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Review of Scientific Instruments

Rico A R Picone, Solomon Davis, Cameron Devine, Joseph L Garbini, John A Sidles
We report the development of an instrumentation and control system instantiated on a microprocessor-field programmable gate array (FPGA) device for a harmonic oscillator comprising a portion of a magnetic resonance force microscope. The specific advantages of the system are that it minimizes computation, increases maintainability, and reduces the technical barrier required to enter the experimental field of magnetic resonance force microscopy. Heterodyne digital control and measurement yields computational advantages...
April 2017: Review of Scientific Instruments
Fu-Hsing Wu, Edzer L Wu, Yi-Hang Tung, Po-Wei Cheng, Tzi-Dar Chiueh, Jyh-Horng Chen
This study proposes a modified Shinnar-Le Roux method to synthesize the excitation radio frequency (RF) pulse for a 2D gradient echo (GRE) based simultaneous multi-slice (SMS) magnetic resonance imaging (MRI) with features of low specific absorption rate (SAR) and small out-of-slice ripple. This synthesis method for SMS RF pulses employs thinner slice bandwidth and lower multislice offset frequencies to reduce SAR values and adopts a weighted Parks-McClellan algorithm to reduce sidelobes. Formulas for estimating relative SAR values of the SMS pulses are also introduced...
April 2017: Review of Scientific Instruments
Ryuichi Nomura, Shintaro Azuma, Kentaro Uesugi, Yuki Nakashima, Tetsuo Irifune, Toru Shinmei, Sho Kakizawa, Yohei Kojima, Hirokazu Kadobayashi
A large-strain, torsional deformation apparatus has been developed based on diamond anvil cells at high pressures, up to 135 GPa with a help of hard nano-polycrystalline diamond anvils. These pressure conditions correspond to the base of the Earth's mantle. An X-ray laminography technique is introduced for high-pressure in situ 3D observations of the strain markers. The technique developed in this study introduces the possibility of the in situ rheological measurements of the deep Earth materials under ultrahigh-pressure conditions...
April 2017: Review of Scientific Instruments
P Walmsley, I R Fisher
Measurements of the resistivity anisotropy can provide crucial information about the electronic structure and scattering processes in anisotropic and low-dimensional materials, but quantitative measurements by conventional means often suffer very significant systematic errors. Here we describe a novel approach to measuring the resistivity anisotropy of orthorhombic materials, using a single crystal and a single measurement that is derived from a π4 rotation of the measurement frame relative to the crystallographic axes...
April 2017: Review of Scientific Instruments
I Braud, S Zamith, J-M L'Hermite
We present the design of a versatile gas aggregation source that allows producing molecular beams of charged clusters containing a controlled amount of chosen impurities. Several examples of clusters production using this source characterized by time of flight mass spectrometry are presented here. We demonstrate the source ability to produce homogeneous clusters, such as pure protonated water and alcohol clusters, as well as inhomogeneous ones such as water clusters containing a few units of uracil, glycine, sulfuric acid, or pyrene...
April 2017: Review of Scientific Instruments
S J Zweben, J L Terry, D P Stotler, R J Maqueda
Gas puff imaging (GPI) is a diagnostic of plasma turbulence which uses a puff of neutral gas at the plasma edge to increase the local visible light emission for improved space-time resolution of plasma fluctuations. This paper reviews gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion research, with a focus on the instrumentation, diagnostic cross-checks, and interpretation issues. The gas puff imaging hardware, optics, and detectors are described for about 10 GPI systems implemented over the past ∼15 years...
April 2017: Review of Scientific Instruments
M K Frampton, N McLaughlin, Hu Jin, R J Zieve
We describe a simple manganin foil resistance manometer for uniaxial stress measurements. The manometer functions at low pressures and over a range of temperatures. In this design, no temperature seasoning is necessary although the manometer must be prestressed to the upper end of the desired pressure range. The prestress pressure cannot be increased arbitrarily; irreversibility arising from shear stress limits its range. Attempting larger pressures yields irreproducible resistance measurements.
April 2017: Review of Scientific Instruments
Hongxia Zhang, Ye Zhou, Jing Liu, Dagong Jia, Tiegen Liu
Particles widely exist in various fields. In practical experiments, sometimes it is necessary to dissolve particles in water in a sample pool. This article proposes two typical layouts of the sample pool in defocused interferometric particle imaging (IPI). Layout I is the sample pool surface perpendicular to the incident light and layout II is the sample pool surface perpendicular to the scattered light. For layout I, the scattered light of the particles does not keep symmetric at the meridional and sagittal planes after being refracted by the sample pool surface, and elliptical interference patterns are formed at the defocused IPI image plane...
