Tasks and structure of the WENDELSTEIN 7-X control system

The super conducting stellarator WENDELSTEIN 7-X will run pulses of up to 30 min duration with full heating power. Short pulses with arbitrary intervals, steady state long discharges and arbitrary sequences of short phases with different characteristics in one discharge will be supported by the control system. Each technical component and each diagnostic system including its data acquisition will have its own control system permitting autonomous operation for commissioning and testing. During the experimental sessions the activity of these devices will be coordinated by a central control system and the machine runs more or less automatically with predefined programs. A session leader program allows the leader of the experiment to choose and chain predefined segments, to start or stop a segment chain as a discharge. The progress of the discharge is shown by a sequence monitor attached to the central sequence controller and the session leader program.W7-X has to be prepared for the experiment and monitored by means of the PLC based operational management system. A safety system working independently of the operational management consists of local units responsible for the safety of each component and a central unit ensuring the safety of the whole W7-X system. This safety system provides interlocks and controls the human access to the device. A safety analysis is the basis for the development of the safety system.