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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Soft x-ray spectromicroscopy using compact scanning transmission x-ray microscope at the photon factory

We report the stability and recent performances of a new type of scanning transmission X-ray microscopy. The optics and compact design of the microscope realized mobility and robust performance. Detailed consideration to the vibration control will be described. The insertion device upgraded to elliptical polarization undulator enabled linear dichroism and circular dichroism experiments.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Generation of topologically diverse acoustic vortex beams using a compact metamaterial aperture

Here, we present a class of metamaterial-based acoustic vortex generators which are both geometrically simple and broadly tunable. The aperture overcomes the significant limitations of both active phasing systems and existing passive coded apertures. The metamaterial approach generates topologically diverse acoustic vortex waves motivated by recent advances in leaky wave antennas by wrapping the antenna back upon itself to produce an acoustic vortex wave antenna. We demonstrate both experimentally and analytically that this single analog structure is capable of creating multiple orthogonal orbital angular momentum modes using only a single transducer. The metamaterial design makes the aperture compact, with a diameter nearly equal to the excitation wavelength and can thus be easily integrated into high-density systems. Applications range from acoustic communications for high bit-rate multiplexing to biomedical devices such as microfluidic mixers.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Ultrathin triple-band polarization-insensitive wide-angle compact metamaterial absorber

In this study, the design, realization, and characterization of an ultrathin triple-band polarization-insensitive wide-angle metamaterial absorber are reported. The metamaterial absorber comprises a periodic array of modified six-fold symmetric snowflake-shaped resonators with strip spiral line load, which is printed on a dielectric substrate backed by a metal ground plane. It is shown that the absorber exhibits three distinct near-unity absorption peaks, which are distributed across C, X, Ku bands, respectively. Owing to the six-fold symmetry, the absorber is insensitive to the polarization of the incident radiation. In addition, the absorber shows excellent absorption performance over wide oblique incident angles for both transverse electric and transverse magnetic polarizations. Simulated surface current and field distributions at the three absorption peaks are demonstrated to understand the absorption mechanism. Particularly, the absorption modes come from the fundamental and high-order dipole resonances. Furthermore, the experimental verification of the designed absorber is conducted, and the measured results are in reasonable agreement with the simulated ones. The proposed ultrathin (∼0.018λ{sub 0}, λ{sub 0} corresponding to the lowest peak absorption frequency) compact (0.168λ{sub 0}×0.168λ{sub 0} corresponding to the area of a unit cell) absorber enables potential applications such as stealth technology, electromagnetic interference and spectrum identification.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Compact setup for the production of {sup 87}Rb |F = 2, m{sub F} = + 2〉 Bose-Einstein condensates in a hybrid trap

We present a compact experimental apparatus for Bose-Einstein condensation of {sup 87}Rb in the |F = 2, m{sub F} = + 2〉 state. A pre-cooled atomic beam of {sup 87}Rb is obtained by using an unbalanced magneto-optical trap, allowing controlled transfer of trapped atoms from the first vacuum chamber to the science chamber. Here, atoms are transferred to a hybrid trap, as produced by overlapping a magnetic quadrupole trap with a far-detuned optical trap with crossed beam configuration, where forced radiofrequency evaporation is realized. The final evaporation leading to Bose-Einstein condensation is then performed by exponentially lowering the optical trap depth. Control and stabilization systems of the optical trap beams are discussed in detail. The setup reliably produces a pure condensate in the |F = 2, m{sub F} = + 2〉 state in 50 s, which includes 33 s loading of the science magneto-optical trap and 17 s forced evaporation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Compact electret energy harvester with high power output

Compact electret energy harvesters, based on a design recently introduced, are presented. Using electret surface potentials in the 400 V regime and a seismic mass of 10 g, it was possible to generate output power up to 0.6 mW at 36 Hz for an input acceleration of 1 g. Following the presentation of an analytical model allowing for the calculation of the power generated in a load resistance at the resonance frequency of the harvesters, experimental results are shown and compared to theoretical predictions. Finally, the performance of the electret harvesters is assessed using a figure of merit.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

A compact neutron scatter camera for field deployment

Here, we describe a very compact (0.9 m high, 0.4 m diameter, 40 kg) battery operable neutron scatter camera designed for field deployment. Unlike most other systems, the configuration of the sixteen liquid-scintillator detection cells are arranged to provide omnidirectional (4π) imaging with sensitivity comparable to a conventional two-plane system. Although designed primarily to operate as a neutron scatter camera for localizing energetic neutron sources, it also functions as a Compton camera for localizing gamma sources. In addition to describing the radionuclide source localization capabilities of this system, we demonstrate how it provides neutron spectra that can distinguish plutonium metal from plutonium oxide sources, in addition to the easier task of distinguishing AmBe from fission sources.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Compact low power infrared tube furnace for in situ X-ray powder diffraction.

