Seamless measurement technology of transient signals based on approximate entropy
The acquisition of waveforms and the analysis of transient characteristics of signals are the fundamental tasks for time-domainmeasurement, while the reduction of themeasuring gap till seamlessmeasurement is extremely important to the acquisition,measurement, and analysis of transient signals. This paper, aimed at the seamless time-domainmeasurement of non-stationary transient signals, proposes an approximate entropy-based characteristic signal extraction algorithm on the basis ofinformationentropytheories. The algorithm quantitatively describes the complexity (amount ofinformation) of sampled signals using the approximate...
Source: Review of Scientific Instruments - October 13, 2016 Category: Physics Authors: Jun Jiang, Shulin Tian, Lianping Guo and Wuhuang Huang Source Type: research
Approaching attometer laser vibrometry
Theheterodyne two-beaminterferometer has been proven to be the optimal solution for laser-Doppler vibrometry (LDV) regarding accuracy and signal robustness. Thetheoretical resolution limit for a two-beaminterferometer of laser class 3R (up to 5 mW visiblemeasurement-light) is in the regime of a few femtometer per square-root Hertz and well suited to study vibrations in microstructures. However, some new applications of radio-frequency microelectromechanical (RF-MEM)resonators, nanostructures, and surface-nano-defect detection require resolutions beyond that limit. The resolution depends only on the photodetector noise and ...
Source: Review of Scientific Instruments - October 13, 2016 Category: Physics Authors: C. Rembe, L. Kadner and M. Giesen Source Type: research
Diagnostics for molybdenum and tungsten erosion and transport in NSTX-U
A comprehensive set of spectroscopicdiagnostics is planned in the National Spherical Torus Experiment Upgrade to connectmeasurements ofmolybdenum andtungstendivertor sources to scrape-off layer (SOL) and core impurity transport, supporting the installation of high-Zplasma facing components which is scheduled to begin with a row ofmolybdenum tiles. Imaging with narrow-bandpass interference filters and high-resolution spectroscopy will be coupled to estimatedivertor impurity influxes. Vacuum ultraviolet andextreme ultravioletspectrometers will allow connecting high-Z sources to SOL transport and core impurity content. The hi...
Source: Review of Scientific Instruments - October 13, 2016 Category: Physics Authors: F. Scotti, V. A. Soukhanovskii and M. E. Weller Source Type: research
Note: Efficient, low-cost cooling system for gloveboxes
Cooling within gloveboxes is often restricted to expensive refrigerated bath circulators or small temperature differences. Here, we present a sturdy, inexpensive coolingsystem which matches various glovebox types and can be readily fabricated by a mechanical workshop in a few days. Thesystem is suitable for cold plates of areas up to 150 cm2 and temperatures as low as −100 °C. (Source: Review of Scientific Instruments)
Source: Review of Scientific Instruments - October 12, 2016 Category: Physics Authors: A. M öller, T. Marioneck and R. Dronskowski Source Type: research
Polymeric cantilever integrated with PDMS/graphene composite strain sensor
This paper describes the mechanical and electricalcharacteristics of apolydimethylsiloxane(PDMS) cantilever integrated with a high-sensitivity strainsensor. The strainsensor isfabricated usingPDMS andgraphene flakes that are uniformly distributed in thePDMS. In order to prepare PDMS/graphenecomposite with uniformresistance, a tetrahydrofuran solution is used to decrease the viscosity of aPDMS basepolymer solution. A horn-type sonicator is then used to mix the basepolymer withgraphene flakes. Low viscosity of the basepolymer solution improves the reliability and reproducibility of the PDMS/graphenecomposite for strainsensor...
