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Olesia I Kucheriv, Viktor V Oliynyk, Volodymyr V Zagorodnii, Vilen L Launets, Il'ya A Gural'skiy
Microwave electromagnetic radiation that ranges from one meter to one millimetre wavelengths is finding numerous applications for wireless communication, navigation and detection, which makes materials able to tune microwave radiation getting widespread interest. Here we offer a new way to tune GHz frequency radiation by using spin-crossover complexes that are known to change their various physical properties under the influence of diverse external stimuli. As a result of electronic re-configuration process, microwave absorption properties differ for high spin and low spin forms of the complex...
December 2, 2016: Scientific Reports
D E Aguiam, A Silva, V Bobkov, P J Carvalho, P F Carvalho, R Cavazzana, G D Conway, O D'Arcangelo, L Fattorini, H Faugel, A Fernandes, H Fünfgelder, B Gonçalves, L Guimarais, G De Masi, L Meneses, J M Noterdaeme, R C Pereira, G Rocchi, J M Santos, A A Tuccillo, O Tudisco
A new multichannel frequency modulated continuous-wave reflectometry diagnostic has been successfully installed and commissioned on ASDEX Upgrade to measure the plasma edge electron density profile evolution in front of the Ion Cyclotron Range of Frequencies (ICRF) antenna. The design of the new three-strap ICRF antenna integrates ten pairs (sending and receiving) of microwave reflectometry antennas. The multichannel reflectometer can use three of these to measure the edge electron density profiles up to 2 × 10(19) m(-3), at different poloidal locations, allowing the direct study of the local plasma layers in front of the ICRF antenna...
November 2016: Review of Scientific Instruments
H Zhong, Y Tan, Y Q Liu, H Q Xie, Z Gao
A single-channel 3 mm interferometer has been developed for plasma density diagnostics in the Sino-UNIted Spherical Tokamak (SUNIST). The extremely compact microwave interferometer utilizes one corrugated feed horn antenna for both emitting and receiving the microwave. The beam path lies on the equatorial plane so the system would not suffer from beam path deflection problems due to the symmetry of the cross section. A focusing lens group and an oblique vacuum window are carefully designed to boost the signal to noise ratio, which allows this system to show good performance even with the small-diameter central column itself as a reflector, without a concave mirror...
November 2016: Review of Scientific Instruments
Zhongbing Shi, Wulu Zhong, Min Jiang, Zengchen Yang, Boyu Zhang, Peiwan Shi, Wei Chen, Jie Wen, Chengyuan Chen, Bingzhong Fu, Zetian Liu, Xuantong Ding, Qingwei Yang, Xuru Duan
A novel 16-channel fixed frequency Doppler backward scattering (DBS) reflectometer system has been developed on the HL-2A tokamak. This system is based on the filter-based feedback loop microwave source (FFLMS) technique, which has lower phase noise and lower power variation compared with present tunable frequency generation and comb frequency array generation techniques [J. C. Hillesheim et al. Rev. Sci. Instrum. 80, 083507 (2009) and W. A. Peebles et al. Rev. Sci. Instrum. 81, 10D902 (2010)]. The 16-channel DBS system is comprised of four × four-frequency microwave transmitters and direct quadrature demodulation receivers...
November 2016: Review of Scientific Instruments
B Tobias, C W Domier, N C Luhmann, C Luo, M Mamidanna, T Phan, A-V Pham, Y Wang
The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate...
November 2016: Review of Scientific Instruments
Teemu Nieminen, Pasi Lähteenmäki, Zhenbing Tan, Daniel Cox, Pertti J Hakonen
We present a microwave correlation measurement system based on two low-cost USB-connected software defined radio dongles modified to operate as coherent receivers by using a common local oscillator. Existing software is used to obtain I/Q samples from both dongles simultaneously at a software tunable frequency. To achieve low noise, we introduce an easy low-noise solution for cryogenic amplification at 600-900 MHz based on single discrete HEMT with 21 dB gain and 7 K noise temperature. In addition, we discuss the quantization effects in a digital correlation measurement and determination of optimal integration time by applying Allan deviation analysis...
November 2016: Review of Scientific Instruments
G Wang, E J Doyle, W A Peebles
A monostatic antenna array arrangement has been designed for the microwave front-end of the ITER low-field-side reflectometer (LFSR) system. This paper presents details of the antenna coupling coefficient analyses performed using GENRAY, a 3-D ray tracing code, to evaluate the plasma height accommodation capability of such an antenna array design. Utilizing modeled data for the plasma equilibrium and profiles for the ITER baseline and half-field scenarios, a design study was performed for measurement locations varying from the plasma edge to inside the top of the pedestal...
