29th Symposium on Fusion Technology (SOFT 2016)

P4.036 Commissioning and first results of the reinstated JET ICRF ILA antenna

8 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 36

Poster B. Plasma Heating and Current Drive P4 Poster session

Speaker

Pierre Dumortier (LPP-ERM/KMS)

Description

The JET ICRF ITER-like Antenna (ILA) is composed of four resonant double loops (RDLs) arranged in a 2 toroidal by 2 poloidal array. Each RDL consists of two poloidally adjacent straps fed through in-vessel matching capacitors from a common Vacuum Transmission Line. Two toroidally adjacent RDLs are fed through a 3dB combiner-splitter. The JET ILA antenna has been operating at 33, 42 and 47MHz in 2008-2009 and has stopped operation in 2009 due to a failure of one of the tuning capacitors inside the antenna. Tests on a spare capacitor showed that a micro-leak was caused by the cycle wear of a capacitor’s internal bellows. The ILA 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 first results on plasma. The capacitors were replaced and high voltage tests of the capacitors were performed. An extensive calibration of all the measurements in the RF circuit was carried out. New simulation tools were created and control algorithms were implemented for the – toroidal and poloidal – phase control of the array as well as for the matching of the second stage. New protections are being implemented for the thermal and voltage protection of the capacitors. Low voltage matching tests were performed before the high power commissioning. Finally the first results on plasma are presented, showing that the new controls allow extending the range of the operation to lower (29MHz) and higher (49MHz) frequencies than previously achieved.