【摘要】 本文介绍一台dc SQUID磁强计。Nb-SiO₂-Nb边缘隧道结dc SQUID器件作为磁敏感元件具有很高的灵敏度。由超导变压器实现dc SQUID 与前置放大器之间的最佳源电阻匹配。磁强计在低频范围内（f<1Hz）最小可分辨能量达2.5×10-²⁸J/Hz,动态范围为±5×10⁶（?）。采用两个极点的积分器提高了仪器的摆率,在频率为1.5kHz 时,最大摆率达1×10⁵φ₀/s。较高的摆率使仪器能长时间运行而不失锁。本文简要说明了磁强计的结构和设计特点。仪器性能的测试结果符合理论计算值。更多还原

【Abstract】 Using Nb-SiO₂-Nb edge tunnel junction,adc SQUID magneto-meter was fabricated.A superconducting resonant transformer is used as theimpendance matching element,and the contribution of the preamplifier to theoutput noise is negligible.The flux noise is 1×10^-4φ₀/（Hz）^1/2 measured at 1 Hz.The magnetometer has an equivalent energy noise of typically 2.5×10^-28J/Hzand a dynamic range of ±5×10⁶/（Hz）^1/2 at frequencies below 1Hz.The flux modulation frequency is 50 kHz.In order to increase the slew rate,a two-pole integration circuit is used.The maximum slew rate is 1×10⁵φ₀/s at1.5 kHz.This slew rate enables the magnetometer to be operated for long pe-riods of time without causing the system to unlock.The design,construction and performance is described.The measured frequ-ency response,maximum slew rate and magnetic flux noise are compared withthe values expected from the open-loop gain,SQUID noise respectively.更多还原