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The existing VxWorks real-time system for the position and shape control in ASDEX Upgrade has been extended to calculate magnetic flux surfaces in real-time using a multi-core PCI Express system running LabVIEW RT 8.6. real-time signal processing of bolometers and manometers is performed with the on-board FPGA to calculate the measured radiated power flux and particle flux respectively from the raw data. Radiation feedback experiments use halo current measurements from the outer divertor with real-time median filter pre-processing to remove the excursions produced by ELMs. Integration of these plasma diagnostics into the control system by the exchange of XML sheets for communicating the real-time variables to be produced and consumed is in operation. Reflective memory and UDP are employed by the LabVIEW RT plasma diagnostics to communicate with the control system and other plasma diagnostics in a multi-platform real-time network.

At the ASDEX Upgrade tokamak experiment, a new feedback control loop is under construction with the aim of stabilizing magneto-hydrodynamic (MHD) instabilities, such as neoclassical tearing modes and sawteeth. It uses the mirrors of the electron cyclotron heating (ECH) launchers, which can be steered in real-time to guide each beam to the position needed to stabilize and suppress the mode. The control system needs highly specialized plasma state information such as island position and ECH beam deposition locations in real-time. Data from several diagnostic systems, like electron cyclotron emission (ECE), magnetic measurements and motional Stark effect must be combined in real-time to obtain the required information. These systems strongly differ in sampling characteristics and time resolutions. High sampling rates as 2 MHz for ECE are often required to provide enough data for correlation or frequency analysis. On the other hand, complex analysis methods, such as equilibrium and profile reconstruction, may operate on slower rates of some milliseconds and need tight interaction with measurement systems and high computing power. In this paper, we describe a concept for distributed real-time diagnostic data handling, integration of data from several asynchronous diagnostic systems, and connection to the discharge control system for a broad spectrum of requirements. The system is structured into distributed diagnostic computer clusters, a real-time signal server to combine all information, and the discharge control system. While the focus is currently on MHD control, further real-time diagnostic related applications will be added in future.

Development of a real-time (RT) data acquisition (DAQ) system for ASDEX Upgrade was started years ago. Based on a modular front-end configuration with serial input/output computer interface a small number of powerful new diagnostics were commissioned. In the course of these developments we concluded that “direct to memory” DAQ concepts hold promise for future DAQ tasks including those with a subsequent RT data processing step. A survey of the requirements of existing and future diagnostics at ASDEX Upgrade was conducted to assess the wider applicability of these DAQ techniques to the upcoming needs for new diagnostics or the refurbishment of old ones. The paper presents the results of the requirements survey and indicates in which cases the developed diagnostic concept can be applied. A series of new diagnostics implemented using these techniques is presented in detail. This covers developed front-end modules as well as whole diagnostic configurations in hardware and software. The achieved DAQ data rates, data transport latencies, and fine-tuning steps to maintain a reliable RT operation are described explicitly. An outlook is given upon the definition of a RT diagnostic standard for ASDEX Upgrade based on the developments described previously.

Diagnostics at ASDEX Upgrade have available a very large number of highly developed measuring channels. The prospect of making this wealth of information usable for plasma optimisation led to the implementation of a number of diagnostics running data acquisition in real-time (RT). Ultimately, this development aims to achieve a network of intelligent diagnostics delivering analysed data for high-level plasma performance control such as profile shaping and NTM stabilisation. The new RT diagnostics consist of standard industrial 19 in. servers organised in clusters and running a standard UNIX multiprocessor RT-capable operating system (RT OS). Built-to-purpose computer interface cards deliver data (e.g. via serial links) from the data acquisition (DAQ) front-ends directly into the main memory of the DAQ servers. An RT data analysis task immediately following the running direct memory access (DMA) data transfers processes the data and delivers the results to follow-up systems in the control chain. Whereas the first systems were implemented in a simple just a bunch of computers (JBOC) configuration being operated as a number of single diagnostics, newer systems are integrated into diagnostic clusters using parallel computing techniques such as message passing interface (MPI). The paper describes the hardware (ADC front-ends, serial I/O, selection criteria and performance of the involved computer busses and systems) and software (DAQ, DA, RT OS, MPI) architecture of the assembled systems. Benchmark results for DAQ and MPI bandwidth and latencies as well as for the behaviour of the RT OS will be given.