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Title: Improved Collective Thomson Scattering measurements of fast ions at ASDEX upgrade

Understanding the behaviour of the confined fast ions is important in both current and future fusion experiments. These ions play a key role in heating the plasma and will be crucial for achieving conditions for burning plasma in next-step fusion devices. Microwave-based Collective Thomson Scattering (CTS) is well suited for reactor conditions and offers such an opportunity by providing measurements of the confined fast-ion distribution function resolved in space, time and 1D velocity space. We currently operate a CTS system at ASDEX Upgrade using a gyrotron which generates probing radiation at 105 GHz. A new setup using two independent receiver systems has enabled improved subtraction of the background signal, and hence the first accurate characterization of fast-ion properties. Here we review this new dual-receiver CTS setup and present results on fast-ion measurements based on the improved background characterization. These results have been obtained both with and without NBI heating, and with the measurement volume located close to the centre of the plasma. The measurements agree quantitatively with predictions of numerical simulations. Hence, CTS studies of fast-ion dynamics at ASDEX Upgrade are now feasible. The new background subtraction technique could be important for the design of CTS systems in other fusionmore » experiments.« less
Authors:
; ; ; ; ; ; ; ;  [1] ;  [2] ; ; ; ; ;
  1. Association Euratom-DTU, Technical University of Denmark, Department of Physics, DTU Riso/ Campus, DK-4000 Roskilde (Denmark)
  2. Association Euratom-FOM Institute DIFFER, 3430 BE Nieuwegein (Netherlands)
Publication Date:
OSTI Identifier:
22308275
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1612; Journal Issue: 1; Conference: International conference on fusion reactor diagnostics, Varenna (Italy), 9-13 Sep 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ASDEX TOKAMAK; BEAM INJECTION HEATING; COMPUTERIZED SIMULATION; DISTRIBUTION FUNCTIONS; MICROWAVE RADIATION; NEUTRAL ATOM BEAM INJECTION; PLASMA; SPACE-TIME; THOMSON SCATTERING