Development of an ICRH antenna system at W7-X for plasma heating and wall conditioning

• Published in: Fusion engineering and design 2017-11, Vol.123, p.303-308
• Main Authors: Schweer, B., Ongena, J., Borsuk, V., Birus, D., Bozhenkov, S., Bardawil, D. Castaño, Durodié, F., Hartmann, D., Hollfeld, K.P., Kallmeyer, P., Krivska, A., Louche, F., Messiaen, A., Neubauer, O., Offermanns, G., Satheeswaran, G., Van Schoor, M., Vervier, M., Wolf, R.
• Format: Article
• Language: English
• Subjects: Antennas; Circuit design; Conditioning; Configurations; Fast particle generation; Heating; ICRH antenna; Magnetic fields; Nuclear reactors; Plasma heating; Plasma sintering; Studies; W7-X; Wall conditioning
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2017.05.019

•ICRH antenna at W7-X,.•LCFS adopted surface of antenna head.•Radially movable for all magnetic field configurations.•Pre-matching with tunable capacitors.•Operational frequencies from 25MHz to 38 MHz. An ICRH antenna system is under construction to be ready for use in the operational phase 1.2 of W7-X. A two strap antenna, with a surface adapted to the 3D shape of the Last Closed Flux Surface (LCFS) of the standard magnetic configuration (m/n=5/5), will be installed in the equatorial plane on the low field side of W7-X. The antenna system is optimised for plasma heating and wall conditioning in presence of the magnetic field in the frequency range 25–38MHz. Each strap is short-circuited on one end, is pre-matched using a tunable capacitor on the other end with connection to the RF power source about halfway in the poloidal direction. To allow optimal coupling to different magnetic configurations in W7-X the antenna can be moved radially over a distance of 350 mm. The cooling circuits in the antenna head are designed to sustain cw W7-X plasma operation in a retracted position and 2MW ICRH pulses with maximum 10s duration every 300s close to the LCFS.