November 2016: Review of Scientific Instruments
K Barada, T L Rhodes, N A Crocker, W A Peebles
We present new measurements of internal magnetic fluctuations obtained with a novel eight channel cross polarization scattering (CPS) system installed on the DIII-D tokamak. Measurements of internal, localized magnetic fluctuations provide a window on an important physics quantity that we heretofore have had little information on. Importantly, these measurements provide a new ability to challenge and test linear and nonlinear simulations and basic theory. The CPS method, based upon the scattering of an incident microwave beam into the opposite polarization by magnetic fluctuations, has been significantly extended and improved over the method as originally developed on the Tore Supra tokamak...
November 2016: Review of Scientific Instruments
Y M Duan, S T Mao, L Q Hu, P Xu, L Q Xu, J Z Zhang, S Y Lin
The foil resistive bolometer diagnostic on experimental advanced superconducting tokamak has been upgraded partly with a new generation of detectors. The new detectors have faster response time. However, the microwave interference is still a serious issue for the bolometer system. The system response to microwave is tested, and the test results show that the closed Wheatstone bridge circuit in the detector is the most sensitive component to high power microwave field. Simulation results of microwave transmission by the high frequency structure simulator software and shielding design are also presented...
November 2016: Review of Scientific Instruments
R G L Vann, K J Brunner, R Ellis, G Taylor, D A Thomas
The Synthetic Aperture Microwave Imaging (SAMI) system is a novel diagnostic consisting of an array of 8 independently phased antennas. At any one time, SAMI operates at one of the 16 frequencies in the range 10-34.5 GHz. The imaging beam is steered in software post-shot to create a picture of the entire emission surface. In SAMI's active probing mode of operation, the plasma edge is illuminated with a monochromatic source and SAMI reconstructs an image of the Doppler back-scattered (DBS) signal. By assuming that density fluctuations are extended along magnetic field lines, and knowing that the strongest back-scattered signals are directed perpendicular to the density fluctuations, SAMI's 2-D DBS imaging capability can be used to measure the pitch of the edge magnetic field...
November 2016: Review of Scientific Instruments
J Kohagura, M Yoshikawa, X Wang, D Kuwahara, N Ito, Y Nagayama, Y Shima, K Nojiri, M Sakamoto, Y Nakashima, A Mase
In conventional multichannel/imaging microwave diagnostics of interferometry, reflectometry, and electron cyclotron emission measurements, a local oscillator (LO) signal is commonly supplied to a receiver array via irradiation using LO optics. In this work, we present a 60-GHz interferometer with a new eight-channel receiver array, called a local oscillator integrated antenna array (LIA). An outstanding feature of LIA is that it incorporates a frequency quadrupler integrated circuit for LO supply to each channel...
November 2016: Review of Scientific Instruments
W Lee, J Leem, G S Yun, H K Park, S H Ko, W X Wang, R V Budny, N C Luhmann, K W Kim
Ion gyroscale turbulent fluctuations with the poloidal wavenumber kθ ∼ 3 cm(-1) have been measured in the core region of the neutral beam (NB) injected low confinement (L-mode) plasmas on Korea superconducting tokamak advanced research. The turbulence poloidal wavenumbers are deduced from the frequencies and poloidal rotation velocities in the laboratory frame, measured by the multichannel microwave imaging reflectometer. Linear and nonlinear gyrokinetic simulations also predict the unstable modes with the normalized wavenumber kθρs ∼ 0...
November 2016: Review of Scientific Instruments
C Mao, X Wang, X Zou, J Lehr
This paper presents the experimental results of a monolithic radial transmission line (MRTL) that may be used in pulsed power generators and microwave devices. The MRTL with a hyperbolic impedance profile is 508 mm in radius, corresponding to a one-way transit time of 15 ns for the electromagnetic wave. In the experiments, up to twenty identical voltage pulses, 10 ns in FWHM and 2 ns in rise-time, were fed into the MRTL through 20 input BNC connectors that are uniformly distributed along the outer circumference of the MRTL...
November 2016: Review of Scientific Instruments
D Sheftman, D Gupta, T Roche, M C Thompson, F Giammanco, F Conti, P Marsili, C D Moreno
Knowledge and control of the axial outflow of plasma particles and energy along open-magnetic-field lines are of crucial importance to the stability and longevity of the advanced beam-driven field-reversed configuration plasma. An overview of the diagnostic methods used to perform measurements on the open field line plasma on C-2U is presented, including passive Doppler impurity spectroscopy, microwave interferometry, and triple Langmuir probe measurements. Results of these measurements provide the jet ion temperature and axial velocity, electron density, and high frequency density fluctuations...
