TY - JOUR
T1 - A high-Tc SQUID-based sensor head cooled by a Joule-Thomson cryocooler
AU - Rijpma, A.P.
AU - Brake, ter, H.J.M.
AU - Vries, de, E.
AU - Nijhof, N.
AU - Holland, H.J.
AU - Rogalla, H.
PY - 2002
Y1 - 2002
N2 - The goal of the so-called FHARMON project is to develop a high-Tc SQUID-based magnetometer system for the measurement of fetal heart activity in std. clin. environments. To lower the threshold for the application of this fetal heart monitor, it should be simple to operate. It is, therefore, advantageous to replace the liq. cryogen bath by a closed-cycle refrigerator. For this purpose, we selected a mixed-gas Joule-Thomson cooler; the APD Cryotiger. Because of its magnetic interference, the compressor of this closed-cycle cooler will be placed at a distance of ~2 m from the actual sensor, which is an axial second order gradiometer. The gradiometer is formed by three magnetometers placed on an alumina cylinder, which is connected to the cold head of the cooler. This paper describes the sensor head in detail and reports on test expts.
AB - The goal of the so-called FHARMON project is to develop a high-Tc SQUID-based magnetometer system for the measurement of fetal heart activity in std. clin. environments. To lower the threshold for the application of this fetal heart monitor, it should be simple to operate. It is, therefore, advantageous to replace the liq. cryogen bath by a closed-cycle refrigerator. For this purpose, we selected a mixed-gas Joule-Thomson cooler; the APD Cryotiger. Because of its magnetic interference, the compressor of this closed-cycle cooler will be placed at a distance of ~2 m from the actual sensor, which is an axial second order gradiometer. The gradiometer is formed by three magnetometers placed on an alumina cylinder, which is connected to the cold head of the cooler. This paper describes the sensor head in detail and reports on test expts.
U2 - 10.1016/S0921-4534(02)00672-X
DO - 10.1016/S0921-4534(02)00672-X
M3 - Article
SN - 0921-4534
VL - 372-376
SP - 209
EP - 212
JO - Physica C : Superconductivity
JF - Physica C : Superconductivity
IS - Part 1
ER -