HT_c SQUID磁强计阵列研究

Research on HT_c SQUID magnetometer array

高温超导量子干涉器(HTcSQUID)已有20多年研究历史。目前,HTcSQUID磁强计以它对磁场高的分辨率、低磁通白噪声和低的1/f噪声起始频率,相对成熟、便宜的制冷技术,被认为是开发无线电频谱低端应用和微弱磁场测量领域有竞争力的新技术。但是,囿于高温超导体的材料特性和高温超导约瑟夫森结的研究水平,当前HTcSQUID磁强计的磁场灵敏度比传统LTcSQUID磁强计仍然要低一个数量级,因而导致它在低频无线电电子学系统和相关领域中的应用还存在一些困难。为在现有条件下积极开展HTcSQUID磁强计技术的应用研究,拓展HTcSQUID磁强计技术的应用范围,作者主要通过试验,在HTcSQUID磁强计当前内禀磁通噪声限制下,使用多HTcSQUID磁强计对待测场的相干检测可能是提高SQUID检测接收系统输出信噪比的有效方法进行了研究。已经获得的初步实验结果表明,在电磁干扰不太大的环境中,多HTcSQUID磁强计技术可以在现有HTcSQUID磁强计的磁场灵敏度指标限制下,使系统的接收信噪比得到提高。

High- temperature superconducting quantum interference device （HT SQUID） has been studied for more than 20 years. At present, it is considered to be a new competitive method in the development applications of low frequency end of the radio spectrum and the measurement field of weak magnetic field by virtue of its high resolution of magnetic field, low magnetic flux white noise, low starting frequency of 1/f noise, the maturity and low cost refrigeration technology. However, the sensitivity of HT SQUID magnetometer is still lower than that of LT SQUID magnetometer by an order of magnitude due to the characteris- tics of high - temperature superconducting materials and research level of high - temperature superconducting Josephson junction. It brings on some problem in the low - frequency radio electronics systems and related application fields. In order to actively carry out the applied research of HTc SQUID magnetometer technology and expand its scope of application under the existing condi- tions, we primarily used multi - channel HT SQUID magnetometer of treating the measured field of coherent detection under the limit of current flux intrinsic noise, which might be an effective way of improving system output SNR at the SQUID receiving sys- tem. In the environment which electromagnetic interference is not too large, preliminary results show that multi -channel HTc SQUID magnetometer technique can improve the current SNR in the limit of existing HTc SQUID magnetometer magnetic field sensitivity index.