April 2017: Review of Scientific Instruments
Renshuai Huang, Xiaoyang Guo, Qinglong Meng, Bin Zhang
A simple digital control system was designed to stabilize CO2 laser based on digital signal processing with the Field-Programmable Gate Array (FPGA) controlling chip and Very-High-Speed Integrated Circuit Hardware Description Language program. In this system, the control parameters were easily determined by software real-time control, and the control circuit was also designed compactly. In addition, the theoretical analysis on the stabilization of CO2 laser output characteristics was presented based on the photoacoustic effect, and the corresponding experiments on the stabilization of CO2 laser output characteristics were further performed...
April 2017: Review of Scientific Instruments
M Palma, D Maradan, L Casparis, T-M Liu, F N M Froning, D M Zumbühl
We present a parallel network of 16 demagnetization refrigerators mounted on a cryofree dilution refrigerator aimed to cool nanoelectronic devices to sub-millikelvin temperatures. To measure the refrigerator temperature, the thermal motion of electrons in a Ag wire-thermalized by a spot-weld to one of the Cu nuclear refrigerators-is inductively picked-up by a superconducting gradiometer and amplified by a SQUID mounted at 4 K. The noise thermometer as well as other thermometers are used to characterize the performance of the system, finding magnetic field independent heat-leaks of a few nW/mol, cold times of several days below 1 mK, and a lowest temperature of 150 μK of one of the nuclear stages in a final field of 80 mT, close to the intrinsic SQUID noise of about 100 μK...
April 2017: Review of Scientific Instruments
D V Koptsov, L G Prokhorov, V P Mitrofanov
A setup for the measurement of the noise associated with the interaction of an electrostatic field produced by an electrostatic drive with a fused silica plate is presented. The fused silica plate is a part of a 63 Hz high-Q torsional oscillator. Its oscillations are measured by an optical interferometric sensor. The measurements are PC-controlled and fully automated. A digital post-processing scheme is described, allowing the calculation of the plate rotation angle fluctuations and the evolution of the charge distribution on the surface of the fused silica plate...
April 2017: Review of Scientific Instruments
O Hüter, F Temps
Femtosecond photoelectron imaging spectroscopy is a powerful technique for following state-resolved molecular transformations in complex coupled potential energy landscapes. To avoid unwanted nonlinear side-effects, the employed laser pulse energies are usually reduced to minimal values. However, the energy calibration of the photoelectron imaging detector is ideally performed using multi-photon above-threshold ionization of suitable atomic species, for which rather high laser intensities are required. In this work, we show that the calibration spectra of xenon obtained with high laser pulse energies cannot be directly used for the evaluation of molecular photoelectron spectra recorded using low-energy laser pulses...
April 2017: Review of Scientific Instruments
K Maru, S Katsumi, R Matsuda
In this study, we propose and demonstrate a nonmechanical compact probe for cross-sectional velocity measurement based on differential laser Doppler velocimetry. The system introduces a method that combines simultaneous multipoint measurement using spatial encoding and nonmechanical scanning of measurement points, in which spatially encoded measurement points aligned along the transverse direction are scanned in the axial direction by changing the wavelength. The use of a waveguide-type LiNbO3 phase shifter array for serrodyne frequency shifting is feasible for the system based on fiber optics with an easily handled probe...
April 2017: Review of Scientific Instruments
Jian Li, Kun Xiong, Xinguo Wei, Guangjun Zhang
On-orbit calibration is aimed at revising the star trackers' measurement model parameters and maintaining its attitude accuracy. The performance of existing calibration methods is quite poor. Among all the model parameters, the estimation of the principal point location is very challenging due to its vulnerability against measurement errors, yet, that it is the only parameter depicting the optical axis' projecting position on the image plane makes it of great significance. Its estimation error adds fixed bias to the output attitudes...
