COMPUTERIZED FACILITY FOR CHARACTERIZING DC SQUIDS

A computer-controlled automatic facility for recording the characteristics of de superconducting quantum interference devices (SQUIDs) has been developed. A specimen SQUID is placed in a transport: helium Dewar inside a low-temperature insert. The low-noise preamplifier and filters are placed at the warm end of the device. The signal from the SQUID is digitized by an ADC and processed by a computer. The sources of bias current and of the current feeding the magnetic coil are controlled by digital devices. The software controls the process on-line, selects the mode of operation, stores the measurements, and plots the SQUID's characteristics.