Commissioning and first results of the reinstated JET ICRF ILA

Abstract

The JET ICRF ITER-like Antenna (ILA) has been operated at 33, 42 and 47 MHz in 2008–2009 but stoppedoperation in 2009 due to the failure of one of the tuning capacitors inside the antenna. Tests on a sparecapacitor showed that a micro-leak was caused by the cycle wear of a capacitor’s internal bellows. TheILA was reinstated with a new operating scheme minimizing the full stroke requests of the capacitor.This contribution gives an overview of the works undertaken to reinstate the JET ILA up to the firstresults on plasma.The capacitors were replaced and high voltage tests of the capacitors were performed. An extensivecalibration of all the measurements in the RF circuit was carried out. New simulation tools were createdand control algorithms were implemented for the – toroidal and poloidal – phase control of the array aswell as for the matching of the second stage. New protections are being implemented for the thermal andvoltage protection of the capacitors. Low voltage matching tests were performed before the high powercommissioning. Finally the first results on plasma are presented, showing that the new controls allowextending the range of the operation to lower (29 MHz) and higher (51 MHz) frequencies than previously achieved.