SQUID system for educational purposes

Supracon would like to contribute to make SQUID technology and application more popular amongst physics students. The SQUID system JESSY edu was developed for practical training and holds a variety of possible applications.

1. how to handle cryogenic liquids
To operate JESSY edu the physics student learns the most important rules dealing with liquid helium/nitrogen when the cryostat is filled and the cryoprobes introduced into the Dewar.

2. measuring SQUID characteristics
Measuring the current-voltage and flux-voltage characteristics a student is taught to understand the SQUID and its most important parameters. An understanding of the practical use as current-voltage converter will be developed.

3. intrinsic noise of a SQUID
The parameters of SQUIDs are important for the determination of the intrinsic flux noise and input current noise respectively. The student finds out the noise limited sensitivity of the sensor. The noise is measured with an external spectrum analyser. Basic knowledge of Fourier transformations and spectrum analysis will be trained.

4. SQUID system as noise thermometer
Different resistors a switched into the input coupling circuit of the current sensor. By the help of a spectrum analyser the student determines the total noise of the system. A calculation of the Nyquist noise for the resistors needs to be done. A comparison with the intrinsic noise lets the student know for which resistors the SQUID system could be used as a noise thermometer.