16 research outputs found

    A portable 3D Imaging FMCW MIMO Radar Demonstrator with a 24x24 Antenna Array for Medium Range Applications

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    © 2018 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] Multiple-input multiple-output (MIMO) radars have been shown to improve target detection for surveillance applications thanks to their proven high-performance properties. In this paper, the design, implementation, and results of a complete 3-D imaging frequency-modulated continuous-wave MIMO radar demonstrator are presented. The radar sensor working frequency range spans between 16 and 17 GHz, and the proposed solution is based on a 24-transmitter and 24-receiver MIMO radar architecture, implemented by timedivision multiplexing of the transmit signals. A modular approach based on conventional low-cost printed circuit boards is used for the transmit and receive systems. Using digital beamforming algorithms and radar processing techniques on the received signals, a high-resolution 3-D sensing of the range, azimuth, and elevation can be calculated. With the current antenna configuration, an angular resolution of 2.9° can be reached. Furthermore, by taking advantage of the 1-GHz bandwidth of the system, a range resolution of 0.5 m is achieved. The radio-frequency front-end, digital system and radar signal processing units are here presented. The medium-range surveillance potential and the high-resolution capabilities of the MIMO radar are proved with results in the form of radar images captured from the field measurements.Ganis, A.; Miralles-Navarro, E.; Schoenlinner, B.; Prechtel, U.; Meusling, A.; Heller, C.; Spreng, T.... (2018). A portable 3D Imaging FMCW MIMO Radar Demonstrator with a 24x24 Antenna Array for Medium Range Applications. IEEE Transactions on Geoscience and Remote Sensing. 56(1):298-312. https://doi.org/10.1109/TGRS.2017.2746739S29831256

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    In situ measurements of the spectral reflectance of metallic mirrors at the Hα line in a low density Ar–H plasma

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    The efficient and reliable control and monitoring of the quality of the optical properties of mirrors is an open problem in laboratory plasmas. Until now, the measurement of the reflectance of the first mirrors was based on the methods that require additional light calibration sources. We propose a new technique based on the ratio of the red- and blue-shifted emission signals of the reflected hydrogen atoms which enables the in situ measurement of the spectral reflectance of metallic mirrors in low-density Ar–H or Ar–D plasmas. The spectral reflectance coefficients were measured for C, Al, Ag, Fe, Pd, Ti, Sn, Rh, Mo, and W mirrors installed in the linear magnetized plasma device PSI-2 operating in the pressure range of 0.01-0.1 Pa. The results are obtained for the Hα line using the emission of fast atoms induced by excitation of H atoms through Ar at a plasma-solid interface by applying a negative potential U = −80, …, −220 V to the mirror. The agreement between the measured and theoretical data of reflectance is found to be within 10% for the investigated materials (except for C). The spectra also allow us to efficiently determine the material of the mirror

    Design status of the ITER core CXRS diagnostic setup

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    The Charge eXchange Recombination Spectroscopy diagnostic system on the ITER plasma core (CXRS core) will provide spatially resolved measurements of plasma parameters. The optical front-end is located in upper port 3 and the light of 460–665 nm is routed to spectrometers housed in the tritium building. This paper describes the layout of the optical system in the port plug, cell and interspace areas. The layout is a continuation of the developments described in [1] and takes into account changes in the design of the upper port plug, considerations for the system lifetime as well as internal and external tolerances on the optical chain. The layout was selected also with a number of additional criteria, including optical performance, radiation shielding, maintainability and robustness. A free-space optical chain was added pushing the optical fibres to the port cell. A line-of-sight finder imaging apertures and masks in the optical chain was added to enable determination of deviations within the optical chain and stabilise the image on the fibres. Where feasible, existing solutions for sub-systems such as the shutter were adapted to the layout
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