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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records

Persistent energy harvesting in the harsh desert environment using a thermal resonance device: Design, testing, and analysis

Thermal fluctuations in the environment are a ubiquitous, yet untapped energy source for harvesting. Our laboratory has introduced the concept of a thermal resonance device for this purpose, with potential to power wireless sensor networks (WSNs), devices embedded into structural elements, and electronics deployed in relatively inaccessible areas. This approach has particular advantages for the desert environment, where conventional energy harvesting devices are severely confounded by frequent sandstorms, extreme temperature and high solar fluence. Herein, we design, fabricate, and test a thermal resonator for the conversion of diurnal temperature fluctuations to electrical power in a harsh desert environment using a thermally conductive phase change composite as a high thermal effusivity material, specifically tuned to the temperature fluctuating environment of Thuwal, Saudi Arabia (22.3095°N, 39.1047°E). The composite consists of a highly porous and thermally conductive nickel foam impregnated with eicosane as a phase change material for enhanced thermal capacity. The high thermal effusivity material is incorporated into a rationally-designed thermal resonance device, which is tested for a period of two weeks in Saudi Arabia, extracting as high as 2 mW from approximately 10 °C diurnal temperature fluctuations. These experimental data provide a test of the theoretical model for the design and operation of the device. Overall, these results highlight the opportunity of employing thermal resonance devices for energy harvesting, particularly in the desert environment.

30 DIRECT ENERGY CONVERSION↗

Modeling of SiC Lateral Resonant Devices Over a Broad Temperature Range

Finite-element analysis (FEA) modal results of 3C-SiC lateral resonant devices anchored to a Si substrate are presented as resonant frequency versus temperature. The suspended elements are etched from a 2 micron, 3C-SiC film grown at 1600 K on a 500 micron-thick, Si substrate. The analysis includes, temperature-dependent properties, shape change due to volume expansion with temperature, and thermal stress caused by differential thermal expansion of different materials. Two designs are considered: type I has anchor locations close to the geometric centroid and a small shuttle; type 11 has a large shuttle with anchors far from the centroid, The resonant frequency decreases approximately 3.5% over a 1000 K temperature increase for the type-I device, and behaves according to theory. The resonant frequency of the type-11 device decreases by 2% over the first 400 K, then rises slightly over the remaining 600 K. This device deviates from theory because of the high thermal stress induced in the beams. The thermal stress is caused by the differential thermal expansion of the suspended element relative to the substrate. The results show that the device geometry must be properly chosen if the resonant frequency of that device will be used to calculate the temperature coefficient of Young's modulus. These results apply only to resonators of one material on a substrate of a different material.

DeAnna, Russell G.↗

Microwave and millimeter-wave resonant-tunneling devices

Resonant-tunneling devices in microelectronic component form, whose structure is the electron analog of a Fabry-Perot resonator, encompass oscillators, self-oscillating mixers, and harmonic multipliers. The negative differential resistance characteristic of these devices has been obtained at room temperature, and resonant-tunneling transistors capable of operation in the THz-frequency range appear to be feasible. Three-terminal resonant-tunneling device development is in its infancy, as is that of devices for digital applications.

Sollner, T. C. L. Gerhard↗

Particle resonances in toroidal fusion devices

Resonances of high energy particles in magnetic confinement devices due to electromagnetic instabilities can strongly modify the distribution, leading to a reduction in fusion power and even discharge termination and particle loss to the device walls through avalanche. The existence of a mode particle resonance depends on properties of the equilibrium, particle trajectories, and perturbation mode harmonic content. Resonance location is a function of particle energy and equilibrium field line helicity. Different methods for finding resonance location and energy dependence are developed. The properties of resonances are discussed using examples from magnetic fusion devices. Here, we show that if mode resonances exist at low particle energy, they very likely also exist at high energy, thus modifying high energy beam particles and fusion products. It is possible for a resonance to appear due to mode induced orbit helicity modification when it is forbidden at low mode amplitude.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Applications and Methods of Operating a Three-dimensional Nano-electro-mechanical Resonator and Related Devices

Carbon nanofiber resonator devices, methods for use, and applications of said devices are disclosed. Carbon nanofiber resonator devices can be utilized in or as high Q resonators. Resonant frequency of these devices is a function of configuration of various conducting components within these devices. Such devices can find use, for example, in filtering and chemical detection.