April 2017: Review of Scientific Instruments
J-J Kim, S H Joo, K S Lee, J H Yoo, M S Park, J S Kwak, Jinho Lee
The Low Temperature Scanning Tunneling Microscope (LT-STM) is an extremely valuable tool not only in surface science but also in condensed matter physics. For years, numerous new ideas have been adopted to perfect LT-STM performances-Ultra-Low Vibration (ULV) laboratory and the rigid STM head design are among them. Here, we present three improvements for the design of the ULV laboratory and the LT-STM: tip treatment stage, sample cleaving stage, and vibration isolation system. The improved tip treatment stage enables us to perform field emission for the purpose of tip treatment in situ without exchanging samples, while our enhanced sample cleaving stage allows us to cleave samples at low temperature in a vacuum without optical access by a simple pressing motion...
April 2017: Review of Scientific Instruments
Hongmin Mao, Fang Ding, Guang-Nan Luo, Zhenhua Hu, Xiahua Chen, Feng Xu, Zhongshi Yang, Jingbo Chen, Liang Wang, Rui Ding, Ling Zhang, Wei Gao, Jichan Xu, Chengrui Wu
To facilitate long-pulse high power operation, an ITER-like actively cooled tungsten (W) divertor was installed in Experimental Advanced Superconducting Tokamak (EAST) to replace the original upper graphite divertor in 2014. A dedicated multichannel visible spectroscopic diagnostic system has been accordingly developed for the characterization of the plasma and impurities in the W divertor. An array of 22 lines-of-sight (LOSs) provides a profile measurement of the light emitted from the plasma along upper outer divertor, and the other 17 vertical LOSs view the upper inner divertor, achieving a 13 mm poloidal resolution in both regions...
April 2017: Review of Scientific Instruments
J Wang, Y R Sun, L-G Tao, A-W Liu, T-P Hua, F Meng, S-M Hu
We present a new method of comb-locked cavity ring-down spectroscopy for the Lamb-dip measurement of molecular ro-vibrational transitions. By locking both the probe laser frequency and a temperature-stabilized high-finesse cavity to an optical frequency comb, we realize saturation spectroscopy of molecules with kilohertz accuracy. The technique is demonstrated by recording the R(9) line in the υ = 3 - 0 overtone band of CO near 1567 nm. The Lamb-dip spectrum of such a weak line (transition rate 0.0075 s(-1)) is obtained using an input laser power of only 3 mW, and the position is determined to be 191 360 212 770 kHz with an uncertainty of 7 kHz (δν/ν∼3...
April 2017: Review of Scientific Instruments
J Dostal, R Dudzak, T Pisarczyk, M Pfeifer, J Huynh, T Chodukowski, Z Kalinowska, E Krousky, J Skala, J Hrebicek, T Medrik, J Golasowski, L Juha, J Ullschmied
A system of precise pulse synchronization between a single-shot large-scale laser exploiting an acousto-optical modulator and a femtosecond high repetition rate laser is reported in this article. This opto-electronical system has been developed for synchronization of the sub-nanosecond kJ-class iodine photodissociation laser system (Prague Asterix Laser System-PALS) with the femtosecond 25-TW Ti:sapphire (Ti:Sa) laser operating at a repetition rate 1 kHz or 10 Hz depending on the required energy level of output pulses...
April 2017: Review of Scientific Instruments
Gang Chen, Hao Wu, Jianwen Gao, Qiang Lin
The limited capabilities of current fatigue testing machines have resulted in studies on the fatigue behavior of rubber under large-displacement amplitude and high frequency being very sparse. In this study, a fatigue testing system that can carry out large-displacement amplitude and high-frequency fatigue tests on rubber was developed using a moving magnet voice coil motor (MMVCM) actuator, with finite element analysis applied to analyze the thrust of the MMVCM actuator. The results of a series of cyclic tension tests conducted on vulcanized natural rubber specimens using the developed fatigue testing system verify that it has high precision, low noise, large-stroke, and high-frequency characteristics...
April 2017: Review of Scientific Instruments
H Yoshida, T Ebina, K Arai, T Kobata, R Ishii, T Aizawa, A Suzuki
Water vapor transmission rate (WVTR) measuring devices with a quadrupole mass spectrometer (QMS) have an advantage in measuring low WVTRs because measurements are taken under an extremely low background of water vapor by realizing ultrahigh vacuum conditions. Here, the reliability of the QMS measurements was improved by including a porous plug with known molecular conductance in the device to generate a reference molar flux for in situ QMS calibration. Then, standard gas barrier (SGB) films made from a clay-polyimide nanocomposite film were also developed and used to validate the measurement...
April 2017: Review of Scientific Instruments
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