Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7133437 | Sensors and Actuators A: Physical | 2018 | 36 Pages |
Abstract
A miniaturized Printed Circuit Board (PCB) sensing coil, jointly developed by CERN and Fermilab for measuring the field of small-gap (less than 10â¯mm) accelerator magnets, is illustrated. A sensing coil array, with a scheme for compensating the main field when measuring the harmonic error components, hosted on a synthetic sapphire-based transducer, is presented. Key innovating features are (i) very-small size, both for the sensing coil array (thickness of 1.380â¯mm) and for the transducer (overall diameter of 7.350â¯mm), (ii) metrological performance, namely accuracy (more than five times better than state of the art), and 1-sigma repeatability (ten times better on harmonics with amplitude less than 100â¯ppm), and (iii) manufacturing technology of both the coil array (13 double layers aligned within 10â¯Î¼m), and the sapphire support (concentricity, the most important uncertainty source for rotating coils, 3â¯Î¼m of uncertainty, namely one order of magnitude better than fiberglass support). After stating the measurement problem, the design of the transducer and a case study of a two-layer PCB sensor array are illustrated. Then, the prototyping and quality control of both the sensor and the transducer are discussed. Furthermore, the calibration and the results obtained with a prototype setup at Fermilab are presented. Finally, in the appendix, the theory of the rotating coil, the sensor geometry, and the harmonic compensation are briefly reviewed for the reader easiness.
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Authors
P. Arpaia, M. Buzio, R. De Oliveira, J. DiMarco, G. Severino,