the concentration of disinfectant required, the size, weight and cost of a model purifier employing that disinfectant were estimated. Model purifiers based on different disinfectants were compared and disinfectants which resulted in the most safe, compact and inexpensive purifiers were identified. Purifiers based on bromine, tincture iodine, calcium hypochlorite and sodium dichloroisocyanurate were found to be most efficient, cost effective and compact with replacement parts costing US$3.60-6.00 for every 3,000 L of water purified and are thus expected to present the most attractive value proposition to end users.

Urban sprawl as a risk factor in motor vehicle crashes

USGS Publications Warehouse

Ewing, Reid; Hamidi, Shima; Grace, James B.

2016-01-01

A decade ago, compactness/sprawl indices were developed for metropolitan areas and counties which have been widely used in health and other research. In this study, we first update the original county index to 2010, then develop a refined index that accounts for more relevant factors, and finally seek to test the relationship between sprawl and traffic crash rates using structural equation modelling. Controlling for covariates, we find that sprawl is associated with significantly higher direct and indirect effects on fatal crash rates. The direct effect is likely due to the higher traffic speeds in sprawling areas, and the indirect effect is due to greater vehicle miles driven in such areas. Conversely, sprawl has negative direct relationships with total crashes and non-fatal injury crashes, and these offset (and sometimes overwhelm) the positive indirect effects of sprawl on both types of crashes through the mediating effect of increased vehicle miles driven. The most likely explanation is the greater prevalence of fender benders and other minor accidents in the low speed, high conflict traffic environments of compact areas, negating the lower vehicle miles travelled per capita in such areas.

Probing the clumpy winds of giant stars with high mass X-ray binaries

NASA Astrophysics Data System (ADS)

Grinberg, Victoria; Hell, Natalie; Hirsch, Maria; Garcia, Javier; Huenemoerder, David; Leutenegger, Maurice A.; Nowak, Michael; Pottschmidt, Katja; Schulz, Norbert S.; Sundqvists, Jon O.; Townsend, Richard D.; Wilms, Joern

2016-04-01

Line-driven winds from early type stars are structured, with small, overdense clumps embedded in tenuous hot gas. High mass X-ray binaries (HMXBs), systems where a neutron star or a black hole accretes from the line-driven stellar wind of an O/B-type companion, are ideal for studying such winds: the wind drives the accretion onto the compact object and thus the X-ray production. The radiation from close to the compact object is quasi-pointlike and effectively X-rays the wind.We used RXTE and Chandra-HETG observations of two of the brightest HMXBs, Cyg X-1 and Vela X-1, to decipher their wind structure. In Cyg X-1, we show that the orbital variability of absorption can be only explained by a clumpy wind model and constrain the porosity of the wind as well as the onion-like structure of the clumps. In Vela X-1 we show, using the newest reference energies for low ionization Si-lines obtained with LLNL’s EBIT-I, that the ionized phase of the circumstellar medium and the cold clumps have different velocities.

Design and implementation of a novel rotary micropositioning system driven by linear voice coil motor.

PubMed

Xu, Qingsong

2013-05-01

Limited-angle rotary micropositioning stages are required in precision engineering applications where an ultrahigh-precision rotational motion within a restricted range is needed. This paper presents the design, fabrication, and control of a compliant rotary micropositioning stage dedicated to the said applications. To tackle the challenge of achieving both a large rotational range and a compact size, a new idea of multi-stage compound radial flexure is proposed. A compact rotary stage is devised to deliver an over 10° rotational range while possessing a negligible magnitude of center shift. The stage is driven by a linear voice coil motor and its output motion is measured by laser displacement sensors. Analytical models are derived to facilitate the parametric design, which is validated by conducting finite element analysis. The actuation and sensing issues are addressed to guarantee the stage performance. A prototype is fabricated and a proportional-integral-derivative control is implemented to achieve a precise positioning. Experimental results demonstrate a resolution of 2 μrad over 10° rotational range as well as a low level of center shift of the rotary micropositioning system.

Quantitative Phase Microscopy for Accurate Characterization of Microlens Arrays

NASA Astrophysics Data System (ADS)

Grilli, Simonetta; Miccio, Lisa; Merola, Francesco; Finizio, Andrea; Paturzo, Melania; Coppola, Sara; Vespini, Veronica; Ferraro, Pietro

Microlens arrays are of fundamental importance in a wide variety of applications in optics and photonics. This chapter deals with an accurate digital holography-based characterization of both liquid and polymeric microlenses fabricated by an innovative pyro-electrowetting process. The actuation of liquid and polymeric films is obtained through the use of pyroelectric charges generated into polar dielectric lithium niobate crystals.

Characterization of a Polymer-Based MEMS Pyroelectric Infrared Detector

DTIC Science & Technology

2007-03-01

The value, K, in Equation (8) is generic to all thermal detectors. This value, depending on the type of thermal detector, varies due to the ... the current generated due to a ramp in temperature. The main rationale for this biasing is to align the polar axis perpendicular to the face of ...PVA_CB-based imaging system . Due to the

Self Assembly and Pyroelectric Poling for Organics

DTIC Science & Technology

2015-07-06

ozone or nitrogen oxides) and energetic species from corona discharge . These problems can strongly inhibit the efficient poling and large-scale...poling techniques. Although contact and corona poling protocols are quite well established for decades, there do exist some challenging problems. In...contact poling, severe charge injection from metal electrodes often results in large current that causes dielectric breakdown of films. Corona poling

Broadband radiometric LED measurements

NASA Astrophysics Data System (ADS)

Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

2016-09-01

At present, broadband radiometric LED measurements with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

Proceedings of the 8th International Symposium on Applications of Ferroelectrics

NASA Astrophysics Data System (ADS)

Liu, M.; Safari, A.; Kingon, A.; Haertling, G.

1993-02-01

The eighth International Symposium on the Applications of Ferroelectrics was held in Greenville, SC, on August 30 to Sept 2, 1992. It was attended by approximately 260 scientists and engineers who presented nearly 200 oral and poster papers. The three plenary presentations covered ferroelectric materials which are currently moving into commercial exploitation or have strong potential to do so. These were (1) pyroelectric imaging, (2) ferroelectric materials integrated with silicon for use as micromotors and microsensors and (3) research activity in Japan on high permittivity materials for DRAM's. Invited papers covered such subjects as pyroelectric and electrooptic properties of thin films, photorefractive effects, ferroelectric polymers, piezoelectric transducers, processing of ferroelectrics, domain switching in ferroelectrics, thin film memories, thin film vacuum deposition techniques and the fabrication of chemically prepared PZT and PLZT thin films. The papers continued to reflect the large interest in ferroelectric thin films. It was encouraging that there have been substantial strides made in both the processing and understanding of the films in the last two years. It was equally clear, however, that much still remains to be done before reliable thin film devices will be available in the marketplace.

Enhance the pyroelectricity of polyvinylidene fluoride by graphene-oxide doping.

PubMed

Hu, Yuh-Chung; Hsu, Wei-Li; Wang, Yi-Ta; Ho, Cheng-Tao; Chang, Pei-Zen

2014-04-16

The high quality properties and benefits of graphene-oxide have generated an active area of research where many investigations have shown potential applications in various technological fields. This paper proposes a methodology for enhancing the pyro-electricity of PVDF by graphene-oxide doping. The PVDF film with graphene-oxide is prepared by the sol-gel method. Firstly, PVDF and graphene-oxide powders are dispersed into dimethylformamide as solvent to form a sol solution. Secondly, the sol solution is deposited on a flexible ITO/PET substrate by spin-coating. Thirdly, the particles in the sol solution are polymerized through baking off the solvent to produce a gel in a state of a continuous network of PVDF and graphene-oxide. The final annealing process pyrolyzes the gel and form a β-phase PVDF film with graphene-oxide doping. A complete study on the process of the graphene oxide doping of PVDF is accomplished. Some key points about the process are addressed based on experiments. The solutions to some key issues are found in this work, such as the porosity of film, the annealing temperature limitation by the use of flexible PET substrate, and the concentrations of PVDF and graphene-oxide.

Intramural Comparison of NIST Laser and Optical Fiber Power Calibrations.

PubMed

Lehman, John H; Vayshenker, Igor; Livigni, David J; Hadler, Joshua

2004-01-01

The responsivity of two optical detectors was determined by the method of direct substitution in four different NIST measurement facilities. The measurements were intended to demonstrate the determination of absolute responsivity as provided by NIST calibration services at laser and optical-communication wavelengths; nominally 633 nm, 850 nm, 1060 nm, 1310 nm, and 1550 nm. The optical detectors have been designated as checks standards for the purpose of routine intramural comparison of our calibration services and to meet requirements of the NIST quality system, based on ISO 17025. The check standards are two optical-trap detectors, one based on silicon and the other on indium gallium arsenide photodiodes. The four measurement services are based on: (1) the laser optimized cryogenic radiometer (LOCR) and free field collimated laser light; (2) the C-series isoperibol calorimeter and free-field collimated laser light; (3) the electrically calibrated pyroelectric radiometer and fiber-coupled laser light; (4) the pyroelectric wedge trap detector, which measures light from a lamp source and monochromator. The results indicate that the responsivity of the check standards, as determined independently using the four services, agree to within the published expanded uncertainty ranging from approximately 0.02 % to 1.24 %.

Bubble migration in a compacting crystal-liquid mush

NASA Astrophysics Data System (ADS)

Boudreau, Alan

2016-04-01

Recent theoretical models have suggested that bubbles are unlikely to undergo significant migration in a compaction crystal mush by capillary invasion while the system remains partly molten. To test this, experiments of bubble migration during compaction in a crystal-liquid mush were modeled using deformable foam crystals in corn syrup in a volumetric burette, compacted with rods of varying weights. A bubble source was provided by sodium bicarbonate (Alka-Seltzer®). Large bubbles (>several crystal sizes) are pinched by the compacting matrix and become overpressured and deformed as the bubbles experience a load change from hydrostatic to lithostatic. Once they begin to move, they move much faster than the compaction-driven liquid. Bubbles that are about the same size as the crystals but larger than the narrower pore throats move by deformation or breaking into smaller bubbles as they are forced through pore restrictions. Bubbles that are less than the typical pore diameter generally move with the liquid: The liquid + bubble mixture behaves as a single phase with a lower density than the bubble-free liquid, and as a consequence it rises faster than bubble-free liquid and allows for faster compaction. The overpressure required to force a bubble through the matrix (max grain size = 5 mm) is modest, about 5 %, and it is estimated that for a grain size of 1 mm, the required overpressure would be about 25 %. Using apatite distribution in a Stillwater olivine gabbro as an analog for bubble nucleation and growth, it is suggested that relatively large bubbles initially nucleate and grow in liquid-rich channels that develop late in the compaction history. Overpressure from compaction allows bubbles to rise higher into hotter parts of the crystal pile, where they redissolve and increase the volatile content of the liquid over what it would have without the bubble migration, leading to progressively earlier vapor saturation during crystallization of the interstitial liquid. Bubbles can also move rapidly by `surfing' on porosity waves that can develop in a compacting mush.

Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

NASA Technical Reports Server (NTRS)

Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

1996-01-01

An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

NASA Technical Reports Server (NTRS)

Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

1994-01-01

An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

Structural origins of pH and ionic strength effects on protein stability. Acid denaturation of sperm whale apomyoglobin.

PubMed

Yang, A S; Honig, B

1994-04-15

A recently developed approach to calculate the pH dependence of protein stability from three-dimensional structure information is applied to the analysis of acid denaturation of sperm whale apomyoglobin. The finite difference Poisson-Boltzmann method is used to calculate pKa values and these are used to obtain titration curves for the folded protein as well as for compact intermediates. The total electrostatic free energy change involved in apomyoglobin unfolding is then evaluated. Calculations are carried out of the unfolding free energy of the native (N) and the compact intermediate (I) of apomyoglobin relative to the unfolded state (U) over a range of pH at various ionic strengths. The contributions from key ionizable groups to the unfolding process are discussed. For the acid-induced partial unfolding of apomyoglobin near pH 5, the transition from N to I is found to be driven by three histidines that are exposed when the B, C, D and E helices unfold. Similarly, the unfolding of the compact intermediate I consisting of the A, G and H helices is driven primarily by a few carboxylic acids with low pKa values in the compact state. This picture is in contrast to the view which attributes acid denaturation to electrostatic repulsion resulting from the build up of positive charge. In fact, charge-charge interactions in myoglobin are found to be attractive at all pH values where the protein unfolds. pH-dependent changes in these interactions contribute to acid denaturation but other electrostatic effects, such as hydrogen bonding and solvation, are important as well. The effect of increasing ionic strength on unfolding is attributed to the decrease of attractive charge-charge interactions which destabilize the N state relative to I, but stabilize the I state relative to U by reducing the pKa shifts of a few critical carboxylic acids. The I state is found to be more stable than U at neutral pH thus accounting for its presence as an intermediate on the protein folding pathway. Our results have implications for the origins of compact intermediates or "molten globule" states.

Laser-driven electron beam and radiation sources for basic, medical and industrial sciences

PubMed Central

NAKAJIMA, Kazuhisa

2015-01-01

To date active research on laser-driven plasma-based accelerators have achieved great progress on production of high-energy, high-quality electron and photon beams in a compact scale. Such laser plasma accelerators have been envisaged bringing a wide range of applications in basic, medical and industrial sciences. Here inheriting the groundbreaker’s review article on “Laser Acceleration and its future” [Toshiki Tajima, (2010)],1) we would like to review recent progress of producing such electron beams due to relativistic laser-plasma interactions followed by laser wakefield acceleration and lead to the scaling formulas that are useful to design laser plasma accelerators with controllability of beam energy and charge. Lastly specific examples of such laser-driven electron/photon beam sources are illustrated. PMID:26062737

Focusing and transport of high-intensity multi-MeV proton bunches from a compact laser-driven source

NASA Astrophysics Data System (ADS)

Busold, S.; Schumacher, D.; Deppert, O.; Brabetz, C.; Frydrych, S.; Kroll, F.; Joost, M.; Al-Omari, H.; Blažević, A.; Zielbauer, B.; Hofmann, I.; Bagnoud, V.; Cowan, T. E.; Roth, M.

2013-10-01

Laser ion acceleration provides for compact, high-intensity ion sources in the multi-MeV range. Using a pulsed high-field solenoid, for the first time high-intensity laser-accelerated proton bunches could be selected from the continuous exponential spectrum and delivered to large distances, containing more than 109 particles in a narrow energy interval around a central energy of 9.4 MeV and showing ≤30mrad envelope divergence. The bunches of only a few nanoseconds bunch duration were characterized 2.2 m behind the laser-plasma source with respect to arrival time, energy width, and intensity as well as spatial and temporal bunch profile.

Urban sprawl and miles driven daily by teenagers in the United States.

PubMed

Trowbridge, Matthew J; McDonald, Noreen C

2008-03-01

Urban sprawl's association with increased automobile reliance and daily mileage is well established among adults. However, sprawl's specific impact on teen driving exposure is unknown. Teen driver fatality rates per mile driven are significantly higher than adults, making the identification of environmental influences on travel behavior particularly important in this age group. Driving and demographic data for 4528 teens (weighted=10.5 million) aged 16-19 years were obtained from the 2001 National Household Transportation Survey (NHTS). County-level sprawl was measured using an index developed by Ewing et al. The association between daily miles driven by teens and sprawl, controlling for demographic characteristics, was modeled using ordinal logistic regression. The predicted probability of driving >20 miles in counties with varying degrees of sprawl also was calculated. Of the surveyed teens, 48% did not drive, 27% drove <20 miles/day, and 25% drove >20 miles/day. Of the 52% of teens who reported driving, the average distance driven was 15.6 miles/day. More-pronounced sprawl was associated with increased daily mileage (p<0.001). Overall, teens in sprawling counties were more than twice as likely to drive >20 miles/day than teens in compact counties. This trend was most prominent among the youngest drivers. For example, the predicted probability of boys aged 16-17 years driving >20 miles per day varied from 9% to 24% in compact versus sprawling counties. Sprawl is associated with increased daily mileage by teen drivers. Given the stark relationship between driving exposure and fatality risk among teens, increased efforts to understand and modify the effects of sprawl on adolescent driving behavior are necessary.

Beyond Testing: Assessment for Teaching and Learning. Viewpoints. [Booklet and Audio Compact Discs].

ERIC Educational Resources Information Center

North Central Regional Educational Lab., Naperville, IL.

This multimedia package, which contains two audio CDs and a short informative booklet, examines the use of assessment to improve teaching and learning. The booklet contains the essay "Assessment-Driven Reform: A Leadership Approach" (Rhetta L. Detrich with Ed Janus and Sabrina W. M. Laine). It discusses the increasing importance of…

Nimbus-6 and -7 Earth Radiation Budget (ERB) sensor details and component tests

NASA Technical Reports Server (NTRS)

Soule, H. V.; Kyle, H. L.; Jacobowitz, H.; Hickey, J.

1983-01-01

Construction details and operating characteristics are described for the thermopile (used in the solar and fixed-Earth channels) and the pyroelectric detector (used in the Earth-scanning channels) carried on the Nimbus 6 and the Nimbus 7 satellites for gathering Earth radiation budget data. Properties of the black coating for the detectors, and sensor testing and calibration are discussed.

Micromechanical Prediction of the Effective Behavior of Fully Coupled Electro-Magneto-Thermo-Elastic Multiphase Composites

NASA Technical Reports Server (NTRS)

Aboudi, Jacob

2000-01-01

The micromechanical generalized method of cells model is employed for the prediction of the effective moduli of electro-magneto-thermo-elastic composites. These include the effective elastic, piezoelectric, piezomagnetic, dielectric, magnetic permeability, electromagnetic coupling moduli, as well as the effective thermal expansion coefficients and the associated pyroelectric and pyromagnetic constants. Results are given for fibrous and periodically bilaminated composites.

Thermal sensor with an improved coating

DOEpatents

LaDelfe, P.C.; Stotlar, S.C.

1984-03-30

The disclosure is directed to an apparatus for detecting radiation having wavelengths from about 0.4 ..mu..m to about 5.6 ..mu..m. An optical coating is applied to a thermal sensor that is normally transparent to radiation with such wavelengths. The optical coating is thin and light and includes a modifier and an absorber. The thermal sensor can be a pyroelectric detector such as strontium barium niobate.

Bibliography of Soviet Laser Developments, Number 60, July - August 1982.

DTIC Science & Technology

1983-07-15

KLDVAD, 7/82, 10417) 155. Sagitov, S.l. (1). Mirrors for the ultraviolet and infrared regions of the spectrum. Tr 1, 118-164. 7. Detectors 156. Andryukhina...23 5. Beam Splitter9.......................................24 6. Mirrors..............................................24 7. Detectors ...E.D., K.S. Kyabilin, and 0.1. Fedyanin (1). Absolute sensitivity of pyroelectric detectors . Fizicheskiy institut AN SSSR. Preprint, no. 23.7, 1982

Thermal sensor with an improved coating

DOEpatents

LaDelfe, Peter C.; Stotlar, Suzanne C.

1986-01-01

The disclosure is directed to an apparatus for detecting radiation having wavelengths from about 0.4 .mu.m to about 5.6 .mu.m. An optical coating is applied to a thermal sensor that is normally transparent to radiation with such wavelengths. The optical coating is thin and light and includes a modifier and an absorber. The thermal sensor can be a pyroelectric detector such as strontium barium niobate.

A Compact Group of Galaxies at z = 2.48 Hosting an AGN-driven Outflow

NASA Astrophysics Data System (ADS)

Shih, Hsin-Yi; Stockton, Alan

2015-12-01

We present observations of a remarkable compact group of galaxies at z = 2.48. Four galaxies, all within 40 kpc of each other, surround a powerful high-redshift radio source. This group comprises two compact red passive galaxies and a pair of merging galaxies. One of the red galaxies, with an apparent stellar mass of 3.6 × 1011M⊙ and an effective radius of 470 pc, is one of the most extreme examples of a massive quiescent compact galaxy found so far. One of the pair of merging galaxies hosts the active galactic nucleus (AGN) producing the large powerful radio structure. The merger is massive and enriched, consistent with the mass-metallicity relation expected at this redshift. Close to the merging nuclei, the emission lines exhibit broad and asymmetric profiles that suggest outflows powered either by a very young expanding radio jet or by AGN radiation. At ≳50 kpc from the system, we found a fainter extended-emission region that may be a part of a radio-jet-driven outflow. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The work is also based, in part, on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

Magnetic Roots and the Driving of Extended Coronal Heating

NASA Technical Reports Server (NTRS)

Porter, Jason G.; Falconer, D. A.; Moore, Ronald L.; Harvey, Karen L.; Rabin, Douglas M.; Shimizu, T.

1998-01-01

We report results from a continuation of a previous study, in which we found large bright coronal loops within active regions and extending from active regions that have one end rooted near an island of included magnetic polarity that is a site of enhanced coronal heating and microflares. This suggested that magnetic activity such as microflaring results in enhanced heating in both the compact core field around the island and in the large loops extending from it. We might expect that the intensity variations due to enhanced heating in the compact and extended structures would be correlated. However, although some ex- tended loops do respond to the largest events taking place in the core fields near their feet, they do not show a clear response to most smaller individual events nor to the overall envelope of coronal heating activity in the core fields at their feet as determined from longer-term observations. Thus, while it is clear that the extended loops' heating is being driven from their ends at the magnetic islands, much of this heating is apparently by some form of footpoint activity that is not strongly coupled to the heating in the footpoint core fields. One possibility is that the remote heating in the extended loops is driven by reconnection at the magnetic null over the island, and that this reconnection is driven mainly by core-field activity that produces little coronal heating within the core field itself, perhaps in the manner of the numerical simulations by Karpen, Antiochos, and DeVore.

Laser-driven electron beam acceleration and future application to compact light sources

NASA Astrophysics Data System (ADS)

Hafz, N.; Jeong, T. M.; Lee, S. K.; Pae, K. H.; Sung, J. H.; Choi, I. W.; Yu, T. J.; Jeong, Y. U.; Lee, J.

2009-07-01

Laser-driven plasma accelerators are gaining much attention by the advanced accelerator community due to the potential these accelerators hold in miniaturizing future high-energy and medium-energy machines. In the laser wakefield accelerator (LWFA), the ponderomotive force of an ultrashort high intensity laser pulse excites a longitudinal plasma wave or bubble. Due to huge charge separation, electric fields created in the plasma bubble can be several orders of magnitude higher than those available in conventional microwave and RF-based accelerator facilities which are limited (up to ˜100 MV/m) by material breakdown. Therefore, if an electron bunch is injected into the bubble in phase with its field, it will gain relativistic energies within an extremely short distance. Here, in the LWFA we show the generation of high-quality and high-energy electron beams up to the GeV-class within a few millimeters of gas-jet plasmas irradiated by tens of terawatt ultrashort laser pulses. Thus we realize approximately four orders of magnitude acceleration gradients higher than available by conventional technology. As a practical application of the stable high-energy electron beam generation, we are planning on injecting the electron beams into a few-meters long conventional undulator in order to realize compact X-ray synchrotron (immediate) and FEL (future) light sources. Stable laser-driven electron beam and radiation devices will surely open a new era in science, medicine and technology and will benefit a larger number of users in those fields.

Observation of Gigawatt-Class THz Pulses from a Compact Laser-Driven Particle Accelerator

NASA Astrophysics Data System (ADS)

Gopal, A.; Herzer, S.; Schmidt, A.; Singh, P.; Reinhard, A.; Ziegler, W.; Brömmel, D.; Karmakar, A.; Gibbon, P.; Dillner, U.; May, T.; Meyer, H.-G.; Paulus, G. G.

2013-08-01

We report the observation of subpicosecond terahertz (T-ray) pulses with energies ≥460μJ from a laser-driven ion accelerator, thus rendering the peak power of the source higher even than that of state-of-the-art synchrotrons. Experiments were performed with intense laser pulses (up to 5×1019W/cm2) to irradiate thin metal foil targets. Ion spectra measured simultaneously showed a square law dependence of the T-ray yield on particle number. Two-dimensional particle-in-cell simulations show the presence of transient currents at the target rear surface which could be responsible for the strong T-ray emission.

Third-harmonic generation of a laser-driven quantum dot with impurity

NASA Astrophysics Data System (ADS)

Sakiroglu, S.; Kilic, D. Gul; Yesilgul, U.; Ungan, F.; Kasapoglu, E.; Sari, H.; Sokmen, I.

2018-06-01

The third-harmonic generation (THG) coefficient for a laser-driven quantum dot with an on-center Gaussian impurity under static magnetic field is theoretically investigated. Laser field effect is treated within the high-frequency Floquet approach and the analytical expression of the THG coefficient is deduced from the compact density-matrix approach. The numerical results demonstrate that the application of intense laser field causes substantial changes on the behavior of THG. In addition the position and magnitude of the resonant peak of THG coefficient is significantly affected by the magnetic field, quantum dot size and the characteristic parameters of the impurity potential.

Pressure Amplification Off High Impedance Barriers in DDT

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

Heatwole, Eric Mann; Broilo, Robert M.; Kistle, Trevin Joseph

The Deflagration-to-Detonation Transition (DDT) in one-dimensional porous explosive, where combustion in an explosive transitions to detonation, can be described by the following model. This simplified model proceeds in five steps, as follows: 1) Ignition of the explosive, surface burning. 2) Convective burning, with the flame front penetrating through the porous network of the explosive. This proceeds until the pressure grows high enough to result in choked flow in the pores restricting the convective burn. 3) The choked flow results in the formation of a high-density compact of explosive. This compact is driven into undisturbed material by the pressure of themore » burning explosive. See Figure1. 4) The compression of the undisturbed porous explosive by the compact leads to the ignition of a compressive burn. This builds in pressure until a supported shock forms. 5) The shock builds in pressure until detonation occurs. See Figure 2 for an overview streak of the proceeding steps.« less

A compact and low-cost laser induced fluorescence detector with silicon based photodetector assembly for capillary flow systems.

PubMed

Geng, Xuhui; Shi, Meng; Ning, Haijing; Feng, Chunbo; Guan, Yafeng

2018-05-15

A compact and low-cost laser induced fluorescence (LIF) detector based on confocal structure for capillary flow systems was developed and applied for analysis of Her2 protein on single Hela cells. A low-power and low-cost 450 nm laser diode (LD) instead of a high quality laser was used as excitation light source. A compact optical design together with shortened optical path length improved the optical efficiency and detection sensitivity. A superior silicon based photodetector assembly was used for fluorescence detection instead of a photomultiplier (PMT). The limit of detection (LOD) for fluorescein sodium was 3 × 10 -12 M or 165 fluorescein molecules in detection volume measured on a homemade capillary electroosmotic driven (EOD)-LIF system, which was similar to commercial LIFs. Compared to commercial LIFs, the whole volume of our LIF was reduced to 1/2-1/3, and the cost was less than 1/3 of them. Copyright © 2018 Elsevier B.V. All rights reserved.

A Physical Model for Three-Phase Compaction in Silicic Magma Reservoirs

NASA Astrophysics Data System (ADS)

Huber, Christian; Parmigiani, Andrea

2018-04-01

We develop a model for phase separation in magma reservoirs containing a mixture of silicate melt, crystals, and fluids (exsolved volatiles). The interplay between the three phases controls the dynamics of phase separation and consequently the chemical and physical evolution of magma reservoirs. The model we propose is based on the two-phase damage theory approach of Bercovici et al. (2001, https://doi.org/10.1029/2000JB900430) and Bercovici and Ricard (2003, https://doi.org/10.1046/j.1365-246X.2003.01854.x) because it offers the leverage of considering interface (in the macroscopic limit) between phases that can deform depending on the mechanical work and phase changes taking place locally in the magma. Damage models also offer the advantage that pressure is defined uniquely to each phase and does not need to be equal among phases, which will enable us to consider, in future studies, the large capillary pressure at which fluids are mobilized in mature, crystal-rich, magma bodies. In this first analysis of three-phase compaction, we solve the three-phase compaction equations numerically for a simple 1-D problem where we focus on the effect of fluids on the efficiency of melt-crystal separation considering the competition between viscous and buoyancy stresses only. We contrast three sets of simulations to explore the behavior of three-phase compaction, a melt-crystal reference compaction scenario (two-phase compaction), a three-phase scenario without phase changes, and finally a three-phase scenario with a parameterized second boiling (crystallization-induced exsolution). The simulations show a dramatic difference between two-phase (melt crystals) and three-phase (melt-crystals-exsolved volatiles) compaction-driven phase separation. We find that the presence of a lighter, significantly less viscous fluid hinders melt-crystal separation.

The diverse evolutionary paths of simulated high-z massive, compact galaxies to z = 0

NASA Astrophysics Data System (ADS)

Wellons, Sarah; Torrey, Paul; Ma, Chung-Pei; Rodriguez-Gomez, Vicente; Pillepich, Annalisa; Nelson, Dylan; Genel, Shy; Vogelsberger, Mark; Hernquist, Lars

2016-02-01

Massive quiescent galaxies have much smaller physical sizes at high redshift than today. The strong evolution of galaxy size may be caused by progenitor bias, major and minor mergers, adiabatic expansion, and/or renewed star formation, but it is difficult to test these theories observationally. Herein, we select a sample of 35 massive, compact galaxies (M* = 1-3 × 1011 M⊙, M*/R1.5 > 1010.5 M⊙/kpc1.5) at z = 2 in the cosmological hydrodynamical simulation Illustris and trace them forwards to z = 0 to uncover their evolution and identify their descendants. By z = 0, the original factor of 3 difference in stellar mass spreads to a factor of 20. The dark matter halo masses similarly spread from a factor of 5 to 40. The galaxies' evolutionary paths are diverse: about half acquire an ex situ envelope and are the core of a more massive descendant, a third survive undisturbed and gain very little mass, 15 per cent are consumed in a merger with a more massive galaxy, and a small remainder are thoroughly mixed by major mergers. The galaxies grow in size as well as mass, and only ˜10 per cent remain compact by z = 0. The majority of the size growth is driven by the acquisition of ex situ mass. The most massive galaxies at z = 0 are the most likely to have compact progenitors, but this trend possesses significant dispersion which precludes a direct linkage to compact galaxies at z = 2. The compact galaxies' merger rates are influenced by their z = 2 environments, so that isolated or satellite compact galaxies (which are protected from mergers) are the most likely to survive to the present day.

Automated detection of extended sources in radio maps: progress from the SCORPIO survey

NASA Astrophysics Data System (ADS)

Riggi, S.; Ingallinera, A.; Leto, P.; Cavallaro, F.; Bufano, F.; Schillirò, F.; Trigilio, C.; Umana, G.; Buemi, C. S.; Norris, R. P.

2016-08-01

Automated source extraction and parametrization represents a crucial challenge for the next-generation radio interferometer surveys, such as those performed with the Square Kilometre Array (SKA) and its precursors. In this paper, we present a new algorithm, called CAESAR (Compact And Extended Source Automated Recognition), to detect and parametrize extended sources in radio interferometric maps. It is based on a pre-filtering stage, allowing image denoising, compact source suppression and enhancement of diffuse emission, followed by an adaptive superpixel clustering stage for final source segmentation. A parametrization stage provides source flux information and a wide range of morphology estimators for post-processing analysis. We developed CAESAR in a modular software library, also including different methods for local background estimation and image filtering, along with alternative algorithms for both compact and diffuse source extraction. The method was applied to real radio continuum data collected at the Australian Telescope Compact Array (ATCA) within the SCORPIO project, a pathfinder of the Evolutionary Map of the Universe (EMU) survey at the Australian Square Kilometre Array Pathfinder (ASKAP). The source reconstruction capabilities were studied over different test fields in the presence of compact sources, imaging artefacts and diffuse emission from the Galactic plane and compared with existing algorithms. When compared to a human-driven analysis, the designed algorithm was found capable of detecting known target sources and regions of diffuse emission, outperforming alternative approaches over the considered fields.

Piezoelectric assisted smart satellite structure (PEASSS): an innovative low cost nano-satellite

NASA Astrophysics Data System (ADS)

Rockberger, D.; Abramovich, H.

2014-03-01

The present manuscript is aimed at describing the PEASSS - PiezoElectric Assisted Smart Satellite Structure project, which was initiated at the beginning of 2013 and financed by the Seventh Framework Program (FP7) of the European Commission. The aims of the project were to develop, manufacture, test and qualify "smart structures" which combine composite panels, piezoelectric materials, and next generation sensors, for autonomously improved pointing accuracy and power generation in space. The smart panels will enable fine angle control, and thermal and vibration compensation, improving all types of future Earth observations, such as environmental and planetary mapping, border and regional imaging. This new technology will help keep Europe on the cutting edge of space research, potentially improving the cost and development time for more accurate future sensor platforms including synthetic aperture optics, moving target detection and identification, and compact radars. The system components include new nano-satellite electronics, a piezo power generation system based on the pyroelectric effect, a piezo actuated smart structure, and a fiber-optic sensor and interrogator system. The present paper will deal only with two of the components, namely the piezo power generation system and the piezo actuated smart structure The designs are going to be prototyped into breadboard models for functional development and testing. Following completion of operational breadboards, components will evolve to flight-test ready hardware and related software, ready to be integrated into a working satellite. Once the nanosattelite is assembled, on ground tests will be performed. Finally, the satellite will be launched and tested in space at the end of 2015.

Stability and instability of axisymmetric droplets in thermocapillary-driven thin films

NASA Astrophysics Data System (ADS)

Nicolaou, Zachary G.

2018-03-01

The stability of compactly supported, axisymmetric droplet states is considered for driven thin viscous films evolving on two-dimensional surfaces. Stability is assessed using Lyapunov energy methods afforded by the Cahn-Hilliard variational form of the governing equation. For general driving forces, a criterion on the gradient of profiles at the boundary of their support (their contact slope) is shown to be a necessary condition for stability. Additional necessary and sufficient conditions for stability are established for a specific driving force corresponding to a thermocapillary-driven film. It is found that only droplets of sufficiently short height that satisfy the contact slope criterion are stable. This destabilization of droplets with increasing height is characterized as a saddle-node bifurcation between a branch of tall, unstable droplets and a branch of short, stable droplets.

