Study and design of the ion cyclotron resonance heating system for the stellarator Wendelstein 7-X

Journal Article · Sun Jun 15 00:00:00 EDT 2014 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4884377· OSTI ID:22299957

Ongena, J.; Messiaen, A.; Van Eester, D.; Schweer, B.; Dumortier, P.; Durodie, F.; Kazakov, Ye. O.; Louche, F.; Vervier, M.; Koch, R.; Krivska, A.; Lyssoivan, A.; Van Schoor, M.; Wauters, T. ^[1]; Borsuk, V.; Neubauer, O.; Schmitz, O. ^[2]; Offermans, G. ^[3]; Altenburg, Y.; Baylard, C. ^[4] ; others, and

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1. Laboratory for Plasmaphysics, Ecole Royale Militaire–Koninklijke Militaire School, TEC Partner, Brussels (Belgium)
2. IEK-4/Plasmaphysik, Forschungszentrum Juelich, TEC Partner, Juelich (Germany)
3. ZEA-1, Forschungszentrum Juelich, Juelich (Germany)
4. Max-Planck Institute für Plasmaphysik, Teilinstitut Greifswald, Greifswald (Germany)

The current status of the mechanical and electromagnetic design for the ICRF antenna system for W7-X is presented. Two antenna plugins are discussed: one consisting of a pair of straps with pre-matching to cover the first frequency band, 25–38 MHz, and a second one consisting of two short strap triplets to cover a frequency band around 76 MHz. This paper focusses on the two strap antenna for the lower frequency band. Power coupling of the antenna to a reference plasma profile is studied with the help of the codes TOPICA and Microwave Studio that deliver the scattering matrix needed for the optimization of the geometric parameters of the straps and antenna box. Radiation power spectra for different phasings of the two straps are obtained using the code ANTITER II and different heating scenario are discussed. The potential for heating, fast particle generation, and current drive is discussed. The problem of RF coupling through the plasma edge and of edge power deposition is summarized. Important elements of the complete ion cyclotron resonance heating system are discussed: a resonator circuit with tap feed to limit the maximum voltage in the system, and a decoupler to counterbalance the large mutual coupling between the 2 straps. The mechanical design highlights the challenges encountered with this antenna: adaptation to a large variety of plasma configurations, the limited space within the port to accommodate the necessary matching components and the watercooling needed for long pulse operation.

• OSTI ID: 22299957
• Journal Information: Physics of Plasmas, Vol. 21, Issue 6; Other Information: (c) 2014 EURATOM; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ANTENNAS
DESIGN
HEATING SYSTEMS
ICR HEATING
ION CYCLOTRON-RESONANCE
MHZ RANGE 01-100
MICROWAVE RADIATION
OPTIMIZATION
PLASMA RADIAL PROFILES
STELLARATORS