We describe the development and implementation of a compact, low power, infrared heated tube furnace for in situ powder X-ray diffraction experiments. Our silicon carbide (SiC) based furnace design exhibits outstanding thermal performance in terms of accuracy control and temperature ramping rates while simultaneously being easy to use, robust to abuse and, due to its small size and low power, producing minimal impact on surrounding equipment. Temperatures in air in excess of 1100 °C can be controlled at an accuracy of better than 1%, with temperature ramping rates up to 100 °C/s. The complete "add-in" device, minus power supply, fits in a cylindrical volume approximately 15 cm long and 6 cm in diameter and resides as close as 1 cm from other sensitive components of our experimental synchrotron endstation without adverse effects.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Compact, energy efficient superconducting asymmetric ERL for ultra-high fluxes of X-ray and THz

To make the light sources compact and energy efficient, an energy recovery Superconducting RF LINAC can be used. We suggest a dual-axis, asymmetric cavity instead of conventional single axis, symmetric cavity configurations to generate average electron beam currents above 1 A, while still avoiding development of the beam breakup instability (BBU). The use of an asymmetric cavity allows one to increase the start current of HOMs participating in BBU instability development, as well as to break the positive feedback, resulting in the capability of a high average current electron beam to be driven without loss through the system. In this work, the results of experimental studies of an asymmetric cavity are presented and compared with theoretical predictions. The following steps toward design of a full-scale superconducting cavity are also discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

A compact fiber optics-based heterodyne combined normal and transverse displacement interferometer

While Photonic Doppler Velocimetry (PDV) has become a common diagnostic tool for the measurement of normal component of particle motion in shock wave experiments, this technique has not yet been modified for the measurement of combined normal and transverse motion, as needed in oblique plate impact experiments. In this study, we discuss the design and implementation of a compact fiber-optics-based heterodyne combined normal and transverse displacement interferometer. Like the standard PDV, this diagnostic tool is assembled using commercially available telecommunications hardware and uses a 1550 nm wavelength 2 W fiber-coupled laser, an optical focuser, and single mode fibers to transport light to and from the target. Two additional optical probes capture first-order beams diffracted from a reflective grating at the target free-surface and deliver the beams past circulators and a coupler where the signal is combined to form a beat frequency. The combined signal is then digitized and analyzed to determine the transverse component of the particle motion. The maximum normal velocity that can be measured by this system is limited by the equivalent transmission bandwidth (3.795 GHz) of the combined detector, amplifier, and digitizer and is estimated to be ~2.9 km/s. Finally, sample symmetric oblique plate-impact experiments are performed to demonstrate the capability of this diagnostic tool in the measurement of the combined normal and transverse displacement particle motion.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

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

Tagging of neutrons (2.45 MeV) with their associated 3He 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. In this work, 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.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

A compact linear accelerator based on a scalable microelectromechanical-system RF-structure

Here, a new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number of parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further red ucing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Finally, ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

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

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 system 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.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Source-to-accelerator quadrupole matching section for a compact linear accelerator

Recently, we presented a new approach for a compact radio-frequency (RF) accelerator structure and demonstrated the functionality of the individual components: acceleration units and focusing elements. In this paper, we combine these units to form a working accelerator structure: a matching section between the ion source extraction grids and the RF-acceleration unit and electrostatic focusing quadrupoles between successive acceleration units. The matching section consists of six electrostatic quadrupoles (ESQs) fabricated using 3D-printing techniques. The matching section enables us to capture more beam current and to match the beam envelope to conditions for stable transport in an acceleration lattice. We present data from an integrated accelerator consisting of the source, matching section, and an ESQ doublet sandwiched between two RF-acceleration units.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Calibration of two compact permanent magnet spectrometers for high current electron linear induction accelerators

In this work, two compact, permanent magnet, electron spectrometers have been built to measure the electron beam energy at the Dual Axis Radiographic Hydrodynamic Test facility. Using H - and OH - anions, the spectrometers were calibrated at the Special Technologies Laboratory in Santa Barbara, California (USA). The spectrometers were mounted on a custom drift tube that allows the magnet assemblies to be translated, which increases the path length of the electrons traveling through the magnetic field and therefore increases the upper bound of the measurable electron kinetic energy. The measurable range of electron kinetic energies is between 2.8 MeV–4.1 MeV for the first spectrometer and 14.1 MeV–21.1 MeV for the second spectrometer, with an overall measurement uncertainty of 0.32%.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Demonstration of waferscale voltage amplifier and electrostatic quadrupole focusing array for compact linear accelerators

Compact linear accelerators, with beam energies in the kiloelectron volt to megaelectron volt range, have applications in medicine, neutron/X-ray generation, surface modifications, etc. The size, weight, and power of existing accelerators preclude them from mass availability in portable formats. This paper presents a specific implementation of an ion accelerator architecture based on planar wafers with accelerating and focusing sections. Our low cost approach allows the control of the final ion beam energy with potential applications, for example, for accelerator-based ion implantation. In this paper, we demonstrate two important waferscale modules required to build a linear particle accelerator; these include (1) on-wafer voltage amplification for beam acceleration using Inductor-Capacitor (LC) resonators and (2) waferscale electrostatic quadrupole arrays (ESQA) to refocus the ion beams during transport. On-board LC resonators were developed using Printed Circuit Board fabrication processes to implement an LC element resonant at ~ 16.6 MHz with a quality factor of 25. An energy gain of ~ 250 eV was observed using a two wafer acceleration unit with an argon ion beam with 6.5 keV initial energy. A 3 × 3 ESQA was fabricated on a glass wafer with metal electrodes formed by depositing copper metal around the beam apertures. The ESQA was used to focus and defocus an argon ion beam, demonstrating a field gradient of ~ 500 V over a gap of ~ 250 μm.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Compact single-shot electro-optic detection system for THz pulses with femtosecond time resolution at MHz repetition rates