Development of Electric Power Units Driven by Waste Heat

NASA Astrophysics Data System (ADS)

Inoue, Naoyuki; Takeuchi, Takao; Kaneko, Atsushi; Uchimura, Tomoyuki; Irie, Kiichi; Watanabe, Hiroyoshi

For the development of a simple and compact power generator driven by waste heat, working fluids and an expander were studied, then a practical electric power unit was put to test. Many working fluids were calculated with the low temperature power cycle (evaporated at 77°C, condensed at 42°C),and TFE,R123,R245fa were selected to be suitable for the cycle. TFE(Trifluoroethanol CF3CH2OH) was adopted to the actual power generator which was tested. A radial turbine was adopted as an expander, and was newly designed and manufactured for working fluid TFE. The equipment was driven by hot water as heat source and cooling water as cooling source, and generated power was connected with electric utility. Characteristics of the power generating cycle and characteristics of the turbine were obtained experimentally.

p-Process Nucleosynthesis inside Supernova-driven Supercritical Accretion Disks

NASA Astrophysics Data System (ADS)

Fujimoto, Shin-ichirou; Hashimoto, Masa-aki; Koike, Osamu; Arai, Kenzo; Matsuba, Ryuichi

2003-03-01

We investigate p-process nucleosynthesis in a supercritical accretion disk around a compact object of 1.4 Msolar, using the self-similar solution of an optically thick advection-dominated flow. Supercritical accretion is expected to occur in a supernova with fallback material accreting onto a newborn compact object. It is found that an appreciable number of p-nuclei are synthesized via the p-process in supernova-driven supercritical accretion disks (SSADs) when the accretion rate m=Mc2/(16LEdd)>105, where LEdd is the Eddington luminosity. Abundance profiles of p-nuclei ejected from SSADs have features similar to those of the oxygen/neon layers in Type II supernovae when the abundance of the fallback gas far from the compact object is that of the oxygen/neon layers in the progenitor. The overall abundance profile is in agreement with that of the solar system. Some p-nuclei, such as Mo, Ru, Sn, and La, are underproduced in the SSADs as in Type II supernovae. If the fallback gas is mixed with a small fraction of protons through Rayleigh-Taylor instability during the explosion, significant amounts of 92Mo are produced inside the SSADs. Isotopes 96Ru and 138La are also produced when the fallback gas contains abundant protons, although the overall abundance profile of p-nuclei is rather different from that of the solar system. The p-process nucleosynthesis in SSADs contributes to the chemical evolution of p-nuclei, in particular 92Mo, if several percent of the fallback matter are ejected via jets and/or winds.

Paleohydrogeology of the San Joaquin basin, California

USGS Publications Warehouse

Wilson, A.M.; Garven, G.; Boles, J.R.

1999-01-01

Mass transport can have a significant effect on chemical diagenetic processes in sedimentary basins. This paper presents results from the first part of a study that was designed to explore the role of an evolving hydrodynamic system in driving mass transport and chemical diagenesis, using the San Joaquin basin of California as a field area. We use coupled hydrogeologic models to establish the paleohydrogeology, thermal history, and behavior of nonreactive solutes in the basin. These models rely on extensive geological information and account for variable-density fluid flow, heat transport, solute transport, tectonic uplift, sediment compaction, and clay dehydration. In our numerical simulations, tectonic uplift and ocean regression led to large-scale changes in fluid flow and composition by strengthening topography-driven fluid flow and allowing deep influx of fresh ground water in the San Joaquin basin. Sediment compaction due to rapid deposition created moderate overpressures, leading to upward flow from depth. The unusual distribution of salinity in the basin reflects influx of fresh ground water to depths of as much as 2 km and dilution of saline fluids by dehydration reactions at depths greater than ???2.5 km. Simulations projecting the future salinity of the basin show marine salinities persisting for more than 10 m.y. after ocean regression. Results also show a change from topography-to compaction-driven flow in the Stevens Sandstone at ca. 5 Ma that coincides with an observed change in the diagenetic sequence. Results of this investigation provide a framework for future hydrologic research exploring the link between fluid flow and diagenesis.

Fluid instabilities and wakes in a soap-film tunnel

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

Vorobieff, P.; Ecke, R.E.

1999-05-01

We present a compact, low-budget two-dimensional hydrodynamic flow visualization system based on a tilted, gravity-driven soap film tunnel. This system is suitable for demonstrations and studies of a variety of fluid mechanics problems, including turbulent wakes past bluff bodies and lifting surfaces, Kelvin{endash}Helmholtz instability, and grid turbulence. {copyright} {ital 1999 American Association of Physics Teachers.}

Watching AGN feedback at its birth: HST observations of nascent outflow host IC860

NASA Astrophysics Data System (ADS)

Alatalo, Katherine

2016-10-01

IC860 is a nearby IR-luminous early-type spiral with a unique set of properties: it is a shocked, poststarburst galaxy that hosts an AGN-driven neutral wind and a compact core of molecular gas. IC860 can serve as a rosetta stone for the early stages of triggering AGN feedback. We propose to use WFC3 on HST to obtain NUV, optical and near-IR imaging of IC860. We will create a spatially-resolved history of star formation quenching through SED-fitting of 7 requested broadband filters, and compare the spatially resolved star formation histories to in different positions within the underlying stellar features (such as spiral structure) that might define a narrative of how star formation is quenching in IC860. These observations will also resolve the super-star cluster sites to trace the most recent star formation. Finally, these observations will trace the mass of the outflow by building an absorption map of the dust. IC860 presents a unique opportunity to study a galaxy at an early stage of transitioning from blue spiral to red early-type galaxy, that also hosts an AGN-driven neutral wind and a compact, turbulent molecular gas core.

THz and Sub-THz Capabilities of a Table-Top Radiation Source Driven by an RF Thermionic Electron Gun

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

Smirnov, Alexei V.; Agustsson, R.; Boucher, S.

Design features and experimental results are presented for a sub-mm wave source [1] based on APS RF thermionic electron gun. The setup includes compact alpha-magnet, quadrupoles, sub-mm-wave radiators, and THz optics. The sub-THz radiator is a planar, oversized structure with gratings. Source upgrade for generation frequencies above 1 THz is discussed. The THz radiator will use a short-period undulator having 1 T field amplitude, ~20 cm length, and integrated with a low-loss oversized waveguide. Both radiators are integrated with a miniature horn antenna and a small ~90°-degree in-vacuum bending magnet. The electron beamline is designed to operate different modes includingmore » conversion to a flat beam interacting efficiently with the radiator. The source can be used for cancer diagnostics, surface defectoscopy, and non-destructive testing. Sub-THz experiment demonstrated a good potential of a robust, table-top system for generation of a narrow bandwidth THz radiation. This setup can be considered as a prototype of a compact, laser-free, flexible source capable of generation of long trains of Sub-THz and THz pulses with repetition rates not available with laser-driven sources.« less

Textural evidence of the significance of compaction in the formation of adcumulates in the Skaergaard intrusion, East Greenland

NASA Astrophysics Data System (ADS)

Vukmanovic, Zoja; Holness, Marian; Mariani, Elisabetta

2017-04-01

It has been argued that the upwards decrease in incompatible element concentration in the Skaergaard Layered Series is due to an upwards increasing significance of compaction driven by gravitational loading. The suggested mechanisms for compaction are dislocation creep and dissolution-reprecipitation creep. Localised elongate zones of strong modal banding in the upper part of the Layered Series, known as trough bands, have also been interpreted as the result of localised recrystallization during compaction. In this study we examine the microstructures of Skaergaard gabbros to determine whether their fabrics (foliations and lineations) preserve a record of compaction. The most common microstructures formed by dislocation creep are low angle boundaries and, as a result of ongoing recovery processes, new grains. The (010)[001] slip system in plagioclase is commonly observed to be a "soft" orientation, creating a crystallographic preferred orientation (CPO) defined by the alignment of (010) planes, with [001] parallel to lineation. Previous work on dissolution-reprecipitation creep, shows a CPO with (010) planes aligned parallel to the principal compressive stress, and preferential mineral growth on (010) planes to form an SPO defined by grains elongated perpendicular to (010). In the Skaergaard Layered Series, the shape of cumulus plagioclase grains (as viewed in thin section) changes systematically up through the stratigraphy from highly tabular to equant. Foliations, defined both by a plagioclase SPO (with tabular grains aligned horizontally) and an associated CPO ((010) parallel to foliation), are strongest lower in the stratigraphy and reduce in strength upwards. Evidence for crystal plasticity is limited to bending of some plagioclase crystals and small numbers of low angle boundaries in all phases. There are no signs of recovery associated with dislocation creep. Compositional zoning is present on all plagioclase growth faces in the lower part of the stratigraphy, inconsistent with preferential dissolution-reprecipitation during compression. There are no fabrics or microstructures that can be attributed to solution-reprecipitation, and evidence for only minor microstructural modification by dislocation creep throughout the entire stratigraphy. The trough bands are characterised by strong lineation of elongate grains, an almost complete absence of microstructures caused by deformation, and euhedral plagioclase grains with concentric compositional zoning. These observations rule out recrystallization driven by compaction, and support the hypothesis that the modal banding in the trough bands is a result of grain sorting by magmatic flow. Our observations suggest that the Skaergaard fabrics throughout the Layered Series, are primary and formed at or close to the magma-mush interface as a consequence of particle re-arrangement by magmatic current, with only minor deformation-related fabric modification deeper in the mush. The Skaergaard adcumulates cannot therefore be attributed to compaction.

Carbon arc solar simulator.

PubMed

Olson, R A; Parker, J H

1991-04-01

Measurements of the spatial, spectral, and temporal characteristics of the beam irradiance of a carbon arc solar simulator are reported. Pyroelectric radiometer measurements of total irradiance and spectroradiometer measurements of spectral irradiance are presented. The solar simulator spectral irradiance is compared with the ASTM standard AM 1.5 global solar spectral irradiance over a wavelength region of 300-2500 nm. The suitability of the solar simulator for laser receiver testing is discussed.

Characterization of compact-toroid injection during formation, translation, and field penetration

NASA Astrophysics Data System (ADS)

Matsumoto, T.; Roche, T.; Allfrey, I.; Sekiguchi, J.; Asai, T.; Gota, H.; Cordero, M.; Garate, E.; Kinley, J.; Valentine, T.; Waggoner, W.; Binderbauer, M.; Tajima, T.

2016-11-01

We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ˜1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation, ejection/translation from the MCPG, and penetration into transverse magnetic fields.

Characterization of compact-toroid injection during formation, translation, and field penetration.

PubMed

Matsumoto, T; Roche, T; Allfrey, I; Sekiguchi, J; Asai, T; Gota, H; Cordero, M; Garate, E; Kinley, J; Valentine, T; Waggoner, W; Binderbauer, M; Tajima, T

2016-11-01

We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ∼1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation, ejection/translation from the MCPG, and penetration into transverse magnetic fields.

Generation of surface-wave microwave microplasmas in hollow-core photonic crystal fiber based on a split-ring resonator.

PubMed

Vial, Florian; Gadonna, Katell; Debord, Benoît; Delahaye, Frédéric; Amrani, Foued; Leroy, Olivier; Gérôme, Frédéric; Benabid, Fetah

2016-05-15

We report on a new and highly compact scheme for the generation and sustainment of microwave-driven plasmas inside the core of an inhibited coupling Kagome hollow-core photonic crystal fiber. The microwave plasma generator consists of a split-ring resonator that efficiently couples the microwave field into the gas-filled fiber. This coupling induces the concomitant generation of a microwave surface wave at the fiber core surround and a stable plasma column confined in the fiber core. The scheme allowed the generation of several centimeters long argon microplasma columns with a very low excitation power threshold. This result represents an important step toward highly compact plasma lasers or plasma-based photonic components.

Note: Coincidence measurements of 3He and neutrons from a compact D-D neutron generator.

PubMed

Ji, Q; Lin, C-J; Tindall, C; Garcia-Sciveres, M; Schenkel, T; Ludewigt, B A

2017-05-01

Tagging of neutrons (2.45 MeV) with their associated 3 He particles from deuterium-deuterium (D-D) fusion reactions has been demonstrated in a compact neutron generator setup enabled by a high brightness, microwave-driven ion source with a high fraction of deuterons. Energy spectra with well separated peaks of the D-D fusion reaction products, 3 He, tritons, and protons, were measured with a silicon PIN diode. The neutrons were detected using a liquid scintillator detector with pulse shape discrimination. By correlating the 3 He detection events with the neutron detection in time, we demonstrated the tagging of emitted neutrons with 3 He particles detected with a Si PIN diode detector mounted inside the neutron generator vacuum vessel.

Broadband Radiometric LED Measurements

PubMed Central

Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

2017-01-01

At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed. PMID:28649167

Broadband Radiometric LED Measurements.

PubMed

Eppeldauer, G P; Cooksey, C C; Yoon, H W; Hanssen, L M; Podobedov, V B; Vest, R E; Arp, U; Miller, C C

2016-01-01

At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

Growth and characterization of crystals for room temperature I.R. detectors and second harmonic generation devices

NASA Technical Reports Server (NTRS)

Lal, R. B.

1995-01-01

One of the major objectives of this program was to modify the triglycine sulfate (TGS) crystals with suitable dopants and variants to achieve better pyroelectric properties and improved infrared detectivities (D(sup *)), and higher Curie transition temperature compared to undoped TGS crystals. Towards these objectives, many promising dopants, both inorganic and organic, were investigated in the last few years. These dopants gave significant improvement in the D(sup *) value of the infrared detectors fabricated from the grown crystals with no significant increase in the Curie temperature (49 C). The IR detectors were fabricated at EDO/Barnes Engineering Division, Shelton, CT. In the last one year many TGS crystals doped with urea were grown using the low temperature solution crystal growth facility. It is found that doping with urea, the normalized growth yield increased significantly compared to pure TGS crystals and there is an improvement in the pyroelectric and dielectric constant values of doped crystals. This gave a significant increase in the materials figure of merits. The Vicker's hardness of 10 wt percent urea doped crystals is found to be about three times higher in the (010) direction compared to undoped crystals. This report describes in detail the results of urea doped TGS crystals.

Hot plate annealing at a low temperature of a thin ferroelectric P(VDF-TrFE) film with an improved crystalline structure for sensors and actuators.

PubMed

Mahdi, Rahman Ismael; Gan, W C; Abd Majid, W H

2014-10-14

Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE) thin films are measured as a function of different annealing temperatures (80 to 140 °C). It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc) has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE) thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

Shear-enhanced compaction in viscoplastic rocks

NASA Astrophysics Data System (ADS)

Yarushina, V. M.; Podladchikov, Y. Y.

2012-04-01

The phenomenon of mutual influence of compaction and shear deformation was repeatedly reported in the literature over the past years. Dilatancy and shear-enhanced compaction of porous rocks were experimentally observed during both rate-independent and rate-dependent inelastic deformation. Plastic pore collapse was preceding the onset of dilatancy and shear-enhanced compaction. Effective bulk viscosity is commonly used to describe compaction driven fluid flow in porous rocks. Experimental data suggest that bulk viscosity of a fluid saturated rock might be a function of both the effective pressure and the shear stress. Dilatancy and shear-enhanced compaction can alter the transport properties of rocks through their influence on permeability and compaction length scale. Recent investigations show that shear stresses in deep mantle rocks can be responsible for spontaneous development of localized melt-rich bands and segregation of small amounts of melt from the solid rock matrix through shear channeling instability. Usually it is assumed that effective viscosity is a function of porosity only. Thus coupling between compaction and shear deformation is ignored. Spherical model which considers a hollow sphere subjected to homogeneous tractions on the outer boundary as a representative elementary volume succeeded in predicting the volumetric compaction behavior of porous rocks and metals to a hydrostatic pressure in a wide range of porosities. Following the success of this simple model we propose a cylindrical model of void compaction and decompaction due to the non-hydrostatic load. The infinite viscoplastic layer with a cylindrical hole is considered as a representative volume element. The remote boundary of the volume is subjected to a homogeneous non-hydrostatic load such that plane strain conditions are fulfilled through the volume. At some critical values of remote stresses plastic zone develops around the hole. The dependence of the effective bulk viscosity on the properties of individual components as well as on the stress state is examined. We show that bulk viscosity is a function of porosity, effective pressure and shear stress. Decreasing porosity tends to increase bulk viscosity whereas increasing shear stress and increasing effective pressure reduce it.

a High Frequency Thermoacoustically-Driven Pulse Tube Cryocooler with Coaxial Resonator

NASA Astrophysics Data System (ADS)

Yu, G. Y.; Wang, X. T.; Dai, W.; Luo, E. C.

2010-04-01

High frequency thermoacoustically-driven pulse tube cryocoolers are quite promising due to their compact size and high reliability, which can find applications in space use. With continuous effort, a lowest cold head temperature of 68.3 K has been obtained on a 300 Hz pulse tube cryocooler driven by a standing-wave thermoacoustic heat engine with 4.0 MPa helium gas and 750 W heat input. To further reduce the size of the system, a coaxial resonator was designed and the two sub-systems, i.e., the pulse tube cryocooler and the standing-wave thermoacoustic heat engine were properly coupled through an acoustic amplifier tube, which leads to a system axial length of only about 0.7 m. The performance of the system with the coaxial resonator was tested, and shows moderate degradation compared to that with the in-line resonator, which might be attributed to the large flow loss of the 180 degree corner.

Guided post-acceleration of laser-driven ions by a miniature modular structure

PubMed Central

Kar, Satyabrata; Ahmed, Hamad; Prasad, Rajendra; Cerchez, Mirela; Brauckmann, Stephanie; Aurand, Bastian; Cantono, Giada; Hadjisolomou, Prokopis; Lewis, Ciaran L. S.; Macchi, Andrea; Nersisyan, Gagik; Robinson, Alexander P. L.; Schroer, Anna M.; Swantusch, Marco; Zepf, Matt; Willi, Oswald; Borghesi, Marco

2016-01-01

All-optical approaches to particle acceleration are currently attracting a significant research effort internationally. Although characterized by exceptional transverse and longitudinal emittance, laser-driven ion beams currently have limitations in terms of peak ion energy, bandwidth of the energy spectrum and beam divergence. Here we introduce the concept of a versatile, miniature linear accelerating module, which, by employing laser-excited electromagnetic pulses directed along a helical path surrounding the laser-accelerated ion beams, addresses these shortcomings simultaneously. In a proof-of-principle experiment on a university-scale system, we demonstrate post-acceleration of laser-driven protons from a flat foil at a rate of 0.5 GeV m−1, already beyond what can be sustained by conventional accelerator technologies, with dynamic beam collimation and energy selection. These results open up new opportunities for the development of extremely compact and cost-effective ion accelerators for both established and innovative applications. PMID:27089200

Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines

NASA Astrophysics Data System (ADS)

Filippi, F.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

2016-09-01

Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC_LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC_LAB is presented.

Method and Characterization of Pyroelectric Coefficients for Determining Material Figures of Merit for Infrared (IR) Detectors

DTIC Science & Technology

2013-12-01

and the signal is read as a photocurrent or at a photovoltaic p-n junction. These detectors can provide high-sensitivity and fast refresh rates and...Alternative methods can be used to modulate the sample temperature directly; for example, by using modern Peltier devices and thermoelectric ...commercially-available hardware. The setup consist of three main components: (1) A temperature regulated thermoelectric stage; (2) A high-sensitivity

SOVRaD - A Digest of Recent Soviet R and D Articles. Volume 2, Number 1, 1976

DTIC Science & Technology

1976-01-01

sensors and for making pyroelectric pow^r generators. [ Chechkin , V . V . , A , I. Leychenko, O. S. Didkovskaya, G. Ye. Savenkova, V . V ...ALlenov, M. I. , A . V . Afomn, M. F. Akhmetzyanov, et al. High-speed apparatus for recording and processing measurements of fluctuations...is included. [Medvedev, G. A . , M. A . Markovich, and V . I. Shlyakhov. Optical light flux demodulation device for optical probes. Author’s

Robotic Tactile Sensors Fabricated from a Monolithic Silicon Integrated Circuit and a Piezoelectric Polyvinylidene Fluoride Thin Film

DTIC Science & Technology

1991-12-01

gradient will be presented. -Finally, a brief discussion of various piezoelectric materials will be presented, including Rochelle salt, quartz, barium...consideringr a microscopic-level dipole arrangement. The strain induced by ain external force or a tempem at ure gradient changes hie orientation of the...pyroelectric materials, an externally applied temperature gradient can be related to the resulting polarization by a l)yroelectric * constant.1 p (130

Optimized Pyroelectric Vidicon Thermal Imager. Volume II. Improper Ferroelectric Crystal Growth.

DTIC Science & Technology

1980-09-01

75 4.1 Hydrothermal Synthesis of Boracite Powders..... 75 4.2 Hydrothermal Growth of Boracite Crystals ......... 77...4.2.1 Apparatus .......................... 77 4.2.2 Growth from Acidic Media .................o 78 4.2.3 Hydrothermal Growth in Basic Media ...... 99...Calculated temperature dependence of p/cc for DSP under biasing fields of 0, 2 and 5 kV/cm... 74 11 LIST OF ILLUSTRATIONS (Cont’d) Page Fig. 44: Hydrothermal

Piezoelectric Polymer Films for Application in Monitoring Devices

DTIC Science & Technology

1977-02-01

pulse is also evident, as is the decay rate of the pressure, and what appears to be a pronounced " dicrotic notch ," which is asso- ciated with heart valve...investigation of factors responsible for this remark- able behavior of an organic polymer. Commercial PVF 2 homopolymer and copolymer films were oriented by... factors such as changes in elastic modulus of the film with temperature, depolarization processes at the higher temperature, and pyroelectric effects

Compact FEL-driven inverse compton scattering gamma-ray source

DOE PAGES

Placidi, M.; Di Mitri, Simone; Pellegrini, C.; ...

2017-02-28

Many research and applications areas require photon sources capable of producing gamma-ray beams in the multi-MeV energy range with reasonably high fluxes and compact footprints. Besides industrial, nuclear physics and security applications, a considerable interest comes from the possibility to assess the state of conservation of cultural assets like statues, columns etc., via visualization and analysis techniques using high energy photon beams. Computed Tomography scans, widely adopted in medicine at lower photon energies, presently provide high quality three-dimensional imaging in industry and museums. We explore the feasibility of a compact source of quasi-monochromatic, multi-MeV gamma-rays based on Inverse Compton Scatteringmore » (ICS) from a high intensity ultra-violet (UV) beam generated in a free-electron laser by the electron beam itself. This scheme introduces a stronger relationship between the energy of the scattered photons and that of the electron beam, resulting in a device much more compact than a classic ICS for a given scattered energy. As a result, the same electron beam is used to produce gamma-rays in the 10–20 MeV range and UV radiation in the 10–15 eV range, in a ~4 × 22 m 2 footprint system.« less

Compact FEL-driven inverse compton scattering gamma-ray source

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

Placidi, M.; Di Mitri, Simone; Pellegrini, C.

Many research and applications areas require photon sources capable of producing gamma-ray beams in the multi-MeV energy range with reasonably high fluxes and compact footprints. Besides industrial, nuclear physics and security applications, a considerable interest comes from the possibility to assess the state of conservation of cultural assets like statues, columns etc., via visualization and analysis techniques using high energy photon beams. Computed Tomography scans, widely adopted in medicine at lower photon energies, presently provide high quality three-dimensional imaging in industry and museums. We explore the feasibility of a compact source of quasi-monochromatic, multi-MeV gamma-rays based on Inverse Compton Scatteringmore » (ICS) from a high intensity ultra-violet (UV) beam generated in a free-electron laser by the electron beam itself. This scheme introduces a stronger relationship between the energy of the scattered photons and that of the electron beam, resulting in a device much more compact than a classic ICS for a given scattered energy. As a result, the same electron beam is used to produce gamma-rays in the 10–20 MeV range and UV radiation in the 10–15 eV range, in a ~4 × 22 m 2 footprint system.« less

Fracture and compaction of andesite in a volcanic edifice.

PubMed

Heap, M J; Farquharson, J I; Baud, P; Lavallée, Y; Reuschlé, T

The failure mode of lava-dilatant or compactant-depends on the physical attributes of the lava, primarily the porosity and pore size, and the conditions under which it deforms. The failure mode for edifice host rock has attendant implications for the structural stability of the edifice and the efficiency of the sidewall outgassing of the volcanic conduit. In this contribution, we present a systematic experimental study on the failure mode of edifice-forming andesitic rocks (porosity from 7 to 25 %) from Volcán de Colima, Mexico. The experiments show that, at shallow depths (<1 km), both low- and high-porosity lavas dilate and fail by shear fracturing. However, deeper in the edifice (>1 km), while low-porosity (<10 %) lava remains dilatant, the failure of high-porosity lava is compactant and driven by cataclastic pore collapse. Although inelastic compaction is typically characterised by the absence of strain localisation, we observe compactive localisation features in our porous andesite lavas manifest as subplanar surfaces of collapsed pores. In terms of volcano stability, faulting in the upper edifice could destabilise the volcano, leading to an increased risk of flank or large-scale dome collapse, while compactant deformation deeper in the edifice may emerge as a viable mechanism driving volcano subsidence, spreading and destabilisation. The failure mode influences the evolution of rock physical properties: permeability measurements demonstrate that a throughgoing tensile fracture increases sample permeability (i.e. equivalent permeability) by about a factor of two, and that inelastic compaction to an axial strain of 4.5 % reduces sample permeability by an order of magnitude. The implication of these data is that sidewall outgassing may therefore be efficient in the shallow edifice, where rock can fracture, but may be impeded deeper in the edifice due to compaction. The explosive potential of a volcano may therefore be subject to increase over time if the progressive compaction and permeability reduction in the lower edifice cannot be offset by the formation of permeable fracture pathways in the upper edifice. The mode of failure of the edifice host rock is therefore likely to be an important factor controlling lateral outgassing and thus eruption style (effusive versus explosive) at stratovolcanoes.

Pressure-Driven Suspension Flow near Jamming

NASA Astrophysics Data System (ADS)

Oh, Sangwon; Song, Yi-qiao; Garagash, Dmitry I.; Lecampion, Brice; Desroches, Jean

2015-02-01

We report here magnetic resonance imaging measurements performed on suspensions with a bulk solid volume fraction (ϕ0) up to 0.55 flowing in a pipe. We visualize and quantify spatial distributions of ϕ and velocity across the pipe at different axial positions. For dense suspensions (ϕ0>0.5 ), we found a different behavior compared to the known cases of lower ϕ0. Our experimental results demonstrate compaction within the jammed region (characterized by a zero macroscopic shear rate) from the jamming limit ϕm≈0.58 at its outer boundary to the random close packing limit ϕrcp≈0.64 at the center. Additionally, we show that ϕ and velocity profiles can be fairly well captured by a frictional rheology accounting for both further compaction of jammed regions as well as normal stress differences.

A compact time reversal emitter-receiver based on a leaky random cavity

PubMed Central

Luong, Trung-Dung; Hies, Thomas; Ohl, Claus-Dieter

2016-01-01

Time reversal acoustics (TRA) has gained widespread applications for communication and measurements. In general, a scattering medium in combination with multiple transducers is needed to achieve a sufficiently large acoustical aperture. In this paper, we report an implementation for a cost-effective and compact time reversal emitter-receiver driven by a single piezoelectric element. It is based on a leaky cavity with random 3-dimensional printed surfaces. The random surfaces greatly increase the spatio-temporal focusing quality as compared to flat surfaces and allow the focus of an acoustic beam to be steered over an angle of 41°. We also demonstrate its potential use as a scanner by embedding a receiver to detect an object from its backscatter without moving the TRA emitter. PMID:27811957

Characterization of compact-toroid injection during formation, translation, and field penetration

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

Matsumoto, T., E-mail: cstd14003@g.nihon-u.ac.jp; Sekiguchi, J.; Asai, T.

2016-11-15

We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ∼1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation,more » ejection/translation from the MCPG, and penetration into transverse magnetic fields.« less

Narrow bandwidth Laser-Plasma Accelerator driven Thomson photon source development

NASA Astrophysics Data System (ADS)

Geddes, C. G. R.; Tsai, H.-E.; Otero, G.; Liu, X.; van Tilborg, J.; Toth, Cs.; Vay, J.-L.; Lehe, R.; Schroeder, C. B.; Esarey, E.; Friedman, A.; Grote, D. P.; Leemans, W. P.

2017-10-01

Compact, high-quality photon sources at MeV energies can be provided by Thomson scattering of a laser from the electron beam of a Laser-Plasma Accelerator (LPA). Recent experiments and simulations demonstrate controllable LPAs in the energy range appropriate to MeV sources. Simulations indicate that high flux with narrow energy spread can be achieved via control of the scattering laser pulse shape and laser guiding, and that undesired background bremsstrahlung can be mitigated by plasma based deceleration of the electron beam after photon production. Construction of experiments and laser capabilities to combine these elements will be presented, along with initial operations, towards a compact photon source system. Work supported by US DOE NNSA DNN R&D and by Sc. HEP under contract DE-AC02-05CH11231.

A compact, low-loss, tunable phase shifter on defect mitigated dielectrics up to 40 GHz

NASA Astrophysics Data System (ADS)

Orloff, Nathan; Long, Christian; Lu, Xifeng; Nair, Hari; Dawley, Natalie; Schlom, Darrell; Booth, James

With the emergence of the internet-of-things and increased connectivity of modern commerce, consumers have driven demand for wireless spectrum beyond current capacity and infrastructure capabilities. One way the telecommunications industry is addressing this problem is by pushing front-end electronics to higher frequencies, introducing carrier aggregation schemes, and developing spectrum-sharing techniques. Some of these solutions require frequency agile components that are vastly different from what is in today's marketplace. Perhaps the most basic and ubiquitous component in front-end electronics is the phase shifter. Phase shifters are particularly important for compact beam-forming antennas that may soon appear in commercial technology. Here, we demonstrate a compact, tunable phase shifter with very low insertion loss up to 40 GHz on a defect mitigated tunable dielectric. We demonstrate performance compared to barium-doped strontium titanate phase shifters. Such phase shifters could potentially meet the stringent size and performance characteristics demanded by telecommunications industry, readily facilitating massive multiple-input multiple-output antennas in the next-generation of mobile handsets.

Spectrometers for compact neutron sources

NASA Astrophysics Data System (ADS)

Voigt, J.; Böhm, S.; Dabruck, J. P.; Rücker, U.; Gutberlet, T.; Brückel, T.

2018-03-01

We discuss the potential for neutron spectrometers at novel accelerator driven compact neutron sources. Such a High Brilliance Source (HBS) relies on low energy nuclear reactions, which enable cryogenic moderators in very close proximity to the target and neutron optics at comparably short distances from the moderator compared to existing sources. While the first effect aims at increasing the phase space density of a moderator, the second allows the extraction of a large phase space volume, which is typically requested for spectrometer applications. We find that competitive spectrometers can be realized if (a) the neutron production rate can be synchronized with the experiment repetition rate and (b) the emission characteristics of the moderator can be matched to the phase space requirements of the experiment. MCNP simulations for protons or deuterons on a Beryllium target with a suitable target/moderator design yield a source brightness, from which we calculate the sample fluxes by phase space considerations for different types of spectrometers. These match closely the figures of todays spectrometers at medium flux sources. Hence we conclude that compact neutron sources might be a viable option for next generation neutron sources.

Compact Superconducting Power Systems for Airborne Applications (Postprint)

DTIC Science & Technology

2009-01-01

rotating machin- ery such as motors and alternators, is to maximize the magnet- ic flux density. This can be achieved by using a higher current...future systems could be driven to much higher power ratios, since the initial machine configuration was a homopolar inductor alternator‡ (HIA). A... Homopolar inductor alternator is an electrically symmetrical synchro- nous generator with a field winding that has a fixed magnetic position in relation to

Protein-like Nanoparticles Based on Orthogonal Self-Assembly of Chimeric Peptides.

PubMed

Jiang, Linhai; Xu, Dawei; Namitz, Kevin E; Cosgrove, Michael S; Lund, Reidar; Dong, He

2016-10-01

A novel two-component self-assembling chimeric peptide is designed where two orthogonal protein folding motifs are linked side by side with precisely defined position relative to one another. The self-assembly is driven by a combination of symmetry controlled molecular packing, intermolecular interactions, and geometric constraint to limit the assembly into compact dodecameric protein nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Saclay Compact Accelerator-driven Neutron Sources (SCANS)

NASA Astrophysics Data System (ADS)

Marchix, A.; Letourneau, A.; Tran, HN; Chauvin, N.; Menelle, A.; Ott, F.; Schwindling, J.

2018-06-01

For next decade, the European neutron scattering community will face of important changes, as many facilities will close, strictly fission-based sources. This statement mainly concerns France with the planned closure of Orphee and ILL. At CEA-Saclay, the project SONATE has been launched in order to provide a high intensity neutron source in Saclay site, this project is based on Compact Accelerator-driven Neutron Sources technology coupled to high-intensity beams. The goal of SONATE is to develop a 50 kW target, aiming to produce at least a neutron yield of 1013 s-1 in pulse mode with a peak current of 100 mA. We have investigated in this document the best combinations of beam/target which would lead to this substantial neutron yields. Further investigations and tests have to be carry out, especially due to sparse data on thick target and such low-energy beams considered in this document. An intermediate step to the SONATE project is under test and development, called IPHI-NEUTRON, which would lead to provide a small-size neutron facility mainly devoted to neutron imagery for industry. This step is based on the existing 3 MeV proton beam, named IPHI. Best target candidates are Lithium and Beryllium, leading respectively to a neutron yield of about 2.1013 s-1 and 4.1012 s-1.

Compact compressive arc and beam switchyard for energy recovery linac-driven ultraviolet free electron lasers

NASA Astrophysics Data System (ADS)

Akkermans, J. A. G.; Di Mitri, S.; Douglas, D.; Setija, I. D.

