Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008. / This thesis relates to the analysis and design of a SQUID microscope. Superconductor theory is discussed
in depth to provide a thorough understanding of Josephson junctions and of dc SQUID magnetometers.
The behaviour and suitability of different types of single-layer dc SQUIDs are looked at. The quality of
the superconducting material patterned onto a substrate and the Josephson junction design used affect
the behaviour of a practical dc SQUID. Noise and cooling play an integral part in the design and operation
of a dc SQUID. The source of noise is looked at in an effort to minimize its effect. Cryocooling is essential
to real world operation so different cooling strategies and their consequences are analyzed. This thesis
focuses on modeling the behaviour of the dc SQUID to creating a practical system for use inside a SQUID
microscope. Operating the dc SQUID with the appropriate electronics will linearize the device, reduce
the effect of noise, and create a device with wide bandwidth. Each step in creating a practical system
is discussed in detail. Simulations are used to create models predicting the behaviour of the dc SQUID
and the electronics. They are then used to design and create practical electronic systems. Measurements
are performed on Josephson junctions and dc SQUID magnetometers using the designed electronics. The
Josephson junctions behave as predicted and were successfully tested. The dc SQUIDs did not behave as
predicted and were not successfully tested. The SQUIDs were damaged, either by a malfunction in the
cryocooler or through age related deterioration. A full test of the flux-locked loop was not possible and
the dc SQUID was not linearized.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2239 |
| Date | 12 1900 |
| Creators | Burger, Willem Adriaan |
| Contributors | Perold, W. J., Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | Stellenbosch University |
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