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Title: Modification of the collective Thomson scattering radiometer in the search for parametric decay on TEXTOR

Abstract

Strong scattering of high-power millimeter waves at 140 GHz has been shown to take place in heating and current-drive experiments at TEXTOR when a tearing mode is present in the plasma. The scattering signal is at present supposed to be generated by the parametric decay instability. Here we describe the heterodyne detection system used to characterize the newly discovered signal measured at TEXTOR, and we present spectral shapes in which the signal can appear under different conditions. The radiation is collected by the receiver through a quasi-optical transmission line that is independent of the electron cyclotron resonance heating transmission line, and so the scattering geometry is variable. The signal is detected with 42 frequency channels ranging from 136 to 142 GHz. We demonstrate that the large signal does not originate from gyrotron spurious radiation. The measured signal agrees well with independent backscattering radiometer data.

Authors:
; ; ; ; ; ;  [1]; ; ;  [2];  [3]
  1. Association EURATOM - DTU, Department of Physics, Technical University of Denmark, Risoe Campus, DK-4000 Roskilde (Denmark)
  2. FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM - FOM, Nieuwegein (Netherlands)
  3. Department of Applied Physics, Science and Technology of Nuclear Fusion, Eindhoven University of Technology, NL-5600 MB Eindhoven (Netherlands)
Publication Date:
OSTI Identifier:
22093985
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 83; Journal Issue: 11; Other Information: (c) 2012 Euratom; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; BACKSCATTERING; DECAY INSTABILITY; DETECTION; ECR HEATING; ELECTROMAGNETIC RADIATION; MODIFICATIONS; PLASMA DIAGNOSTICS; RADIOMETERS; SIGNALS; TEARING INSTABILITY; TEXTOR TOKAMAK; THOMSON SCATTERING

Citation Formats

Nielsen, S. K., Salewski, M., Korsholm, S. B., Leipold, F., Meo, F., Michelsen, P., Stejner, M., Bongers, W., Moseev, D., Westerhof, E., and Oosterbeek, J. W. Modification of the collective Thomson scattering radiometer in the search for parametric decay on TEXTOR. United States: N. p., 2012. Web. doi:10.1063/1.4768668.
Nielsen, S. K., Salewski, M., Korsholm, S. B., Leipold, F., Meo, F., Michelsen, P., Stejner, M., Bongers, W., Moseev, D., Westerhof, E., & Oosterbeek, J. W. Modification of the collective Thomson scattering radiometer in the search for parametric decay on TEXTOR. United States. doi:10.1063/1.4768668.
Nielsen, S. K., Salewski, M., Korsholm, S. B., Leipold, F., Meo, F., Michelsen, P., Stejner, M., Bongers, W., Moseev, D., Westerhof, E., and Oosterbeek, J. W. Thu . "Modification of the collective Thomson scattering radiometer in the search for parametric decay on TEXTOR". United States. doi:10.1063/1.4768668.
@article{osti_22093985,
title = {Modification of the collective Thomson scattering radiometer in the search for parametric decay on TEXTOR},
author = {Nielsen, S. K. and Salewski, M. and Korsholm, S. B. and Leipold, F. and Meo, F. and Michelsen, P. and Stejner, M. and Bongers, W. and Moseev, D. and Westerhof, E. and Oosterbeek, J. W.},
abstractNote = {Strong scattering of high-power millimeter waves at 140 GHz has been shown to take place in heating and current-drive experiments at TEXTOR when a tearing mode is present in the plasma. The scattering signal is at present supposed to be generated by the parametric decay instability. Here we describe the heterodyne detection system used to characterize the newly discovered signal measured at TEXTOR, and we present spectral shapes in which the signal can appear under different conditions. The radiation is collected by the receiver through a quasi-optical transmission line that is independent of the electron cyclotron resonance heating transmission line, and so the scattering geometry is variable. The signal is detected with 42 frequency channels ranging from 136 to 142 GHz. We demonstrate that the large signal does not originate from gyrotron spurious radiation. The measured signal agrees well with independent backscattering radiometer data.},
doi = {10.1063/1.4768668},
journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 11,
volume = 83,
place = {United States},
year = {2012},
month = {11}
}