2017-08-01

High gain free electron lasers (FELs) driven by high repetition rate recirculating accelerators have received considerable attention in the scientific and industrial communities in recent years. Cost-performance optimization of such facilities encourages limiting machine size and complexity, and a compact machine can be realized by combining bending and bunch length compression during the last stage of recirculation, just before lasing. The impact of coherent synchrotron radiation (CSR) on electron beam quality during compression can, however, limit FEL output power. When methods to counteract CSR are implemented, appropriate beam diagnostics become critical to ensure that the target beam parameters are met before lasing, as well as to guarantee reliable, predictable performance and rapid machine setup and recovery. This article describes a beam line for bunch compression and recirculation, and beam switchyard accessing a diagnostic line for EUV lasing at 1 GeV beam energy. The footprint is modest, with 12 m compressive arc diameter and ˜20 m diagnostic line length. The design limits beam quality degradation due to CSR both in the compressor and in the switchyard. Advantages and drawbacks of two switchyard lines providing, respectively, off-line and on-line measurements are discussed. The entire design is scalable to different beam energies and charges.

Low-loss integrated electrical surface plasmon source with ultra-smooth metal film fabricated by polymethyl methacrylate 'bond and peel' method.

PubMed

Liu, Wenjie; Hu, Xiaolong; Zou, Qiushun; Wu, Shaoying; Jin, Chongjun

2018-06-15

External light sources are mostly employed to functionalize the plasmonic components, resulting in a bulky footprint. Electrically driven integrated plasmonic devices, combining ultra-compact critical feature sizes with extremely high transmission speeds and low power consumption, can link plasmonics with the present-day electronic world. In an effort to achieve this prospect, suppressing the losses in the plasmonic devices becomes a pressing issue. In this work, we developed a novel polymethyl methacrylate 'bond and peel' method to fabricate metal films with sub-nanometer smooth surfaces on semiconductor wafers. Based on this method, we further fabricated a compact plasmonic source containing a metal-insulator-metal (MIM) waveguide with an ultra-smooth metal surface on a GaAs-based light-emitting diode wafer. An increase in propagation length of the SPP mode by a factor of 2.95 was achieved as compared with the conventional device containing a relatively rough metal surface. Numerical calculations further confirmed that the propagation length is comparable to the theoretical prediction on the MIM waveguide with perfectly smooth metal surfaces. This method facilitates low-loss and high-integration of electrically driven plasmonic devices, thus provides an immediate opportunity for the practical application of on-chip integrated plasmonic circuits.

Low-loss integrated electrical surface plasmon source with ultra-smooth metal film fabricated by polymethyl methacrylate ‘bond and peel’ method

NASA Astrophysics Data System (ADS)

Liu, Wenjie; Hu, Xiaolong; Zou, Qiushun; Wu, Shaoying; Jin, Chongjun

2018-06-01

External light sources are mostly employed to functionalize the plasmonic components, resulting in a bulky footprint. Electrically driven integrated plasmonic devices, combining ultra-compact critical feature sizes with extremely high transmission speeds and low power consumption, can link plasmonics with the present-day electronic world. In an effort to achieve this prospect, suppressing the losses in the plasmonic devices becomes a pressing issue. In this work, we developed a novel polymethyl methacrylate ‘bond and peel’ method to fabricate metal films with sub-nanometer smooth surfaces on semiconductor wafers. Based on this method, we further fabricated a compact plasmonic source containing a metal-insulator-metal (MIM) waveguide with an ultra-smooth metal surface on a GaAs-based light-emitting diode wafer. An increase in propagation length of the SPP mode by a factor of 2.95 was achieved as compared with the conventional device containing a relatively rough metal surface. Numerical calculations further confirmed that the propagation length is comparable to the theoretical prediction on the MIM waveguide with perfectly smooth metal surfaces. This method facilitates low-loss and high-integration of electrically driven plasmonic devices, thus provides an immediate opportunity for the practical application of on-chip integrated plasmonic circuits.

X-ray astronomy in the laboratory with a miniature compact object produced by laser-driven implosion

NASA Astrophysics Data System (ADS)

Fujioka, Shinsuke; Takabe, Hideaki; Yamamoto, Norimasa; Salzmann, David; Wang, Feilu; Nishimura, Hiroaki; Li, Yutong; Dong, Quanli; Wang, Shoujun; Zhang, Yi; Rhee, Yong-Joo; Lee, Yong-Woo; Han, Jae-Min; Tanabe, Minoru; Fujiwara, Takashi; Nakabayashi, Yuto; Zhao, Gang; Zhang, Jie; Mima, Kunioki

2009-11-01

X-ray spectroscopy is an important tool for understanding the extreme photoionization processes that drive the behaviour of non-thermal equilibrium plasmas in compact astrophysical objects such as black holes. Even so, the distance of these objects from the Earth and the inability to control or accurately ascertain the conditions that govern their behaviour makes it difficult to interpret the origin of the features in astronomical X-ray measurements. Here, we describe an experiment that uses the implosion driven by a 3TW, 4kJ laser system to produce a 0.5keV blackbody radiator that mimics the conditions that exist in the neighbourhood of a black hole. The X-ray spectra emitted from photoionized silicon plasmas resemble those observed from the binary stars Cygnus X-3 (refs 7, 8) and Vela X-1 (refs 9, 10 11) with the Chandra X-ray satellite. As well as demonstrating the ability to create extreme radiation fields in a laboratory plasma, our theoretical interpretation of these laboratory spectra contrasts starkly with the generally accepted explanation for the origin of similar features in astronomical observations. Our experimental approach offers a powerful means to test and validate the computer codes used in X-ray astronomy.

A compact membrane-driven diamond anvil cell and cryostat system for nuclear resonant scattering at high pressure and low temperature

DOE PAGES

Zhao, J. Y.; Bi, W.; Sinogeikin, S.; ...

2017-12-13

In order to study the vibrational and thermal dynamic properties of materials using the nuclear resonant inelastic X-ray scattering (NRIXS) and the hyperfine interactions and magnetic properties using the synchrotron Mössbauer spectroscopy (SMS) at simultaneously high pressure (multi-Mbar) and low temperature (T< 10 K), a new miniature panoramic diamond anvil cell (mini-pDAC) as well as a special gas membrane driven mechanism have been developed and implemented at 3ID, Advanced Photon Source. The gas membrane system allows in situ pressure tuning of the mini- pDAC at low temperature. The mini-pDAC fits into a specially designed compact liquid helium flow cryostat systemmore » to achieve low temperature, where liquid helium flows through the holder of the mini-pDAC to cool the sample more efficiently. The sample temperature as low as 9 K has been achieved. Through the membrane, the sample pressure as high as 1.4 Mbar has been generated from this mini-pDAC. The instrument has been routinely used at 3ID for NRIXS and SMS studies. In this paper, technical details of the mini-pDAC, membrane engaging mechanism and the cryostat system are described, and some experimental results are discussed.« less

A compact membrane-driven diamond anvil cell and cryostat system for nuclear resonant scattering at high pressure and low temperature

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

Zhao, J. Y.; Bi, W.; Sinogeikin, S.

In order to study the vibrational and thermal dynamic properties of materials using the nuclear resonant inelastic X-ray scattering (NRIXS) and the hyperfine interactions and magnetic properties using the synchrotron Mössbauer spectroscopy (SMS) at simultaneously high pressure (multi-Mbar) and low temperature (T< 10 K), a new miniature panoramic diamond anvil cell (mini-pDAC) as well as a special gas membrane driven mechanism have been developed and implemented at 3ID, Advanced Photon Source. The gas membrane system allows in situ pressure tuning of the mini- pDAC at low temperature. The mini-pDAC fits into a specially designed compact liquid helium flow cryostat systemmore » to achieve low temperature, where liquid helium flows through the holder of the mini-pDAC to cool the sample more efficiently. The sample temperature as low as 9 K has been achieved. Through the membrane, the sample pressure as high as 1.4 Mbar has been generated from this mini-pDAC. The instrument has been routinely used at 3ID for NRIXS and SMS studies. In this paper, technical details of the mini-pDAC, membrane engaging mechanism and the cryostat system are described, and some experimental results are discussed.« less

Inverse modeling of geochemical and mechanical compaction in sedimentary basins

NASA Astrophysics Data System (ADS)

Colombo, Ivo; Porta, Giovanni Michele; Guadagnini, Alberto

2015-04-01

We study key phenomena driving the feedback between sediment compaction processes and fluid flow in stratified sedimentary basins formed through lithification of sand and clay sediments after deposition. Processes we consider are mechanic compaction of the host rock and the geochemical compaction due to quartz cementation in sandstones. Key objectives of our study include (i) the quantification of the influence of the uncertainty of the model input parameters on the model output and (ii) the application of an inverse modeling technique to field scale data. Proper accounting of the feedback between sediment compaction processes and fluid flow in the subsurface is key to quantify a wide set of environmentally and industrially relevant phenomena. These include, e.g., compaction-driven brine and/or saltwater flow at deep locations and its influence on (a) tracer concentrations observed in shallow sediments, (b) build up of fluid overpressure, (c) hydrocarbon generation and migration, (d) subsidence due to groundwater and/or hydrocarbons withdrawal, and (e) formation of ore deposits. Main processes driving the diagenesis of sediments after deposition are mechanical compaction due to overburden and precipitation/dissolution associated with reactive transport. The natural evolution of sedimentary basins is characterized by geological time scales, thus preventing direct and exhaustive measurement of the system dynamical changes. The outputs of compaction models are plagued by uncertainty because of the incomplete knowledge of the models and parameters governing diagenesis. Development of robust methodologies for inverse modeling and parameter estimation under uncertainty is therefore crucial to the quantification of natural compaction phenomena. We employ a numerical methodology based on three building blocks: (i) space-time discretization of the compaction process; (ii) representation of target output variables through a Polynomial Chaos Expansion (PCE); and (iii) model inversion (parameter estimation) within a maximum likelihood framework. In this context, the PCE-based surrogate model enables one to (i) minimize the computational cost associated with the (forward and inverse) modeling procedures leading to uncertainty quantification and parameter estimation, and (ii) compute the full set of Sobol indices quantifying the contribution of each uncertain parameter to the variability of target state variables. Results are illustrated through the simulation of one-dimensional test cases. The analyses focuses on the calibration of model parameters through literature field cases. The quality of parameter estimates is then analyzed as a function of number, type and location of data.

Terahertz Microscope

DTIC Science & Technology

2010-05-01

at the Brewster angle . The area of the elliptical laser spot on the semiconductor is approximately 0.5 mm2, the average optical power is about 50 mW...approximately above 100 THz, with quantum transition as the dominating physics and lens and mirror as the guiding elements for optics. The science and...waveguides are tested with a gas laser and a pyroelectric detector. A CW THz beam at 1.62 THz is collimated from the gas laser and focused by a lens

Novel Engineered Compound Semiconductor Heterostructures for Advanced Electronics Applications

DTIC Science & Technology

1992-06-22

Mechanism of light -induced reactivation of acceptors in p-type hydrogenated gallium arsenide. I. Szafranek, M. Szafranek, and G.E. Stillman. Phys. Rev.B...observed in these data. The heterojunc- techniques employed were first developed in tion is illuminated through the InP substrate with the light of GaAs-Al... light . The photocurrent was detected using conventional chopper and lock-in amplifier ’ 1h s techniques. A pyroelectric detector was used as a reference

Targeted Basic Studies of Ferroelectric and Ferroelastic Materials for Piezoelectric Transducer Applications.

DTIC Science & Technology

1983-03-01

PLZT ceramics. Low temperature studies on pure and doped PZTs have given the first clear indi- cation of the intrinsic (averaged) single domain...8217 11 4.0 PYROELECTRIC MATERIALS 27 4.1 Micro Composites 27 4.2 ’ Doped ’ Tungsten Bronze and TGS Structure Single Crystals 28 5.0 FERROELECTRIC...differences in piezo- electric activity, coupling constant and permittivity between differently doped PZTs are extrinsic and freeze out at 4°K. Extending

Pyroelectric A1GaN/GaN HEMTs for ion-, gas- and Polar-Liquid Sensors

DTIC Science & Technology

2004-08-17

including the manipulation of pico- and nanofluid volumes on chemical or structural modified surfaces and defining suitable interfaces to the macroworld. A... nanofluidic dispensers based on piezo actuators, the micro periphery and the electronics for measuring biochemical assay systems (in vivo and in vitro...interface without the need of a modulation doped barrier. The carrier concentration and electron mobility within the 2DEG can be very high and build

Phase transformations, anisotropic pyroelectric energy harvesting and electrocaloric properties of (Pb,La)(Zr,Sn,Ti)O3 single crystals.

PubMed

Zhuo, Fangping; Li, Qiang; Gao, Jinghan; Yan, Qingfeng; Zhang, Yiling; Xi, Xiaoqing; Chu, Xiangcheng

2017-05-31

(Pb,La)(Zr,Sn,Ti)O 3 (PLZST) single crystals with their chemical composition located at the tetragonal antiferroelectric region are grown via the flux method in a PbO-PbF 2 -B 2 O 3 mixture. Segregation of the Ti 4+ component in the as-grown crystals is observed due to the strong affinity between the oxygen anion and Ti 4+ ions. The critical electric field of the antiferroelectric to ferroelectric phase transition is determined to be about 0.5 kV mm -1 . The electric field induced ferroelectric phase transforms back into the antiferroelectric phase at a depolarization temperature of 125 °C. Anisotropy of the harvested energy density and electrocaloric behaviors are achieved for the [100], [110] and [111]-oriented PLZST crystals. Based on the thermodynamic theory approach, all the abovementioned behaviors originate from the anisotropic total entropy change. Enhanced electrocaloric strength (0.3 K mm kV -1 ) and the harvested energy density of 0.62 J cm -3 are obtained in the [111]-oriented PLZST crystals. Our results demonstrate the competence of PLZST single crystals for cooling devices and pyroelectric energy harvesting and provide new opportunities to improve energy harvesting density and electrocaloric properties via the anisotropic structural layout, which make the PLZST crystals attractive for solid state cooling devices and energy conversion technologies.

Magneto-inductive skin sensor for robot collision avoidance: A new development

NASA Technical Reports Server (NTRS)

Chauhan, D. S.; Dehoff, Paul H.

1989-01-01

Safety is a primary concern for robots operating in space. The tri-mode sensor addresses that concern by employing a collision avoidance/management skin around the robot arms. This rf-based skin sensor is at present a dual mode (proximity and tactile). The third mode, pyroelectric, will complement the other two. The proximity mode permits the robot to sense an intruding object, to range the object, and to detect the edges of the object. The tactile mode permits the robot to sense when it has contacted an object, where on the arm it has made contact, and provides a three-dimensional image of the shape of the contact impression. The pyroelectric mode will be added to permit the robot arm to detect the proximity of a hot object and to add sensing redundancy to the two other modes. The rf-modes of the sensing skin are presented. These modes employ a highly efficient magnetic material (amorphous metal) in a sensing technique. This results in a flexible sensor array which uses a primarily inductive configuration to permit both capacitive and magnetoinductive sensing of object; thus optimizing performance in both proximity and tactile modes with the same sensing skin. The fundamental operating principles, design particulars, and theoretical models are provided to aid in the description and understanding of this sensor. Test results are also given.

Study of Lead Free Ferroelectric Films for New Solar Cells

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

Fasquelle, D.; Mascot, M.; Carru, J. C.

2009-09-14

We report on the deposition by a sol-gel process of Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} and Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} films on platinum coated silicon substrates. X-Ray diffraction patterns show that the films are (111) preferentially oriented. The surface morphology is smooth, without cracks and the grain size is about 50 nm as determined by AFM and SEM. The dielectric constant measured from 10{sup 2} to 10{sup 6} Hz decreases slightly and is around 400 at 10{sup 4} Hz. The losses are constant in a first approximation for a 1.5 {mu}m thick BST(80/20) film with a value of 0.03 at 10more » kHz. The existence of an hysteresis cycle attests that the films, whatever their thickness, are in a ferroelectric state. Pyroelectric coefficients have been determined and the best figure of merit obtained on BST(90/10) at 293 K and 10 kHz is of 149 {mu}C/m{sup 3}/K. The best dielectric and pyroelectric properties (tg{delta} = 0.006 at 1 MHz, tunability = 30%, {gamma} = 340 {mu}C/m{sup 2}/K) were obtained on the 400 nm BST(90/10) film. Work is in progress to characterize the piezoelectric and photovoltaic properties of our BST films.« less

Spectral and spatial characterisation of laser-driven positron beams

DOE PAGES

Sarri, G.; Warwick, J.; Schumaker, W.; ...

2016-10-18

The generation of high-quality relativistic positron beams is a central area of research in experimental physics, due to their potential relevance in a wide range of scientific and engineering areas, ranging from fundamental science to practical applications. There is now growing interest in developing hybrid machines that will combine plasma-based acceleration techniques with more conventional radio-frequency accelerators, in order to minimise the size and cost of these machines. Here we report on recent experiments on laser-driven generation of high-quality positron beams using a relatively low energy and potentially table-top laser system. Lastly, the results obtained indicate that current technology allowsmore » to create, in a compact setup, positron beams suitable for injection in radio-frequency accelerators.« less

Ultrafast observation of lattice dynamics in laser-irradiated gold foils

DOE PAGES

Hartley, N. J.; Ozaki, Norimasa; Matsuoka, T.; ...

2017-02-13

Here, we have observed the lattice expansion before the onset of compression in an optical-laser-driven target, using diffraction of femtosecond X-ray beams generated by the SPring-8 Angstrom Compact Free-electron Laser. The change in diffraction angle provides a direct measure of the lattice spacing, allowing the density to be calculated with a precision of ±1%. From the known equation of state relations, this allows an estimation of the temperature responsible for the expansion as <1000 K. The subsequent ablation-driven compression was observed with a clear rise in density at later times. This demonstrates the feasibility of studying the dynamics of preheatingmore » and shock formation with unprecedented detail.« less

Ultrafast observation of lattice dynamics in laser-irradiated gold foils

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

Hartley, N. J.; Ozaki, Norimasa; Matsuoka, T.

Here, we have observed the lattice expansion before the onset of compression in an optical-laser-driven target, using diffraction of femtosecond X-ray beams generated by the SPring-8 Angstrom Compact Free-electron Laser. The change in diffraction angle provides a direct measure of the lattice spacing, allowing the density to be calculated with a precision of ±1%. From the known equation of state relations, this allows an estimation of the temperature responsible for the expansion as <1000 K. The subsequent ablation-driven compression was observed with a clear rise in density at later times. This demonstrates the feasibility of studying the dynamics of preheatingmore » and shock formation with unprecedented detail.« less

High-pressure portable pneumatic drive unit.

PubMed

Hete, B F; Savage, M; Batur, C; Smith, W A; Golding, L A; Nosé, Y

1989-12-01

The left ventricular assist device (LVAD) of the Cleveland Clinic Foundation (CCF) is a single-chamber assist pump, driven by a high-pressure pneumatic cylinder. A low-cost, portable driver that will allow cardiac care patients, with a high-pressure pneumatic ventricle assist, more freedom of movement has been developed. The compact and light-weight configuration can provide periods of 2 h of freedom from a fixed position driver and does not use exotic technology.

Properties of Ferroelectric Perovskite Structures under Non-equilibrium Conditions

NASA Astrophysics Data System (ADS)

Zhang, Qingteng

Ferroelectric materials have received lots of attention thanks to their intriguing properties such as the piezoelectric and pyroelectric effects, as well as the large dielectric constants and the spontaneous polarization which can potentially be used for information storage. In particular, perovskite crystal has a very simple unit cell structure yet a very rich phase transition diagram, which makes it one of the most intensively studied ferroelectric materials. In this dissertation, we use effective Hamiltonian, a first-principles-based computational technique to study the finite-temperature properties of ferroelectric perovskites. We studied temperature-graded (BaxSr 1-x)TiO3 (BST) bulk alloys as well as the dynamics of nanodomain walls (nanowalls) in Pb(Zr xTi1-x)O 3 (PZT) ultra-thin films under the driving force of an AC field. Our computations suggest that, for the temperature-graded BST, the polarization responds to the temperature gradient (TG), with the "up" and "down" offset observed in polarization components along the direction of TG, in agreement with the findings from experiments. For the nanowalls in PZT, the dynamics can be described by the damped-harmonic-oscillator model, and we observed a size-driven transition from resonance to relaxational dynamics at a critical thickness of 7.2 nm. The transition originates from the change in the effective mass of a nanowall as a film thickness increases. Some of the findings may find potential applications in various devices, such as thermal sensors, energy converters, or novel memory units.

The land-use of Bandung, its density, overcrowded area and public facility toward a compact city

NASA Astrophysics Data System (ADS)

Paramita, B.

2016-04-01

The concept of a compact city has been introduced since 1973. It is a utopian vision largely driven by a desire to see more efficient uses of resources. In 1980s, the reconfiguration of the physical urban form of metropolitan areas was increasingly debated by both theorists and practitioners. Recently, the concept of a compact city has been more focused on developed countries in which the population tends to decrease. However, in Asia, except Japan which contains many dense cities, it has become a concept which promotes relatively high residential density with mixed land uses, though rather only in population and density. This paper addresses the land-use of Bandung that having the density over 14,000 people/km2, which has been so much potential toward a compact city. Somehow, unprepared ness of urban planning and regulation, the city seemed overwrought to serve its inhabitants. This condition is shown from the demographic condition, especially population density in Bandung based on its sub areas of the city (SWK). The stack of public facilities in a certain district has led the concentration of density and activity, which finally raising the slum and overcrowded settlement. Finally, this paper explores the implications of land use management and describes challenges faced and possible approaches, especially in land-use management strategies to be implemented in Bandung.

Dense CO in Mrk 71-A: Superwind Suppressed in a Young Super Star Cluster

NASA Astrophysics Data System (ADS)

Oey, M. S.; Herrera, C. N.; Silich, Sergiy; Reiter, Megan; James, Bethan L.; Jaskot, A. E.; Micheva, Genoveva

2017-11-01

We report the detection of CO(J=2-1) coincident with the super star cluster (SSC) Mrk 71-A in the nearby Green Pea analog galaxy, NGC 2366. Our observations with the Northern Extended Millimeter Array reveal a compact, ˜7 pc, molecular cloud whose mass ({10}5 {M}⊙ ) is similar to that of the SSC, consistent with a high star formation efficiency, on the order of 0.5. There are two spatially distinct components separated by 11 {km} {{{s}}}-1. If expanding, these could be due to momentum-driven stellar wind feedback. Alternatively, we may be seeing remnants of the infalling, colliding clouds responsible for triggering the SSC formation. The kinematics are also consistent with a virialized system. These extreme, high-density, star-forming conditions inhibit energy-driven feedback; the co-spatial existence of a massive, molecular cloud with the SSC supports this scenario, and we quantitatively confirm that any wind-driven feedback in Mrk 71-A is momentum-driven, rather than energy-driven. Since Mrk 71-A is a candidate Lyman continuum emitter, this implies that energy-driven superwinds may not be a necessary condition for the escape of ionizing radiation. In addition, the detection of nebular continuum emission yields an accurate astrometric position for the Mrk 71-A. We also detect four other massive molecular clouds in this giant star-forming complex.

Miniaturized X-ray Generation by Pyroelectric Effect using Short Pulse Laser

DTIC Science & Technology

2011-11-30

turned out that only 0.2 ℃ temperature change during 10 ns caused a giant current such as 20 mA. This value was 104 ~ 105 times larger than the...where εosc = qeEl2 /(meω2) is the electron quiver energy, EI ≈ 19√ = 4.65x 104 V/cm is the electric field of laser radiation for I = 6x106 W...duration the integration of Eq. (5) gives: (9) where )(/ adR NNha   , Rhb

Develop Techniques for Ion Implantation of PLZT for Adaptive Optics

DTIC Science & Technology

1989-11-01

WL-TR-89-26 FIGURES (Continued) Fizure Page 20 EDX elemental spectrum from perovskite region of the sample shown in Fig. 15. 65 21 EDX elemental...pyroelectric response. 126 84 Result of doping PZT with La and Mn (Ref. 7). 127 85 APW results along the lin for several perovskite - type compounds and ReO 2...structure of the calcined powder was analyzed and shown to be mainly the hexagonal/rhombohedral phase within 17 WL-TR-89-26 the perovskite structure of

A Study of the Nature and Origins of Pyroelectricity and Piezoelectricity in Polyvinylidenefluoride and Its Co-Polymers.

DTIC Science & Technology

1980-01-01

OF THIS PAOE(3tn Dea afm 20. Contd. It is possible that space charges are also present in the’film. However, the distribution of space charges in the...the discontinuities so that space charge effects may cause field perturbations. On the other hand, the corona charging procedure may drive ions into...trapped space charge effects; (iv) tunnelling of charge from the electrodes to empty traps; (v) hopping of charge carriers through localized states. The

Note from the Publishers. Pyroelectric behavior and dielectric properties of linear copolysiloxane/eicosylamine superlattice by A.R.M. Yusoff and W.H. Abd. Majid

NASA Astrophysics Data System (ADS)

Publishers, The; Majid, W. H. Abd.

2006-08-01

In spite of the precautions taken to check the originality of the articles, it happens, unfortunately that our scientific colleagues' vigilance is sometimes caught up unprepared. Today, it has come to our attention that the following article results from a plagiarism. We apologize to the authors who suffered from it. You will find hereafter a note written by Dr Majid which summarizes the situation.

High Precision Material Study at Near Millimeter Wavelengths.

DTIC Science & Technology

1983-08-30

propagating through these tubes , the beams are allowed to expand for a short distance in free space before they are combined by a mylar -film beam- splitter...Laser Precision Rkp-5200). 22 6 The attenuation of the low-loss EH mode in circular plexiglass tubes of I.D. 0.95 cm, and of various lengths. he...pyroelectric detectors (Laser Precision Rkp-545): L L, and L TPx lens; BS1, wire-mesh beam splitter; BS, mylar -film beam splitter; DPC, double-prism coupler

Photothermal method using a pyroelectric sensor for thermophysical characterization of agricultural and biological samples

NASA Astrophysics Data System (ADS)

Frandas, A.; Dadarlat, Dorin; Chirtoc, Mihai; Jalink, Henk; Bicanic, Dane D.; Paris, D.; Antoniow, Jean S.; Egee, Michel; Ungureanu, Costica

1998-07-01

The photopyroelectric method in different experimental configurations was used for thermophysical characterization of agricultural and biological samples. The study appears important due to the relation of thermal parameters to the quality of foodstuffs (connected to their preservation, storage and adulteration), migration profiles in biodegradable packages, and the mechanism of desiccation tolerance of seeds. Results are presented on the thermal parameters measurement and their dependence on temperature and water content for samples such as: honey, starch, seeds.

Method of improving BeO as a thermoluminescent detector

DOEpatents

Gammage, Richard B.; Thorngate, John H.; Christian, Danny J.

1980-01-01

Measurements of radiation exposure below 1 mR are possible with a BeO ceramic thermoluminescent detector (TLD) by treating the TL signal in a manner that discriminates against an interferring pyroelectric incandescence (PI). This is accomplished by differentiating the signals electronically to cause the composite signal to cross the baseline. A zero-crossing detector then senses and clips the negative-going portion of the signal. The resultant signal is integrated, producing a result wherein the true TL signal is substantially greater than the PI signal.

Electropyroelectric technique: A methodology free of fitting procedures for thermal effusivity determination in liquids.

PubMed

Ivanov, R; Marin, E; Villa, J; Gonzalez, E; Rodríguez, C I; Olvera, J E

2015-06-01

This paper describes an alternative methodology to determine the thermal effusivity of a liquid sample using the recently proposed electropyroelectric technique, without fitting the experimental data with a theoretical model and without having to know the pyroelectric sensor related parameters, as in most previous reported approaches. The method is not absolute, because a reference liquid with known thermal properties is needed. Experiments have been performed that demonstrate the high reliability and accuracy of the method with measurement uncertainties smaller than 3%.

Development of anthropomorphic robotic hand driven by Pneumatic Artificial Muscles for robotic applications

NASA Astrophysics Data System (ADS)

Farag, Mohannad; Zainul Azlan, Norsinnira; Hayyan Alsibai, Mohammed

2018-04-01

This paper presents the design and fabrication of a three-fingered anthropomorphic robotic hand. The fingers are driven by tendons and actuated by human muscle-like actuators known as Pneumatic Artificial Muscle (PAM). The proposed design allows the actuators to be mounted outside the hand where each finger can be driven by one PAM actuator and six indirectly interlinked tendons. With this design, the three-fingered hand has a compact size and a lightweight with a mass of 150.25 grams imitating the human being hand in terms of size and weight. The hand also successfully grasped objects with different shapes and weights up to 500 g. Even though the number of PAM actuators equals the number of Degrees of Freedom (DOF), the design guarantees driving of three joints by only one actuator reducing the number of required actuators from 3 to 1. Therefore, this hand is suitable for researches of robotic applications in terms of design, cost and ability to be equipped with several types of sensors.

nDEP-driven cell patterning and bottom-up construction of cell aggregates using a new bioelectronic chip.

PubMed

Menad, S; Franqueville, L; Haddour, N; Buret, F; Frenea-Robin, M

2015-04-01

Creating cell aggregates of controlled size and shape and patterning cells on substrates using a bottom-up approach constitutes important challenges for tissue-engineering applications and studies of cell-cell interactions. In this paper, we report nDEP (negative dielectrophoresis) driven assembly of cells as compact aggregates or onto defined areas using a new bioelectronic chip. This chip is composed of a quadripolar electrode array obtained using coplanar electrodes partially covered with a thin, micropatterned PDMS membrane. This thin PDMS layer was coated with poly-L-lysine and played the role of adhesive substrate for cell patterning. For the formation of detachable cell aggregates, the PDMS was not pretreated and cells were simply immobilized into assemblies maintained by cell-cell adhesion after the electric field removal. Cell viability after exposition to DEP buffer was also assessed, as well as cell spreading activity following DEP-driven assembly. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Ultra high-speed x-ray imaging of laser-driven shock compression using synchrotron light

NASA Astrophysics Data System (ADS)

Olbinado, Margie P.; Cantelli, Valentina; Mathon, Olivier; Pascarelli, Sakura; Grenzer, Joerg; Pelka, Alexander; Roedel, Melanie; Prencipe, Irene; Laso Garcia, Alejandro; Helbig, Uwe; Kraus, Dominik; Schramm, Ulrich; Cowan, Tom; Scheel, Mario; Pradel, Pierre; De Resseguier, Thibaut; Rack, Alexander

2018-02-01

A high-power, nanosecond pulsed laser impacting the surface of a material can generate an ablation plasma that drives a shock wave into it; while in situ x-ray imaging can provide a time-resolved probe of the shock-induced material behaviour on macroscopic length scales. Here, we report on an investigation into laser-driven shock compression of a polyurethane foam and a graphite rod by means of single-pulse synchrotron x-ray phase-contrast imaging with MHz frame rate. A 6 J, 10 ns pulsed laser was used to generate shock compression. Physical processes governing the laser-induced dynamic response such as elastic compression, compaction, pore collapse, fracture, and fragmentation have been imaged; and the advantage of exploiting the partial spatial coherence of a synchrotron source for studying low-density, carbon-based materials is emphasized. The successful combination of a high-energy laser and ultra high-speed x-ray imaging using synchrotron light demonstrates the potentiality of accessing complementary information from scientific studies of laser-driven shock compression.

Bio-inspired mechanical design of a tendon-driven dexterous prosthetic hand.

PubMed

Controzzi, Marco; Cipriani, Christian; Jehenne, Beryl; Donati, Marco; Carrozza, Maria Chiara

2010-01-01

This paper presents the preliminary design of a new dexterous upper-limb prosthesis provided with a novel anthropomorphic hand, a compact wrist based on bevel gears and a modular forearm able to cover different levels of upper-limb amputations. The hand has 20 DoFs and 11 motors, with a dexterous three fingered subsystem composed by a fully actuated thumb, and an hybrid index and middle fingers to enable dexterous manipulation and enhance grasp performance.

Compact antenna for two-dimensional beam scan in the JT-60U electron cyclotron heating/current drive system

NASA Astrophysics Data System (ADS)

Moriyama, S.; Kajiwara, K.; Takahashi, K.; Kasugai, A.; Seki, M.; Ikeda, Y.; Fujii, T.

2005-11-01

A compact antenna system was designed and fabricated to enable millimeter-wave beam scanning in the toroidal and poloidal directions of the JT-60U tokamak for electron cyclotron heating (ECH) and electron cyclotron current drive (ECCD) experiments. The antenna consists of a fast movable flat mirror mounted on the tokamak vacuum vessel and a rotary focusing mirror attached at the end of the waveguide that is supported from outside the vacuum vessel. This separate support concept enables a compact structure inside a shallow port (0.68×0.54×0.2m) that is shared with a subport for an independent diagnostic system. During a plasma shot, the flat mirror is driven by a servomotor with a 3-m-long drive shaft to reduce the influence of the high magnetic field on the motor. The focusing mirror is rotated by a simple mechanism utilizing a push rod and an air cylinder. The antenna has been operated reliably for 3 years after a small improvement to the rotary drive mechanism. It has made significant contributions to ECH and ECCD experiments, especially the current profile control in JT-60U.

Numerical study of multiscale compaction-initiated detonation

NASA Astrophysics Data System (ADS)

Gambino, J. R.; Schwendeman, D. W.; Kapila, A. K.

2018-02-01

A multiscale model of heterogeneous condensed-phase explosives is examined computationally to determine the course of transient events following the application of a piston-driven stimulus. The model is a modified version of that introduced by Gonthier (Combust Sci Technol 175(9):1679-1709, 2003. https://doi.org/10.1080/00102200302373) in which the explosive is treated as a porous, compacting medium at the macro-scale and a collection of closely packed spherical grains capable of undergoing reaction and diffusive heat transfer at the meso-scale. A separate continuum description is ascribed to each scale, and the two scales are coupled together in an energetically consistent manner. Following piston-induced compaction, localized energy deposition at the sites of intergranular contact creates hot spots where reaction begins preferentially. Reaction progress at the macro-scale is determined by the spatial average of that at the grain scale. A parametric study shows that combustion at the macro-scale produces an unsteady detonation with a cyclical character, in which the lead shock loses strength and is overtaken by a stronger secondary shock generated in the partially reacted material behind it. The secondary shock in turn becomes the new lead shock and the process repeats itself.

