The next KE Hub online Triage Workshop will be presented by UKAEA:
Dimensionality reduction for plasma chemistry dynamical systems
Plasma chemistry is becoming increasingly important in fusion applications. At the lowest level, modelling the population of atomic and molecular states requires large systems of non-linear ODEs with widely varying timescales. These need to have their dimensionality reduced before they can be used in tokamak transport simulations (usually in a form of extended CFD). Traditional methods in the field rely on the quasi-steady-state assumption (QSSA) and on linearity, the latter applicable only to a subset of models with restricting assumptions. However, these methods cannot handle non-linear systems, such as those resulting from complicated molecular plasma chemistry. At UKAEA, we have recently begun development of a new generalised framework for (plasma) chemical analysis and reduction, and are interested in implementing and testing various advanced methods from other fields. We are looking at chemical kinetics methods for dimensionality reduction, such as the intrinsic low dimensionality manifold method (ILDM) [1], computational singular perturbation method (CSP) [2], as well as various graph theory methods [3] in addition to the traditional dynamical systems approaches. We would be interested in interfacing with experts in non-linear dynamical system dimensionality reduction, chemical reaction network theory, as well as related fields such as climate, atmospheric, and combustion modelling.
The methods we are planning to try out are:
[1] U. Maas and S. B. Pope, “Simplifying Chemical Kinetics: Intrinsic Low-Dimensional Manifolds in Composition Space,” Combustion and Flame, vol. 88, no. 3-4, 1992.
[2] S. H. Lam and D. A. Goussis, “Understanding complex chemical kinetics with computational singular perturbation,” Symposium (International) on Combustion, vol. 22, no. 1, 1988.
[3] T. D. Holmes, R. H. Rothman, and W. B. Zimmerman, “Graph Theory Applied to Plasma Chemical Reaction Engineering,” Plasma Chem Plasma Process, vol. 41, no. 2, 2021.
