3D, LTCC-type, high-frequency magnetic sensors for the TCV Tokamak

High-frequency, 3D magnetic sensors have been designed and manufactured in-house for installation on the Tokamak a Configuration Variable (TCV). To optimize the in-vessel volume occupation, the sensors are based on combining the Low Temperature Co-fired Ceramic (LTCC) and the classical thick-film technologies. The target requirements for the three measurement axes are an effective area NA(EFF) =100 cm(2) and end-to-end resonant frequency omega(0)/2 pi = 1 MHz. For the as-built sensors, an effective area NA(EFF) similar to 220 cm(2), self-inductance L-SELF similar to 8 mu H and self-resonant frequency omega(0)/2 pi similar to 16 MHz are obtained for the primary delta B-NOR measurement, while NA(EFF) similar to 265 cm(2), NA(EFF) similar to 300 cm(2), L-SELF similar to 150 mu H and omega(0)/2 pi similar to 5.5 MHz are obtained for the secondary delta B-TOR and delta B-POL measurements. When including the cabling up to the front-end electronics, omega(0)/2 pi > 2 MHz is expected for all three measurement axes. To optimize the measurement performance of this new magnetic diagnostic system while limiting the number of elements for the first phase of installation on TCV, five 3D sensors will be installed along the toroidal direction, allowing detection of magnetic perturbations with toroidal mode numbers vertical bar n vertical bar >30, thus significantly improving on the previous detection capabilities, which were Nyquist-limited to vertical bar n vertical bar = 8. (c) 2015 Elsevier B.V. All rights reserved.