Handheld probe for portable high frame photoacoustic/ultrasound imaging system

NASA Astrophysics Data System (ADS)

Daoudi, K.; van den Berg, P. J.; Rabot, O.; Kohl, A.; Tisserand, S.; Brands, P.; Steenbergen, W.

2013-03-01

Photoacoustics is a hybrid imaging modality that is based on the detection of acoustic waves generated by absorption of pulsed light by tissue chromophors. In current research, this technique uses large and costly photoacoustic systems with a low frame rate imaging. To open the door for widespread clinical use, a compact, cost effective and fast system is required. In this paper we report on the development of a small compact handset pulsed laser probe which will be connected to a portable ultrasound system for real-time photoacoustic imaging and ultrasound imaging. The probe integrates diode lasers driven by an electrical driver developed for very short high power pulses. It uses specifically developed highly efficient diode stacks with high frequency repetition rate up to 10 kHz, emitting at 800nm wavelength. The emitted beam is collimated and shaped with compact micro optics beam shaping system delivering a homogenized rectangular laser beam intensity distribution. The laser block is integrated with an ultrasound transducer in an ergonomically designed handset probe. This handset is a building block enabling for a low cost high frame rate photoacoustic and ultrasound imaging system. The probe was used with a modified ultrasound scanner and was tested by imaging a tissue mimicking phantom.

On the acoustic radiation modes of compact regular polyhedral arrays of independent loudspeakers.

PubMed

Pasqual, Alexander Mattioli; Martin, Vincent

2011-09-01

Compact spherical loudspeaker arrays can be used to provide control over their directivity pattern. Usually, this is made by adjusting the gains of preprogrammed spatial filters corresponding to a finite set of spherical harmonics, or to the acoustic radiation modes of the loudspeaker array. Unlike the former, the latter are closely related to the radiation efficiency of the source and span the subspace of the directivities it can produce. However, the radiation modes depend on frequency for arbitrary distributions of transducers on the sphere, which yields complex directivity filters. This work focuses on the most common loudspeaker array configurations, those following the regular shape of the Platonic solids. It is shown that the radiation modes of these sources are frequency independent, and simple algebraic expressions are derived for their radiation efficiencies. In addition, since such modes are vibration patterns driven by electrical signals, the transduction mechanism of compact multichannel sources is also investigated, which is an important issue, especially if the transducers interact inside a shared cabinet. For Platonic solid loudspeakers, it is shown that the common enclosure does not lead to directivity filters that depend on frequency. © 2011 Acoustical Society of America

Ion flow measurements during the rotating kink behavior of the central column in the HIST device

NASA Astrophysics Data System (ADS)

Yamada, S.; Yoshikawa, T.; Hashimoto, S.; Nishioka, T.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2007-11-01

Plasma flow is essentially driven in self-organization and magnetic reconnection process of compact spherical torus (ST) and spheromak in the helicity-driven systems. For example, when reversing the external toroidal field of ST, the direction not only of the plasma current but also of the toroidal ion flow is self-reversed during the formation of the flipped ST relaxed states. Mach probe measurement shows that the velocity of the ion flow reversed after the flip increases to about 20 km/s. We have been newly developing an ion Doppler spectrometer (IDS) system using a compact 16 or 64 channel photomultiplier tube (PMT) in order to measure the spatial profile of ion temperature and rotation velocity in the HIST device. The IDS system consists of a light collection system including optical fibers, 1 m-spectrometer and the PMT detector. The optical fibers covered with glass tubes are inserted into the plasma. The glass tubes can be rotated in the poloidal and the toroidal directions. The new IDS system will be applied to observations of ion temperature and plasma rotation in the flipped ST formation and in the MHD control of kinking behaviors of the central column by using the rotating magnetic field (RMF). Preliminary IDS results will be compared to those from Mach probe measurements in space.

Design and construction of the X-2 two-stage free piston driven expansion tube

NASA Technical Reports Server (NTRS)

Doolan, Con

1995-01-01

This report outlines the design and construction of the X-2 two-stage free piston driven expansion tube. The project has completed its construction phase and the facility has been installed in the new impulsive research laboratory where commissioning is about to take place. The X-2 uses a unique, two-stage driver design which allows a more compact and lower overall cost free piston compressor. The new facility has been constructed in order to examine the performance envelope of the two-stage driver and how well it couple to sub-orbital and super-orbital expansion tubes. Data obtained from these experiments will be used for the design of a much larger facility, X-3, utilizing the same free piston driver concept.

Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

PubMed Central

Hofmann, Kerstin M; Schell, Stefan; Wilkens, Jan J

2012-01-01

Abstract Laser-accelerated particles are a promising option for radiation therapy of cancer by potentially combining a compact, cost-efficient treatment unit with the physical advantages of charged particle beams. To design such a treatment unit we consider different dose delivery schemes and analyze the necessary devices in the required particle beam line for each case. Furthermore, we point out that laser-driven treatment units may be ideal tools for motion adaptation during radiotherapy. Reasons for this are the potential of a flexible gantry and the time structure of the beam with high particle numbers in ultrashort bunches. One challenge that needs to be addressed is the secondary radiation produced in several beam line elements. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) PMID:22930653

Transparent active matrix organic light-emitting diode displays driven by nanowire transistor circuitry.

PubMed

Ju, Sanghyun; Li, Jianfeng; Liu, Jun; Chen, Po-Chiang; Ha, Young-Geun; Ishikawa, Fumiaki; Chang, Hsiaokang; Zhou, Chongwu; Facchetti, Antonio; Janes, David B; Marks, Tobin J

2008-04-01

Optically transparent, mechanically flexible displays are attractive for next-generation visual technologies and portable electronics. In principle, organic light-emitting diodes (OLEDs) satisfy key requirements for this application-transparency, lightweight, flexibility, and low-temperature fabrication. However, to realize transparent, flexible active-matrix OLED (AMOLED) displays requires suitable thin-film transistor (TFT) drive electronics. Nanowire transistors (NWTs) are ideal candidates for this role due to their outstanding electrical characteristics, potential for compact size, fast switching, low-temperature fabrication, and transparency. Here we report the first demonstration of AMOLED displays driven exclusively by NW electronics and show that such displays can be optically transparent. The displays use pixel dimensions suitable for hand-held applications, exhibit 300 cd/m2 brightness, and are fabricated at temperatures suitable for integration on plastic substrates.

Assessment of Laser-Driven Pulsed Neutron Sources for Poolside Neutron-based Advanced NDE – A Pathway to LANSCE-like Characterization at INL

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

Roth, Markus; Vogel, Sven C.; Bourke, Mark Andrew M.

A variety of opportunities for characterization of fresh nuclear fuels using thermal (~25meV) and epithermal (~10eV) neutrons have been documented at Los Alamos National Laboratory. They include spatially resolved non-destructive characterization of features, isotopic enrichment, chemical heterogeneity and stoichiometry. The LANSCE spallation neutron source is well suited in neutron fluence and temporal characteristics for studies of fuels. However, recent advances in high power short pulse lasers suggest that compact neutron sources might, over the next decade, become viable at a price point that would permit their consideration for poolside characterization on site at irradiation facilities. In a laser-driven neutron sourcemore » the laser is used to accelerate deuterium ions into a beryllium target where neutrons are produced. At this time, the technology is new and their total neutron production is approximately four orders of magnitude less than a facility like LANSCE. However, recent measurements on a sub-optimized system demonstrated >10 10 neutrons in sub-nanosecond pulses in predominantly forward direction. The compactness of the target system compared to a spallation target may allow exchanging the target during a measurement to e.g. characterize a highly radioactive sample with thermal, epithermal, and fast neutrons as well as hard X-rays, thus avoiding sample handling. At this time several groups are working on laser-driven neutron production and are advancing concepts for lasers, laser targets, and optimized neutron target/moderator systems. Advances in performance sufficient to enable poolside fuels characterization with LANSCE-like fluence on sample within a decade may be possible. This report describes the underlying physics and state-of-the-art of the laser-driven neutron production process from the perspective of the DOE/NE mission. It also discusses the development and understanding that will be necessary to provide customized capability for characterization of irradiated fuels. Potential operational advantages compared to a spallation neutron source include reduced shielding complexity, reduced energy requirements, and a production target free of fission products. Contributors to this report include experts in laser-driven neutron production (Roth, Fernandez), laser design (Haefner, Siders, Leemans), laser target design (Glenzer), spallation target/moderator design (Mocko), neutron instrumentation and characterization applications (Vogel, Bourke).« less

Pyro-phototronic nanogenerator based on flexible 2D ZnO/graphene heterojunction and its application in self-powered near infrared photodetector and active analog frequency modulation.

PubMed

Sahatiya, Parikshit; Shinde, Akash; Badhulika, Sushmee

2018-08-10

Even though 2D ZnO has been utilized for enhanced self-powered sensing by strain modulation due to its piezoelectric property, study on utilizing the pyroelectric property of ZnO remains unexplored. The piezoelectric property of 2D ZnO works on mechanical strain, which disrupts the structure of ZnO leading to the failure of the device. For a pyroelectric nanogenerator, the temperature difference can be triggered by an external light source, which does not disrupt the ZnO structure and also avoids the need for physical bending/pressing, as in the case of a piezoelectric nanogenerator. This work represents the first demonstration of the fabrication of a flexible 2D ZnO/Gr pyro-phototronic diode where the pyro-potential generated in the 2D ZnO due to the near infrared (NIR) illumination adds to or subtracts from the built-in electric field of the heterojunction and modulates the depletion region of the heterojunction thereby enabling bias-free operation. Furthermore, the variation in the depletion width of the heterojunction was utilized as a variable capacitor in the frequency modulator, wherein, with the increasing intensity, the frequency of oscillations increased from 9.8 to 10.42 MHz. The work presented provides an alternative approach for a self-powered NIR photodetector and the utilization of the same at circuit level, having potential applications in the fields of optothermal detection, electronic tuning circuits, etc.

Stabilization of Joule Heating in the Electropyroelectric Method

NASA Astrophysics Data System (ADS)

Ivanov, R.; Hernández, M.; Marín, E.; Araujo, C.; Alaniz, D.; Araiza, M.; Martínez-Ordoñez, E. I.

2012-11-01

Recently the so-called electropyroelectric technique for thermal characterization of liquids has been proposed (Ivanov et al., J. Phys. D: Appl. Phys. 43, 225501 (2010)). In this method a pyroelectric sensor, in good thermal contact with the investigated sample, is heated by passing an amplitude-modulated electrical current through the electrical contacts. As a result of the heat dissipated to the sample, the pyroelectric signal measured as a voltage drop across the electrical contacts changes in a periodical way. The amplitude and phase of this signal can be measured by lock-in detection as a function of the electrical current modulation frequency. Because the signal amplitude and phase depend on the thermal properties of the sample, these can be determined straightforwardly by fitting the experimental data to a theoretical model based on the solution of the heat diffusion equation with proper boundary conditions. In general, the experimental conditions are selected so that the thermal effusivity becomes the measured magnitude. The technique has the following handicap. As the result of heating and wear of the metal coating layers (previously etched to achieve a serpentine form) with time, their electrical resistance changes with time, so that the heat power dissipated by the Joule effect can vary, and thermal effusivity measurement can become inaccurate. To avoid this problem in this study, a method is proposed that allows maintaining stable the Joule dissipated power. An electronic circuit is designed whose stability and characteristics are investigated and discussed.

Electroactive polymers for healthcare and biomedical applications

NASA Astrophysics Data System (ADS)

Bauer, Siegfried

2017-04-01

Electroactivity was noticed early in biological substances, including proteins, polynucleotides and enzymes, even piezoand pyroelectricity were found in wool, hair, wood, bone and tendon. Recently, ferroelectricity has been identified in a surprisingly large number of biologically relevant materials, including hydroxyapatite, aortic walls and elastin. Inspired by the variety of natural electroactive materials, a wealth of new elastomers and polymers were designed recently, including an all organic elastomer electret and self-healing dielectric elastomers. Let's further draw inspiration from nature and widen the utilization of electroactive polymers towards (mobile) healthcare and biomedical applications. Ferroelectrets, internally charged polymer foams with a strong piezoelectric thickness coefficient are employed in biomedical sensing, for example as blood pressure and pulse sensor, as vital signs monitor or for the detection of tonicclonic seizures. Piezo- and pyroelectric polymers are booming in printed electronics research. They provide electronic skin the ability to "feel" pressure and temperature changes, or to generate electrical energy from vibrations and motions, even from contractile and relaxation motions of the heart and lung. Dielectric elastomers are pioneered by StretchSense as wearable motion capture sensors, monitoring pressure, stretch, bend and shear, quantifying comfort in sports and healthcare. On the cellular level, electroactive polymer arrays are used to study mechanotransduction of individual cells. Ionic electroactive polymers show potential to be used in implantable electroactive biomedical devices. Already with the currently available science and technology, we are at the verge of witnessing the demonstration of truly complex bionic systems.

A simple and compact mechanical velocity selector of use to analyze/select molecular alignment in supersonic seeded beams

NASA Astrophysics Data System (ADS)

Pirani, F.; Cappelletti, D.; Vecchiocattivi, F.; Vattuone, L.; Gerbi, A.; Rocca, M.; Valbusa, U.

2004-02-01

A light and compact mechanical velocity selector, of novel design, for applications in supersonic molecular-beam studies has been developed. It represents a simplified version of the traditional, 50 year old, slotted disks velocity selector. Taking advantage of new materials and improved machining techniques, the new version has been realized with only two rotating slotted disks, driven by an electrical motor with adjustable frequency of rotation, and thus has a much smaller weight and size with respect to the original design, which may allow easier implementation in most of the available molecular-beam apparatuses. This new type of selector, which maintains a sufficiently high velocity resolution, has been developed for sampling molecules with different degrees of rotational alignment, like those emerging from a seeded supersonic expansion. This sampling is the crucial step to realize new molecular-beam experiments to study the effect of molecular alignment in collisional processes.

Ultrafast optical ranging using microresonator soliton frequency combs

NASA Astrophysics Data System (ADS)

Trocha, P.; Karpov, M.; Ganin, D.; Pfeiffer, M. H. P.; Kordts, A.; Wolf, S.; Krockenberger, J.; Marin-Palomo, P.; Weimann, C.; Randel, S.; Freude, W.; Kippenberg, T. J.; Koos, C.

2018-02-01

Light detection and ranging is widely used in science and industry. Over the past decade, optical frequency combs were shown to offer advantages in optical ranging, enabling fast distance acquisition with high accuracy. Driven by emerging high-volume applications such as industrial sensing, drone navigation, or autonomous driving, there is now a growing demand for compact ranging systems. Here, we show that soliton Kerr comb generation in integrated silicon nitride microresonators provides a route to high-performance chip-scale ranging systems. We demonstrate dual-comb distance measurements with Allan deviations down to 12 nanometers at averaging times of 13 microseconds along with ultrafast ranging at acquisition rates of 100 megahertz, allowing for in-flight sampling of gun projectiles moving at 150 meters per second. Combining integrated soliton-comb ranging systems with chip-scale nanophotonic phased arrays could enable compact ultrafast ranging systems for emerging mass applications.

Electrode structure of a compact microwave driven capacitively coupled atomic beam source

NASA Astrophysics Data System (ADS)

Shimabukuro, Yuji; Takahashi, Hidenori; Wada, Motoi

2018-01-01

A compact magnetic field free atomic beam source was designed, assembled and tested the performance to produce hydrogen and nitrogen atoms. A forced air-cooled solid-state microwave power supply at 2.45 GHz frequency drives the source up to 100 W through a coaxial transmission cable coupled to a triple stub tuner for realizing a proper matching condition to the discharge load. The discharge structure of the source affected the range of operation pressure, and the pressure was reduced by four orders of magnitude through improving the electrode geometry to enhance the local electric field intensity. Optical emission spectra of the produced plasmas indicate production of hydrogen and nitrogen atoms, while the flux intensity of excited nitrogen atoms monitored by a surface ionization type detector showed the signal level close to a source developed for molecular beam epitaxy applications with 500 W RF power.

A compact 3 T all HTS cryogen-free MRI system

NASA Astrophysics Data System (ADS)

Parkinson, B. J.; Bouloukakis, K.; Slade, R. A.

2017-12-01

We have designed and built a passively shielded, cryogen-free 3 T 160 mm bore bismuth strontium calcium copper oxide HTS magnet with shielded gradient coils suitable for use in small animal imaging applications. The magnet is cooled to approximately 16 K using a two-stage cryocooler and is operated at 200 A. The magnet has been passively shimmed so as to achieve ±10 parts per million (ppm) homogeneity over a 60 mm diameter imaging volume. We have demonstrated that B 0 temporal stability is fit-for-purpose despite the magnet operating in the driven mode. The system has produced good quality spin-echo and gradient echo images. This compact HTS-MRI system is emerging as a true alternative to conventional low temperature superconductor based cryogen-free MRI systems, with much more efficient cryogenics since it operates entirely from a single phase alternating current electrical supply.

Compact and lightweight support platform with electromagnetic disturbance elimination for interferometer on reversed field pinch Keda Torus eXperiment

NASA Astrophysics Data System (ADS)

Mao, Wenzhe; Yuan, Peng; Zheng, Jian; Ding, Weixing; Li, Hong; Lan, Tao; Liu, Adi; Liu, Wandong; Xie, Jinlin

2016-11-01

A compact and lightweight support platform has been used as a holder for the interferometer system on the Keda Torus eXperiment (KTX), which is a reversed field pinch device. The vibration caused by the interaction between the time-varying magnetic field and the induced current driven in the metal optical components has been measured and, following comparison with the mechanical vibration of the KTX device and the refraction effect of the ambient turbulent air flow, has been identified as the primary vibration source in this case. To eliminate this electromagnetic disturbance, nonmetallic epoxy resin has been selected as the material for the support platform and the commercially available metal optical mounts are replaced. Following these optimization steps and mechanical reinforcements, the stability of the interferometer platform has improved significantly. The phase shift caused by the vibration has been reduced to the level of background noise.

Analysis of compaction shock interactions during DDT of low density HMX

NASA Astrophysics Data System (ADS)

Rao, Pratap T.; Gonthier, Keith A.

2017-01-01

Deflagration-to-Detonation Transition (DDT) in confined, low density granular HMX occurs by a complex mechanism that involves compaction shock interactions within the material. Piston driven DDT experiments indicate that detonation is abruptly triggered by the interaction of a strong combustion-supported secondary shock and a piston-supported primary (input) shock, where the nature of the interaction depends on initial packing density and primary shock strength. These interactions influence transition by affecting dissipative heating within the microstructure during pore collapse. Inert meso-scale simulations of successive shock loading of low density HMX are performed to examine how dissipation and hot-spot formation are affected by the initial density, and the primary and secondary shock strengths. This information is used to formulate an ignition and burn model for low density HMX that accounts for the effect of shock densensitization on burn. Preliminary DDT predictions are presented that illustrate how primary shock strength affects the transition mechanism.

Molecular interactions and residues involved in force generation in the T4 viral DNA packaging motor.

PubMed

Migliori, Amy D; Smith, Douglas E; Arya, Gaurav

2014-12-12

Many viruses utilize molecular motors to package their genomes into preformed capsids. A striking feature of these motors is their ability to generate large forces to drive DNA translocation against entropic, electrostatic, and bending forces resisting DNA confinement. A model based on recently resolved structures of the bacteriophage T4 motor protein gp17 suggests that this motor generates large forces by undergoing a conformational change from an extended to a compact state. This transition is proposed to be driven by electrostatic interactions between complementarily charged residues across the interface between the N- and C-terminal domains of gp17. Here we use atomistic molecular dynamics simulations to investigate in detail the molecular interactions and residues involved in such a compaction transition of gp17. We find that although electrostatic interactions between charged residues contribute significantly to the overall free energy change of compaction, interactions mediated by the uncharged residues are equally if not more important. We identify five charged residues and six uncharged residues at the interface that play a dominant role in the compaction transition and also reveal salt bridging, van der Waals, and solvent hydrogen-bonding interactions mediated by these residues in stabilizing the compact form of gp17. The formation of a salt bridge between Glu309 and Arg494 is found to be particularly crucial, consistent with experiments showing complete abrogation in packaging upon Glu309Lys mutation. The computed contributions of several other residues are also found to correlate well with single-molecule measurements of impairments in DNA translocation activity caused by site-directed mutations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Uncooled 17 μm ¼ VGA IRFPA development for compact and low power systems

NASA Astrophysics Data System (ADS)

Robert, P.; Tissot, J.; Pochic, D.; Gravot, V.; Bonnaire, F.; Clerambault, H.; Durand, A.; Tinnes, S.

2012-11-01

The high level of accumulated expertise by ULIS and CEA/LETI on uncooled microbolometers made from amorphous silicon enables ULIS to develop ¼ VGA IRFPA formats with 17μm pixel-pitch to enable the development of small power, small weight (SWAP) and high performance IR systems. ROIC architecture will be described where innovations are widely on-chip implemented to enable an easier operation by the user. The detector configuration (integration time, windowing, gain, scanning direction…), is driven by a standard I²C link. Like most of the visible arrays, the detector adopts the HSYNC/VSYNC free-run mode of operation driven with only one master clock (MC) supplied to the ROIC which feeds back pixel, line and frame synchronizations. On-chip PROM memory for customer operational condition storage is available for detector characteristics. Low power consumption has been taken into account and less than 60 mW is possible in analog mode at 60 Hz and < 175 mW in digital mode (14 bits). A wide electrical dynamic range (2.4V) is maintained despite the use of advanced CMOS node. The specific appeal of this unit lies in the high uniformity and easy operation it provides. The reduction of the pixel-pitch turns this TEC-less ¼ VGA array into a product well adapted for high resolution and compact systems. NETD of 35 mK and thermal time constant of 10 ms have been measured leading to 350 mK.ms figure of merit. We insist on NETD trade-off with wide thermal dynamic range, as well as the high characteristics uniformity and pixel operability, achieved thanks to the mastering of the amorphous silicon technology coupled with the ROIC design. This technology node associated with advanced packaging technique, paves the way to compact low power system.

Easy to use uncooled ¼ VGA 17 µm FPA development for high performance compact and low-power systems

NASA Astrophysics Data System (ADS)

Robert, P.; Tissot, JL.; Pochic, D.; Gravot, V.; Bonnaire, F.; Clerambault, H.; Durand, A.; Tinnes, S.

2012-06-01

The high level of accumulated expertise by ULIS and CEA/LETI on uncooled microbolometers made from amorphous silicon enables ULIS to develop ¼ VGA IRFPA formats with 17μm pixel-pitch to enable the development of small power, small weight (SWAP) and high performance IR systems. ROIC architecture will be described where innovations are widely on-chip implemented to enable an easier operation by the user. The detector configuration (integration time, windowing, gain, scanning direction...), is driven by a standard I²C link. Like most of the visible arrays, the detector adopts the HSYNC/VSYNC free-run mode of operation driven with only one master clock (MC) supplied to the ROIC which feeds back pixel, line and frame synchronizations. On-chip PROM memory for customer operational condition storage is available for detector characteristics. Low power consumption has been taken into account and less than 60 mW is possible in analog mode at 60 Hz and < 175 mW in digital mode (14 bits). A wide electrical dynamic range (2.4V) is maintained despite the use of advanced CMOS node. The specific appeal of this unit lies in the high uniformity and easy operation it provides. The reduction of the pixel-pitch turns this TEC-less ¼ VGA array into a product well adapted for high resolution and compact systems. NETD of 35 mK and thermal time constant of 10 ms have been measured leading to 350 mK.ms figure of merit. We insist on NETD trade-off with wide thermal dynamic range, as well as the high characteristics uniformity and pixel operability, achieved thanks to the mastering of the amorphous silicon technology coupled with the ROIC design. This technology node associated with advanced packaging technique, paves the way to compact low power system.

Extremely compact secondary mirror unit for the SOFIA Telescope capable of 6-degree-of-freedom alignment plus chopping

NASA Astrophysics Data System (ADS)

Zago, Lorenzo; Genequand, Pierre M.; Moerschell, Joseph

1998-08-01

SOFIA is a 2.5-m telescope to be carried on a special Boeing 747 for airborne observations at about 15'000 m. The paper describes the main features of the secondary mirror unit. The SOFIA secondary mirror needs active control for alignment along five degrees of freedom as well as for very fast chopping with a frequency up to 20 Hz. Moreover the general optical concept and the housing of the telescope inside a Boeing 747 have required the design of a very compact mechanism: indeed while the secondary mirror has a diameter of 350 mm the entire height of the secondary mirror unit (including the mirror) cannot be greater than 300 mm, which makes the SOFIA design much more compact than any other similar project. The objective is achieved by a very tight integration between a novel hexapod mechanism, in charge of tilt offsets and alignment along 3 axes, and a fast chopping mechanism based on advanced flexure structure technology. In the hexapod mechanism (which is in fact capable of 6-dof), the six linear actuators are arranged in an original geometry in order to leave as much space as possible to the overlying chopping system. Also, the actuators' `hinges' are here materialized by flexure elements. Three motorized levers are linked by flexure elements to the mirror isostatic interface as well as to a reaction ring for compensating angular momentum, which is mechanically driven together with the mirror. This a major difference from other designs (e.g. Keck or VLT) where the compensation mass is driven and controlled separately. The SOFIA solution obtains thus various advantages in term of used volume and has a simpler control system. Various details of the chopping mechanism are provided in the paper. Simulation preliminary results are also given.

Advanced processing methods to introduce and preserve dipole orientation in organic electro-optic materials for next generation photonic devices

NASA Astrophysics Data System (ADS)

Huang, Su

Organic electro-optic (E-O) materials have attracted considerable research attention in the past 20 years due to their rising potentials in a lot of novel photonic applications, such as high-speed telecommunication, terahertz generation and ultra-fast optical interconnections. Chapter 2 of this dissertation focuses on a barrier layer approach to improve the poling efficiency of electro-optic polymers. First of all, high conduction current from excessive charge injection is identified as a fundamental challenge of effective poling. After analyzing the conduction mechanism, we introduce a sol-gel derived thin titanium dioxide (TiO2) layer that can significantly block excessive charge injection and reduce the leakage current during high field poling. Ultralarge E-O coefficients, up to 160-350 pm/V at 1310 nm have been achieved by poling with such a barrier, which are 26%-40% higher than the results poled without such a TiO2 layer. This enhancement is explained by the suppressed charge injection and space charge accumulation by the insertion of the high injection barrier from the TiO2 barrier layer. In Chapter 3, the impact of the inserted barrier layer on the temporal alignment stability of E-O polymers is discussed. Considerable stability enhancement is confirmed using both standard 500-hour temporal alignment stability test at 85 °C and thermally stimulated discharge method. We suggest that the enhancement comes from improved stability of the screening charge. During poling the additional barrier layer helps to lower the injection and thus the space charge accumulation. And this reduced space charge accumulation further helps to replace the space charge part in the total formulation of screening charge with more stable interface trapped charge. We thus expand this knowledge to a group of other materials that can also block excessive charge injection and suppressed space charge accumulation, including dielectric polymers polyvinyl alcohol (PVA), poly(4-vinylphenol) (PVP) and TOPAS as well as ferroelectric polymer poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE), 65/35 copolymer), which differ largely from the others in dielectric constant, conductivity and surface properties. The only common feature of them is that they all lowered the charge injection and leakage current for 1-2 orders during poling. On every buffer layer we tried, similar trend of stability enhancement is found. These results suggest that the observed temporal stability enhancement is indeed an effect from the abovementioned mechanism. Chapter 4 focuses on the development of an innovative new poling method, which utilizes pyroelectric effect instead of external power sources to overcome the limitations of conventional contact poling and corona poling. With careful theory assisted design, we developed a reliable protocol to efficiently introduce dipole orientation in organic E-O materials by heating and cooling them with detachable pyroelectric crystals. This new method can potentially improve the process adaptability of organic E-O materials in a variety of photonic devices. Large Pockels coefficients (up to 81 pm/V at 1.3 micron) have been successfully achieved in thin films poled using this method. The effective fields in these experiments are estimated to be around 0.5 to 0.9 MV/cm, which agree well with the electrostatics analysis using an idealized model. The same method is directly applied to surface modified hybrid polymer silicon slot waveguide ring-resonator modulators devices. A 25 pm/V tunability of resonance peak wavelength shift has been realized, which was higher than any reported results in similar devices. Chapter 5 discusses about the possible application of the pyroelectric poling in a multi-stack waveguide device architecture. A long-existing challenge to pole E-O polymer based photonic devices is how to effectively drop the poling voltage to the core layer, which is usually sandwiched between two dielectric claddings. In the past, this was done by using relatively conductive claddings, which on the other hand can bring larger optical loss and dielectric loss to the waveguide. Thus careful engineering compromise must be made between better poling efficiency and lower loss. Pyroelectric poling as discussed in Chapter 4 opens up new possibilities. In this chapter, it is demonstrated that E-O polymer films can be poled even with 3 orders thicker dielectric layer in circuit using pyroelectric poling. The theoretical analysis matches well with the experimental results. (Abstract shortened by UMI.).

Uniform rotating field network structure to efficiently package a magnetic bubble domain memory

NASA Technical Reports Server (NTRS)

Murray, Glen W. (Inventor); Chen, Thomas T. (Inventor); Wolfshagen, Ronald G. (Inventor); Ypma, John E. (Inventor)

1978-01-01

A unique and compact open coil rotating magnetic field network structure to efficiently package an array of bubble domain devices is disclosed. The field network has a configuration which effectively enables selected bubble domain devices from the array to be driven in a vertical magnetic field and in an independent and uniform horizontal rotating magnetic field. The field network is suitably adapted to minimize undesirable inductance effects, improve capabilities of heat dissipation, and facilitate repair or replacement of a bubble device.

High-Energy Laser for Detection, Inspection, and Non-Destructive Testing

DTIC Science & Technology

2011-03-21

at the gra odes. The -2 at 0.1 Hz -cm-2, and mage thre n array of beam. Th burns on pled to a to measur laser is eq micron lev ent beam ( rget...project or resulting research?  Defense Threat Reduction Agency, “Compact Source of Laser -Driven Monoenergetic Gamma-Rays” --$2,982,685... LASER FOR DETECTION, INSPECTION, AND NON-DESTRUCTIVE TESTING 3) Grant/Contract Number: FA9550-07-1-0521 4) Reporting Period Start: 06/21/2007

SP-100 flight qualification testing assessment

NASA Technical Reports Server (NTRS)

Jeanmougin, Nanette M.; Moore, Roger M.; Wait, David L.; Jacox, Michael G.

1988-01-01

The SP-100 is a compact space power system driven by a nuclear reactor that provides 100 kWe to the user at 200 VDC. The thermal energy generated by the nuclear reactor is converted into electrical energy by passive thermoelectric devices. Various options for tailoring the MIL-STD-1540B guidelines to the SP-100 nuclear power system are discussed. This study aids in selecting the appropriate qualification test program based on the cost, schedule, and test effectiveness of the various options.

Electromagnetically driven radiative shocks and their measurements

NASA Astrophysics Data System (ADS)

Kondo, K.; Nakajima, M.; Kawamura, T.; Horioka, K.

2006-06-01

Experimental results on a generation of strong shocks in a compact pulse power device are reported. To make a strong and plain shock wave, electrodes are tapered and an acrylic guiding tube is located on the top of the electrodes. It drives a quasi-one-dimensional strong shock in the guiding tube. When the front speed is more than the critical speed Drad, an interesting structure is confirmed at the shock front, which indicate a phenomenon proceeded by the radiative transport.

A 300 GHz collective scattering diagnostic for low temperature plasmas.

PubMed

Hardin, Robert A; Scime, Earl E; Heard, John

2008-10-01

A compact and portable 300 GHz collective scattering diagnostic employing a homodyne detection scheme has been constructed and installed on the hot helicon experiment (HELIX). Verification of the homodyne detection scheme was accomplished with a rotating grooved aluminum wheel to Doppler shift the interaction beam. The HELIX chamber geometry and collection optics allow measurement of scattering angles ranging from 60 degrees to 90 degrees. Artificially driven ion-acoustic waves are also being investigated as a proof-of-principle test for the diagnostic system.

Novel infrared detector based on a tunneling displacement transducer

NASA Technical Reports Server (NTRS)

Kenny, T. W.; Kaiser, W. J.; Waltman, S. B.; Reynolds, J. K.

1991-01-01

The paper describes the design, fabrication, and characteristics of a novel infrared detector based on the principle of Golay's (1947) pneumatic infrared detector, which uses the expansion of a gas to detect infrared radiation. The present detector is constructed entirely from micromachined silicon and uses an electron tunneling displacement transducer for the detection of gas expansion. The sensitivity of the new detector is competitive with the best commercial pyroelectric sensors and can be readily improved by an order of magnitude through the use of an optimized transducer.

Portable wireless power transmission system for video capsule endoscopy.

PubMed

Zhiwei, Jia; Guozheng, Yan; Bingquan, Zhu

2014-10-01

Wireless power transmission is considered a practical way of overcoming the power shortage of wireless capsule endoscopy (VCE). However, most patients cannot tolerate the long hours of lying in a fixed transmitting coil during diagnosis. To develop a portable wireless power transmission system for VCE, a compact transmitting coil and a portable inverter circuit driven by rechargeable batteries are proposed. The couple coils, optimized considering the stability and safety conditions, are 28 turns of transmitting coil and six strands of receiving coil. The driven circuit is designed according to the portable principle. Experiments show that the integrated system could continuously supply power to a dual-head VCE for more than 8 h at a frame rate of 30 frames per second with resolution of 320 × 240. The portable VCE exhibits potential for clinical applications, but requires further improvement and tests.

