TY - JOUR
T1 - HTS planar gradiometer consisting of SQUID with multi-turn input coil and large pickup coil made of GdBCO coated conductor
AU - Tsukamoto, Akira
AU - Adachi, Seiji
AU - Oshikubo, Yasuo
AU - Hato, Tsunehiro
AU - Enpuku, Keiji
AU - Sugisaki, Masaki
AU - Arai, Eiichi
AU - Tanabe, Keiichi
PY - 2013/1/15
Y1 - 2013/1/15
N2 - We have investigated the fabrication of a high-temperature superconducting (HTS) gradiometer with long baseline for geophysical applications. The proof-of-concept gradiometer using a 1-turn pickup coil made of a GdBa 2Cu3Oy coated conductor (GCC) and 5.5-turn input coil integrated on a SQUID was fabricated in our previous work. In this study, we have optimized the device structure to improve the frequency response, gradient field sensitivity and gradiometer balance. The fabricated flux transformer consists of a 6-turn planar gradiometric pickup coil and a 26-turn input coil made of an HTS thin film. A low-melting-point alloy was used to connect polished Ag surfaces of the CGG pickup coil and Au pads of the input coil. An HTS SQUID was formed on another substrate and stacked on the input coil. A mechanical balancing structure using three pieces of GCC as a superconducting shield was also implemented. The fabricated gradiometer showed a gradient field noise of 0.8 fT/cm Hz1/2 in the white noise regions, a gradiometer balance of 1/142, and a cutoff frequency of 9 Hz corresponding to a 2 mΩ contact resistance between the pickup coil and the input coil.
AB - We have investigated the fabrication of a high-temperature superconducting (HTS) gradiometer with long baseline for geophysical applications. The proof-of-concept gradiometer using a 1-turn pickup coil made of a GdBa 2Cu3Oy coated conductor (GCC) and 5.5-turn input coil integrated on a SQUID was fabricated in our previous work. In this study, we have optimized the device structure to improve the frequency response, gradient field sensitivity and gradiometer balance. The fabricated flux transformer consists of a 6-turn planar gradiometric pickup coil and a 26-turn input coil made of an HTS thin film. A low-melting-point alloy was used to connect polished Ag surfaces of the CGG pickup coil and Au pads of the input coil. An HTS SQUID was formed on another substrate and stacked on the input coil. A mechanical balancing structure using three pieces of GCC as a superconducting shield was also implemented. The fabricated gradiometer showed a gradient field noise of 0.8 fT/cm Hz1/2 in the white noise regions, a gradiometer balance of 1/142, and a cutoff frequency of 9 Hz corresponding to a 2 mΩ contact resistance between the pickup coil and the input coil.
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U2 - 10.1016/j.physc.2012.03.006
DO - 10.1016/j.physc.2012.03.006
M3 - Article
AN - SCOPUS:84875654955
VL - 484
SP - 191
EP - 194
JO - Physica C: Superconductivity and its Applications
JF - Physica C: Superconductivity and its Applications
SN - 0921-4534
ER -