ter Brake H J, Flokstra J, Jaszczuk W, Stammis R, van Ancum G K, Martinez A, Rogalla H
University of Twente, Faculty of Applied Physics, Enschede, The Netherlands.
Clin Phys Physiol Meas. 1991;12 Suppl B:45-50. doi: 10.1088/0143-0815/12/b/006.
A 19-channel DC SQUID based neuromagnetometer is under construction at the University of Twente (UT). Except for the cryostat all elements of the system are developed at the UT. It comprises 19 wire-wound first-order gradiometers in a hexagonal configuration. The gradiometers are connected to planar DC SQUIDs fabricated with a Nb/Al, AlO kappa/Nb technology. For this connection we developed a method to bond a Nb wire to a Nb thin-film. The SQUIDs are placed in compartmentalised Nb modules. Further, external feedback is incorporated in order to eliminate cross talk between the gradiometers. The electronics basically consist of a phase-locked loop operating with a modulation frequency of 100 kHz. Between SQUID and preamplifier a small transformer is used to limit the noise contribution of the preamplifier. In the paper the overall system is described, and special attention is paid to the SQUID module (bonding, compartments, external-feedback setup, output transformer).
特温特大学（UT）正在建造一台基于19通道直流超导量子干涉仪的神经磁强计。除了低温恒温器外，该系统的所有元件均由特温特大学研发。它包括19个呈六边形配置的绕线式一阶梯度仪。这些梯度仪连接到采用Nb/Al、AlO κ/Nb技术制造的平面直流超导量子干涉仪上。为了实现这种连接，我们开发了一种将铌线连接到铌薄膜上的方法。超导量子干涉仪放置在分隔式铌模块中。此外，采用了外部反馈以消除梯度仪之间的串扰。电子设备主要由一个工作在100kHz调制频率的锁相环组成。在超导量子干涉仪和前置放大器之间使用了一个小型变压器来限制前置放大器的噪声贡献。本文描述了整个系统，并特别关注了超导量子干涉仪模块（键合、隔室、外部反馈设置、输出变压器）。