Modeling of Heat and Mass Transfer in a TEC-Driven Lyophilizer

NASA Technical Reports Server (NTRS)

Yuan, Zeng-Guang; Hegde, Uday; Litwiller, Eric; Flynn, Michael; Fisher, John

2006-01-01

Dewatering of wet waste during space exploration missions is important for crew safety as it stabilizes the waste. It may also be used to recover water and serve as a preconditioning step for waste compaction. A thermoelectric cooler (TEC)-driven lyophilizer is under development at NASA Ames Research Center for this purpose. It has three major components: (i) an evaporator section where water vapor sublimes from the frozen waste, (ii) a condenser section where this water vapor deposits as ice, and (iii) a TEC section which serves as a heat pump to transfer heat from the condenser to the evaporator. This paper analyses the heat and mass transfer processes in the lyophilizer in an effort to understand the ice formation behavior in the condenser. The analysis is supported by experimental observations of ice formation patterns in two different condenser units.

Portable radiography system using a relativistic electron beam

DOEpatents

Hoeberling, Robert F.

1990-01-01

A portable radiographic generator is provided with an explosive magnetic flux compression generator producing the high voltage necessary to generate a relativistic electron beam. The relativistic electron beam is provided with target materials which generates the desired radiographic pulse. The magnetic flux compression generator may require at least two conventional explosively driven generators in series to obtain a desired output voltage of at least 1 MV. The cathode and anode configuration of the diode are selected to provide a switching action wherein a high impedance load is presented to the magnetic flux compression generator when the high voltage is being generated, and thereafter switching to a low impedance load to generate the relativistic electron beam. Magnetic flux compression generators can be explosively driven and provided in a relatively compact, portable form for use with the relativistic x-ray equipment.

Portable radiography system using a relativistic electron beam

DOEpatents

Hoeberling, R.F.

1987-09-22

A portable radiographic generator is provided with an explosive magnetic flux compression generator producing the high voltage necessary to generate a relativistic electron beam. The relativistic electron beam is provided with target materials which generates the desired radiographic pulse. The magnetic flux compression generator may require at least two conventional explosively driven generators in series to obtain a desired output voltage of at least 1 MV. The cathode and anode configuration of the diode are selected to provide a switching action wherein a high impedance load is presented to the magnetic flux compression generator when the high voltage is being generated, and thereafter switching to a low impedance load to generate the relativistic electron beam. Magnetic flux compression generators can be explosively driven and provided in a relatively compact, portable form for use with the relativistic x-ray equipment. 8 figs.

Multimodal tuned dynamic absorber for split Stirling linear cryocooler

NASA Astrophysics Data System (ADS)

Veprik, A.; Tuito, A.

2017-02-01

Forthcoming low size, weight, power and price split Stirling linear cryocoolers may rely on electro-dynamically driven single-piston compressors and pneumatically driven expanders interconnected by the configurable transfer line. For compactness, compressor and expander units may be placed in a side-by-side manner, thus producing tonal vibration export comprising force and moment components. In vibration sensitive applications, this may result in excessive angular line of sight jitter and translational defocusing affecting the image quality. The authors present Multimodal Tuned Dynamic Absorber (MTDA), having one translational and two tilting modes essentially tuned to the driving frequency. The dynamic reactions (force and moment) produced by such a MTDA are simultaneously counterbalancing force and moment vibration export produced by the cryocooler. The authors reveal the design details, the method of fine modal tuning and outcomes of numerical simulation on attainable performance.

Multiple reinjections and crystal mush compaction in the solidification evolution of the Karaj Dam basement Sill, Northern Iran

NASA Astrophysics Data System (ADS)

Maghdour-Mashhour, Reza; Shabani, Amir Ali Tabbakh

2017-07-01

The Karaj Dam basement Sill is a 460 m-thick saucer shaped sill, situated in the Alborz Magmatic Belt, Northern Iran. The results of geochemical, textural and field relations reveal characteristics of a sill with a well-developed S-shaped compositional profile which could be subdivided into distinct parts and suggest that the sill was repeatedly split and reinjected with fresh magma in the upper half of the previous emplacements (over- to partly intra-accretion). Whole rock and mineral compositional profiles have recorded five to six discrete injections of magma, each of which individually show an upward increase in terms of primitivity which represents partial crystallization in feeder conduits. The first three small successive pulses of magma, emplaced in the basal 150 m of the floor sequence, were followed by voluminous fourth and fifth pulses in the upper portion of the sill. During final two pulses the system acts as a closed system for each independently, and evolves through compositional convection or compaction aided in-situ crystallization. Theoretical models for convection and compaction shows the significance of both processes. Considering the final porosity of 0.1 < φ < 0.45, calculated convective velocities (0.2 < Vc < 227 m/year) are higher than the calculated crystal accumulation rate of the basal 150 m and upper portion of the sill (Va = 1 and 0.1 m/year), when the crystal mush varies between 1 to 0.01 m with the liquid viscosity ranging from 85 to 15 Pa·s. Our calculations further indicate that compaction driven velocity of liquid expulsion (ω - w) hardly exceeds the Va in the basal 150 m of the floor sequence. The highest velocity is reached (ω - w = 1 m/year) only if the crystal mush thickness is no less than 240 m with the porosity of 0.6 and the liquid viscosity of no more than 15 Pa·s. On the other hand, compaction is highly effective in the upper portion of the sill. Transfer of residual liquid from the compacting lower solidification front to the dilating upper solidification front resulted in characteristic chemical and mineralogical effects, such as the depletion of the lower half of the sill and the enrichment of the sandwich zone in incompatible elements and modal granophyre. Crystallization of the fourth pulse of magma produced a peak in incompatible clement concentrations at a sandwich horizon located at the 410 m level, where the floor and roof of the sill appeared to converge at this stage. Subsequent to the time of this enriched zone crystallizing, the fifth pulse of magma was emplaced near this level and inflated the chamber vertically for 200 m. Cumulus material containing interstitial melt and subsequent buoyancy driven upward transport of interstitial melt in this pulse concentrated incompatible elements at 47 m below the main peak, at the stratigraphic height of 360-370 m. The boundaries between the successive pulses were cryptic and represent a gradational contact in terms of grain size, chemical composition and crystallization sequence. This implies a short time interval between the emplacements of the magma. This sill is comparable with Antarctica Beacon Sill and Hudson River Palisades Sill, and the recognition of evidence for reinjection and compaction in these macroscopically uniform sills, as well as the Karaj Dam basement Sill, suggests that these processes may be common in the construction of sills with a thickness of more than 100 m.

Quasistationary magnetic field generation with a laser-driven capacitor-coil assembly.

PubMed

Tikhonchuk, V T; Bailly-Grandvaux, M; Santos, J J; Poyé, A

2017-08-01

Recent experiments are showing possibilities to generate strong magnetic fields on the excess of 500 T with high-energy nanosecond laser pulses in a compact setup of a capacitor connected to a single turn coil. Hot electrons ejected from the capacitor plate (cathode) are collected at the other plate (anode), thus providing the source of a current in the coil. However, the physical processes leading to generation of currents exceeding hundreds of kiloamperes in such a laser-driven diode are not sufficiently understood. Here we present a critical analysis of previous results and propose a self-consistent model for the high current generation in a laser-driven capacitor-coil assembly. It accounts for three major effects controlling the diode current: the space charge neutralization, the plasma magnetization between the capacitor plates, and the Ohmic heating of the external circuit-the coil-shaped connecting wire. The model provides the conditions necessary for transporting strongly super-Alfvenic currents through the diode on the time scale of a few nanoseconds. The model validity is confirmed by a comparison with the available experimental data.

Dense blocks of energetic ions driven by multi-petawatt lasers

PubMed Central

Weng, S. M.; Liu, M.; Sheng, Z. M.; Murakami, M.; Chen, M.; Yu, L. L.; Zhang, J.

2016-01-01

Laser-driven ion accelerators have the advantages of compact size, high density, and short bunch duration over conventional accelerators. Nevertheless, it is still challenging to simultaneously enhance the yield and quality of laser-driven ion beams for practical applications. Here we propose a scheme to address this challenge via the use of emerging multi-petawatt lasers and a density-modulated target. The density-modulated target permits its ions to be uniformly accelerated as a dense block by laser radiation pressure. In addition, the beam quality of the accelerated ions is remarkably improved by embedding the target in a thick enough substrate, which suppresses hot electron refluxing and thus alleviates plasma heating. Particle-in-cell simulations demonstrate that almost all ions in a solid-density plasma of a few microns can be uniformly accelerated to about 25% of the speed of light by a laser pulse at an intensity around 1022 W/cm2. The resulting dense block of energetic ions may drive fusion ignition and more generally create matter with unprecedented high energy density. PMID:26924793

Electronic band-gap modified passive silicon optical modulator at telecommunications wavelengths.

PubMed

Zhang, Rui; Yu, Haohai; Zhang, Huaijin; Liu, Xiangdong; Lu, Qingming; Wang, Jiyang

2015-11-13

The silicon optical modulator is considered to be the workhorse of a revolution in communications. In recent years, the capabilities of externally driven active silicon optical modulators have dramatically improved. Self-driven passive modulators, especially passive silicon modulators, possess advantages in compactness, integration, low-cost, etc. Constrained by a large indirect band-gap and sensitivity-related loss, the passive silicon optical modulator is scarce and has been not advancing, especially at telecommunications wavelengths. Here, a passive silicon optical modulator is fabricated by introducing an impurity band in the electronic band-gap, and its nonlinear optics and applications in the telecommunications-wavelength lasers are investigated. The saturable absorption properties at the wavelength of 1.55 μm was measured and indicates that the sample is quite sensitive to light intensity and has negligible absorption loss. With a passive silicon modulator, pulsed lasers were constructed at wavelengths at 1.34 and 1.42 μm. It is concluded that the sensitive self-driven passive silicon optical modulator is a viable candidate for photonics applications out to 2.5 μm.

Design of an electron-accelerator-driven compact neutron source for non-destructive assay

NASA Astrophysics Data System (ADS)

Murata, A.; Ikeda, S.; Hayashizaki, N.

2017-09-01

The threat of nuclear and radiological terrorism remains one of the greatest challenges to international security, and the threat is constantly evolving. In order to prevent nuclear terrorism, it is important to avoid unlawful import of nuclear materials, such as uranium and plutonium. Development of technologies for non-destructive measurement, detection and recognition of nuclear materials is essential for control at national borders. At Tokyo Institute of Technology, a compact neutron source system driven by an electron-accelerator has been designed for non-destructive assay (NDA). This system is composed of a combination of an S-band (2.856 GHz) RF-gun, a tungsten target to produce photons by bremsstrahlung, a beryllium target, which is suitable for use in generating neutrons because of the low threshold energy of photonuclear reactions, and a moderator to thermalize the fast neutrons. The advantage of this system can accelerate a short pulse beam with a pulse width less than 1 μs which is difficult to produce by neutron generators. The amounts of photons and neutron produced by electron beams were simulated using the Monte Carlo simulation code PHITS 2.82. When the RF-gun is operated with an average electron beam current of 0.1 mA, it is expected that the neutron intensities are 1.19 × 109 n/s and 9.94 × 109 n/s for incident electron beam energies of 5 MeV and 10 MeV, respectively.

Towards ion beam therapy based on laser plasma accelerators.

PubMed

Karsch, Leonhard; Beyreuther, Elke; Enghardt, Wolfgang; Gotz, Malte; Masood, Umar; Schramm, Ulrich; Zeil, Karl; Pawelke, Jörg

2017-11-01

Only few ten radiotherapy facilities worldwide provide ion beams, in spite of their physical advantage of better achievable tumor conformity of the dose compared to conventional photon beams. Since, mainly the large size and high costs hinder their wider spread, great efforts are ongoing to develop more compact ion therapy facilities. One promising approach for smaller facilities is the acceleration of ions on micrometre scale by high intensity lasers. Laser accelerators deliver pulsed beams with a low pulse repetition rate, but a high number of ions per pulse, broad energy spectra and high divergences. A clinical use of a laser based ion beam facility requires not only a laser accelerator providing beams of therapeutic quality, but also new approaches for beam transport, dosimetric control and tumor conformal dose delivery procedure together with the knowledge of the radiobiological effectiveness of laser-driven beams. Over the last decade research was mainly focused on protons and progress was achieved in all important challenges. Although currently the maximum proton energy is not yet high enough for patient irradiation, suggestions and solutions have been reported for compact beam transport and dose delivery procedures, respectively, as well as for precise dosimetric control. Radiobiological in vitro and in vivo studies show no indications of an altered biological effectiveness of laser-driven beams. Laser based facilities will hardly improve the availability of ion beams for patient treatment in the next decade. Nevertheless, there are possibilities for a need of laser based therapy facilities in future.

Development of 3-dimensional compact magnetic dosimeter for environmental magnetic field monitoring

NASA Astrophysics Data System (ADS)

Kubota, Yusuke; Obayashi, Haruo; Miyahara, Akira; Ohno, Kazuko; Nakamura, Kouichi; Horii, Kenzi

1991-07-01

A computer-driven, three-dimensional magnetic fluxmeter to be used for magnetic field dosimetry has been developed. A magnetic monitor applicable to this object should be measurable to an absolute value of local magnetic field strength and also be able to record its time integration as a measure of exposed dose to the magnetic field. The present fluxmeter consists of signal amplifiers, rectifiers, an A/D converter, and a pocket computer (PC). The signal outputs from the sensors are processed with the PC to compose an absolute strength of magnetic flux density and its time-integrated value. The whole system is driven by a battery and is quite compact in size to be used as a handy portable system. Further details of the design, idea, construction, specification, and testing result of the fluxmeter are described. The measurable range are from 0.4G to 20,000G in normal mode and 8mG to 400G in high-sensitivity AC mode, and the sensitivity is well independent of the magnetic field direction. These measured data are displayed in real time on the LCD panel of the PC and memorized in RAM files. Possible application of the fluxmeter is discussed with special attention to the search of the leakage and/or disturbing error fields around LHD (Large Helical Device) and other magnetic systems, the individual dose control to the workers in strong magnetic fields, and the evaluation of the effects of long irradiation of magnetic fields.

Reaction Rate of Ti0.18Zr0.84Cr1.0Fe0.7Mn0.3Cu0.057 to Use for the Heat Driven Type Compact Metal Hydride Refrigerator

NASA Astrophysics Data System (ADS)

Bae, Sang-Chul; Katsuta, Masafumi

Our final goal of this study is to develop the heat driven type compact metal hydride (MH) refrigeration system for the vending machine and the show case, and to attain a refrigeration temperature of 243 K by using a heat source of about 423K. The reaction rate of the MH to use for the heat source, MH used for heat source is studied firstly because the MH refrigeration system consists of two MHs, one is used for the heat source and the other is used for the cooling load extracting. As for the reaction rate in the hydriding process, initially, a rapid surface reaction, governed by the relation 1-(1-F )1/3=kht . After the MH surface has been covered by hydride, the reaction becomes diffusion controlled with the relation 1-3(1-F ' )2/3+2(1-F ' )=k'ht . The reaction rates, kh and k'h , are exponentially proportional to the pressure difference and increase with temperature. And, as for the dehydriding process, it is found out that the rate-controlling step is uniquely diffusion reaction. The dehydriding reaction rate is exponentially proportional to the pressure difference and the initial reacted fraction, and increases with temperature. Finally, on the basis of these experimental results, the brand new rate correlations are reasonably derived. The predicted results for this correlation are in successfully agreement with the experimental ones.

High-resolution μCT of a mouse embryo using a compact laser-driven X-ray betatron source.

PubMed

Cole, Jason M; Symes, Daniel R; Lopes, Nelson C; Wood, Jonathan C; Poder, Kristjan; Alatabi, Saleh; Botchway, Stanley W; Foster, Peta S; Gratton, Sarah; Johnson, Sara; Kamperidis, Christos; Kononenko, Olena; De Lazzari, Michael; Palmer, Charlotte A J; Rusby, Dean; Sanderson, Jeremy; Sandholzer, Michael; Sarri, Gianluca; Szoke-Kovacs, Zsombor; Teboul, Lydia; Thompson, James M; Warwick, Jonathan R; Westerberg, Henrik; Hill, Mark A; Norris, Dominic P; Mangles, Stuart P D; Najmudin, Zulfikar

2018-06-19

In the field of X-ray microcomputed tomography (μCT) there is a growing need to reduce acquisition times at high spatial resolution (approximate micrometers) to facilitate in vivo and high-throughput operations. The state of the art represented by synchrotron light sources is not practical for certain applications, and therefore the development of high-brightness laboratory-scale sources is crucial. We present here imaging of a fixed embryonic mouse sample using a compact laser-plasma-based X-ray light source and compare the results to images obtained using a commercial X-ray μCT scanner. The radiation is generated by the betatron motion of electrons inside a dilute and transient plasma, which circumvents the flux limitations imposed by the solid or liquid anodes used in conventional electron-impact X-ray tubes. This X-ray source is pulsed (duration <30 fs), bright (>10 10 photons per pulse), small (diameter <1 μm), and has a critical energy >15 keV. Stable X-ray performance enabled tomographic imaging of equivalent quality to that of the μCT scanner, an important confirmation of the suitability of the laser-driven source for applications. The X-ray flux achievable with this approach scales with the laser repetition rate without compromising the source size, which will allow the recording of high-resolution μCT scans in minutes. Copyright © 2018 the Author(s). Published by PNAS.

Developing a compact toroid injector in the ThermoElectric driven Liquid metal plasma facing Structures device

NASA Astrophysics Data System (ADS)

Christenson, Michael; Szott, Matthew; Kalathiparambil, Kishor; Sovinec, Carl; Ruzic, David

2016-10-01

The ThermoElectric-driven Liquid-metal plasma-facing Structures (TELS) device at the University of Illinois is a theta-pinched, plasma-material interaction test stand used to simulate extreme events in the edge and divertor regions of a tokamak plasma. Previous measurements of the electron and ion temperatures have shown that the isotropic heat load on target ranges between 0.1 and 0.2 MJ m-2 over a pulse lasting 0.2 ms. While this compares well to the heat loads from Type 1 ELMs in larger toroidal devices, it is still much less than the energy deposition from Type 1 ELMs expected in ITER, which are in excess of 1 MJ m-2. To this end, a compact toroid (CT) injector has been proposed as a modification to the existing TELS device. By using an externally applied bias field to force reconnection at the muzzle of the coaxial plasma accelerator source that drives ionization, NIMROD MHD simulations have shown a peak magnetic flux of 3.5 mWb is reached 0.025 ms into the pulse - more than sufficient to form a CT. Early calorimetry and magnetic field measurements indicate that a new plasma structure has been formed in the magnetized coaxial plasma source. This work presents the current results of CT generation with respect to the bias field strength as well as the coaxial source geometry. DOE OFES DE-SC0008587, DE-SC0008658, DE-FG02-99ER54515.

Compact quasi-monoenergetic photon sources from laser-plasma accelerators for nuclear detection and characterization

NASA Astrophysics Data System (ADS)

Geddes, Cameron G. R.; Rykovanov, Sergey; Matlis, Nicholas H.; Steinke, Sven; Vay, Jean-Luc; Esarey, Eric H.; Ludewigt, Bernhard; Nakamura, Kei; Quiter, Brian J.; Schroeder, Carl B.; Toth, Csaba; Leemans, Wim P.

2015-05-01

Near-monoenergetic photon sources at MeV energies offer improved sensitivity at greatly reduced dose for active interrogation, and new capabilities in treaty verification, nondestructive assay of spent nuclear fuel and emergency response. Thomson (also referred to as Compton) scattering sources are an established method to produce appropriate photon beams. Applications are however restricted by the size of the required high-energy electron linac, scattering (photon production) system, and shielding for disposal of the high energy electron beam. Laser-plasma accelerators (LPAs) produce GeV electron beams in centimeters, using the plasma wave driven by the radiation pressure of an intense laser. Recent LPA experiments are presented which have greatly improved beam quality and efficiency, rendering them appropriate for compact high-quality photon sources based on Thomson scattering. Designs for MeV photon sources utilizing the unique properties of LPAs are presented. It is shown that control of the scattering laser, including plasma guiding, can increase photon production efficiency. This reduces scattering laser size and/or electron beam current requirements to scale compatible with the LPA. Lastly, the plasma structure can decelerate the electron beam after photon production, reducing the size of shielding required for beam disposal. Together, these techniques provide a path to a compact photon source system.

Sample-to-answer palm-sized nucleic acid testing device towards low-cost malaria mass screening.

PubMed

Choi, Gihoon; Prince, Theodore; Miao, Jun; Cui, Liwang; Guan, Weihua

2018-05-19

The effectiveness of malaria screening and treatment highly depends on the low-cost access to the highly sensitive and specific malaria test. We report a real-time fluorescence nucleic acid testing device for malaria field detection with automated and scalable sample preparation capability. The device consists a compact analyzer and a disposable microfluidic reagent compact disc. The parasite DNA sample preparation and subsequent real-time LAMP detection were seamlessly integrated on a single microfluidic compact disc, driven by energy efficient non-centrifuge based magnetic field interactions. Each disc contains four parallel testing units which could be configured either as four identical tests or as four species-specific tests. When configured as species-specific tests, it could identify two of the most life-threatening malaria species (P. falciparum and P. vivax). The NAT device is capable of processing four samples simultaneously within 50 min turnaround time. It achieves a detection limit of ~0.5 parasites/µl for whole blood, sufficient for detecting asymptomatic parasite carriers. The combination of the sensitivity, specificity, cost, and scalable sample preparation suggests the real-time fluorescence LAMP device could be particularly useful for malaria screening in the field settings. Copyright © 2018 Elsevier B.V. All rights reserved.

Monitoring millimeter wave stray radiation during ECRH operation at ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Schubert, M.; Honecker, F.; Monaco, F.; Schmid-Lorch, D.; Schütz, H.; Stober, J.; Wagner, D.

2012-09-01

Due to imperfection of the single path absorption, ECRH at ASDEX Upgrade (AUG) is always accompanied by stray radiation in the vacuum vessel. New ECRH scenarios with O2 and X3 heating schemes extend the operational space, but they have also the potential to increase the level of stray radiation. There are hazards for invessel components. Damage on electric cables has already been encountered. It is therefore necessary to monitor and control the ECRH with respect to the stray radiation level. At AUG a system of Sniffer antennas equipped with microwave detection diodes is installed. The system is part of the ECRH interlock circuit. We notice, however, that during plasma operation the variations of the Sniffer antenna signal are very large. In laboratory measurements we see variations of up to 20 dB in the directional sensitivity and we conclude that an interference pattern is formed inside the copper sphere of the antenna. When ECRH is in plasma operation at AUG, the plasma is acting as a phase and mode mixer for the millimeter waves and thus the interference pattern inside the sphere changes with the characteristic time of the plasma dynamics. In order to overcome the difficulty of a calibrated measurement of the average stray radiation level, we installed bolometer and pyroelectric detectors, which intrinsically average over interference structures due to their large active area. The bolometer provides a robust calibration but with moderate temporal resolution. The pyroelectric detector provides high sensitivity and a good temporal resolution, but it raises issues of possible signal drifts in long pulses.

The Physics of Local Helicity Injection Non-Solenoidal Tokamak Startup

NASA Astrophysics Data System (ADS)

Redd, A. J.; Barr, J. L.; Bongard, M. W.; Fonck, R. J.; Hinson, E. T.; Jardin, S.

2013-10-01

Non-solenoidal startup via Local Helicity Injection (LHI) uses compact current injectors to produce toroidal plasma current Ip up to 170 kA in the PEGASUS Toroidal Experiment, driven by 4-8 kA injector current on timescales of 5-20 milliseconds. Increasing the Ip buildup duration enables experimental demonstration of plasma position control on timescales relevant for high-current startup. LHI-driven discharges exhibit bursty MHD activity, apparently line-tied kinking of LHI-driven field lines, with the bursts correlating with rapid equilibrium changes, sharp Ip rises, and sharp drops in the injector impedance. Preliminary NIMROD results suggest that helical LHI-driven current channels remain coherent, with Ip increases due to reconnection between adjacent helical turns forming axisymmetric plasmoids, and corresponding sharp drops in the bias circuit impedance. The DC injector impedance is consistent with a space charge limit at low bias current and a magnetic limit at high bias current. Internal measurements show the current density profile starts strongly hollow and rapidly fills in during Ip buildup. Simulations of LHI discharges using the Tokamak Simulation Code (TSC) will provide insight into the detailed current drive mechanism and guide experiments on PEFASUS and NSTX-U. Work supported by US DOE Grants DE-FG02-96ER54375 and DE-SC0006928.

Laser acceleration of quasi-monoenergetic MeV ion beams.

PubMed

Hegelich, B M; Albright, B J; Cobble, J; Flippo, K; Letzring, S; Paffett, M; Ruhl, H; Schreiber, J; Schulze, R K; Fernández, J C

2006-01-26

Acceleration of particles by intense laser-plasma interactions represents a rapidly evolving field of interest, as highlighted by the recent demonstration of laser-driven relativistic beams of monoenergetic electrons. Ultrahigh-intensity lasers can produce accelerating fields of 10 TV m(-1) (1 TV = 10(12) V), surpassing those in conventional accelerators by six orders of magnitude. Laser-driven ions with energies of several MeV per nucleon have also been produced. Such ion beams exhibit unprecedented characteristics--short pulse lengths, high currents and low transverse emittance--but their exponential energy spectra have almost 100% energy spread. This large energy spread, which is a consequence of the experimental conditions used to date, remains the biggest impediment to the wider use of this technology. Here we report the production of quasi-monoenergetic laser-driven C5+ ions with a vastly reduced energy spread of 17%. The ions have a mean energy of 3 MeV per nucleon (full-width at half-maximum approximately 0.5 MeV per nucleon) and a longitudinal emittance of less than 2 x 10(-6) eV s for pulse durations shorter than 1 ps. Such laser-driven, high-current, quasi-monoenergetic ion sources may enable significant advances in the development of compact MeV ion accelerators, new diagnostics, medical physics, inertial confinement fusion and fast ignition.

The Compaction of Ultramafic Cumulates in Layered Intrusions - Time and Length Scales (Invited)

NASA Astrophysics Data System (ADS)

Schmidt, M. W.; Manoochehri, S.

2013-12-01

Many large mafic intrusions have thick series of mostly ultramafic cumulates composed of dense cumulus minerals (chromite, olivine, pyroxenes) precipitated from low viscosity (roughly basaltic) liquids. To understand the time and length scales involved, the crystal settling and compaction process was simulated through centrifuge-assisted experiments of olivine or chromite in basaltic melt. Experiments were performed in a centrifuging piston cylinder at 200-1500 g, 1200-1300 C, 0.5-1.1 GPa on previously annealed and texturally equilibrated samples. The mechanical settling of the dense olivine or chromite suspensions occurs at 1/6 and 1/2 the speed of simple Stokes settling. The porosity (φm ) of orthocumulates resulting from gravitational settling is 50-55 %, pile up times for natural grain sizes result to 0.1-10 m/day. Hence, gravitational deposition (including re-deposition) of crystals may take place within years, i.e. almost instantaneously with progressing crystallization. After (re-)deposition, grains rest on each other. Further (chemical) compaction occurs through pressure dissolution at grain contacts, olivine or chromite re-precipitates where in contact with melt. Concomitantly excess liquid is expulsed from the cumulate layer. Centrifugation let to porosities as low as 30.3 vol% for olivine. The crystal content at the bottom of the experimentally compacted cumulate is 1-φm ~ log(Δρ h a t), where Δρ = crystal-melt density difference, h = crystal layer thickness, a = acceleration and t = time. Compaction is hence proportional to effective stress integrated over time indicating that pressure dissolution is the dominant mechanism. Notably, chromite crystals compact only about half as fast as olivine crystals. The compaction limit, i.e. the lowermost porosity to be reached, is calculated by equating the lithostatic and hydraulic pressure gradients in the cumulate and results to 3-5 % porosity for the experiments. Crystal size distribution curves and a growth exponent n of 3.1(3) (for olivine) indicate that diffusion controlled Ostwald ripening is the dominant crystal growth mechanism. The experimentally calibrated compaction relationship, combined with a linear scaling for grain size as appropriate for reaction-controlled pressure solution creep, allows calculation of formation times of natural adcumulates. A single layer of olivine adcumulate of 1/2 m thickness with 70-75 vol% olivine at the base (as observed in Rhum), would have typical formation times of 0.4-3 yrs for grain sizes of 2-10 mm, comparing favourably with characteristic cooling times of sills. If a >20 m thick series of cumulate layers pressurizes a base layer with the porosity still filled by a melt, then compaction proceeds to the compaction limit within a few years. To understand the thickness of a simultaneously compacting (layered) crystal pile, (paleo)-porosity gradients determined from incompatible trace elements can be employed when combined with modelled characteristic cooling times. In layered mafic intrusions where cumulates are deposited from a large magma chamber, compaction zones of several tens to hundreds of meter may form adcumulates with porosities in the order of 5%. In conclusion, gravitation driven chemical compaction is feasible for dense mafic minerals in basaltic magmas, in particular in large layered intrusions. The limiting factor appears to be rather the supply of crystals then the time necessary for compaction.

A non-linear dimension reduction methodology for generating data-driven stochastic input models

NASA Astrophysics Data System (ADS)

Ganapathysubramanian, Baskar; Zabaras, Nicholas

2008-06-01

Stochastic analysis of random heterogeneous media (polycrystalline materials, porous media, functionally graded materials) provides information of significance only if realistic input models of the topology and property variations are used. This paper proposes a framework to construct such input stochastic models for the topology and thermal diffusivity variations in heterogeneous media using a data-driven strategy. Given a set of microstructure realizations (input samples) generated from given statistical information about the medium topology, the framework constructs a reduced-order stochastic representation of the thermal diffusivity. This problem of constructing a low-dimensional stochastic representation of property variations is analogous to the problem of manifold learning and parametric fitting of hyper-surfaces encountered in image processing and psychology. Denote by M the set of microstructures that satisfy the given experimental statistics. A non-linear dimension reduction strategy is utilized to map M to a low-dimensional region, A. We first show that M is a compact manifold embedded in a high-dimensional input space Rn. An isometric mapping F from M to a low-dimensional, compact, connected set A⊂Rd(d≪n) is constructed. Given only a finite set of samples of the data, the methodology uses arguments from graph theory and differential geometry to construct the isometric transformation F:M→A. Asymptotic convergence of the representation of M by A is shown. This mapping F serves as an accurate, low-dimensional, data-driven representation of the property variations. The reduced-order model of the material topology and thermal diffusivity variations is subsequently used as an input in the solution of stochastic partial differential equations that describe the evolution of dependant variables. A sparse grid collocation strategy (Smolyak algorithm) is utilized to solve these stochastic equations efficiently. We showcase the methodology by constructing low-dimensional input stochastic models to represent thermal diffusivity in two-phase microstructures. This model is used in analyzing the effect of topological variations of two-phase microstructures on the evolution of temperature in heat conduction processes.

Robustness of waves with a high phase velocity

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

Tajima, T., E-mail: ttajima@uci.edu; Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, CA 92688; Necas, A., E-mail: anecas@trialphaenergy.com

Norman Rostoker pioneered research of (1) plasma-driven accelerators and (2) beam-driven fusion reactors. The collective acceleration, coined by Veksler, advocates to drive above-ionization plasma waves by an electron beam to accelerate ions. The research on this, among others, by the Rostoker group incubated the idea that eventually led to the birth of the laser wakefield acceleration (LWFA), by which a large and robust accelerating collective fields may be generated in plasma in which plasma remains robust and undisrupted. Besides the emergence of LWFA, the Rostoker research spawned our lessons learned on the importance of adiabatic acceleration of ions in collectivemore » accelerators, including the recent rebirth in laser-driven ion acceleration efforts in a smooth adiabatic fashion by a variety of ingenious methods. Following Rostoker’s research in (2), the beam-driven Field Reversed Configuration (FRC) has accomplished breakthroughs in recent years. The beam-driven kinetic plasma instabilities have been found to drive the reactivity of deuteron-deuteron fusion beyond the thermonuclear yield in C-2U plasma that Rostoker started. This remarkable result in FRCs as well as the above mentioned LWFA may be understood with the aid of the newly introduced idea of the “robustness hypothesis of waves with a high phase velocity”. It posits that when the wave driven by a particle beam (or laser pulse) has a high phase velocity, its amplitude is high without disrupting the supporting bulk plasma. This hypothesis may guide us into more robust and efficient fusion reactors and more compact accelerators.« less

Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas

PubMed Central

Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald C.; Hamilton, Christopher E.; Santiago, Miguel A.; Kreuzer, Christian; Sefkow, Adam B.; Shah, Rahul C.; Fernández, Juan C.

2015-01-01

Table-top laser–plasma ion accelerators have many exciting applications, many of which require ion beams with simultaneous narrow energy spread and high conversion efficiency. However, achieving these requirements has been elusive. Here we report the experimental demonstration of laser-driven ion beams with narrow energy spread and energies up to 18 MeV per nucleon and ∼5% conversion efficiency (that is 4 J out of 80-J laser). Using computer simulations we identify a self-organizing scheme that reduces the ion energy spread after the laser exits the plasma through persisting self-generated plasma electric (∼1012 V m−1) and magnetic (∼104 T) fields. These results contribute to the development of next generation compact accelerators suitable for many applications such as isochoric heating for ion-fast ignition and producing warm dense matter for basic science. PMID:26657147

Estimation and Analysis of Nonlinear Stochastic Systems. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Marcus, S. I.

1975-01-01

The algebraic and geometric structures of certain classes of nonlinear stochastic systems were exploited in order to obtain useful stability and estimation results. The class of bilinear stochastic systems (or linear systems with multiplicative noise) was discussed. The stochastic stability of bilinear systems driven by colored noise was considered. Approximate methods for obtaining sufficient conditions for the stochastic stability of bilinear systems evolving on general Lie groups were discussed. Two classes of estimation problems involving bilinear systems were considered. It was proved that, for systems described by certain types of Volterra series expansions or by certain bilinear equations evolving on nilpotent or solvable Lie groups, the optimal conditional mean estimator consists of a finite dimensional nonlinear set of equations. The theory of harmonic analysis was used to derive suboptimal estimators for bilinear systems driven by white noise which evolve on compact Lie groups or homogeneous spaces.

Development of hand rehabilitation system for paralysis patient - universal design using wire-driven mechanism.

