Search

In the framework of the Ion Cyclotron (IC) antenna design, ITER Organization requested qualification tests on sliding Radio-Frequency (RF) contacts, to verify that these contacts (quality class 1) are designed appropriately to guarantee a sufficient operational life time. These RF contacts will be integrated into the antenna structure at different locations to facilitate the assembly and decouple the different mechanical parts. This design will in addition lower the thermo-mechanical constraints and allow radial shimming of the antenna front face. As commercial contacts were not suitable for the ITER ICRH antenna operation, substantial efforts have been made on mechanical design of the new RF contact. Two prototypes have been manufactured and delivered to CEA for testing. In parallel a test stand facility (TITAN) has been refurbished to provide a way to test these RF contacts in relevant conditions (2.25kA @ 62.5MHz, vacuum pressure <10-3Pa, 1000s). This paper reports on main results we get during the commissioning of the test stand facility. Roadmap of the tests is also detailed with RF power tests for long shot duration (1000s) under vacuum and extensive sliding tests in order to assess the reliability of the RF contact for a relevant life time duration (specified to 10 years). A description of the RF contact is also given with the latest results on the manufacturing process (copper and gold plating and brazing, general assembly). [ABSTRACT FROM AUTHOR]

In the framework of the Ion Cyclotron (IC) developments held in Cadarache, the design of a new Faraday Screen (FS) was initiated to replace the aging ones mounted on the 3 Tore Supra (TS) antennas. The new conceptual design proposed is steered by conclusive results of electrical simulation stressing the need to suppress the parallel RF currents flowing on the FS frame to reduce the RF sheaths. Two major modifications are implemented on a TS FS to reduce the j// circulation: apertures on the top and bottom closure walls of the antenna radiating box, and cantilevered FS bars (that is, bars not connected to the vertical central septum). This single connection point also eases the FS rod thermal expansion, resulting in less mechanical stresses. In addition, the cantilevered bar design avoids eddy current loops which reduces electromagnetically induced stresses during disruptions. If successful with plasma operation, this RF structure provides a promising new option to simplify the ITER IC Faraday screen design. [ABSTRACT FROM AUTHOR]

The antenna design proposed here is based on the resonant double loop concept with conjugate T matching to make the circuit resilient to strong plasma load variations as ELMs. The antenna is constituted of two main parts; the in-vessel launcher which is inside the primary torus vacuum and the Compact Vacuum Tuners (CVT) that is located after the first barrier in a private vacuum. This CVT allows to match at the strap location, the antenna impedance with the plasma load, over the 45 to 55 MHz frequency range. It has been designed to ease its repair and maintenance, and can be easily removed from the rear without breaking the primary vacuum. Apart from the Faradays screens fit to shape the plasma edge, the in-vessel launcher and CVT are made out of 6 identical modules, to allow the best economical approach for the manufacture, the assembly and the maintenance of the antenna. [ABSTRACT FROM AUTHOR]