Anett Spring

Cutting edge concepts for control and data acquisition for Wendelstein 7-X

Wendelstein 7-X is intended to demonstrate steady state high performance plasma operation and to explore the physics basis of the Helias reactor concept. From there, the W7-X CoDaC concepts aim for steady state plasma stabilization at favorite operation points and largely or even fully documented plasma experiments for achieving efficiently scientific results. Several concepts are being employed that are not common to the fusion research so far. The plasma control system is based on segments consisting of control parameters and transition conditions to other segments. The data acquisition system aims at streaming all acquired data for archiving, control and monitoring purposes and tries to prevent early data reduction. This leads to data streaming rates of up to 30 GBytes/s during plasma operation of up to half an hour. The data analyses framework is intended to support largely automation with analyses chains based on service oriented architectures. A coupling to real time systems is envisaged later in the project for solving complex control problems. The envisaged model based data analyses rely on the existence of unanalyzed raw data in combination with a systematic documentation of the experimental setup, in particular for the diagnostics.

Wall conditioning for Wendelstein 7-X by glow discharge

Abstract The basic design of a reliable and robust glow discharge cleaning (GDC) system for Wendelstein 7-X is presented. Preliminary experiments at the DEMO cryostat, a full size prototype sector of W7-X, result in conclusions about the operating range, power consumption and discharge stability of a GDC in W7-X dimensions. Ten electrodes are planned to be integrated into the first wall of W7-X, thus avoiding complex manipulators. A spherical calotte anode made of graphite mounted in a shielding trough was found as the optimum electrode design assuring stable discharge operation without active cooling, even when exposed to steady state stellarator discharges.

A new concept for experiment program planning for the fusion experiment Wendelstein 7-X

The control and data acquisition system (CODAC system) for the fusion experiment Wendelstein 7-X is designed for miscellaneous operational scenarios: short pulses with arbitrary intervals, steady-state long pulse operation and arbitrary sequences of short phases with different characteristics in one discharge. The data structures for a description of experiment runs are very complex and comprehensive. A special editor is necessary to guide the user through the different phases of experiment program planning. A more abstract and physics-oriented description of the required machine and plasma behaviour is a suitable way to handle the complexity and to make the experiment program definition process effective and easier. This contribution introduces a concept for experiment planning based on a so called segment program boxes (SEGPROGBOX). The planned work flow of the experiment program creation will be discussed after an introduction of the SEGPROGBOX design.