PubMed

Yamaura, Hiroshi; Matsushita, Kojiro; Kato, Ryu; Yokoi, Hiroshi

2009-01-01

We have developed a hand rehabilitation system for patients suffering from paralysis or contracture. It consists of two components: a hand rehabilitation machine, which moves human finger joints with motors, and a data glove, which provides control of the movement of finger joints attached to the rehabilitation machine. The machine is based on the arm structure type of hand rehabilitation machine; a motor indirectly moves a finger joint via a closed four-link mechanism. We employ a wire-driven mechanism and develop a compact design that can control all three joints (i.e., PIP, DIP and MP ) of a finger and that offers a wider range of joint motion than conventional systems. Furthermore, we demonstrate the hand rehabilitation process, finger joints of the left hand attached to the machine are controlled by the finger joints of the right hand wearing the data glove.

Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas

DOE PAGES

Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald C.; ...

2015-12-11

Here, table-top laser–plasma ion accelerators have many exciting applications, many of which require ion beams with simultaneous narrow energy spread and high conversion efficiency. However, achieving these requirements has been elusive. Here we report the experimental demonstration of laser-driven ion beams with narrow energy spread and energies up to 18 MeV per nucleon and ~5% conversion efficiency (that is 4 J out of 80-J laser). Using computer simulations we identify a self-organizing scheme that reduces the ion energy spread after the laser exits the plasma through persisting self-generated plasma electric (~10 12 V m –1) and magnetic (~10 4 T)more » fields. These results contribute to the development of next generation compact accelerators suitable for many applications such as isochoric heating for ion-fast ignition and producing warm dense matter for basic science.« less

A 300-mV 220-nW event-driven ADC with real-time QRS detection for wearable ECG sensors.

PubMed

Zhang, Xiaoyang; Lian, Yong

2014-12-01

This paper presents an ultra-low-power event-driven analog-to-digital converter (ADC) with real-time QRS detection for wearable electrocardiogram (ECG) sensors in wireless body sensor network (WBSN) applications. Two QRS detection algorithms, pulse-triggered (PUT) and time-assisted PUT (t-PUT), are proposed based on the level-crossing events generated from the ADC. The PUT detector achieves 97.63% sensitivity and 97.33% positive prediction in simulation on the MIT-BIH Arrhythmia Database. The t-PUT improves the sensitivity and positive prediction to 97.76% and 98.59% respectively. Fabricated in 0.13 μm CMOS technology, the ADC with QRS detector consumes only 220 nW measured under 300 mV power supply, making it the first nanoWatt compact analog-to-information (A2I) converter with embedded QRS detector.

Intermittent gravity-driven flow of grains through narrow pipes

NASA Astrophysics Data System (ADS)

Alvarez, Carlos A.; de Moraes Franklin, Erick

2017-01-01

Grain flows through pipes are frequently found in various settings, such as in pharmaceutical, chemical, petroleum, mining and food industries. In the case of size-constrained gravitational flows, density waves consisting of alternating high- and low-compactness regions may appear. This study investigates experimentally the dynamics of density waves that appear in gravitational flows of fine grains through vertical and slightly inclined pipes. The experimental device consisted of a transparent glass pipe through which different populations of glass spheres flowed driven by gravity. Our experiments were performed under controlled ambient temperature and relative humidity, and the granular flow was filmed with a high-speed camera. Experimental results concerning the length scales and celerities of density waves are presented, together with a one-dimensional model and a linear stability analysis. The analysis exhibits the presence of a long-wavelength instability, with the most unstable mode and a cut-off wavenumber whose values are in agreement with the experimental results.

High performance bonded neo magnets using high density compaction

NASA Astrophysics Data System (ADS)

Herchenroeder, J.; Miller, D.; Sheth, N. K.; Foo, M. C.; Nagarathnam, K.

2011-04-01

This paper presents a manufacturing method called Combustion Driven Compaction (CDC) for the manufacture of isotropic bonded NdFeB magnets (bonded Neo). Magnets produced by the CDC method have density up to 6.5 g/cm3 which is 7-10% higher compared to commercially available bonded Neo magnets of the same shape. The performance of an actual seat motor with a representative CDC ring magnet is presented and compared with the seat motor performance with both commercial isotropic bonded Neo and anisotropic NdFeB rings of the same geometry. The comparisons are made at both room and elevated temperatures. The airgap flux for the magnet produced by the proposed method is 6% more compared to the commercial isotropic bonded Neo magnet. After exposure to high temperature due to the superior thermal aging stability of isotropic NdFeB powders the motor performance with this material is comparable to the motor performance with an anisotropic NdFeB magnet.

Exploring Ramsey-coherent population trapping atomic clock realized with pulsed microwave modulated laser

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

Yang, Jing; Yun, Peter; Tian, Yuan

2014-03-07

A scheme for a Ramsey-coherent population trapping (CPT) atomic clock that eliminates the acousto-optic modulator (AOM) is proposed and experimentally studied. Driven by a periodically microwave modulated current, the vertical-cavity surface-emitting laser emits a continuous beam that switches between monochromatic and multichromatic modes. Ramsey-CPT interference has been studied with this mode-switching beam. In eliminating the AOM, which is used to generate pulsed laser in conventional Ramsey-CPT atomic clock, the physics package of the proposed scheme is virtually the same as that of a conventional compact CPT atomic clock, although the resource budget for the electronics will slightly increase as amore » microwave switch should be added. By evaluating and comparing experimentally recorded signals from the two Ramsey-CPT schemes, the short-term frequency stability of the proposed scheme was found to be 46% better than the scheme with AOM. The experimental results suggest that the implementation of a compact Ramsey-CPT atomic clock promises better frequency stability.« less

Studies on Plasmoid Merging using Compact Toroid Injectors

NASA Astrophysics Data System (ADS)

Allfrey, Ian; Matsumoto, Tadafumi; Roche, Thomas; Gota, Hiroshi; Edo, Takahiro; Asai, Tomohiko; Sheftman, Daniel; Osin Team; Dima Team

2017-10-01

C-2 and C-2U experiments have used magnetized coaxial plasma guns (MCPG) to inject compact toroids (CTs) for refueling the long-lived advanced beam-driven field-reversed configuration (FRC) plasma. This refueling method will also be used for the C-2W experiment. To minimize momentum transfer from the CT to the FRC two CTs are injected radially, diametrically opposed and coincident in time. To improve understanding of the CT characteristics TAE has a dedicated test bed for the development of CT injectors (CTI), where plasmoid merging experiments are performed. The test bed has two CTIs on axis with both axial and transverse magnetic fields. The 1 kG magnetic fields, intended to approximate the magnetic field strength and injection angle on C-2W, allow studies of cross-field transport and merging. Both CTIs are capable of injecting multiple CTs at up to 1 kHz. The resulting merged CT lives >100 μs with a radius of 25 cm. More detailed results of CT parameters will be presented.

Nucleosynthesis inside Supernova-Driven Supercritical Accretion Disks

NASA Astrophysics Data System (ADS)

Fujimoto, Shin-Ichirou; Arai, Kenzo; Matsuba, Ryuichi; Hashimoto, Masa-Aki; Koike, Osamu; Mineshige, Shin

2001-06-01

We have investigated nucleosynthesis in a supercritical accretion disk around a compact object of 1.4Msolar, using the self-similar solution of an optically thick advection dominated flow. Supercritical accretion is expected to occur in a supernova with fallback material accreting onto a new-born compact object. It has been found that appreciable nuclear reactions take place even for a reasonable value of the viscosity parameter, αvissimeq 0.01, when the accretion rate dot{m}=dot{M}c2/(16LEdd) > 105, where LEdd is the Eddington luminosity. If dot{m} ge 4 × 106, all heavy elements are destroyed to 4He through photodisintegrations at the inner part of the disk. Even 4He is also disintegrated to protons and neutrons near the inner edge when dot{m} ge 2 × 107. If the fallback matter of the supernova explosion has the composition of a helium-rich layer of the progenitor, a considerable amount of 44Ti could be ejected via a jet from the disk.

Compact ultra-fast vertical nanopositioner for improving scanning probe microscope scan speed

NASA Astrophysics Data System (ADS)

Kenton, Brian J.; Fleming, Andrew J.; Leang, Kam K.

2011-12-01

The mechanical design of a high-bandwidth, short-range vertical positioning stage is described for integration with a commercial scanning probe microscope (SPM) for dual-stage actuation to significantly improve scanning performance. The vertical motion of the sample platform is driven by a stiff and compact piezo-stack actuator and guided by a novel circular flexure to minimize undesirable mechanical resonances that can limit the performance of the vertical feedback control loop. Finite element analysis is performed to study the key issues that affect performance. To relax the need for properly securing the stage to a working surface, such as a laboratory workbench, an inertial cancellation scheme is utilized. The measured dominant unloaded mechanical resonance of a prototype stage is above 150 kHz and the travel range is approximately 1.56 μm. The high-bandwidth stage is experimentally evaluated with a basic commercial SPM, and results show over 25-times improvement in the scanning performance.

Non-axisymmetric equilibrium reconstruction on the Compact Toroidal Hybrid Experiment using external magnetic and soft x-ray inversion radius measurements

NASA Astrophysics Data System (ADS)

Ma, X.; Cianciosa, M.; Hanson, J. D.; Hartwell, G. J.; Knowlton, S. F.; Maurer, D. A.; Ennis, D. A.; Herfindal, J. L.

2015-11-01

Non-axisymmetric free-boundary equilibrium reconstructions of stellarator plasmas are performed for discharges in which the magnetic configuration is strongly modified by the driven plasma current. Studies were performed on the Compact Toroidal Hybrid device using the V3FIT reconstruction code incorporating a set of 50 magnetic diagnostics external to the plasma, combined with information from soft X-ray (SXR) arrays. With the assumption of closed magnetic flux surfaces, the reconstructions using external magnetic measurements allow accurate estimates of the net toroidal flux within the last closed flux surface, the edge safety factor, and the outer boundary of these highly non-axisymmetric plasmas. The inversion radius for sawtoothing plasmas is used to identify the location of the q = 1 surface, and thus infer the current profile near the magnetic axis. With external magnetic diagnostics alone, we find the reconstruction to be insufficiently constrained. This work is supported by US Department of Energy Grant No. DE-FG02-00ER54610.

Sintering of polydisperse viscous droplets

NASA Astrophysics Data System (ADS)

Wadsworth, Fabian B.; Vasseur, Jérémie; Llewellin, Edward W.; Dingwell, Donald B.

2017-03-01

Sintering—or coalescence—of compacts of viscous droplets is driven by the interfacial tension between the droplets and the interstitial gas phase. The process, which occurs in a range of industrial and natural settings, such as the manufacture of ceramics and the welding of volcanic ash, causes the compact to densify, to become stronger, and to become less permeable. We investigate the role of droplet polydispersivity in sintering dynamics by conducting experiments in which populations of glass spheres with different size distributions are heated to temperatures above the glass transition interval. We quantify the progress of sintering by tracking changes in porosity with time. The sintering dynamics is modeled by treating the system as a random distribution of interstitial gas bubbles shrinking under the action of interfacial tension only. We identify the scaling between the polydispersivity of the initial droplets and the dynamics of bulk densification. The framework that we develop allows the sintering dynamics of arbitrary polydisperse populations of droplets to be predicted if the initial droplet (or particle) size distribution is known.

Multi-species trace gas sensing with dual-wavelength QCLs

NASA Astrophysics Data System (ADS)

Hundt, P. Morten; Tuzson, Béla; Aseev, Oleg; Liu, Chang; Scheidegger, Philipp; Looser, Herbert; Kapsalidis, Filippos; Shahmohammadi, Mehran; Faist, Jérôme; Emmenegger, Lukas

2018-06-01

Instrumentation for environmental monitoring of gaseous pollutants and greenhouse gases tends to be complex, expensive, and energy demanding, because every compound measured relies on a specific analytical technique. This work demonstrates an alternative approach based on mid-infrared laser absorption spectroscopy with dual-wavelength quantum cascade lasers (QCLs). The combination of two dual- and one single-DFB QCL yields high-precision measurements of CO (0.08 ppb), CO2 (100 ppb), NH3 (0.02 ppb), NO (0.4 ppb), NO2 (0.1 ppb), N2O (0.045 ppb), and O3 (0.11 ppb) simultaneously in a compact setup (45 × 45 cm2). The lasers are driven time-multiplexed in intermittent continuous wave mode with a repetition rate of 1 kHz. The individual spectra are real-time averaged (1 s) by an FPGA-based data acquisition system. The instrument was assessed for environmental monitoring and benchmarked with reference instrumentation to demonstrate its potential for compact multi-species trace gas sensing.

Lo que los educadores necesitan saber sobre...El agrupamiento por habilidad [y] La compactacion del curriculum [y] Los alumnos dotados y el aprendizaje cooperativo [y] La actividad tutoral. Guias practica (What Educators Need To Know about...Ability Grouping [and] Curriculum Compacting [and] Gifted Students and Cooperative Learning [and] Mentoring. Practitioners' Guides).

ERIC Educational Resources Information Center

Siegle, Del, Ed.

These four pamphlets in Spanish offer guidelines supported by theory-driven quality research that is problem-based, practice-relevant, and consumer-oriented. Each pamphlet has a section summarizing research from the literature or topic notes as well as implications for the classroom. The first guide offers principles for teachers concerning the…

Recent developments in materials and detectors for the infrared; Proceedings of the Meeting, Cannes, France, November 25, 26, 1985

NASA Technical Reports Server (NTRS)

Morten, F. D. (Editor); Seeley, John S. (Editor)

1986-01-01

The present conference on advancements in IR-sensitive materials and detector technologies employing them gives attention to thermal detectors, focal plane array processing detectors, novel detector designs, general properties of IR optics materials, and preparation methods for such materials. Specific topics encompass the fabrication of InSb MIS structures prepared by photochemical vapor deposition, IR heterodyne detectors employing cadmium mercury telluride, low microphony pyroelectric arrays, IR detection based on minority carrier extrusion, longwave reststrahl in IR crystals, and molecular beam techniques for optical thin film fabrication.

A survey and analysis of experimental hydrogen sensors

NASA Technical Reports Server (NTRS)

Hunter, Gary W.

1992-01-01

In order to ascertain the applicability of hydrogen sensors to aerospace applications, a survey was conducted of promising experimental point-contact hydrogen sensors and their operation was analyzed. The techniques discussed are metal-oxide-semiconductor or MOS based sensors, catalytic resistor sensors, acoustic wave detectors, and pyroelectric detectors. All of these sensors depend on the interaction of hydrogen with Pd or a Pd-alloy. It is concluded that no single technique will meet the needs of aerospace applications but a combination of approaches is necessary. The most promising combination is an MOS based sensor with a catalytic resistor.

Voltage generation of piezoelectric cantilevers by laser heating

PubMed Central

Hsieh, Chun-Yi; Liu, Wei-Hung; Chen, Yang-Fang; Shih, Wan Y.; Gao, Xiaotong; Shih, Wei-Heng

2012-01-01

Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity. PMID:23258941

Resistance switching in polyvinylidene fluoride (PVDF) thin films

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

Pramod, K.; Sahu, Binaya Kumar; Gangineni, R. B., E-mail: rameshg.phy@pondiuni.edu.in

2015-06-24

Polyvinylidene fluoride (PDVF), one of the best electrically active polymer material & an interesting candidate to address the electrical control of its functional properties like ferroelectricity, piezoelectricity, pyroelectricity etc. In the current work, with the help of spin coater and DC magnetron sputtering techniques, semi-crystallized PVDF thin films prominent in alpha phase is prepared in capacitor like structure and their electrical characterization is emphasized. In current-voltage (I-V) and resistance-voltage (R-V) measurements, clear nonlinearity and resistance switching has been observed for films prepared using 7 wt% 2-butanone and 7 wt% Dimethyl Sulfoxide (DMSO) solvents.

From rock to magma and back again: The evolution of temperature and deformation mechanism in conduit margin zones

NASA Astrophysics Data System (ADS)

Heap, Michael J.; Violay, Marie; Wadsworth, Fabian B.; Vasseur, Jérémie

2017-04-01

Explosive silicic volcanism is driven by gas overpressure in systems that are inefficient at outgassing. The zone at the margin of a volcanic conduit-thought to play an important role in the outgassing of magma and therefore pore pressure changes and explosivity-is the boundary through which heat is exchanged from the hot magma to the colder country rock. Using a simple heat transfer model, we first show that the isotherm for the glass transition temperature (whereat the glass within the groundmass transitions from a glass to an undercooled liquid) moves into the country rock when the magma within the conduit can stay hot, or into the conduit when the magma is quasi-stagnant and cools (on the centimetric scale over days to months). We then explore the influence of a migrating viscous boundary on compactive deformation micromechanisms in the conduit margin zone using high-pressure (effective pressure of 40 MPa), high-temperature (up to 800 °C) triaxial deformation experiments on porous andesite. Our experiments show that the micromechanism facilitating compaction in andesite is localised cataclastic pore collapse at all temperatures below the glass transition of the amorphous groundmass glass Tg (i.e., rock). In this regime, porosity is only reduced within the bands of crushed pores; the porosity outside the bands remains unchanged. Further, the strength of andesite is a positive function of temperature below the threshold Tg due to thermal expansion driven microcrack closure. The micromechanism driving compaction above Tg (i.e., magma) is the distributed viscous flow of the melt phase. In this regime, porosity loss is distributed and is accommodated by the widespread flattening and closure of pores. We find that viscous flow is much more efficient at reducing porosity than cataclastic pore collapse, and that it requires stresses much lower than those required to form bands of crushed pores. Our study therefore highlights that temperature excursions can result in a change in deformation micromechanism that drastically alters the mechanical and hydraulic properties of the material within the conduit margin zone, with possible implications for pore pressure augmentation and explosive behaviour.

Human Movement Detection and Idengification Using Pyroelectric Infrared Sensors

PubMed Central

Yun, Jaeseok; Lee, Sang-Shin

2014-01-01

Pyroelectric infrared (PIR) sensors are widely used as a presence trigger, but the analog output of PIR sensors depends on several other aspects, including the distance of the body from the PIR sensor, the direction and speed of movement, the body shape and gait. In this paper, we present an empirical study of human movement detection and idengification using a set of PIR sensors. We have developed a data collection module having two pairs of PIR sensors orthogonally aligned and modified Fresnel lenses. We have placed three PIR-based modules in a hallway for monitoring people; one module on the ceiling; two modules on opposite walls facing each other. We have collected a data set from eight subjects when walking in three different conditions: two directions (back and forth), three distance intervals (close to one wall sensor, in the middle, close to the other wall sensor) and three speed levels (slow, moderate, fast). We have used two types of feature sets: a raw data set and a reduced feature set composed of amplitude and time to peaks; and passage duration extracted from each PIR sensor. We have performed classification analysis with well-known machine learning algorithms, including instance-based learning and support vector machine. Our findings show that with the raw data set captured from a single PIR sensor of each of the three modules, we could achieve more than 92% accuracy in classifying the direction and speed of movement, the distance interval and idengifying subjects. We could also achieve more than 94% accuracy in classifying the direction, speed and distance and idengifying subjects using the reduced feature set extracted from two pairs of PIR sensors of each of the three modules. PMID:24803195

Built-in-polarization field effect on lattice thermal conductivity of AlxGa1-xN/GaN heterostructure

NASA Astrophysics Data System (ADS)

Pansari, Anju; Gedam, Vikas; Kumar Sahoo, Bijaya

2015-12-01

The built-in-polarization field at the interface of AlxGa1-xN/GaN heterostructure enhances elastic constant, phonon velocity, Debye temperature and their bowing constants of barrier material AlxGa1-xN. The combined phonon relaxation time of acoustics phonons has been computed for with and without built-in-polarization field at room temperature for different aluminum (Al) content (x). Our result shows that the built-in-polarization field suppresses the scattering mechanisms and enhances the combined relaxation time. The thermal conductivity of AlxGa1-xN has been estimated as a function of temperature for x=0, 0.1, 0.5 and 1 for with and without polarization field. Minimum thermal conductivity has been observed for x=0.1 and 0.5. Analysis shows that up to a certain temperature (different for different x) the polarization field acts as negative effect and reduces the thermal conductivity and after this temperature thermal conductivity is significantly contributed by polarization field. This signifies pyroelectric character of AlxGa1-xN. The pyroelectric transition temperature of AlxGa1-xN alloy has been predicted for different x. Our study reports that room temperature thermal conductivity of AlxGa1-xN/GaN heterostructure is enhanced by built-in-polarization field. The temperature dependence of thermal conductivity for x=0.1 and 0.5 are in line with prior experimental studies. The method we have developed can be used for the simulation of heat transport in nitride devices to minimize the self heating processes and in polarization engineering strategies to optimize the thermoelectric performance of AlxGa1-xN/GaN heterostructures.

Smart material-based radiation sources

NASA Astrophysics Data System (ADS)

Kovaleski, Scott

2014-10-01

From sensors to power harvesters, the unique properties of smart materials have been exploited in numerous ways to enable new applications and reduce the size of many useful devices. Smart materials are defined as materials whose properties can be changed in a controlled and often reversible fashion by use of external stimuli, such as electric and magnetic fields, temperature, or humidity. Smart materials have been used to make acceleration sensors that are ubiquitous in mobile phones, to make highly accurate frequency standards, to make unprecedentedly small actuators and motors, to seal and reduce friction of rotating shafts, and to generate power by conversion of either kinetic or thermal energy to electrical energy. The number of useful devices enabled by smart materials is large and continues to grow. Smart materials can also be used to generate plasmas and accelerate particles at small scales. The materials discussed in this talk are from non-centrosymmetric crystalline classes including piezoelectric, pyroelectric, and ferroelectric materials, which produce large electric fields in response to external stimuli such as applied electric fields or thermal energy. First, the use of ferroelectric, pyroelectric and piezoelectric materials for plasma generation and particle acceleration will be reviewed. The talk will then focus on the use of piezoelectric materials at the University of Missouri to construct plasma sources and electrostatic accelerators for applications including space propulsion, x-ray imaging, and neutron production. The basic concepts of piezoelectric transformers, which are analogous to conventional magnetic transformers, will be discussed, along with results from experiments over the last decade to produce micro-thrusters for space propulsion and particle accelerators for x-ray and neutron production. Support from ONR, AFOSR, and LANL.

Lightning generation in Titan due to the electrical self-polarization properties of Methane

NASA Astrophysics Data System (ADS)

Quintero, A.; Falcón, N.

2009-05-01

We describe an electrical charge process in Titan's thunderclouds, due to the self-polarization properties or pyroelectricity of methane, which increases the internal electric field in thunderclouds and facilitates the charge generation and separation processes. Microphysics that generates lightning flashes is associated with the physical and chemical properties of the local atmosphere, so methane could be the principal agent of the electrical activity because of its great concentration in Titan's atmosphere. Besides, Titan's electrical activity should not be very influenced by Saturn's magnetosphere because lightning occurs at very low altitude above Titan's surface, compared with the greater distance of Saturn's magnetosphere and Titan's troposphere. Using an electrostatic treatment, we calculate the internal electric field of Titan's thunderclouds due to methane's pyroelectrical properties, 7.05×10^11 Vm^-1; and using the telluric capacitor approximation for thunderclouds, we calculate the total charge obtained for a typical Titan thundercloud, 2.67×10^9 C. However, it is not right to use an electrostatic treatment because charge times are very fast due to the large methane concentration in Titan's clouds and the life time of thunderclouds is very low (around 2 hours). We consider a time dependent mechanism, employing common Earth atmospheric approaches, because of the similitude in chemical composition of both atmospheres (mainly nitrogen), so the typical charge of a thundercloud in Titan should reach between 20 C to 40 C, like on Earth. We obtain that lightning occurs with a frequency between 2 and 6 KHz. In Titan's atmosphere, methane concentration is higher than on Earth, and atmospheric electrical activity is stronger, so this model could be consistent with the observed phenomenology.

Evaluation of a silicon 5 MHz p–n diode actuator with a laterally vibrating extensional mode

NASA Astrophysics Data System (ADS)

Miyazaki, Fumito; Baba, Kazuki; Tanigawa, Hiroshi; Furutsuka, Takashi; Suzuki, Kenichiro

2018-05-01

In this paper, we describe p–n diode actuators that are laterally driven by the force induced in a depletion layer. The previously reported p–n diode actuators have been vertically driven. Because the resonant frequency depends on the thickness of the vibrating plate, the integration of resonators with different frequencies on a chip has been difficult. The resonators in this work are driven laterally by using length-extensional vibration. We have developed a compact model based on an analytical expression, in which p–n diode actuators are driven by the forces induced by the spread of the depletion layer. The deflection generated by the p–n diode actuators was proportional to the ratio of the depletion layer width to the resonator thickness as well as the position of the p–n junction. Good agreement of experimental results with the theory was confirmed by comparing the measured values for silicon p–n diode rectangular-plate actuators fabricated using a silicon-on-insulator (SOI) substrate. The displacement amplitude of the actuators was proportional to the DC bias, while the resonant frequency was independent of the DC bias. The latter characteristic is very different from that of widely used electrostatic actuators. Although the amplitude of the actuator measured in this work was very small, it is expected that the amplitude will increase greatly by increasing the doping of the p–n diode actuators.

Generation of quasi-monoenergetic heavy ion beams via staged shock wave acceleration driven by intense laser pulses in near-critical plasmas

NASA Astrophysics Data System (ADS)

Zhang, W. L.; Qiao, B.; Shen, X. F.; You, W. Y.; Huang, T. W.; Yan, X. Q.; Wu, S. Z.; Zhou, C. T.; He, X. T.

2016-09-01

Laser-driven ion acceleration potentially offers a compact, cost-effective alternative to conventional accelerators for scientific, technological, and health-care applications. A novel scheme for heavy ion acceleration in near-critical plasmas via staged shock waves driven by intense laser pulses is proposed, where, in front of the heavy ion target, a light ion layer is used for launching a high-speed electrostatic shock wave. This shock is enhanced at the interface before it is transmitted into the heavy ion plasmas. Monoenergetic heavy ion beam with much higher energy can be generated by the transmitted shock, comparing to the shock wave acceleration in pure heavy ion target. Two-dimensional particle-in-cell simulations show that quasi-monoenergetic {{{C}}}6+ ion beams with peak energy 168 MeV and considerable particle number 2.1 × {10}11 are obtained by laser pulses at intensity of 1.66 × {10}20 {{W}} {{cm}}-2 in such staged shock wave acceleration scheme. Similarly a high-quality {{Al}}10+ ion beam with a well-defined peak with energy 250 MeV and spread δ E/{E}0=30 % can also be obtained in this scheme.

Electrically driven monolithic subwavelength plasmonic interconnect circuits

PubMed Central

Liu, Yang; Zhang, Jiasen; Liu, Huaping; Wang, Sheng; Peng, Lian-Mao

2017-01-01

In the post-Moore era, an electrically driven monolithic optoelectronic integrated circuit (OEIC) fabricated from a single material is pursued globally to enable the construction of wafer-scale compact computing systems with powerful processing capabilities and low-power consumption. We report a monolithic plasmonic interconnect circuit (PIC) consisting of a photovoltaic (PV) cascading detector, Au-strip waveguides, and electrically driven surface plasmon polariton (SPP) sources. These components are fabricated from carbon nanotubes (CNTs) via a CMOS (complementary metal-oxide semiconductor)–compatible doping-free technique in the same feature size, which can be reduced to deep-subwavelength scale (~λ/7 to λ/95, λ = 1340 nm) compared with the 14-nm technique node. An OEIC could potentially be configured as a repeater for data transport because of its “photovoltaic” operation mode to transform SPP energy directly into electricity to drive subsequent electronic circuits. Moreover, chip-scale throughput capability has also been demonstrated by fabricating a 20 × 20 PIC array on a 10 mm × 10 mm wafer. Tailoring photonics for monolithic integration with electronics beyond the diffraction limit opens a new era of chip-level nanoscale electronic-photonic systems, introducing a new path to innovate toward much faster, smaller, and cheaper computing frameworks. PMID:29062890

New compact hohlraum configuration research at the 1.7 MA Z-pinch generator

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

Kantsyrev, V. L., E-mail: victor@unr.edu; Shrestha, I. K.; Esaulov, A. A.

A new compact Z-pinch x-ray hohlraum design with parallel-driven x-ray sources was experimentally demonstrated in a full configuration with a central target and tailored shine shields (to provide a symmetric temperature distribution on the target) at the 1.7 MA Zebra generator. This presentation reports on the joint success of two independent lines of research. One of these was the development of new sources – planar wire arrays (PWAs). PWAs turned out to be a prolific radiator. Another success was the drastic improvement in energy efficiency of pulsed-power systems, such as the Load Current Multiplier (LCM). The Zebra/LCM generator almost doubledmore » the plasma load current to 1.7 MA. The two above-mentioned innovative approaches were used in combination to produce a new compact hohlraum design for ICF, as jointly proposed by SNL and UNR. Good agreement between simulated and measured radiation temperature of the central target is shown. Experimental comparison of PWAs with planar foil liners (PFL) - another viable alternative to wire array loads at multi-MA generators show promising data. Results of research at the University of Nevada Reno allowed for the study of hohlraum coupling physics at University-scale generators. The advantages of new hohlraum design applications for multi-MA facilities with W or Au double PWAs or PFL x-ray sources are discussed.« less

Wavefront-sensor-based electron density measurements for laser-plasma accelerators.

PubMed

Plateau, G R; Matlis, N H; Geddes, C G R; Gonsalves, A J; Shiraishi, S; Lin, C; van Mourik, R A; Leemans, W P

2010-03-01

Characterization of the electron density in laser produced plasmas is presented using direct wavefront analysis of a probe laser beam. The performance of a laser-driven plasma-wakefield accelerator depends on the plasma wavelength and hence on the electron density. Density measurements using a conventional folded-wave interferometer and using a commercial wavefront sensor are compared for different regimes of the laser-plasma accelerator. It is shown that direct wavefront measurements agree with interferometric measurements and, because of the robustness of the compact commercial device, offer greater phase sensitivity and straightforward analysis, improving shot-to-shot plasma density diagnostics.

Overview of Alternative Bunching and Current-shaping Techniques for Low-Energy Electron Beams

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

Piot, Philippe

2015-12-01

Techniques to bunch or shape an electron beam at low energies (E <15 MeV) have important implications toward the realization of table-top radiation sources [1] or to the design of compact multi-user free-electron lasers[2]. This paper provides an overview of alternative methods recently developed including techniques such as wakefield-based bunching, space-charge-driven microbunching via wave-breaking [3], ab-initio shaping of the electron-emission process [4], and phase space exchangers. Practical applications of some of these methods to foreseen free-electron-laser configurations are also briefly discussed [5].

Optical design of MOEMS-based micro-mechatronic modules for applications in spectroscopy

NASA Astrophysics Data System (ADS)

Tortschanoff, A.; Kremer, M.; Sandner, T.; Kenda, A.

2014-05-01

One of the important challenges for widespread application of MOEMS devices is to provide a modular interface for easy handling and accurate driving of the MOEMS elements, in order to enable seamless integration in larger spectroscopic system solutions. In this contribution we present in much detail the optical design of MOEMS driver modules comprising optical position sensing together with driver electronics, which can actively control different electrostatically driven MOEMS. Furthermore we will present concepts for compact spectroscopic devices, based on different MOEMS scanner modules with lD and 2D optical elements.

Landau-Zener extension of the Tavis-Cummings model: Structure of the solution

DOE PAGES

Sun, Chen; Sinitsyn, Nikolai A.

2016-09-07

We explore the recently discovered solution of the driven Tavis-Cummings model (DTCM). It describes interaction of an arbitrary number of two-level systems with a bosonic mode that has linearly time-dependent frequency. We derive compact and tractable expressions for transition probabilities in terms of the well-known special functions. In this form, our formulas are suitable for fast numerical calculations and analytical approximations. As an application, we obtain the semiclassical limit of the exact solution and compare it to prior approximations. Furthermore, we also reveal connection between DTCM and q-deformed binomial statistics.

Tunable, superconducting, surface-emitting teraherz source

DOEpatents

Welp, Ulrich [Lisle, IL; Koshelev, Alexei E [Bolingbrook, IL; Gray, Kenneth E [Evanston, IL; Kwok, Wai-Kwong [Evanston, IL; Vlasko-Vlasov, Vitalii [Downers Grove, IL

2009-10-27

A compact, solid-state THz source based on the driven Josephson vortex lattice in a highly anisotropic superconductor such as Bi.sub.2Sr.sub.2CaCu.sub.2O.sub.8 that allows cw emission at tunable frequency. A second order metallic Bragg grating is used to achieve impedance matching and to induce surface emission of THz-radiation from a Bi.sub.2Sr.sub.2CaCu.sub.2O.sub.8 sample. Steering of the emitted THz beam is accomplished by tuning the Josephson vortex spacing around the grating period using a superimposed magnetic control field.

Tunable, superconducting, surface-emitting teraherz source

DOEpatents

Welp, Ulrich; Koshelev, Alexei E.; Gray, Kenneth E.; Kwok, Wai-Kwong; Vlasko-Vlasov, Vitalii

2010-05-11

A compact, solid-state THz source based on the driven Josephson vortex lattice in a highly anisotropic superconductor such as Bi.sub.2Sr.sub.2CaCu.sub.2O.sub.8 that allows cw emission at tunable frequency. A second order metallic Bragg grating is used to achieve impedance matching and to induce surface emission of THz-radiation from a Bi.sub.2Sr.sub.2CaCu.sub.2O.sub.8 sample. Steering of the emitted THz beam is accomplished by tuning the Josephson vortex spacing around the grating period using a superimposed magnetic control field.

Design and performance of a beetle-type double-tip scanning tunneling microscope

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

Jaschinsky, Philipp; Coenen, Peter; Pirug, Gerhard

2006-09-15

A combination of a double-tip scanning tunneling microscope with a scanning electron microscope in ultrahigh vacuum environment is presented. The compact beetle-type design made it possible to integrate two independently driven scanning tunneling microscopes in a small space. Moreover, an additional level for coarse movement allows the decoupling of the translation and approach of the tunneling tip. The position of the two tips can be controlled from the millimeter scale down to 50 nm with the help of an add-on electron microscope. The instrument is capable of atomic resolution imaging with each tip.