Source: Review of Scientific Instruments - October 12, 2016 Category: Physics Authors: Young-Soo Choi, Min-Joo Gwak and Dong-Weon Lee Source Type: research
A high-performance wave guide cryogenic thermal break
We describe a high-performancewave guidecryogenic thermal break. This has been constructed both for Ka band, using WR28wave guide, and Q band, using WR22wave guide. The mechanical structure consists of a hexapod (Stewart platform) made from pultrudedcarbon fibre tubing. We present a tentative examination of thecryogenic Young ’s modulus of this material. Thethermal conductivity ismeasured attemperatures above the range explored by Runyan and Jones, resulting in predictedconductive loads through our thermal breaks of 3.7 mW to 3 K and 17 μK to 1 K. (Source: Review of Scientific Instruments)
Source: Review of Scientific Instruments - October 12, 2016 Category: Physics Authors: S. J. Melhuish, M. A. McCulloch, L. Piccirillo and C. Stott Source Type: research
Digital holographic interferometry employing Fresnel transform reconstruction for the study of flow shear stabilized Z-pinch plasmas
The ZaP-HDflowZ-pinch project provides a platform to explore how shearflow stabilizedZ-pinches could scale to high-energy-densityplasma(plasma with pressures exceeding 1 Mbar) and fusion reactor conditions. TheZ-pinch is a linearplasma confinement geometry in which theplasma carries axial electric current and is confined by its self-induced magnetic field. ZaP-HD generates shear stabilized, axisymmetricZ-pinches with stable lifetimes approaching 60μs. The goal of the project is to increase theplasma density andtemperature compared to the previous ZaP project by compressing theplasma to smaller radii ( ≈1 mm). Radial and...
Source: Review of Scientific Instruments - October 12, 2016 Category: Physics Authors: M. P. Ross and U. Shumlak Source Type: research
Multichannel emission spectrometer for high dynamic range optical pyrometry of shock-driven materials
An emission spectrometer (450-850 nm) using a high-throughput, high numerical aperture (N.A. = 0.3)prism spectrograph with stepped fiberoptic coupling, 32 fastphotomultipliers and thirty-two 1.25 GHz digitizers is described. The spectrometer can capture single-shot events with a high dynamic range in amplitude and time (nanoseconds to milliseconds or longer). Methods to calibrate the spectrometer and verify its performance and accuracy are described. When a reference thermal source is used forcalibration, the spectrometer can function as a fast opticalpyrometer. Applications of the spectrometer are illustrated by using it ...
Source: Review of Scientific Instruments - October 12, 2016 Category: Physics Authors: Will P. Bassett and Dana D. Dlott Source Type: research
Response measurement by laser Doppler vibrometry in vibration qualification tests with non-Gaussian random excitation
In the field of vibration qualification testing, random excitations are typically imposed on the tested system in terms of a power spectral density (PSD) profile. This is the one of the most popular ways to control the shaker or slip table for durability tests. However, these excitations (and the corresponding system responses) exhibit a Gaussianprobability distribution, whereas not all real-life excitations are Gaussian, causing the response to be also non-Gaussian. In order to introduce non-Gaussian peaks, a further parameter, i.e., kurtosis, has to be controlled in addition to the PSD. However, depending on the specimen...
Source: Review of Scientific Instruments - October 12, 2016 Category: Physics Authors: M. Troncossi, R. Di Sante and A. Rivola Source Type: research
Design of a digital holography system for PFC erosion measurements on Proto-MPEX
A project has been started at ORNL to develop a dual-wavelengthdigital holography system for plasma facing componenterosionmeasurements on prototype material plasma exposure experiment. Such a system will allowin situ real-timemeasurements of componenterosion. Initially the system will be developed with one laser, and first experimental laboratorymeasurements will be made with the single laser system. In the second year of development, a second CO2 laser will be added andmeasurements with the dual wavelength system will begin. Adding the second wavelength allowsmeasurements at a much longer synthetic wavelength. (Source: R...
