Extracting individual contributions from their mixture: a blind source separation approach, with examples from space and laboratory plasmas

TL;DR

This paper discusses the application of blind source separation techniques to plasma physics, demonstrating how to disentangle mixed signals in space and laboratory plasmas for better physical understanding.

Contribution

It introduces the use of blind source separation in plasma physics and provides practical examples in tokamak temperature response and solar spectral imaging.

Findings

Separation of concurrent processes in tokamak electron temperature

Construction of empirical temperature maps from solar UV images

Enhanced insight into plasma dynamics through source separation

Abstract

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.