Improved Collective Thomson Scattering measurements of fast ions at ASDEX upgrade

Journal Article · Thu Aug 21 00:00:00 EDT 2014 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.4894036· OSTI ID:22308275

Rasmussen, J.; Nielsen, S. K.; Stejner, M.; Salewski, M.; Jacobsen, A. S.; Korsholm, S. B.; Leipold, F.; Meo, F.; Michelsen, P. K. ^[1]; Moseev, D. ^[2]; Schubert, M.; Stober, J.; Tardini, G.; Wagner, D.

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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)

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 fusion experiments.

• OSTI ID: 22308275
• Journal Information: AIP Conference Proceedings, Vol. 1612, 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); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

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