Source: Review of Scientific Instruments - October 12, 2016 Category: Physics Authors: C. E. (Tommy) Thomas Jr., T. M. Biewer, L. R. Baylor, S. K. Combs, S. J. Meitner, J. Rapp, D. L. Hillis, E. M. Granstedt, R. Majeski and R. Kaita Source Type: research
Design and testing of 45 kV, 50 kHz pulse power supply for dielectric barrier discharges
The design, construction, andtesting of high frequency, high voltage pulse power supply are reported. The purpose of the power supply is to generatedielectric barrierdischarges for industrial applications. The power supply is compact and has the advantage of low cost, over current protection, and convenient control for voltage and frequency selection. The power supply can generate high voltage pulses of up to 45 kV at the repetitive frequency range of 1 kHz –50 kHz with 1.2 kW input power. The output current of the power supply is limited to 500 mA. The pulse rise time and fall time are less than 2μs and the pulse width...
Source: Review of Scientific Instruments - October 11, 2016 Category: Physics Authors: Surender Kumar Sharma and Anurag Shyam Source Type: research
Vertical wicking tester for monitoring water transportation behavior in fibrous assembly
An instrument based on the principle of change ofresistance of fibrous assembly onwetting has been developed for precise monitoring of thewater transportation behaviour in the fibrous assemblies. The conducting probes sense the change inresistance of a dry fibrous assembly onwetting. This change inresistance generates analog signals which trigger an amplifying circuit. This circuit produces an enlarged copy of the received signals which are further converted to digital signals by a Darlington pair and are encoded to measurable quantity with the help of a microcontroller. The data thus obtained are displayed on a suitable d...
Source: Review of Scientific Instruments - October 11, 2016 Category: Physics Authors: Pratibha Singh, Arobindo Chatterjee and Subrata Ghosh Source Type: research
Static phase improvements in the LNE watt balance
This paper describes the mechanical and electrical modifications carried out on the LNE watt balance to reduce the noise level associated with thestatic phase. The mechanical improvements concern the home-made balance beam using flexure hinges as pivots of the forcecomparator. The electrical improvements involve the source used to servo-control the equilibrium position of the beam during thestatic phase. All these modifications have led to a significant improvement of the repeatability and reproducibility of the results ofstatic phase measurements. (Source: Review of Scientific Instruments)
Source: Review of Scientific Instruments - October 11, 2016 Category: Physics Authors: P. Pinot, P. Espel, Y. Liu, M. Thomas, D. Ziane, M.-A. Palacios-Restrepo and F. Piquemal Source Type: research
ITER-like antenna capacitors voltage probes: Circuit/electromagnetic calculations and calibrations
The analyses illustrated in this manuscript have been performed in order to provide the required data for the amplitude-and-phasecalibration of the D-dot voltage probes used in the ITER-likeantenna at the Joint European Torus tokamak. Their equivalent electrical circuit has been extracted and analyzed, and it has been compared to the one of voltage probes installed in simple transmission lines. A radio-frequencycalibration technique has been formulated and exact mathematical relations have been derived. This technique mixes in an elegant fashion data extracted from measurements and numerical calculations to retrieve thecal...
Source: Review of Scientific Instruments - October 11, 2016 Category: Physics Authors: W. Helou, P. Dumortier, F. Durodi é, G. Lombard, K. Nicholls and JET Contributors Source Type: research
A broadband configuration for static Fourier transform spectroscopy with bandpass sampling
In this work a newbroadband staticFourier transform spectrometer (static-FTS) configuration based on the division of thespectrum into multiple narrow-bands is proposed. This configuration not only decreases thespectrometer size but also allows operation in the traditionalspectrometer wavelength range, namely, 400 nm –1100 nm with 1 cm−1 or better resolution. This technique solves the Nyquist sampling rate issue and enables us to record high resolutionspectrums with regularCCDs. An algorithm is developed to process the signal and calculate theFourier transform of the recorded interferograms on theCCD camera. (Source:...
Source: Review of Scientific Instruments - October 11, 2016 Category: Physics Authors: Behzad Sardari, Federico Davoli and Meri ç Özcan Source Type: research
