Development of the plasma scenario for EU-DEMO: Status and plans

This paper is part of a series of publications concerning the development of the European DEMO during the Pre-Concept Design Phase (2014-2020), and also describing the strategy for the next phase. In particular, it deals with the physics basis of the plasma scenarios employed for the definition of the various DEMO baselines released so far, and the assumptions adopted where necessary. In the course of the Pre-Concept Design Phase, some of these assumptions have been progressively replaced with the results of dedicated modelling activities or code developments in general, which are summarized here. The considered baselines, obtained with the systems code PROCESS, are the DEMO 2015, 2017 and 2018, based on an ITER-like ELMy H-mode confinement regime. In addition, since it is now essential to avoid ELMs, baselines with some of the characteristics of QH-mode and I-mode have been produced in 2019. It has been concluded that the present integrated plasma scenarios are not secure enough for an engineering design, so a strong programme to improve them is required and planned. A discussion on the main knowledge gaps, as well as the strategy to be adopted in the next phases to close them, is provided.