Development of the Persistent Actor Framework (PAF) version of the European Transport Simulator (ETS)

Paper i proceeding, 2025

The first version of the ETS was developed within the EFDA Work Package on Integrated Tokamak Modelling [ETS-2008, ETS-2010a, ETS2010b]. That version was essentially a Fortran workflow using Consistent Physical Objects (CPOs)[CPO-2010] to couple a number of codes providing the standard building blocks of a core plasma simulation (equilibrium codes, the calculation of sources and transport coefficients, and the transport solver). To allow for the inclusion of components in other languages, KEPLER [KEPLER-2006] was used as a coupling environment [ETS-2012, ETS-2013a, ETS-2013b, ETS-2014, ETS-2018, ETS-2019, ETS2021a], and after some years of using CPOs, these were replaced by Interface Data Structures (IDSs) [IMAS-2015] [ETS-2020, ETS-2021b, ETS-2022, ETS-2024]. This has been in use for a number of years, but the decision has been made to look at other coupling frameworks. This contribution describes the development of the ETS-PAF, which uses the MUSCLE3 framework [MUSCLE3-2020] to couple the various physics modules (mostly in fortran, C or C++), together with python modules to implement some of the workflow logic. The workflow takes the form of a number of separate programs (currently about 60) that communicate IDSs to other programs via one-way communication channels (currently about 150) sending/receiving IDSs.