Design and performance of the collective Thomson scattering receiver at ASDEX Upgrade

Journal Article · Sun Jan 15 00:00:00 EST 2012 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3675886· OSTI ID:22063772

Furtula, V; Salewski, M; Leipold, F; Michelsen, P K; Korsholm, S B; Meo, F; Moseev, D; Nielsen, S K; Stejner, M ^[1]; Johansen, T ^[2]

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1. Association Euratom - Risoe National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark)
2. DTU Elektro, Technical University of Denmark, DK-2800 Lyngby (Denmark)

Here we present the design of the fast-ion collective Thomson scattering receiver for millimeter wave radiation installed at ASDEX Upgrade, a tokamak for fusion plasma experiments. The receiver can detect spectral power densities of a few eV against the electron cyclotron emission background on the order of 100 eV under presence of gyrotron stray radiation that is several orders of magnitude stronger than the signal to be detected. The receiver down converts the frequencies of scattered radiation (100-110 GHz) to intermediate frequencies (IF) (4.5-14.5 GHz) by heterodyning. The IF signal is divided into 50 IF channels tightly spaced in frequency space. The channels are terminated by square-law detector diodes that convert the signal power into DC voltages. We present measurements of the transmission characteristics and performance of the main receiver components operating at mm-wave frequencies (notch, bandpass, and lowpass filters, a voltage-controlled variable attenuator, and an isolator), the down-converter unit, and the IF components (amplifiers, bandpass filters, and detector diodes). Furthermore, we determine the performance of the receiver as a unit through spectral response measurements and find reasonable agreement with the expectation based on the individual component measurements.

• OSTI ID: 22063772
• Journal Information: Review of Scientific Instruments, Vol. 83, Issue 1; Other Information: (c) 2012 EURATOM; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ASDEX TOKAMAK
CYCLOTRON RADIATION
DESIGN
ELECTRIC POTENTIAL
ELECTROMAGNETIC FILTERS
ELECTRON EMISSION
EV RANGE
GHZ RANGE
IONS
MICROWAVE AMPLIFIERS
MICROWAVE RADIATION
PERFORMANCE
PLASMA
POWER DENSITY
SIGNALS
SPECTRAL RESPONSE
STRAY RADIATION
THOMSON SCATTERING
TRANSMISSION