ASDEX Upgrade Discharge Control System—A real-time plasma control framework

Abstract

ASDEX Upgrade is a fusion experiment with a size and complexity to allow extrapolation of technical and physical conditions and requirements to devices like ITER and even beyond. In addressing advanced physics topics it makes extensive use of sophisticated real-time control methods. It comprises real-time diagnostic integration, dynamically adaptable multivariable feedback schemes, actuator management including load distribution schemes and a powerful monitoring and pulse supervision concept based on segment scheduling and exception handling. The Discharge Control System (DCS) supplies all this functionality on base of a modular software framework architecture designed for real-time operation. It provides system-wide services like workflow management, logging and archiving, self-monitoring and inter-process communication on Linux, VxWorks and Solaris operating systems. By default DCS supports distributed computing, and a communication layer allows multi-directional signal transfer and data-driven process synchronisation over shared memory as well as over a number of real-time networks. The entire system is built following the same common design concept combining a rich set of re-usable generic but highly customisable components with a configurationdriven component deployment method.We will give an overview on the architectural concepts as well as on the outstanding capabilities of DCS in the domains of inter-process communication, generic feedback control and pulse supervision. In each of these domains, DCS has contributed important ideas and methods to the on-going design of the ITER plasma control system. We will identify and describe these essential features and illustrate them with examples from ASDEX Upgrade operation.

Control system-plasma synchronization and naturally occurring edge localized modes in a tokamak

“…The ASDEX Upgrade control system is specifically designed to suppress known plasma instabilities. 27 It does this on a fast timescale: "the entire control loop is executed in a base cycle of up to 1 ms duration. This length is given by the response time of ASDEX Upgrade fastest actuator, the power supply for the vertical stabilisation coils."…”

“…[24][25][26] Active control of the plasma is required to automatically maintain a global steady state and this is achieved by the control system's real-time monitoring of the plasma (Ref. 27 and references therein). The control system takes a variety of inputs, and one of its automatic, internally generated outputs is to apply voltages to field coils that regulate the vertical plasma position (vertical stabilization control coils, see Fig.…”

Transforming the ASDEX Upgrade discharge control system to a general-purpose plasma control platform

“…They already permitted to connect DCS to other external frameworks like MARTe [5] and design tools like Simulink [3]. An analysis of the necessary interfaces between the DCS framework and a different control environment like the WEST project, however, revealed, that these measures were not sufficient.…”

“…Recently, the control system framework of the ASDEX Upgrade (AUG) experiment, DCS [3], was adopted as a base control system of the WEST project [4] and moved from a dedicated implementation to a general-purpose platform. From its beginning DCS had been built on the above-mentioned principles for portable design.…”

Coupling DCS and MARTe: two real-time control frameworks in collaboration

“…For the control software, a framework architecture -where applications are designed based on templates and generic base libraries encourage code re-use -is well suited to fulfil these requirements. The potential has been demonstrated by two control frameworks which have been developed independently within the fusion community -DCS (Discharge Control System) [1] was deployed at ASDEX Upgrade in 2003 and MARTe (Multithreaded Application Real-Time executor) [2] at JET in 2008. Both of these frameworks have been developed with Email address: chris.rapson@ipp.mpg.de (Christopher Rapson) emphasis on different aspects of tokamak control.…”