Development and testing of a fast Fourier transform high dynamic-range spectral diagnostics for millimeter wave characterization

Journal Article · Thu Oct 15 00:00:00 EDT 2009 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3244091· OSTI ID:22051061

Thoen, D J; Bongers, W A; Westerhof, E; Baar, M R. de; Berg, M A. van den; Beveren, V van; Goede, A P. H.; Graswinckel, M F; Schueller, F C ^[1]; Oosterbeek, J W; Buerger, A ^[2]; Hennen, B A ^[1]

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1. Association EURATOM-FOM, Trilateral Euregio Cluster, FOM-Institute for Plasma Physics Rijnhuizen, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands)
2. Association EURATOM-FZJ, Institut fuer Energieforschung-Plasmaphysik, Forschungszentrum Juelich GMBH, 52425 Juelich (Germany)

A fast Fourier transform (FFT) based wide range millimeter wave diagnostics for spectral characterization of scattered millimeter waves in plasmas has been successfully brought into operation. The scattered millimeter waves are heterodyne downconverted and directly digitized using a fast analog-digital converter and a compact peripheral component interconnect computer. Frequency spectra are obtained by FFT in the time domain of the intermediate frequency signal. The scattered millimeter waves are generated during high power electron cyclotron resonance heating experiments on the TEXTOR tokamak and demonstrate the performance of the diagnostics and, in particular, the usability of direct digitizing and Fourier transformation of millimeter wave signals. The diagnostics is able to acquire 4 GHz wide spectra of signals in the range of 136-140 GHz. The rate of spectra is tunable and has been tested between 200 000 spectra/s with a frequency resolution of 100 MHz and 120 spectra/s with a frequency resolution of 25 kHz. The respective dynamic ranges are 52 and 88 dB. Major benefits of the new diagnostics are a tunable time and frequency resolution due to postdetection, near-real time processing of the acquired data. This diagnostics has a wider application in astrophysics, earth observation, plasma physics, and molecular spectroscopy for the detection and analysis of millimeter wave radiation, providing high-resolution spectra at high temporal resolution and large dynamic range.

• OSTI ID: 22051061
• Journal Information: Review of Scientific Instruments, Vol. 80, Issue 10; Other Information: (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DATA PROCESSING
ECR HEATING
FOURIER TRANSFORMATION
GHZ RANGE
KHZ RANGE
MHZ RANGE
MICROWAVE RADIATION
PERFORMANCE
PLASMA
PLASMA DIAGNOSTICS
RADIATION DETECTION
REAL TIME SYSTEMS
RF SYSTEMS
SPECTRA
TEXTOR TOKAMAK
TIME RESOLUTION