Wavefront-sensor-based electron density measurements for laser-plasma accelerators

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

Plateau, Guillaume; Matlis, Nicholas; Geddes, Cameron

2010-02-20

Characterization of the electron density in laser produced plasmas is presented using direct wavefront analysis of a probe laser beam. The performance of a laser-driven plasma-wakefield accelerator depends on the plasma wavelength, hence on the electron density. Density measurements using a conventional folded-wave interferometer and using a commercial wavefront sensor are compared for different regimes of the laser-plasma accelerator. It is shown that direct wavefront measurements agree with interferometric measurements and, because of the robustness of the compact commercial device, have greater phase sensitivity, straightforward analysis, improving shot-to-shot plasma-density diagnostics.

Relativistic jets in SS 433

NASA Astrophysics Data System (ADS)

Margon, B.

1982-01-01

A variety of recent optical, radio, and X-ray observations have confirmed the hypothesis that the peculiar star SS 433 is ejecting two narrow, opposed, highly collimated jets of matter at one-quarter the speed of light. This unique behavior is probably driven by mass exchange between a relatively normal star and a compact companion, either a neutron star or a black hole. However, numerous details regarding the energetics, radiation, acceleration, and collimation of the jets remain to be understood. This phenomenon may well be a miniature example of similar collimated ejection of gas by active extragalactic objects such as quasars and radio galaxies.

Compact, high energy gas laser

DOEpatents

Rockwood, Stephen D.; Stapleton, Robert E.; Stratton, Thomas F.

1976-08-03

An electrically pumped gas laser amplifier unit having a disc-like configuration in which light propagation is radially outward from the axis rather than along the axis. The input optical energy is distributed over a much smaller area than the output optical energy, i.e., the amplified beam, while still preserving the simplicity of parallel electrodes for pumping the laser medium. The system may thus be driven by a comparatively low optical energy input, while at the same time, owing to the large output area, large energies may be extracted while maintaining the energy per unit area below the threshold of gas breakdown.

One‐Dimensional Ferroelectric Nanostructures: Synthesis, Properties, and Applications

PubMed Central

Liang, Longyue; Kang, Xueliang

2016-01-01

One‐dimensional (1D) ferroelectric nanostructures, such as nanowires, nanorods, nanotubes, nanobelts, and nanofibers, have been studied with increasing intensity in recent years. Because of their excellent ferroelectric, ferroelastic, pyroelectric, piezoelectric, inverse piezoelectric, ferroelectric‐photovoltaic (FE‐PV), and other unique physical properties, 1D ferroelectric nanostructures have been widely used in energy‐harvesting devices, nonvolatile random access memory applications, nanoelectromechanical systems, advanced sensors, FE‐PV devices, and photocatalysis mechanisms. This review summarizes the current state of 1D ferroelectric nanostructures and provides an overview of the synthesis methods, properties, and practical applications of 1D nanostructures. Finally, the prospects for future investigations are outlined. PMID:27812477

Improved ferroelectric and pyroelectric parameters in iminodiacetic acid doped TGS crystal

NASA Astrophysics Data System (ADS)

Rai, Chitharanjan; Sreenivas, K.; Dharmaprakash, S. M.

2010-01-01

Single crystals of Iminodiacetic acid (HN(CH 2COOH) 2) doped Triglycine sulphate (IDATGS) has been grown from aqueous solution at constant temperature by slow evaporation technique. The concentration of the dopant in the TGS solution was 2 mol%. The X-ray diffraction analysis indicates that there is significant change in the lattice parameters compared to pure TGS crystal. The IDATGS crystal has larger transition temperature and observed higher and uniform figure of merit over most part of the ferroelectric phase. These crystals also exhibit higher internal bias field and micro-hardness number compared to pure TGS. Therefore IDATGS may be a potential material for IR detectors.

Direct conversion technology

NASA Technical Reports Server (NTRS)

Massier, Paul F.; Bankston, C. P.; Williams, R.; Underwood, M.; Jeffries-Nakamura, B.; Fabris, G.

1989-01-01

The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal Magnetohydrodynamic Electrical Generator (LMMHD) for the period January 1, 1989 through December 31, 1989. Research on these concepts was initiated during October 1987. Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (nitinol heat engines); and also, more complete discussions of AMTEC and LMMHD systems.

High-power, single-longitudinal-mode terahertz-wave generation pumped by a microchip Nd:YAG laser [Invited].

PubMed

Hayashi, Shin'ichiro; Nawata, Koji; Sakai, Hiroshi; Taira, Takunori; Minamide, Hiroaki; Kawase, Kodo

2012-01-30

We report on the development of a high-peak-power, single-longitudinal-mode and tunable injection-seeded terahertz-wave parametric generator using MgO:LiNbO3, which operates at room temperature. The high peak power (> 120 W) is enough to allow easy detection by commercial and calibrated pyroelectric detectors, and the spectral resolution (< 10 GHz) is the Fourier transform limit of the sub-nanosecond terahertz-wave pulse. The tunability (1.2-2.8 THz) and the small footprint size (A3 paper, 29.7 × 42 cm) are suitable for a variety of applications.

Optical actuators for fly-by-light applications

NASA Astrophysics Data System (ADS)

Chee, Sonny H. S.; Liu, Kexing; Measures, Raymond M.

1993-04-01

A review of optomechanical interfaces is presented. A detailed quantitative and qualitative analysis of the University of Toronto Institute for Aerospace Studies (UTIAS) box, optopneumatics, optical activation of a bimetal, optical activation of the shape memory effect, and optical activation of the pyroelectric effects is given. The UTIAS box is found to display a good conversion efficiency and a high bandwidth. A preliminary UTIAS box design has achieved a conversion efficiency of about 1/6 of the theoretical limit and a bandwidth of 2 Hz. In comparison to previous optomechanical interfaces, the UTIAS box has the highest pressure development to optical power ratio (at least an order of magnitude greater).

Competition between reaction-induced expansion and creep compaction during gypsum formation: Experimental and numerical investigation

NASA Astrophysics Data System (ADS)

Skarbek, R. M.; Savage, H. M.; Spiegelman, M. W.; Kelemen, P. B.; Yancopoulos, D.

2017-12-01

Deformation and cracking caused by reaction-driven volume increase is an important process in many geological settings, however the conditions controlling these processes are poorly understood. The interaction of rocks with reactive fluids can change permeability and reactive surface area, leading to a large variety of feedbacks. Gypsum is an ideal material to study these processes. It forms rapidly at room temperature via bassanite hydration, and is commonly used as an analogue for rocks in high-temperature, high-pressure conditions. We conducted uniaxial strain experiments to study the effects of applied axial load on deformation and fluid flow during the formation of gypsum from bassanite. While hydration of bassanite to gypsum involves a solid volume increase, gypsum exhibits significant creep compaction when in contact with water. These two volume changing processes occur simultaneously during fluid flow through bassanite. We cold-pressed bassanite powder to form cylinders 2.5 cm in height and 1.2 cm in diameter. Samples were compressed with a static axial load of 0.01 to 4 MPa. Water infiltrated initially unsaturated samples through the bottom face and the height of the samples was recorded as a measure of the total volume change. We also performed experiments on pure gypsum samples to constrain the amount of creep observed in tests on bassanite hydration. At axial loads < 0.15 MPa, volume increase due to the reaction dominates and samples exhibit monotonic expansion. At loads > 1 MPa, creep in the gypsum dominates and samples exhibit monotonic compaction. At intermediate loads, samples exhibit alternating phases of compaction and expansion due to the interplay of the two volume changing processes. We observed a change from net compaction to net expansion at an axial load of 0.250 MPa. We explain this behavior with a simple model that predicts the strain evolution, but does not take fluid flow into account. We also implement a 1D poro-visco-elastic model of the imbibition process that includes the reaction and gypsum creep. We use the results of these models, with models of the creep rate in gypsum, to estimate the temperature dependence of the axial load where total strain transitions from compaction to expansion. Our results have implications for the depth dependence of reaction induced volume changes in the Earth.

Development of a High Reliability Compact Air Independent PEMFC Power System

NASA Technical Reports Server (NTRS)

Vasquez, Arturo; Wynne, Bob

2013-01-01

Autonomous Underwater Vehicles (AUV's) have received increasing attention in recent years as military and commercial users look for means to maintain a mobile and persistent presence in the undersea world. Compact, neutrally buoyant power systems are needed for both small and large vehicles. Historically, batteries have been employed in these applications, but the energy density and therefore mission duration are limited with current battery technologies. Vehicles with stored energy requirements greater than approximately 10 kWh have an alternate means to get long duration power. High efficiency Proton Exchange Membrane (PEM) fuel cell systems utilizing pure hydrogen and oxygen reactants show the potential for an order of magnitude energy density improvement over batteries as long as the subsystems are compact. One key aspect to achieving a compact and energy dense system is the design of the fuel cell balance of plant (BOP). Recent fuel cell work, initially focused on NASA applications requiring high reliability, has developed systems that can meet target power and energy densities. Passive flow through systems using ejector driven reactant (EDR) circulation have been developed to provide high reactant flow and water management within the stack, with minimal parasitic losses compared to blowers. The ejectors and recirculation loops, along with valves and other BOP instrumentation, have been incorporated within the stack end plate. In addition, components for water management and reactant conditioning have been incorporated within the stack to further minimize the BOP. These BOP systems are thermally and functionally integrated into the stack hardware and fit into the small volumes required for AUV and future NASA applications to maximize the volume available for reactants. These integrated systems provide a compact solution for the fuel cell BOP and maximize the efficiency and reliability of the system. Designs have been developed for multiple applications ranging from less than 1 kWe to 70 kWe. These systems occupy a very small portion of the overall energy system, allowing most of the system volume to be used for reactants. The fuel cell systems have been optimized to use reactants efficiently with high stack efficiency and low parasitic losses. The resulting compact, highly efficient fuel cell system provides exceptional reactant utilization and energy density. Key design variables and supporting test data are presented. Future development activities are described.

Scalable, Economical Fabrication Processes for Ultra-Compact Warm-White LEDs

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

Lowes, Ted

Conventional warm-white LED component fabrication consists of a large number of sequential steps which are required to incorporate electrical, mechanical, and optical functionality into the component. Each of these steps presents cost and yield challenges which multiply throughout the entire process. Although there has been significant progress in LED fabrication over the last decade, significant advances are needed to enable further reductions in cost per lumen while not sacrificing efficacy or color quality. Cree conducted a focused 18-month program to develop a new low-cost, high-efficiency light emitting diode (LED) architecture enabled by novel large-area parallel processing technologies, reduced number ofmore » fabrication steps, and minimized raw materials use. This new scheme is expected to enable ultra-compact LED components exhibiting simultaneously high efficacy and high color quality. By the end of the program, Cree fabricated warm-white LEDs with a room-temperature “instant on” efficacy of >135 lm/W at ~3500K and 90 CRI (when driven at the DOE baseline current density of 35 A/cm2). Cree modified the conventional LED fabrication process flow in a manner that is expected to translate into simultaneously high throughput and yield for ultra-compact packages. Building on its deep expertise in LED wafer fabrication, Cree developed these ultra-compact LEDs to have no compromises in color quality or efficacy compared to their conventional counterparts. Despite their very small size, the LEDs will also be robustly electrically integrated into luminaire systems with the same attach yield as conventional packages. The versatility of the prototype high-efficacy LED architecture will likely benefit solid-state lighting (SSL) luminaire platforms ranging from bulbs to troffers. We anticipate that the prototype LEDs will particularly benefit luminaires with large numbers of distributed compact packages, such as linear and area luminaires (e.g. troffers). The fraction of total SSL luminaire cost made up by the LEDs themselves has steadily fallen over the past several years, but can still make up 30% or more of the bill of materials; the new LED design will radically lower this proportion. Ultra-compact, highly efficient LEDs with optimal distribution in the system will further benefit luminaire materials and assembly costs by reducing the complexity and volume of thermal management and optical subsystems.« less

A non-linear dimension reduction methodology for generating data-driven stochastic input models

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

Ganapathysubramanian, Baskar; Zabaras, Nicholas

Stochastic analysis of random heterogeneous media (polycrystalline materials, porous media, functionally graded materials) provides information of significance only if realistic input models of the topology and property variations are used. This paper proposes a framework to construct such input stochastic models for the topology and thermal diffusivity variations in heterogeneous media using a data-driven strategy. Given a set of microstructure realizations (input samples) generated from given statistical information about the medium topology, the framework constructs a reduced-order stochastic representation of the thermal diffusivity. This problem of constructing a low-dimensional stochastic representation of property variations is analogous to the problem ofmore » manifold learning and parametric fitting of hyper-surfaces encountered in image processing and psychology. Denote by M the set of microstructures that satisfy the given experimental statistics. A non-linear dimension reduction strategy is utilized to map M to a low-dimensional region, A. We first show that M is a compact manifold embedded in a high-dimensional input space R{sup n}. An isometric mapping F from M to a low-dimensional, compact, connected set A is contained in R{sup d}(d<

Polarity of the ascidian egg cortex and relocalization of cER and mRNAs in the early embryo.

PubMed

Prodon, François; Dru, Philippe; Roegiers, Fabrice; Sardet, Christian

2005-06-01

The mature ascidian oocyte is a large cell containing cytoplasmic and cortical domains polarized along a primary animal-vegetal (a-v) axis. The oocyte cortex is characterized by a gradient distribution of a submembrane monolayer of cortical rough endoplasmic reticulum (cER) and associated maternal postplasmic/PEM mRNAs (cER-mRNA domain). Between fertilization and first cleavage, this cER-mRNA domain is first concentrated vegetally and then relocated towards the posterior pole via microfilament-driven cortical contractions and spermaster-microtubule-driven translocations. The cER-mRNA domain further concentrates in a macroscopic cortical structure called the centrosome attracting body (CAB), which mediates a series of asymmetric divisions starting at the eight-cell stage. This results in the segregation of determinant mRNAs and their products in posterior cells of the embryo precursors of the muscle and germ line. Using two species of ascidians (Ciona intestinalis and Phallusia mammillata), we have pursued and amplified the work initiated in Halocynthia roretzi. We have analysed the cortical reorganizations in whole cells and in cortical fragments isolated from oocytes and from synchronously developing zygotes and embryos. After fertilization, we observe that a cortical patch rich in microfilaments encircles the cER-mRNA domain, concentrated into a cortical cap at the vegetal/contraction pole (indicating the future dorsal pole). Isolated cortices also retain microtubule asters rich in cER (indicating the future posterior pole). Before mitosis, parts of the cER-mRNA domain are detected, together with short microtubules, in isolated posterior (but not anterior) cortices. At the eight-cell stage, the posteriorly located cER-mRNA domain undergoes a cell-cycle-dependant compaction into the CAB. The CAB with embedded centrosomal microtubules can be isolated with cortical fragments from eight-cell-stage embryos. These and previous observations indicate that cytoskeleton-driven repositioning and compaction of a polarized cortical domain made of rough ER is a conserved mechanism used for polarization and segregation of cortical maternal mRNAs in embryos of evolutionarily distant species of ascidians.

Radiation tolerant compact image sensor using CdTe photodiode and field emitter array (Conference Presentation)

NASA Astrophysics Data System (ADS)

Masuzawa, Tomoaki; Neo, Yoichiro; Mimura, Hidenori; Okamoto, Tamotsu; Nagao, Masayoshi; Akiyoshi, Masafumi; Sato, Nobuhiro; Takagi, Ikuji; Tsuji, Hiroshi; Gotoh, Yasuhito

2016-10-01

A growing demand on incident detection is recognized since the Great East Japan Earthquake and successive accidents in Fukushima nuclear power plant in 2011. Radiation tolerant image sensors are powerful tools to collect crucial information at initial stages of such incidents. However, semiconductor based image sensors such as CMOS and CCD have limited tolerance to radiation exposure. Image sensors used in nuclear facilities are conventional vacuum tubes using thermal cathodes, which have large size and high power consumption. In this study, we propose a compact image sensor composed of a CdTe-based photodiode and a matrix-driven Spindt-type electron beam source called field emitter array (FEA). A basic principle of FEA-based image sensors is similar to conventional Vidicon type camera tubes, but its electron source is replaced from a thermal cathode to FEA. The use of a field emitter as an electron source should enable significant size reduction while maintaining high radiation tolerance. Current researches on radiation tolerant FEAs and development of CdTe based photoconductive films will be presented.

A compact centrifugal blood pump for extracorporeal circulation: design and performance.

PubMed

Tanaka, S; Yamamoto, S; Yamakoshi, K; Kamiya, A

1987-08-01

A new compact centrifugal blood pump driven by a miniature DC servomotor has been designed for use for short-term extra corporeal and cardiac-assisted circulation. The impeller of the pump was connected directly to the motor by using a simple-gear coupling. The shaft for the impeller was sealed from blood by both a V-ring and a seal bearing. Either pulsatile or nonpusatile flow was produced by controlling the current supply to the motor. The pump characteristics and the degree of hemolysis were evaluated with regard to the configuration of the impeller with a 38-mm outer diameter in vitro tests; the impeller having the blade angles at the inlet of 20 deg and at the outlet of 50 deg was the most appropriate as a blood pump. The performance in an operation, hemolysis and thrombus formation in the pump were assessed by a left ventricular bypass experiment in dogs. It was suggested by this study that this prototype pump appears promising for use not only in animal experiments but also in clinical application.

Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator

NASA Astrophysics Data System (ADS)

Skalyga, V.; Izotov, I.; Golubev, S.; Razin, S.; Sidorov, A.; Maslennikova, A.; Volovecky, A.; Kalvas, T.; Koivisto, H.; Tarvainen, O.

2014-12-01

Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D-D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm2 is demonstrated. Estimations based on obtained experimental results show that neutron target bombarded by such deuteron beams would theoretically yield a neutron flux density up to 6·1010 cm-2/s. Thus, neutron generator based on a high-current deuteron ECR source with a powerful plasma heating by gyrotron radiation could fulfill the BNCT requirements significantly lower price, smaller size and ease of operation in comparison with existing reactors and accelerators.

Design of compact piezoelectric transducers for shock wave applications

NASA Astrophysics Data System (ADS)

Dreyer, Thomas; Liebler, Marko; Riedlinger, Rainer E.; Ginter, Siegfried

2003-10-01

The application of focused intense sound pulses to treat several orthopedic diseases has gained in importance during the past years. Self-focusing piezoelectric transducers known from ESWL are not well suited for this purpose due to their size. Therefore compact transducers have to be designed. This implies an increase of the pressure pulse amplitude generated at the radiating surface. A stacked placement of two piezoelectric layers driven by two high-voltage pulses with an adjustable delay accomplishes this. Several designs are presented here representing transducers of different sizes. In principle piezoelectric transducers have the ability to vary the pressure pulse shape to a wider extent than other shock wave sources. Based on FEM simulations of the transducer the influence of some driving parameters, like a variation of the interpulse delay or shape of the driving voltage, on the resulting focal pressure signal is demonstrated. The results show the feasibility to control some parameters of the signal, for example the peak negative pressure amplitude. This possibility could provide new aspects in basic research as well as in clinical applications.

A Pre-ionization System to Limit Neutral Gas in a Compact Toroid Injector

NASA Astrophysics Data System (ADS)

Allfrey, Ian; Roche, Thomas; Matsumoto, Tadafumi; Garate, Eusebio; Gota, Hiroshi; Asai, Tomohiko; the TAE Team

2016-10-01

Fusion plasmas require long lifetimes and high temperatures, both of which are limited by particle loss, among other factors. Therefore, refueling a long-lived advanced beam-driven field-reversed configuration (FRC) plasma in C-2U is necessary, and injecting a supersonic compact toroid (CT) is an effective means of introducing particles into the FRC core. However, neutral gas that trails the CT into the target chamber cools the FRC. Pre-ionization (PI) system assists the break down between electrodes of the CT injector (CTI), so the amount of introduced gas can be lowered by up to a factor of two, effectively increasing the ionization fraction; thus, reducing the amount of neutral gas in the system. Additionally, the PI decreases the delay in CTI breakdown so a highly reproducible operation is achievable. The PI system consists of a fast, high voltage, pulse discharge circuit coupled to a Teflon insulated semi-rigid coaxial cable inserted into the CTI. System details and experimental data will be presented, in addition to issues such as the introduction of impurities and pre-ionizer lifetime.

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

Isfahani, RN; Moghaddam, S

An experimental study on absorption characteristics of water vapor into a thin lithium bromide (LiBr) solution flow is presented. The LiBr solution flow is constrained between a superhydrophobic vapor permeable wall and a solid surface that removes the heat of absorption. As opposed to conventional falling film absorbers, in this configuration, the solution film thickness and velocity can be controlled independently to enhance the absorption rate. The effects of water vapor pressure, cooling surface temperature, solution film thickness, and solution flow velocity on the absorption rate are studied. An absorption rate of approximately 0.006 kg/m(2) s was measured at amore » LiBr solution channel thickness and flow velocity of 100 mu m and 5 mm/s, respectively. The absorption rate increased linearly with the water vapor driving potential at the test conditions of this study. It was demonstrated that decreasing the solution film thickness and increasing the solution velocity enhance the absorption rate. The high absorption rate and the inherently compact form of the proposed,absorber facilitate development of compact small-scale waste heat or solar-thermal driven cooling systems. Published by Elsevier Ltd.« less

Compact sub-nanosecond pulse seed source with diode laser driven by a high-speed circuit

NASA Astrophysics Data System (ADS)

Wang, Xiaoqian; Wang, Bo; Wang, Junhua; Cheng, Wenyong

2018-06-01

A compact sub-nanosecond pulse seed source with 1550 nm diode laser (DL) was obtained by employing a high-speed circuit. The circuit mainly consisted of a short pulse generator and a short pulse driver. The short pulse generator, making up of a complex programmable logic device (CPLD), a level translator, two programmable delay chips and an AND gate chip, output a triggering signal to control metal-oxide-semiconductor field-effect transistor (MOSFET) switch of the short pulse driver. The MOSFET switch with fast rising time and falling time both shorter than 1 ns drove the DL to emit short optical pulses. Performances of the pulse seed source were tested. The results showed that continuously adjustable repetition frequency ranging from 500 kHz to 100 MHz and pulse duration in the range of 538 ps to 10 ns were obtained, respectively. 537 μW output was obtained at the highest repetition frequency of 100 MHz with the shortest pulse duration of 538 ps. These seed pulses were injected into an fiber amplifier, and no optical pulse distortions were found.

Liquid phase sintered compacts in space

NASA Technical Reports Server (NTRS)

Mookherji, T. K.; Mcanelly, W. B.

1974-01-01

A model that will explain the effect of gravity on liquid phase sintering was developed. Wetting characteristics and density segregation which are the two important phenomena in liquid phase sintering are considered in the model development. Experiments were conducted on some selected material combinations to study the gravity effects on liquid phase sintering, and to verify the validity of the model. It is concluded that: (1) The surface tension forces acting on solid particles in a one-g environment are not appreciably different from those anticipated in a 0.00001g/g sub 0 (or lower) environment. (2) The capillary forces are dependent on the contact angle, the quantity of the liquid phase, and the distance between solid particles. (3) The pores (i.e., bubbles) do not appear to be driven to the surface by gravity-produced buoyancy forces. (4) The length of time to produce the same degree of settling in a low-gravity environment will be increased significantly. (5) A low gravity environment would appear to offer a unique means of satisfactorily infiltrating a larger and/or complex shaped compact.

Modeling of the multilevel conduction characteristics and fatigue profile of Ag/La1/3Ca2/3MnO3/Pt structures using a compact memristive approach

NASA Astrophysics Data System (ADS)

Miranda, E.; Román Acevedo, W.; Rubi, D.; Lüders, U.; Granell, P.; Suñé, J.; Levy, P.

2017-05-01

The hysteretic conduction characteristics and fatigue profile of La1/3Ca2/3MnO3 (LCMO)-based memristive devices were investigated. The oxide films were grown by pulsed laser deposition (PLD) and sandwiched between Ag and Pt electrodes. The devices exhibit bipolar resistive switching (RS) effect with well-defined intermediate conduction states that arise from partial SET and RESET events. The current-voltage curves are modeled and simulated using a compact memristive approach. Two equations are considered: one for the electron transport based on the double-diode equation and the other for the memory state of the device driven by the play operator with logistic ridge functions. An expression that accounts for the remnant resistance of the device is obtained after simplifying the model equations in the low-voltage limit. The role played by the power dissipation in the LCMO reset dynamics as well as the asymmetrical reduction of the resistance window caused by long trains of switching pulses are discussed.

Laser Acceleration of Ions for Radiation Therapy

NASA Astrophysics Data System (ADS)

Tajima, Toshiki; Habs, Dietrich; Yan, Xueqing

Ion beam therapy for cancer has proven to be a successful clinical approach, affording as good a cure as surgery and a higher quality of life. However, the ion beam therapy installation is large and expensive, limiting its availability for public benefit. One of the hurdles is to make the accelerator more compact on the basis of conventional technology. Laser acceleration of ions represents a rapidly developing young field. The prevailing acceleration mechanism (known as target normal sheath acceleration, TNSA), however, shows severe limitations in some key elements. We now witness that a new regime of coherent acceleration of ions by laser (CAIL) has been studied to overcome many of these problems and accelerate protons and carbon ions to high energies with higher efficiencies. Emerging scaling laws indicate possible realization of an ion therapy facility with compact, cost-efficient lasers. Furthermore, dense particle bunches may allow the use of much higher collective fields, reducing the size of beam transport and dump systems. Though ultimate realization of a laser-driven medical facility may take many years, the field is developing fast with many conceptual innovations and technical progress.

Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors

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

Kumar, Suhas; Wang, Ziwen; Huang, Xiaopeng

Due to the favorable operating power, endurance, speed, and density., transition-metal-oxide memristors, or resistive random-access memory (RRAM) switches, are under intense development for storage-class memory. Their commercial deployment critically depends on predictive compact models based on understanding nanoscale physiocochemical forces, which remains elusive and controversial owing to the difficulties in directly observing atomic motions during resistive switching, Here, using scanning transmission synchrotron X-ray spectromicroscopy to study in situ switching of hafnium oxide memristors, we directly observed the formation of a localized oxygen-deficiency-derived conductive channel surrounded by a low-conductivity ring of excess oxygen. Subsequent thermal annealing homogenized the segregated oxygen, resettingmore » the cells toward their as-grown resistance state. We show that the formation and dissolution of the conduction channel are successfully modeled by radial thermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This confirmation and quantification of two opposing nanoscale radial forces that affect bipolar memristor switching are important components for any future physics-based compact model for the electronic switching of these devices.« less

Generation and application of ultrashort coherent mid-infrared electromagnetic radiation

NASA Astrophysics Data System (ADS)

Wandel, Scott

Particle accelerators are useful instruments that help address critical issues for the future development of nuclear energy. Current state-of-the-art accelerators based on conventional radio-frequency (rf) cavities are too large and expensive for widespread commercial use, and alternative designs must be considered for supplying relativistic beams to small-scale applications, including medical imaging, secu- rity screening, and scientific research in a university-scale laboratory. Laser-driven acceleration using micro-fabricated dielectric photonic structures is an attractive approach because such photonic microstructures can support accelerating fields that are 10 to 100 times higher than that of rf cavity-based accelerators. Dielectric laser accelerators (DLAs) use commercial lasers as a driving source, which are smaller and less expensive than the klystrons used to drive current rf-based accelerators. Despite the apparent need for compact and economical laser sources for laser-driven acceleration, the availability of suitable high-peak-power lasers that cover a broad spectral range is currently limited. To address the needs of several innovative acceleration mechanisms like DLA, it is proposed to develop a coherent source of mid-infrared (IR) electromagnetic radiation that can be implemented as a driving source of laser accelerators. The use of ultrashort mid-IR high peak power laser systems in various laser-driven acceleration schemes has shown the potential to greatly reduce the optical pump intensities needed to realize high acceleration gradients. The optical intensity needed to achieve a given ponderomotive potential is 25 times less when using a 5-mum mid-IR laser as compared to using a 1-mum near-IR solid-state laser. In addition, dielectric structure breakdown caused by multiphoton ionization can be avoided by using longer-wavelength driving lasers. Current mid-IR laser sources do not produce sufficiently short pulse durations, broad spectral bandwidths, or high energies as required by certain accelerator applications. The use of a high-peak-power mid-IR laser system in DLA could enable tabletop accelerators on the MeV to GeV scale for security scanners, medical therapy devices, and compact x-ray light sources. This dissertation reports on the design and construction of a simple and robust, short-pulse parametric source operating at a center wavelength of 5 mum. The design and construction of a high-energy, short-pulse 2-mum parametric source is also presented, which serves as a surrogate pumping source for the 5-mum source. An elegant method for mid-IR pulse characterization is demonstrated, which makes use of ubiquitous silicon photodetectors, traditionally reserved for the characterization of near-IR radiation. In addition, a dual-chirped parametric amplification technique is extended into the mid-IR spectral region, producing a bandwidth-tunable mid-IR source in a simple design without sacrificing conversion efficiency. The design and development of a compact single-shot mid-IR prism spectrometer is also reported, and its implementation in a number of condensed matter studies at the Linac Coherent Light Source (LCLS) at the Stanford Linear Accelerator Center is discussed. Rapid tuning and optimization of a high-energy parametric laser system using the mid-IR spectrometer is demonstrated, which significantly enhances the capabilities of performing optical measurements on superconducting materials using the LCLS instrument. All of the laser sources and optical technologies presented in this dissertation were developed using relatively simple designs to provide compact and cost-e ective systems to address some of the challenges facing accelerator and IR spectroscopy technologies. (Abstract shortened by ProQuest.).

Status of intense permanent magnet proton source for China-accelerator driven sub-critical system Linac.

PubMed

Wu, Q; Ma, H Y; Yang, Y; Sun, L T; Zhang, X Z; Zhang, Z M; Zhao, H Y; He, Y; Zhao, H W

2016-02-01

Two compact intense 2.45 GHz permanent magnet proton sources and their corresponding low energy beam transport (LEBT) system were developed successfully for China accelerator driven sub-critical system in 2014. Both the proton sources operate at 35 kV potential. The beams extracted from the ion source are transported by the LEBT, which is composed of two identical solenoids, to the 2.1 MeV Radio-Frequency Quadrupole (RFQ). In order to ensure the safety of the superconducting cavities during commissioning, an electrostatic-chopper has been designed and installed in the LEBT line that can chop the continuous wave beam into a pulsed one. The minimum width of the pulse is less than 10 μs and the fall/rise time of the chopper is about 20 ns. The performance of the proton source and the LEBT, such as beam current, beam profile, emittance and the impact to RFQ injection will be presented.

Status of intense permanent magnet proton source for China-accelerator driven sub-critical system Linac

NASA Astrophysics Data System (ADS)

Wu, Q.; Ma, H. Y.; Yang, Y.; Sun, L. T.; Zhang, X. Z.; Zhang, Z. M.; Zhao, H. Y.; He, Y.; Zhao, H. W.

2016-02-01

Two compact intense 2.45 GHz permanent magnet proton sources and their corresponding low energy beam transport (LEBT) system were developed successfully for China accelerator driven sub-critical system in 2014. Both the proton sources operate at 35 kV potential. The beams extracted from the ion source are transported by the LEBT, which is composed of two identical solenoids, to the 2.1 MeV Radio-Frequency Quadrupole (RFQ). In order to ensure the safety of the superconducting cavities during commissioning, an electrostatic-chopper has been designed and installed in the LEBT line that can chop the continuous wave beam into a pulsed one. The minimum width of the pulse is less than 10 μs and the fall/rise time of the chopper is about 20 ns. The performance of the proton source and the LEBT, such as beam current, beam profile, emittance and the impact to RFQ injection will be presented.

Radiobiological effectiveness of laser accelerated electrons in comparison to electron beams from a conventional linear accelerator.

PubMed

Laschinsky, Lydia; Baumann, Michael; Beyreuther, Elke; Enghardt, Wolfgang; Kaluza, Malte; Karsch, Leonhard; Lessmann, Elisabeth; Naumburger, Doreen; Nicolai, Maria; Richter, Christian; Sauerbrey, Roland; Schlenvoigt, Hans-Peter; Pawelke, Jörg

2012-01-01

The notable progress in laser particle acceleration technology promises potential medical application in cancer therapy through compact and cost effective laser devices that are suitable for already existing clinics. Previously, consequences on the radiobiological response by laser driven particle beams characterised by an ultra high peak dose rate have to be investigated. Therefore, tumour and non-malignant cells were irradiated with pulsed laser accelerated electrons at the JETI facility for the comparison with continuous electrons of a conventional therapy LINAC. Dose response curves were measured for the biological endpoints clonogenic survival and residual DNA double strand breaks. The overall results show no significant differences in radiobiological response for in vitro cell experiments between laser accelerated pulsed and clinical used electron beams. These first systematic in vitro cell response studies with precise dosimetry to laser driven electron beams represent a first step toward the long term aim of the application of laser accelerated particles in radiotherapy.

Development of solid tunable optics for ultra-miniature imaging systems

NASA Astrophysics Data System (ADS)

Yongchao, Zou

This thesis focuses on the optimal design, fabrication and testing of solid tunable optics and exploring their applications in miniature imaging systems. It starts with the numerical modelling of such lenses, followed by the optimum design method and alignment tolerance analysis. A miniature solid tunable lens driven by a piezo actuator is then developed. To solve the problem of limited maximum optical power and tuning range in conventional lens designs, a novel multi-element solid tunable lens is proposed and developed. Inspired by the Alvarez principle, a novel miniature solid tunable dual-focus lens, which is designed using freeform surfaces and driven by one micro-electro-mechanical-systems (MEMS) rotary actuator, is demonstrated. To explore the applications of these miniature solid tunable lenses, a miniature adjustable-focus endoscope and one compact adjustable-focus camera module are developed. The adjustable-focus capability of these two miniature imaging systems is fully proved by electrically focusing targets placed at different positions.

