用于极低频通信的超导量子干涉器研究

In order to protect and develop marine resources, communication, especially deeply submerged communication, for underwater tools and facilities is vitally important. Extremely Low Frequency (ELF) electromagnetic waves in the earth ionosphere waveguide are very stable, and can penetrate water for more than 300 meters, which are therefore very suitable for deeply submerged communication. However such low-frequency and weak signals are difficult to receive using ordinary antenna. Superconducting QUantum Interference Device ( SQUID ) is the most sensitive magnetic detector and its high sensitivity extends easily to the ELF or even the DC regime. It also has good frequency response and high dynamic range. Hence it is very suitable for the ELF communication applications. In this project, we will develop an ELF weak magnetic signal receiving system using low-temperature SQUID and superconducting filter device as its core parts. The system is designed with high sensitivity and stability to solve the ELF signal reception problems, which can be the foundation for the deeply submerged communication and defence applications.

为了保卫和开发海洋资源，水下工具和设施的通信尤其是深海通信成为一个问题。极低频电磁波在大地与电离层形成的波导内传播非常稳定，对海水的穿透能力能达到300米以上，作为深海通信的载体非常合适。但如此低频和微弱的信号，普通的天线很难接收到。超导量子干涉器（SQUID）是最灵敏的磁场探测器，它的高灵敏度特性可以延伸至极低频甚至直流区域，并同时具有良好的宽频响应和高动态范围，极适合用做极低频通信的接收器。本项目的研究内容是建立以低温SQUID 及超导低通滤波装置为核心的、具有高灵敏度和稳定性的极低频弱磁信号接收系统，以解决极低频信号的接收问题，从而为深海通信的应用、特别是国防应用奠定基础。

超导量子干涉器（SQUID）是最灵敏的磁场探测器，并且这种高灵敏度可以延伸至极低频甚至直流，此外还有良好的宽频响应和高的动态范围，这使它在极低频弱磁测量中有不可替代的地位。这在军事上，如探潜、低频通讯（潜艇通讯）以及地磁导航，有着重大的应用前景。本项目制备了用于低频探测的SQUID器件、设计和制作了磁通偏置反转电路，试制了超导低频接收前端，并初步探讨了磁通锁定模式下工作的SQUID信号畸变与恢复。从而为解决极低频磁信号探测中的科学和技术问题奠定了基础。