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中国物理学会期刊

阻尼型高温直流超导量子干涉器磁强计的设计

CSTR: 32037.14.aps.47.1369

DESIGN OF THE HIGH-Tc dc-SQUID MAGNETOMETER WITH A RESISTIVELY SHUNTED INDUCTANCE

CSTR: 32037.14.aps.47.1369
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  • 理论分析了超导环路与一个电阻并联结构的直流超导量子干涉器(dc-SQUID)的特性.给出了这种阻尼型dc-SQUID的电压噪声谱密度、传输函数和磁通噪声谱密度随偏置电流变化的曲线.与无阻尼型高温器件比较,调制参量β大于1的阻尼型高温dc-SQUID磁强计具有高稳定性和易调试等优点.当β大于4时,因传输函数的增大,阻尼型dc-SQUID还能降低它的磁通噪声谱密度从而提高磁强计的检测灵敏度.根据现有高温超导薄膜器件的工艺条件,设计了β等于4的阻尼型高温dc-SQUID磁强计的芯片、其磁通噪声和磁场噪声的理论值

     

    The properties of dc-SQUIDs with a resistively shunted inductance(Rdc-SQUID) were theoretically analyzed. The dependencies of Sv,S1/2,and dv-/da on the bias current ib for Rdc-SQUID were presented. The advantages of the high-Tc dc-SQUID magnetometer with using Rdc-SQUID have been discussed. A chip of high-Tc dc-SQUID magnetometer with modulation parameter β=4 and damping parameter γ=0.5 was designed under the conditions of the depositing and lithographic technology in laboratory. A gold thin film (≈50nm thickness and 10μm width) was deposited on the superconductive loop as the damping resistance. The theoretical values of S1/2Φ and S1/2B for the magnetometer are respectively 2.4×10-6Φ0/Hz and 200fT/Hz. Comparing the properties between dc-SQUID and Rdc-SQUID,the experimental value S1/2B,which is about 400 fT/Hz,for the magnetometer directly coupling with a 8 mm- input coil was estimated.

     

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