Author/Authors :
Testa، نويسنده , , D. and Carfantan، نويسنده , , H. M. Toussaint، نويسنده , , M. and Chavan، نويسنده , , R. and Fournier، نويسنده , , Y. and Guterl، نويسنده , , J. and Lister، نويسنده , , J.B. and Maeder، نويسنده , , T. and Moret، نويسنده , , J.-M. and Perez، نويسنده , , A. and Sanchez، نويسنده , , F. and Schaller، نويسنده , , B. K. Slater، نويسنده , , C. and Stoeck، نويسنده , , M. and Tonetti، نويسنده , , G.، نويسنده ,
Abstract :
The ITER high-frequency (HF) magnetic diagnostic system has to provide essential measurements of MHD instabilities with |δBMEAS/BPOL| ∼ 10−4 (∼1 G) for frequencies up to 2 MHz to resolve toroidal mode numbers (n) in the range |n| = 10 to |n| = 50. A review of the measurement requirements for HF MHD instabilities in ITER was initiated during the TW4 work-program and led to significant interest for physics and real-time control issues in measuring modes with |δBMEAS| as low as ∼10−3 G at the position of the sensors, with |n| ≤ 30 and poloidal mode numbers |m| ∼ 2|n| up to |n| ∼ 15, for a frequency range extending up to ∼500 kHz. We have examined the ability of the current ITER design for the individual sensors and the diagnostic system as a whole to meet these needs, and have explored what adjustments to the design (of the individual sensors and/or of the system as a whole) or to the requirements would be needed to meet them when considering different hypothesis for the financial costs and risk management over the ITER life-time. First, we find that the proposed diagnostic layout, with 168 sensors in total, does not meet the more stringent measurement requirements and risk management criteria: these can only be met by a revision of the design requiring 350–500 sensors, depending on different costing and risk management options. Second, we find that the current design for the ITER HF Mirnov-type pick-up coil could be usefully revised.