Electro-optical detection has proven to be a valuable technique to study temporal profiles of THz pulses with pulse durations down to femtoseconds. As the Coulomb field around a relativistic electron bunch resembles the current profile, electro-optical detection can be exploited for non-invasive bunch length measurements at accelerators. We have developed a very compact and robust electro-optical detection system based on spectral decoding for single-shot longitudinal bunch profile monitoring at the European X-ray Free Electron Laser (XFEL) for electron bunch lengths down to 200 fs (rms). Apart from the GaP crystal and the corresponding laser optics at the electron beamline, all components are housed in 19 in. chassis for rack mount and remote operation inside the accelerator tunnel. An advanced laser synchronization scheme based on radio-frequency down-conversion has been developed for locking a custom-made Yb-fiber laser to the radio-frequency of the European XFEL accelerator. In order to cope with the high bunch repetition rate of the superconducting accelerator, a novel linear array detector has been employed for spectral measurements of the Yb-fiber laser pulses at frame rates of up to 2.26 MHz. In this paper, we describe all sub-systems of the electro-optical detection system as well as the measurement procedure in detail and discuss the first measurement results of longitudinal bunch profiles of around 400 fs (rms) with an arrival-time jitter of 35 fs (rms).

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Compact and efficient elastocaloric heat pumps—Is there a path forward?

Elastocaloric cooling holds promise for energy-efficient heat pumping near room temperature with low environmental impact. Its adoption is, however, impeded by disproportionally large sizes of actuators compared with the active material volume. Taking magnetocaloric cooling as the baseline, the value of no more than 10:1 actuator volume to active material volume should lead to both size- and cost-effective solutions that may potentially be competitive with vapor-compression devices. With the goal to establish performance metrics that can lead to informed actuator selection for specific regenerator requirements, we analyze a wide range of elastocaloric materials and actuator technologies to find the best matches. We find that actuation with magnetic shape memory alloys meets all requirements; however, this technology is currently in early developmental stages and such actuators are not widely commercially available. Another promising and easily accessible option is standard rotary electric motors in combination with rotary-to-linear transduction mechanisms. A theoretical analysis of two case studies of elastocaloric systems using rotary electric motors with a Scotch yoke mechanism demonstrates the usefulness of our approach. Actuator requirements are based on two different regenerator configurations: one starting from zero strain without any mechanical energy recovery and another with 2% pre-strain and mechanical energy recovery to reduce the power and torque required from the motor. Our results indicate that the 10:1 target actuator to active material volume ratio can be met and feasibly lowered further, demonstrating that the proposed method for selecting actuators makes compact and efficient elastocaloric systems possible.

42 ENGINEERING↗
DOE OSTI2020

Simple, compact, high-resolution monochromatic x-ray source for characterization of x-ray calorimeter arrays

X-ray calorimeters routinely achieve very high spectral resolution, typically a few eV full width at half maximum (FWHM). Measurements of calorimeter line shapes are usually dominated by the natural linewidth of most laboratory calibration sources. This compounds the data acquisition time necessary to statistically sample the instrumental line broadening and can add systematic uncertainty if the intrinsic line shape of the source is not well known. To address these issues, we have built a simple, compact monochromatic x-ray source using channel cut crystals. A commercial x-ray tube illuminates a pair of channel cut crystals that are aligned in a dispersive configuration to select the Kα1 line of the x-ray tube anode material. The entire device, including the x-ray tube, can be easily hand-carried by one person and may be positioned manually or using a mechanical translation stage. The output monochromatic beam provides a collimated image of the anode spot with magnification of unity in the dispersion direction (typically 100 μm–200 μm for the x-ray tubes used here) and is unfocused in the cross-dispersion direction so that the source image in the detector plane appears as a line. We measured output count rates as high as 10 count/s/pixel for the Hitomi soft x-ray spectrometer, which had 819 μm square pixels. We implemented different monochromator designs for energies of 5.4 keV (one design) and 8.0 keV (two designs), which have effective theoretical FWHM energy resolution of 0.125 eV, 0.197 eV, and 0.086 eV, respectively; these are well-suited for optimal calibration measurements of state-of-the art x-ray calorimeters. We measured an upper limit for the energy resolution of our Cr Kα1 monochromator of 0.7 eV FWHM at 5.4 keV, consistent with the theoretical prediction of 0.125 eV.

47 OTHER INSTRUMENTATION↗