Kaul, Anupama B.↗

Tunable resonator-based devices for producing variable delays and narrow spectral linewidths

Devices with two or more coupled resonators to produce narrow spectral responses due to interference of signals that transmit through the resonators and techniques for operating such devices to achieve certain operating characteristics are described. The devices may be optical devices where optical resonators such as whispering gallery mode resonators may be used. In one implementation, at least one of the coupled optical resonators is a tunable resonator and is tuned to change its resonance frequency to tune the spectral response of the device. The described devices and techniques may be applied in optical filters, optical delays, optical waveform generators, and other applications.

Savchenkov, Anatoliy↗

Tunable Magnetic Resonance in Microwave Spintronics Devices

Magnetic resonance is one of the key properties of magnetic materials for the application of microwave spintronics devices. The conventional method for tuning magnetic resonance is to use an electromagnet, which provides very limited tuning range. Hence, the quest for enhancing the magnetic resonance tuning range without using an electromagnet has attracted tremendous attention. In this paper, we exploit the huge exchange coupling field between magnetic interlayers, which is on the order of 4000 Oe and also the high frequency modes of coupled oscillators to enhance the tuning range. Furthermore, we demonstrate a new scheme to control the magnetic resonance frequency. Moreover, we report a shift in the magnetic resonance frequency as high as 20 GHz in CoFe based tunable microwave spintronics devices, which is 10X higher than conventional methods.

Microwave Detectors↗

Tunable Magnetic Resonance in Microwave Spintronics Devices

Magnetic resonance is one of the key properties of magnetic materials for the application of microwave spintronics devices. The conventional method for tuning magnetic resonance is to use an electromagnet, which provides very limited tuning range. Hence, the quest for enhancing the magnetic resonance tuning range without using an electromagnet has attracted tremendous attention. In this paper, we exploit the huge exchange coupling field between magnetic interlayers, which is on the order of 4000 Oe and also the high frequency modes of coupled oscillators to enhance the tuning range. Furthermore, we demonstrate a new scheme to control the magnetic resonance frequency. Moreover, we report a shift in the magnetic resonance frequency as high as 20 GHz in CoFe-based tunable microwave spintronics devices, which is 10X higher than conventional methods.

Microwave Detectors↗

A 32-bit Ultrafast Parallel Correlator using Resonant Tunneling Devices

An ultrafast 32-bit pipeline correlator has been implemented using resonant tunneling diodes (RTD) and hetero-junction bipolar transistors (HBT). The negative differential resistance (NDR) characteristics of RTD's is the basis of logic gates with the self-latching property that eliminates pipeline area and delay overheads which limit throughput in conventional technologies. The circuit topology also allows threshold logic functions such as minority/majority to be implemented in a compact manner resulting in reduction of the overall complexity and delay of arbitrary logic circuits. The parallel correlator is an essential component in code division multi-access (CDMA) transceivers used for the continuous calculation of correlation between an incoming data stream and a PN sequence. Simulation results show that a nano-pipelined correlator can provide and effective throughput of one 32-bit correlation every 100 picoseconds, using minimal hardware, with a power dissipation of 1.5 watts. RTD plus HBT based logic gates have been fabricated and the RTD plus HBT based correlator is compared with state of the art complementary metal oxide semiconductor (CMOS) implementations.

Kulkarni, Shriram↗

A scanning resonator for probing quantum coherent devices

Superconducting resonators with high quality factors are extremely sensitive detectors of the complex impedance of materials and devices coupled to them. This capability has been used to measure losses in multiple different materials and, in the case of circuit quantum electrodynamics (circuit QED), has been used to measure the coherent evolution of multiple different types of qubits. Here, we report on the implementation of a scanning resonator for probing quantum coherent devices. Our scanning setup enables tunable coherent coupling to systems of interest without the need for fabricating on-chip superconducting resonators. We measure the internal quality factor of our resonator sensor in the single-photon regime to be >104 and demonstrate capacitive imaging using our sensor with zeptoFarad sensitivity and micron spatial resolution at milliKelvin temperatures. We then use our setup to characterize the energy spectrum and coherence times of multiple transmon qubits with no on-chip readout circuitry. Our experiments introduce a new tool for using circuit QED to measure existing and proposed qubit platforms.