Wide operating window spin-torque majority gate towards large-scale integration of logic circuits

NASA Astrophysics Data System (ADS)

Vaysset, Adrien; Zografos, Odysseas; Manfrini, Mauricio; Mocuta, Dan; Radu, Iuliana P.

2018-05-01

Spin Torque Majority Gate (STMG) is a logic concept that inherits the non-volatility and the compact size of MRAM devices. In the original STMG design, the operating range was restricted to very small size and anisotropy, due to the exchange-driven character of domain expansion. Here, we propose an improved STMG concept where the domain wall is driven with current. Thus, input switching and domain wall propagation are decoupled, leading to higher energy efficiency and allowing greater technological optimization. To ensure majority operation, pinning sites are introduced. We observe through micromagnetic simulations that the new structure works for all input combinations, regardless of the initial state. Contrary to the original concept, the working condition is only given by threshold and depinning currents. Moreover, cascading is now possible over long distances and fan-out is demonstrated. Therefore, this improved STMG concept is ready to build complete Boolean circuits in absence of external magnetic fields.

A high performance field-reversed configuration

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

Binderbauer, M. W.; Tajima, T.; Steinhauer, L. C.

2015-05-15

Conventional field-reversed configurations (FRCs), high-beta, prolate compact toroids embedded in poloidal magnetic fields, face notable stability and confinement concerns. These can be ameliorated by various control techniques, such as introducing a significant fast ion population. Indeed, adding neutral beam injection into the FRC over the past half-decade has contributed to striking improvements in confinement and stability. Further, the addition of electrically biased plasma guns at the ends, magnetic end plugs, and advanced surface conditioning led to dramatic reductions in turbulence-driven losses and greatly improved stability. Together, these enabled the build-up of a well-confined and dominant fast-ion population. Under such conditions,more » highly reproducible, macroscopically stable hot FRCs (with total plasma temperature of ∼1 keV) with record lifetimes were achieved. These accomplishments point to the prospect of advanced, beam-driven FRCs as an intriguing path toward fusion reactors. This paper reviews key results and presents context for further interpretation.« less

Quasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV

PubMed Central

Wang, Xiaoming; Zgadzaj, Rafal; Fazel, Neil; Li, Zhengyan; Yi, S. A.; Zhang, Xi; Henderson, Watson; Chang, Y.-Y.; Korzekwa, R.; Tsai, H.-E.; Pai, C.-H.; Quevedo, H.; Dyer, G.; Gaul, E.; Martinez, M.; Bernstein, A. C.; Borger, T.; Spinks, M.; Donovan, M.; Khudik, V.; Shvets, G.; Ditmire, T.; Downer, M. C.

2013-01-01

Laser-plasma accelerators of only a centimetre’s length have produced nearly monoenergetic electron bunches with energy as high as 1 GeV. Scaling these compact accelerators to multi-gigaelectronvolt energy would open the prospect of building X-ray free-electron lasers and linear colliders hundreds of times smaller than conventional facilities, but the 1 GeV barrier has so far proven insurmountable. Here, by applying new petawatt laser technology, we produce electron bunches with a spectrum prominently peaked at 2 GeV with only a few per cent energy spread and unprecedented sub-milliradian divergence. Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion. Simulations indicate that with improvements in the laser-pulse focus quality, acceleration to nearly 10 GeV should be possible with the available pulse energy. PMID:23756359

Wind-Driven Formation of Ice Bridges in Straits.

PubMed

Rallabandi, Bhargav; Zheng, Zhong; Winton, Michael; Stone, Howard A

2017-03-24

Ice bridges are static structures composed of tightly packed sea ice that can form during the course of its flow through a narrow strait. Despite their important role in local ecology and climate, the formation and breakup of ice bridges is not well understood and has proved difficult to predict. Using long-wave approximations and a continuum description of sea ice dynamics, we develop a one-dimensional theory for the wind-driven formation of ice bridges in narrow straits, which is verified against direct numerical simulations. We show that for a given wind stress and minimum and maximum channel widths, a steady-state ice bridge can only form beyond a critical value of the thickness and the compactness of the ice field. The theory also makes quantitative predictions for ice fluxes, which are particularly useful to estimate the ice export associated with the breakup of ice bridges. We note that similar ideas are applicable to dense granular flows in confined geometries.

Enhanced betatron radiation by steering a laser-driven plasma wakefield with a tilted shock front

NASA Astrophysics Data System (ADS)

Yu, Changhai; Liu, Jiansheng; Wang, Wentao; Li, Wentao; Qi, Rong; Zhang, Zhijun; Qin, Zhiyong; Liu, Jiaqi; Fang, Ming; Feng, Ke; Wu, Ying; Ke, Lintong; Chen, Yu; Wang, Cheng; Xu, Yi; Leng, Yuxin; Xia, Changquan; Li, Ruxin; Xu, Zhizhan

2018-03-01

We have experimentally realized a scheme to enhance betatron radiation by manipulating transverse oscillation of electrons in a laser-driven plasma wakefield with a tilted shock front (TSF). Very brilliant betatron x-rays have been produced with significant enhancement both in photon yield and peak energy but almost maintain the e-beam energy spread and charge. Particle-in-cell simulations indicate that the accelerated electron beam (e beam) can acquire a very large transverse oscillation amplitude with an increase in more than 10-fold, after being steered into the deflected wakefield due to the refraction of the driving laser at the TSF. Spectral broadening of betatron radiation can be suppressed owing to the small variation in the peak energy of the low-energy-spread e beam in a plasma wiggler regime. It is demonstrated that the e-beam generation, refracting, and wiggling can act as a whole to realize the concurrence of monoenergetic e beams and bright x-rays in a compact laser-wakefield accelerator.

Motion analysis and trials of the deep sea hybrid underwater glider Petrel-II

NASA Astrophysics Data System (ADS)

Liu, Fang; Wang, Yan-hui; Wu, Zhi-liang; Wang, Shu-xin

2017-03-01

A hybrid underwater glider Petrel-II has been developed and field tested. It is equipped with an active buoyancy unit and a compact propeller unit. Its working modes have been expanded to buoyancy driven gliding and propeller driven level-flight, which can make the glider work in strong currents, as well as many other complicated ocean environments. Its maximal gliding speed reaches 1 knot and the propelling speed is up to 3 knots. In this paper, a 3D dynamic model of Petrel-II is derived using linear momentum and angular momentum equations. According to the dynamic model, the spiral motion in the underwater space is simulated for the gliding mode. Similarly the cycle motion on water surface and the depth-keeping motion underwater are simulated for the level-flight mode. These simulations are important to the performance analysis and parameter optimization for the Petrel-II underwater glider. The simulation results show a good agreement with field trials.

Poynting-Flux-Driven Bubbles and Shocks Around Merging Neutron Star Binaries

NASA Astrophysics Data System (ADS)

Medvedev, M. V.; Loeb, A.

2013-04-01

Merging binaries of compact relativistic objects are thought to be progenitors of short gamma-ray bursts. Because of the strong magnetic field of one or both binary members and high orbital frequencies, these binaries are strong sources of energy in the form of Poynting flux. The steady injection of energy by the binary forms a bubble filled with matter with the relativistic equation of state, which pushes on the surrounding plasma and can drive a shock wave in it. Unlike the Sedov-von Neumann-Taylor blast wave solution for a point-like explosion, the shock wave here is continuously driven by the ever-increasing pressure inside the bubble. We calculate from the first principles the dynamics and evolution of the bubble and the shock surrounding it, demonstrate that it exhibits finite time singularity and find the corresponding analytical solution. We predict that such binaries can be observed as radio sources a few hours before and after the merger.

Specific and highly efficient condensation of GC and IC DNA by polyaza pyridinophane derivatives.

PubMed

Stojković, Marijana Radić; Gonzalez-Garcia, Jorge; Šupljika, Filip; Galiana-Rosello, Cristina; Guijarro, Lluis; Gazze, Salvatore A; Francis, Lewis W; Piantanida, Ivo; Garcia-Espana, Enrique

2018-04-01

Two bis-polyaza pyridinophane derivatives and their monomeric reference compounds revealed strong interactions with ds-DNA and RNA. The bis-derivatives show a specific condensation of GC- and IC-DNA, which is almost two orders of magnitude more efficient than the well-known condensation agent spermine. The type of condensed DNA was identified as ψ-DNA, characterized by the exceptionally strong CD signals. At variance to the almost silent AT(U) polynucleotides, these strong CD signals allow the determination of GC-condensates at nanomolar nucleobase concentrations. Detailed thermodynamic characterisation by ITC reveals significant differences between the DNA binding of the bis-derivative compounds (enthalpy driven) and that of spermine and of their monomeric counterparts (entropy driven). Atomic force microscopy confirmed GC-DNA compaction by the bis-derivatives and the formation of toroid- and rod-like structures responsible for the ψ-type pattern in the CD spectra. Copyright © 2017 Elsevier B.V. All rights reserved.

Non-inductively driven tokamak plasmas at near-unity βt in the Pegasus toroidal experiment

NASA Astrophysics Data System (ADS)

Reusch, J. A.; Bodner, G. M.; Bongard, M. W.; Burke, M. G.; Fonck, R. J.; Pachicano, J. L.; Perry, J. M.; Pierren, C.; Rhodes, A. T.; Richner, N. J.; Rodriguez Sanchez, C.; Schlossberg, D. J.; Weberski, J. D.

2018-05-01

A major goal of the spherical tokamak (ST) research program is accessing a state of low internal inductance ℓi, high elongation κ, and high toroidal and normalized beta ( βt and βN) without solenoidal current drive. Local helicity injection (LHI) in the Pegasus ST [Garstka et al., Nucl. Fusion 46, S603 (2006)] provides non-solenoidally driven plasmas that exhibit these characteristics. LHI utilizes compact, edge-localized current sources for plasma startup and sustainment. It results in hollow current density profiles with low ℓi. The low aspect ratio ( R0/a ˜1.2 ) of Pegasus allows access to high κ and high normalized plasma currents ( IN=Ip/a BT>14 ). Magnetic reconnection during LHI provides auxiliary ion heating. Together, these features provide access to very high βt plasmas. Equilibrium analyses indicate that βt up to ˜100% is achieved. These high βt discharges disrupt at the ideal no-wall β limit at βN˜7.

Synthetic Bursae for Robots

NASA Technical Reports Server (NTRS)

Lovchik, Christopher S.

2005-01-01

Synthetic bursae are under development for incorporation into robot joints that are actuated by motor-driven cables in a manner similar to that of arthropod joints actuated by muscle-driven tendons. Like natural bursae, the synthetic bursae would serve as cushions and friction reducers. A natural bursa is a thin bladder filled with synovial fluid, which serves to reduce friction and provide a cushion between a bone and a muscle or a tendon. A synthetic bursa would be similar in form and function: It would be, essentially, a compact, soft roller consisting of a bladder filled with a non-Newtonian fluid. The bladder would be constrained to approximately constant volume. The synthetic bursa would cushion an actuator cable against one of the members of a robot joint and would reduce the friction between the cable and the member. Under load, the pressure in the bladder would hold the opposite walls of the bladder apart, making it possible for them to move freely past each other without rubbing.

Neutron-star–black-hole binaries produced by binary-driven hypernovae

DOE PAGES

Fryer, Chris L.; Oliveira, F. G.; Rueda, Jorge A.; ...

2015-12-04

Here, binary-driven hypernovae (BdHNe) within the induced gravitational collapse paradigm have been introduced to explain energetic (E iso ≳10 52 erg), long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe). The progenitor is a tight binary composed of a carbon-oxygen (CO) core and a neutron-star (NS) companion, a subclass of the newly proposed “ultrastripped” binaries. The CO-NS short-period orbit causes the NS to accrete appreciable matter from the SN ejecta when the CO core collapses, ultimately causing it to collapse to a black hole (BH) and producing a GRB. These tight binaries evolve through the SN explosion very differentlymore » than compact binaries studied in population synthesis calculations. First, the hypercritical accretion onto the NS companion alters both the mass and the momentum of the binary. Second, because the explosion time scale is on par with the orbital period, the mass ejection cannot be assumed to be instantaneous. This dramatically affects the post-SN fate of the binary. Finally, the bow shock created as the accreting NS plows through the SN ejecta transfers angular momentum, braking the orbit. These systems remain bound even if a large fraction of the binary mass is lost in the explosion (well above the canonical 50% limit), and even large kicks are unlikely to unbind the system. Indeed, BdHNe produce a new family of NS-BH binaries unaccounted for in current population synthesis analyses and, although they may be rare, the fact that nearly 100% remain bound implies that they may play an important role in the compact merger rate, important for gravitational waves that, in turn, can produce a new class of ultrashort GRBs.« less

Compact D-D Neutron Source-Driven Subcritical Multiplier and Beam-Shaping Assembly for Boron Neutron Capture Therapy

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

Francesco Ganda; Jasmina Vujic; Ehud Greenspan

2010-12-01

This work assesses the feasibility of using a small, safe, and inexpensive keff 0.98 subcritical fission assembly [subcritical neutron multiplier (SCM)] to amplify the treatment neutron beam intensity attainable from a compact deuterium-deuterium (D-D) fusion neutron source delivering [approximately]1012 n/s. The objective is to reduce the treatment time for deep-seated brain tumors to [approximately]1 h. The paper describes the optimal SCM design and two optimal beam-shaping assemblies (BSAs) - one designed to maximize the dose rate and the other designed to maximize the total dose that can be delivered to a deep-seated tumor. The neutron beam intensity amplification achieved withmore » the optimized SCM and BSA results in an increase in the treatment dose rate by a factor of 18: from 0.56 Gy/h without the SCM to 10.1 Gy/h. The entire SCM is encased in an aluminum structure. The total amount of 20% enriched uranium required for the SCM is 8.5 kg, and the cost (not including fabrication) is estimated to be less than $60,000. The SCM power level is estimated at 400 W when driven by a 1012 n/s D-D neutron source. This translates into consumption of only [approximately]0.6% of the initially loaded 235U atoms during 50 years of continuous operation and implies that the SCM could operate continuously for the entire lifetime of the facility without refueling. Cooling the SCM does not pose a challenge; it may be accomplished by natural circulation as the maximum heat flux is only 0.034 W/cm2.« less

Neutron-Star-Black-Hole Binaries Produced by Binary-Driven Hypernovae.

PubMed

Fryer, Chris L; Oliveira, F G; Rueda, J A; Ruffini, R

2015-12-04

Binary-driven hypernovae (BdHNe) within the induced gravitational collapse paradigm have been introduced to explain energetic (E_{iso}≳10^{52}  erg), long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe). The progenitor is a tight binary composed of a carbon-oxygen (CO) core and a neutron-star (NS) companion, a subclass of the newly proposed "ultrastripped" binaries. The CO-NS short-period orbit causes the NS to accrete appreciable matter from the SN ejecta when the CO core collapses, ultimately causing it to collapse to a black hole (BH) and producing a GRB. These tight binaries evolve through the SN explosion very differently than compact binaries studied in population synthesis calculations. First, the hypercritical accretion onto the NS companion alters both the mass and the momentum of the binary. Second, because the explosion time scale is on par with the orbital period, the mass ejection cannot be assumed to be instantaneous. This dramatically affects the post-SN fate of the binary. Finally, the bow shock created as the accreting NS plows through the SN ejecta transfers angular momentum, braking the orbit. These systems remain bound even if a large fraction of the binary mass is lost in the explosion (well above the canonical 50% limit), and even large kicks are unlikely to unbind the system. Indeed, BdHNe produce a new family of NS-BH binaries unaccounted for in current population synthesis analyses and, although they may be rare, the fact that nearly 100% remain bound implies that they may play an important role in the compact merger rate, important for gravitational waves that, in turn, can produce a new class of ultrashort GRBs.

The radio properties of infrared-faint radio sources

NASA Astrophysics Data System (ADS)

Middelberg, E.; Norris, R. P.; Hales, C. A.; Seymour, N.; Johnston-Hollitt, M.; Huynh, M. T.; Lenc, E.; Mao, M. Y.

2011-02-01

Context. Infrared-faint radio sources (IFRS) are objects that have flux densities of several mJy at 1.4 GHz, but that are invisible at 3.6 μm when using sensitive Spitzer observations with μJy sensitivities. Their nature is unclear and difficult to investigate since they are only visible in the radio. Aims: High-resolution radio images and comprehensive spectral coverage can yield constraints on the emission mechanisms of IFRS and can give hints to similarities with known objects. Methods: We imaged a sample of 17 IFRS at 4.8 GHz and 8.6 GHz with the Australia Telescope Compact Array to determine the structures on arcsecond scales. We added radio data from other observing projects and from the literature to obtain broad-band radio spectra. Results: We find that the sources in our sample are either resolved out at the higher frequencies or are compact at resolutions of a few arcsec, which implies that they are smaller than a typical galaxy. The spectra of IFRS are remarkably steep, with a median spectral index of -1.4 and a prominent lack of spectral indices larger than -0.7. We also find that, given the IR non-detections, the ratio of 1.4 GHz flux density to 3.6 μm flux density is very high, and this puts them into the same regime as high-redshift radio galaxies. Conclusions: The evidence that IFRS are predominantly high-redshift sources driven by active galactic nuclei (AGN) is strong, even though not all IFRS may be caused by the same phenomenon. Compared to the rare and painstakingly collected high-redshift radio galaxies, IFRS appear to be much more abundant, but less luminous, AGN-driven galaxies at similar cosmological distances.

Laser technologies for ultrasensitive groundwater dating using long-lived isotopes

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

Backus, Sterling

In this phase I work, we propose to construct and demonstrate a 103 nm laser based on resonantly enhanced and phase matched fifth harmonic generation in hollow waveguides driven by a high power, low cost and compact ultrafast fiber laser. (Figure 4) This VUV laser source can potentially produce >100 milliwatts of VUV light at 103 nm with pulse repetition-rates of 100 kHz to 100 MHz, ideal for the above-mentioned applications. This technology is state-of-the-art and potentially compact, fieldable, low-cost, and of broad interest for a variety of science and technology applications. Laser-based VUV sources in the past have exhibitedmore » low repetition rate, low efficiency, low beam quality, and are based on expensive laser sources. Our approch is to combine ultrafast fiber laser drive technology, ultrafast pulses, and our proven waveguide technology, to create a high repetition rate, high average power VUV source for producing high yield metastable Krypton. At KMLabs we have been offering EUV light sources employing the high harmonic generation (HHG) process driven by high-power femtosecond lasers for >5 years now. Recently, we have developed much smaller scale (briefcase size), but still high average power femtosecond fiber laser sources to supply other markets, and create new ones. By combining these new laser sources with our patented waveguide frequency upconversion technology, we expect to be able to obtain >20mW average power initially, with potentially much higher powers depending on wavelength, in an affordable VUV product. For comparison, our current EUV light sources based on ti:sapphire generate an average power of ~5 µW (albeit at shorter 29 nm wavelength), and we are aware of one other supplier that has developed a VUV (112 nm) light source with ~10-20 µW power.« less

Melt segregation from silicic crystal mushes: a critical appraisal of possible mechanisms and their microstructural record

NASA Astrophysics Data System (ADS)

Holness, Marian B.

2018-06-01

One of the outstanding problems in understanding the behavior of intermediate-to-silicic magmatic systems is the mechanism(s) by which large volumes of crystal-poor rhyolite can be extracted from crystal-rich mushy storage zones in the mid-deep crust. The mechanisms commonly invoked are hindered settling, micro-settling, and compaction. The concept of micro-settling involves extraction of grains from a crystal framework during Ostwald ripening and has been shown to be non-viable in the metallic systems for which it was originally proposed. Micro-settling is also likely to be insignificant in silicic mushes, because ripening rates are slow for quartz and plagioclase, contact areas between grains in a crystal mush are likely to be large, and abundant low-angle grain boundaries promote grain coalescence rather than ripening. Published calculations of melt segregation rates by hindered settling (Stokes settling in a crystal-rich system) neglect all but fluid dynamical interactions between particles. Because tabular silicate minerals are likely to form open, mechanically coherent, frameworks at porosities as high as 75%, settling of single crystals is only likely in very melt-rich systems. Gravitationally-driven viscous compaction requires deformation of crystals by either dissolution-reprecipitation or dislocation creep. There is, as yet, no reported microstructural evidence of extensive, syn-magmatic, internally-generated, viscous deformation in fully solidified silicic plutonic rocks. If subsequent directed searches do not reveal clear evidence for internally-generated buoyancy-driven melt segregation processes, it is likely that other factors, such as rejuvenation by magma replenishment, gas filter-pressing, or externally-imposed stress during regional deformation, are required to segregate large volumes of crystal-poor rhyolitic liquids from crustal mushy zones.

Neutron-Star-Black-Hole Binaries Produced by Binary-Driven Hypernovae

NASA Astrophysics Data System (ADS)

Fryer, Chris L.; Oliveira, F. G.; Rueda, J. A.; Ruffini, R.

2015-12-01

Binary-driven hypernovae (BdHNe) within the induced gravitational collapse paradigm have been introduced to explain energetic (Eiso≳1052 erg ), long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe). The progenitor is a tight binary composed of a carbon-oxygen (CO) core and a neutron-star (NS) companion, a subclass of the newly proposed "ultrastripped" binaries. The CO-NS short-period orbit causes the NS to accrete appreciable matter from the SN ejecta when the CO core collapses, ultimately causing it to collapse to a black hole (BH) and producing a GRB. These tight binaries evolve through the SN explosion very differently than compact binaries studied in population synthesis calculations. First, the hypercritical accretion onto the NS companion alters both the mass and the momentum of the binary. Second, because the explosion time scale is on par with the orbital period, the mass ejection cannot be assumed to be instantaneous. This dramatically affects the post-SN fate of the binary. Finally, the bow shock created as the accreting NS plows through the SN ejecta transfers angular momentum, braking the orbit. These systems remain bound even if a large fraction of the binary mass is lost in the explosion (well above the canonical 50% limit), and even large kicks are unlikely to unbind the system. Indeed, BdHNe produce a new family of NS-BH binaries unaccounted for in current population synthesis analyses and, although they may be rare, the fact that nearly 100% remain bound implies that they may play an important role in the compact merger rate, important for gravitational waves that, in turn, can produce a new class of ultrashort GRBs.

A Broadband IR Compact High Resolution Spectrometer (BIRCHES) for a Lunar Water Distribution (LWaDi) Cubesat Mission

NASA Astrophysics Data System (ADS)

Clark, Pamela E.; Macdowall, Robert J.; Reuter, Dennis; Mauk, Robin

2014-11-01

We are in the process of developing the BIRCH (Broadband IR for Cubesats with High Resolution) Spectrometer for characterization of a range of deep space targets. BIRCH is the first extremely compact Broadband IR spectrometer with high spectral resolution designed to measure water type and component distribution for a science-driven cubesat mission, such as the lunar orbital mission LWaDi (Lunar Water Distribution) designed to determine the systematics of lunar water and volatiles as a function of time of day, latitude, and terrain. The development of cubesat form factor instruments, such as BIRCH, capable of providing high priority science goals identified in the decadal survey is critical to achieve low cost planetary exploration promised by the cubesat paradigm by exploring volatile systems via orbiting or landed packages. On the Moon, as well as Mercury, Mars, and the asteroids, the source, distribution, and role of volatiles is a question of major importance, and has implications for formation processes, including interior structure, differentiation, and the origin of life in the early solar system. The form and distribution of water has implications for human exploration, resource exploitation, and sample curation. Recent lunar missions gave unanticipated evidence for the water from NIR instruments not optimized for finding it. Our instrument includes a compact broadband HgCdTe detector with a linear variable filter and a compact cryocooler (for operation below 140K) attached to a compact optical system with 2 off-axis parabolic mirrors and variable field stop operating below 240K. Its 10 nm or better resolution and longer wavelength upper range (1.3 to 3.7 microns) are necessary to identify and separate features associated with water type (adsorbed, bound, ice) and components. Its 4-sided adjustable iris at the field stop enables a constant spot size (10 x 10 km) regardless of altitude. BIRCH will be able to provide systematic and extensive enough information to understand water’s life cycle, temporal and spatial distribution and interactions as a function of lunar cycles, characteristic features, and regolith composition.

Pulse-driven micro gas sensor fitted with clustered Pd/SnO2 nanoparticles.

PubMed

Suematsu, Koichi; Shin, Yuka; Ma, Nan; Oyama, Tokiharu; Sasaki, Miyuki; Yuasa, Masayoshi; Kida, Tetsuya; Shimanoe, Kengo

2015-08-18

Real-time monitoring of specific gas concentrations with a compact and portable gas sensing device is required to sense potential health risk and danger from toxic gases. For such purposes, we developed an ultrasmall gas sensor device, where a micro sensing film was deposited on a micro heater integrated with electrodes fabricated by the microelectromechanical system (MEMS) technology. The developed device was operated in a pulse-heating mode to significantly reduce the heater power consumption and make the device battery-driven and portable. Using clustered Pd/SnO2 nanoparticles, we succeeded in introducing mesopores ranging from 10 to 30 nm in the micro gas sensing film (area: ϕ 150 μm) to detect large volatile organic compounds (VOCs). The micro sensor showed quick, stable, and high sensor responses to toluene at ppm (parts per million) concentrations at 300 °C even by operating the micro heater in a pulse-heating mode where switch-on and -off cycles were repeated at one-second intervals. The high performance of the micro sensor should result from the creation of efficient diffusion paths decorated with Pd sensitizers by using the clustered Pd/SnO2 nanoparticles. Hence we demonstrate that our pulse-driven micro sensor using nanostructured oxide materials holds promise as a battery-operable, portable gas sensing device.

Seeding magnetic fields for laser-driven flux compression in high-energy-density plasmas.

PubMed

Gotchev, O V; Knauer, J P; Chang, P Y; Jang, N W; Shoup, M J; Meyerhofer, D D; Betti, R

2009-04-01

A compact, self-contained magnetic-seed-field generator (5 to 16 T) is the enabling technology for a novel laser-driven flux-compression scheme in laser-driven targets. A magnetized target is directly irradiated by a kilojoule or megajoule laser to compress the preseeded magnetic field to thousands of teslas. A fast (300 ns), 80 kA current pulse delivered by a portable pulsed-power system is discharged into a low-mass coil that surrounds the laser target. A >15 T target field has been demonstrated using a <100 J capacitor bank, a laser-triggered switch, and a low-impedance (<1 Omega) strip line. The device has been integrated into a series of magnetic-flux-compression experiments on the 60 beam, 30 kJ OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The initial application is a novel magneto-inertial fusion approach [O. V. Gotchev et al., J. Fusion Energy 27, 25 (2008)] to inertial confinement fusion (ICF), where the amplified magnetic field can inhibit thermal conduction losses from the hot spot of a compressed target. This can lead to the ignition of massive shells imploded with low velocity-a way of reaching higher gains than is possible with conventional ICF.

Study of Plasma Liner Driven Magnetized Target Fusion Via Advanced Simulations

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

Samulyak, Roman V.; Brookhaven National Lab.; Parks, Paul

The feasibility of the plasma liner driven Magnetized Target Fusion (MTF) via terascale numerical simulations will be assessed. In the MTF concept, a plasma liner, formed by merging of a number (60 or more) of radial, highly supersonic plasma jets, implodes on the target in the form of two compact plasma toroids, and compresses it to conditions of the fusion ignition. By avoiding major difficulties associated with both the traditional laser driven inertial confinement fusion and solid liner driven MTF, the plasma liner driven MTF potentially provides a low-cost and fast R&D path towards the demonstration of practical fusion energy.more » High fidelity numerical simulations of full nonlinear models associated with the plasma liner MTF using state-of-art numerical algorithms and terascale computing are necessary in order to resolve uncertainties and provide guidance for future experiments. At Stony Brook University, we have developed unique computational capabilities that ideally suite the MTF problem. The FronTier code, developed in collaboration with BNL and LANL under DOE funding including SciDAC for the simulation of 3D multi-material hydro and MHD flows, has beenbenchmarked and used for fundamental and engineering problems in energy science applications. We have performed 3D simulations of converging supersonic plasma jets, their merger and the formation of the plasma liner, and a study of the corresponding oblique shock problem. We have studied the implosion of the plasma liner on the magnetized plasma target by resolving Rayleigh-Taylor instabilities in 2D and 3D and other relevant physics and estimate thermodynamic conditions of the target at the moment of maximum compression and the hydrodynamic efficiency of the method.« less

Design for the Structure and the Mechanics of Moballs

NASA Technical Reports Server (NTRS)

Davoodi, Faranak; Davoudi, Farhooman

2012-01-01

The moball is envisioned to be a round, self-powered, and wind-driven multifunctioning sensor used in the Gone with the Wind ON-Mars (GOWON) [http://www.lpi.usra.edu/meetings/ marsconcepts2012/pdf/4238.pdf]: A Wind-Driven Networked System of Mobile sensors on Mars. The moballs would have sensing, processing, and communication capabilities. The moballs would perform in situ detection of key environmental elements such as vaporized water, trace gases, wind, dust, clouds, light and UV exposure, temperature, as well as minerals of interest, possible biosignatures, surface magnetic and electric fields, etc. The embedded various low-power micro instruments could include a Multispectral Microscopic Imager (to detect various minerals), a compact curved focal plane array camera (UV/Vis/NIR) with a large field of view, a compact UV/Visible spectrometer, a micro-weather station, etc. The moballs could communicate with each other and an orbiter. Their wind- or gravity-driven rolling movement could be used to harvest and store electric energy. They could also generate and store energy using the sunlight, when available, and the diurnal temperature variations on Mars. The moballs would be self-aware of their (and their neighbors ) positions, energy storage, and memory availability; they would have processing power and could intelligently cooperate with neighboring moballs by distributing tasks, sharing data, and fusing information. The major advantages of using the wind-driven and spherical moball network over rovers or other fixed sensor webs to explore Mars would be: (1) moballs could explore a much larger expanse of Mars in a much faster fashion, (2) they could explore the difficult terrains such as steep slopes and sand dunes, and (3) they would be self-energy- generating and could work together and move around autonomously. The challenge in designing the structure and the mechanics of the moball would be that it should be sturdy enough to withstand the impact of its initial fall, as well as other impacts from obstacles in its way. A mechanism would be needed that could enable hundreds of moballs to be carried while they would be deflated and compact, then would inflate them just after deploying them to their drop site. Furthermore, the moballs should also be light enough to allow them to move easily over obstacles by force of the wind. They also should have some kind of maneuvering mechanism in place to help them avoid very hazardous sharp objects or events, and to enable them to get closer to the objects of interest. The structure of the moballs was designed so that they would have different layers. The outer layer should comprise a sturdy, yet light, polymer that could withstand both the impact of the initial drop, as well as the impact of the different obstacles it would encounter while traversing the surface of Mars. This polymer should not deteriorate with the 100 K daily temperature swings on Mars. The inner layer should consist of a very light gas such as nitrogen or helium. In terms of maneuvering, six very light weights placed at strategic locations would give moballs the ability to turn, or even hop, over hazardous (e.g., sharp) obstacles, or even initiate a movement (before getting more help from the wind to be carried around) when stuck. Maneuvering would be necessary in order to get closer to objects of interest. If the weights would be allowed to move freely, they could also be used to generate energy.

Double Blind Test For Bio-Stimulation Effects On Pain Relief By Diode Laser

NASA Astrophysics Data System (ADS)

Saeki, Norio; Sembokuya, Iwajiro; Arakawa, Kazuo; Fujimasa, Iwao; Mabuchi, Kunihiko; Abe, Yuusuke; Atsumi, Kazuhiko

1989-09-01

The bio-stimulation effect of semiconductor laser on therapeutic pain relief was investigated by conducting a double blind test performed on more than one hundred patient subjects suffering from various neualgia. A compact laser therapeutic equipment with two laser probes each having 60 mW power was developed and utilized for the experiment. Each probe was driven by either the active or the dummy source selected randomly, and its results were stored in the memory for statistical processing. The therapeutic treatments including active and dummy treatments were performed on 102 subjects. The pain relief effects were confirmed for 85.5% of the subjects.

A Machine-Learning-Driven Sky Model.

PubMed

Satylmys, Pynar; Bashford-Rogers, Thomas; Chalmers, Alan; Debattista, Kurt

2017-01-01

Sky illumination is responsible for much of the lighting in a virtual environment. A machine-learning-based approach can compactly represent sky illumination from both existing analytic sky models and from captured environment maps. The proposed approach can approximate the captured lighting at a significantly reduced memory cost and enable smooth transitions of sky lighting to be created from a small set of environment maps captured at discrete times of day. The author's results demonstrate accuracy close to the ground truth for both analytical and capture-based methods. The approach has a low runtime overhead, so it can be used as a generic approach for both offline and real-time applications.

Invited review article: high-speed flexure-guided nanopositioning: mechanical design and control issues.

PubMed

Yong, Y K; Moheimani, S O R; Kenton, B J; Leang, K K

2012-12-01

Recent interest in high-speed scanning probe microscopy for high-throughput applications including video-rate atomic force microscopy and probe-based nanofabrication has sparked attention on the development of high-bandwidth flexure-guided nanopositioning systems (nanopositioners). Such nanopositioners are designed to move samples with sub-nanometer resolution with positioning bandwidth in the kilohertz range. State-of-the-art designs incorporate uniquely designed flexure mechanisms driven by compact and stiff piezoelectric actuators. This paper surveys key advances in mechanical design and control of dynamic effects and nonlinearities, in the context of high-speed nanopositioning. Future challenges and research topics are also discussed.

Recent Observational Progress on Accretion Disks Around Compact Objects

NASA Astrophysics Data System (ADS)

Miller, Jon M.

2016-04-01

Studies of accretion disks around black holes and neutron stars over the last ten years have made remarkable progress. Our understanding of disk evolution as a function of mass accretion rate is pushing toward a consensus on thin/thick disk transitions; an apparent switching between disk-driven outflow modes has emerged; and monitoring observations have revealed complex spectral energy distributions wherein disk reprocessing must be important. Detailed studies of disk winds, in particular, have the potential to reveal the basic physical processes that mediate disk accretion, and to connect with numerical simulations. This talk will review these developments and look ahead to the potential of Astro-H.