November 2016: Review of Scientific Instruments
K J Brunner, J C Chorley, N A Dipper, G Naylor, R M Sharples, G Taylor, D A Thomas, R G L Vann
The synthetic aperture microwave imaging diagnostic has been operating on the MAST experiment since 2011. It has provided the first 2D images of B-X-O mode conversion windows and showed the feasibility of conducting 2D Doppler back-scattering experiments. The diagnostic heavily relies on field programmable gate arrays to conduct its work. Recent successes and newly gained experience with the diagnostic have led us to modify it. The enhancements will enable pitch angle profile measurements, O and X mode separation, and the continuous acquisition of 2D DBS data...
November 2016: Review of Scientific Instruments
Kunito Fukuda, Naoki Asakawa
A straightforward method for a variable frequency electron spin resonance/electrically detected magnetic resonance (ESR/EDMR) spectroscopy using a C-band microwave cavity equipped with waveguide windows is presented. The method enables us to perform quasi-continuous multiple resonance frequency (MF-ESR/EDMR) experiments for electronic devices. The C-band microwave circuitry was selected because of larger available sample volume than that for conventional X-band one. All the measurements were performed using a combined sample of 2,2-diphenyl-1-picrylhydrazyl/ pn-junction Si diode...
November 2016: Review of Scientific Instruments
Y L Zhu, J L Xie, C X Yu, Z L Zhao, B X Gao, D X Chen, W D Liu, W Liao, C M Qu, C Luo, X Hu, A G Spear, N C Luhmann, C W Domier, M Chen, X Ren, B J Tobias
Millimeter-wave imaging diagnostics, with large poloidal span and wide radial range, have been developed on the EAST tokamak for visualization of 2D electron temperature and density fluctuations. A 384 channel (24 poloidal × 16 radial) Electron Cyclotron Emission Imaging (ECEI) system in F-band (90-140 GHz) was installed on the EAST tokamak in 2012 to provide 2D electron temperature fluctuation images with high spatial and temporal resolution. A co-located Microwave Imaging Reflectometry (MIR) will be installed for imaging of density fluctuations by December 2016...
November 2016: Review of Scientific Instruments
Selime Mutlu, Kevser Kahraman, Serpil Öztürk
The effects of microwave irradiation on resistant starch (RS) formation and functional properties in high-amylose corn starch, Hylon VII, by applying microwave-storing cycles and drying processes were investigated. The Response Surface Methodology (RSM) was used to optimize the reaction conditions, microwave time (2-4min) and power (20-100%), for RS formation. The starch:water (1:10) mixtures were cooked and autoclaved and then different microwave-storing cycles and drying (oven or freeze drying) processes were applied...
November 28, 2016: International Journal of Biological Macromolecules
Evgenii J Drobyshev, Nikolay D Solovyev, Natalya B Ivanenko, Maria Yu Kombarova, Alexander A Ganeev
In the current study, a biomonitoring of 18 hair trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Se, V, Zn, Ca, Na and P) in school children from Leningradskaya Oblast' is reported. A case group, residing in a proximity to the toxic waste disposal grounds (Krasniy Bor), has been assessed vs. controls from a non-urban settlement Seltso. In total, 166 hair samples were analysed using double focusing sector field inductively coupled plasma mass spectrometry after microwave-assisted sample digestion with nitric acid...
January 2017: Journal of Trace Elements in Medicine and Biology
Zeinab Salari, Atefeh Ameri, Hamid Forootanfar, Mahboubeh Adeli-Sardou, Mandana Jafari, Mitra Mehrabani, Mojtaba Shakibaie
The present study was designed for microwave assisted synthesis of zinc nanoparticles (Zn NPs) using Lavandula vera leaf extract in the presence of ZnSO4 (1mM). The biogenic Zn NPs were then characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction spectroscopy (XRD), UV-visible spectroscopy, and Fourier transform infrared spectroscopy (FTIR) techniques. Thereafter, the cytotoxic effect of ZnSO4 and Zn NPs on different cell lines was investigated by MTT-based cytotoxicity assay and their antioxidant properties were assessed using DPPH scavenging activity and reducing power assay...
January 2017: Journal of Trace Elements in Medicine and Biology
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