Design of the ITER Ion Cyclotron Heating Current Drive System Based on in-Vessel Tuning System

Since the release of the ITER ICRH system Reference Design report [ITER Final Design Report : DDD 5.1 -Ion Cyclotron and Current Drive System, July 2001], many studies have been conducted. The basic of the reference design [Final Report on EFDA contract 04/1129, '' ITER ICRF antenna and Matching system design (Internal matching) '', April 2005] is kept unchanged but several significant modifications have been proposed for a better efficiency and reliability. The main modification concerns the Compact Vacuum Tuner (CVT) that is now located 2 meter back from its original position and simply made with a variable open-circuit line. The CVT being now close to the torus chamber and surrounded by 400 mm of neutron shield, it is therefore less exposed to demanding ITER operating conditions. Moreover, this tuning element, larger in dimension presents the advantage to lower the maximum E-field inside the component, allowing a smoother use all over the required frequency band. The design also address technical aspects insufficiently covered in previous studies like its full integration on a mid-plane port satisfying the constraints of the current ITER port design. Others changes and studies will be also described in the paper, like handling and assembly procedure, supporting and cooling methods of the inner component. Thermo-mechanical calculation of the structure including neutron field loads will also illustrate this article. (author)