  Multipoint or multichannel observations in plasmas can frequently be modelled
as an instantaneous mixture of contributions (waves, emissions, ...) of
different origins. Recovering the individual sources from their mixture then
becomes one of the key objectives. However, unless the underlying mixing
processes are well known, these situations lead to heavily underdetermined
problems. Blind source separation aims at disentangling such mixtures with the
least possible prior information on the sources and their mixing processes.
Several powerful approaches have recently been developed, which can often
provide new or deeper insight into the underlying physics. This tutorial paper
briefly discusses some possible applications of blind source separation to the
field of plasma physics, in which this concept is still barely known. Two
examples are given. The first one shows how concurrent processes in the
dynamical response of the electron temperature in a tokamak can be separated.
The second example deals with solar spectral imaging in the Extreme UV and
shows how empirical temperature maps can be built.
