Speaker
Ian Jenkins
(CCFE)
Description
A project on the scale of DEMO requires a formal systems engineering approach. Mapping the interfaces, dependencies and relationships between subsystems permits an understanding of a conceptual design from a set of complementary and consistent perspectives. It also helps to prevent clashes and incompatibility between subsystems at a later stage of engineering design.
The first stage of this work has focussed on the DEMO Plasma Operation State (POS), where the tokamak executes a pulse sequence. For each of the substates within the POS, information gained from experience on JET has been used to create a matrix detailing which subsystems will be active. This involves attempting to define, characterise and, if possible, quantify the salient attributes and functions for each required subsystem. The resulting information has been incorporated into a model using the systems engineering language SysML.
The resulting model, which forms part of a broader Model Based System Engineering (MBSE) activity within DEMO, will be presented. Such a model should provide a framework for analytical decision making as the project progresses and should detail the following perspectives:
A tokamak has composition, comprising a number of subsystems, e.g. the Gas Injection subsystem.
The tokamak has one associated Tokamak State Machine, comprising a number of states, and a number of transitions that allow movement from one state to another.
Each subsystem has allocated to it a set of operational modes. These subsystem modes provide a behavioural definition.
Each subsystem has key parameters. Parameter values in a given state identify the relevant subsystem characteristics of that state.
Each tokamak state can involve one or more subsystem modes. In addition, subsystem modes may be involved when in one or more tokamak states.
The resultant SysML model provides a mechanism for analysing the inherent complexity of tokamak subsystem modes during specific tokamak states.
Co-authors
Ian Jenkins
(CCFE, Oxford, United Kingdom)
Paul Curson
(CCFE, Oxford, United Kingdom)
