  The formation and dynamics of topological defects of different structure has
been of central interest in the study of the 3He superfluids. Compared to
superfluid 4He-II, the variability of the important parameters with temperature
and pressure is wider and many features are more ideal. This has made
experimentally new approaches possible. An example is the formation of
quantized vortices and other topological defects in a rapid time-dependent
phase transition from the normal state to 3He-B. This vortex formation process
is known as the Kibble-Zurek mechanism and is one the central topics of this
review. It demonstrates the use of 3He-B as a model system for quantum fields,
with detailed control from the laboratory.