47 OTHER INSTRUMENTATION↗

Superconducting resonators and devices.

The high-frequency properties of superconductors are reviewed, including the London, Pippard, and Mattis-Bardeen surface impedance, and techniques for measuring and separating losses are discussed. Residual resistance mechanisms are described and evaluated, including high field effects. The state of knowledge is shown to be adequate for engineering design. Applications of superconducting resonators and lines to filters, tuners, oscillators, amplifiers and mixers, transmission lines, antennas, optical and radiation detection, and materials research are discussed.

Hartwig, W. H.↗

Development of hypertension after long-term exposure to static magnetic fields among workers from a magnetic resonance imaging device manufacturing facility

Highlights: • High cumulative exposure to MRI-related static magnetic fields is associated with hypertension. • No association was apparent for low cumulative exposure to static magnetic fields. • New association pointing at long term effects of static magnetic fields needs corroboration. To assess the association between long-term exposure to static magnetic fields (SMF) in a magnetic resonance imaging (MRI)-manufacturing environment and hypertension.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Acoustic manipulation of fluids based on eigenfrequency

An acoustic resonator device includes a fluid chamber with a carrier surface and a reflector surface. The fluid chamber is filled with a volume of a fluid that includes a phase-separate material such as algae. The carrier surface is coupled to a transducer, which may be a lead zirconate titanate (PZT) transducer. The transducer, when supplied with electricity, emits an acoustic wave-based output of an output frequency (e.g., ultrasound). A sensor may be used to track one or more eigenfrequencies of the volume of fluid, the acoustic resonator device, or some combination thereof. A controller may receive tracking data from the sensor and control the voltage source, the transducer, or some combination thereof to ensure that the output frequency matches one of the tracked eigenfrequencies, thereby maximizing excitation of the fluid to improve efficiency of mixing, stimulation, and separation of materials from fluid (e.g., for algal biocrude production).

09 BIOMASS FUELS↗

In-situ measurement of irradiation behavior in LiNbO 3

In-situ measurement of LiNbO 3 based surface acoustic wave (SAW) crystal resonator device under irradiation was demonstrated and used to characterize the impact of radiation on physical properties of this material. The resonant frequency of the SAW device was monitored as the output power of the reactor was varied. Upon step increase of the reactor power, a gradual shift in the device’s resonant frequency was observed. This frequency shift initially exhibits a linear growth and eventually reaches an equilibrium value proportional to the reactor power. The observed behavior can be attributed to two competing processes: increase of temperature due to gamma heating or accumulation of irradiation induced defects. In both cases, the response is attributed to changes in the physical properties of LiNbO 3 , particularly the elastic constants. This demonstrated ability to measure materials properties under irradiation is attractive for development of sensors and performing materials science under irradiation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Low-Loss Microstrip Transmission Line Fabricated with Improved Liftoff Process

The µ-Spec integrated spectrometer operating at ~500 GHz, employs thin film superconducting Nb microstrip transmission lines deposited directly on a thin (450 nm) single-crystal silicon dielectric. This single-crystal silicon layer is chosen as the dielectric layer due to its low intrinsic loss, with the goal of achieving both high- efficiency and precise phase control in a compact spectrometer architecture. To avoid roughening or etching through the thin single-crystal silicon dielectric a liftoff technique was developed for patterning these microstrip transmission lines and ground plane structures. This two- layer liftoff process was designed for use with sputter deposition and resulted in a US patent. Although this original technique provided precise control of linewidth, results of initial prototype spectrometer devices and separate diagnostic co-planer waveguide resonator devices showed that unexpected loss was being introduced due to the lift-off process. This extra loss was believed to be due to the “tails” (thin tapered regions) at the edge of the metal traces resulting from the sputtering process, as well as an amorphous oxide layer at the Nb-Si interface. We have since demonstrated an improved lift-off technique, which provides a clean metal-Si interface and removes the loss-inducing tails by a two-step selective etching method. This results in a decrease in microwave loss by more than an order of magnitude when measured in co-planar waveguide microwave resonator structures. We present these microwave test results and also SEM and TEM images of the microstrip interfaces and edge profiles before and after application of the improved process.

Hess, Larry A.↗