Development of the supervisory systems for the ITER diagnostic systems in JADA

In ITER, it is important how the CODAC system conducts many plant systems including diagnostic systems. In order to establish necessary communications between the diagnostics systems and the CODAC system, Japan domestic agency (JADA) has proposed the new concept of supervisory system for the diagnostic system based on our experiences in operating plasma diagnostic systems. The supervisory system manages operation sequences, current state and configuration parameters for the measurement. JADA designed the supervisory system satisfying the requirements from both CODAC system and diagnostic systems. In our design, the tool which converts operational steps described as flowcharts into the EPICS (experimental physics and industrial control system) records source codes is introduced. This tool will ensure reduction of the system designers’ efforts. We designed a communication protocol to configure measurement parameters and proposed configuration parameter validation function. We also analyzed the management of the central/local control mode for the diagnostic systems. The function which selects the adequate limit values and consistency check algorithms in accordance with the conditions of the diagnostics system is proposed. JADA will develop a prototype of the supervisory system and validate the design in 2013.     

ITER CODAC interface for the visible and infra-red wide angle viewing cameras

The amount of data generated by the infra-red and visible cameras at ITER is expected to be considerably larger than most diagnostics. ITER will have 12 infra-red cameras plus 12 visible cameras in four different equatorial port plugs. Each of the ports will have a Plant System Host (PSH) that will provide a standard image of the plant system to the ITER's Control and Data Access and Communication (CODAC) system.The two key functions of these cameras will be the scientific exploitation with the detection of interesting physics events and the operational protection of the machine, namely the first wall. Already assuming high bandwidth requirements for both audio and video, ITER will provide a separate network for this kind of communication, which will be used to transmit both the experimental and informational data provided by the cameras.This paper presents the current camera plant system design and its interaction with ITER CODAC system and networks. Starting from the camera specifications several alternatives for data collection and compression are discussed. The required inputs from CODAC and a first specification for the internal finite state machine are also presented. Finally, a possible hardware straw man design solution for the plant system hardware is proposed.     

Physics of the conceptual design of the ITER plasma control system

The ITER plasma control system (PCS) will play a central role in enabling the experimental program to attempt to sustain DT plasmas with Q = 10 for several hundred seconds and also support research toward the development of steady-state operation in ITER. The PCS is now in the final phase of its conceptual design. The PCS relies on about 45 diagnostic systems to assess real-time plasma conditions and about 20 actuator systems for overall control of ITER plasmas. It will integrate algorithms required for active control of a wide range of plasma parameters with sophisticated event forecasting and handling functions, which will enable appropriate transitions to be implemented, in real-time, in response to plasma evolution or actuator constraints.In specifying the PCS conceptual design, it is essential to define requirements related to all phases of plasma operation, ranging from early (non-active) H/He plasmas through high fusion gain inductive plasmas to fully non-inductive steady-state operation, to ensure that the PCS control functionality and architecture will be capable of satisfying the demands of the ITER research plan. The scope of the control functionality required of the PCS includes plasma equilibrium and density control commonly utilized in existing experiments, control of the plasma heat exhaust, control of a range of MHD instabilities (including mitigation of disruptions), and aspects such as control of the non-inductive current and the current profile required to maintain stable plasmas in steady-state scenarios. Control areas are often strongly coupled and the integrated control of the plasma to reach and sustain high plasma performance must apply multiple control functions simultaneously with a limited number of actuators. A sophisticated shared actuator management system is being designed to prioritize the goals that need to be controlled or weigh the algorithms and actuators in real-time according to dynamic control needs. The underlying architecture will be event-based so that many possible plasma or plant system events or faults could trigger automatic changes in the control algorithms or operational scenario, depending on real-time operating limits and conditions.     

A simulation environment for ITER PCS development

A simulation environment known as the Plasma Control System Simulation Platform (PCSSP), specifically designed to support development of the ITER Plasma Control System (PCS), is currently under construction by an international team encompassing a cross-section of expertise in simulation and exception handling for plasma control. The proposed design addresses the challenging requirements of supporting the PCS design. This paper provides an overview of the PCSSP project and a discussion of some of the major features of its design. Plasma control for the ITER tokamak will be significantly more challenging than for existing fusion devices. An order of magnitude greater performance (e.g. [1], [2]) is needed for some types of control, which together with limited actuator authority, implies that optimized individual controllers and nonlinear saturation logic are required. At the same time, consequences of control failure are significantly more severe, which implies a conflicting requirement for robust control. It also implies a requirement for comprehensive and robust exception handling. Coordinated control of multiple competing objectives with significant interactions, together with many shared uses of actuators to control multiple variables, implies that highly integrated control logic and shared actuator management will be required. It remains a challenge for the integrated technologies to simultaneously address these multiple and often competing requirements to be demonstrated on existing fusion devices and adapted for ITER in time to support its operational schedule. We describe ways in which the PCSSP will help address these challenges to support design of both the ITER PCS itself and the algorithms that will be implemented therein, and at the same time greatly reduce the cost of that development. We summarize the current status of the PCSSP design task, including system requirements and preliminary design documents already delivered as well as features of the ongoing detailed architectural design. The methods being incorporated in the detailed design are based on prior experience with control simulation environments in fusion and on standard practices prevalent in development of control-intensive industrial product designs.     

Preliminary design of the control and data acquisition systems for the Neutral Beam Test Facility

The Neutral Beam Test Facility, which will be built in Padova, Italy, is aimed at developing the ITER heating neutral beam injector (HNB) and at testing and optimizing its operation up to nominal performance before installation on ITER. It requires the development of two independent experiments referred to as SPIDER (source for production of ions of deuterium extracted from Rf plasma) and MITICA (megavolt ITer injector & concept advancement). SPIDER will explore the full-size negative ion source for ITER, whereas MITICA will explore the full-size ITER neutral beam injector. Both experiments will be designed for long-pulse operation, up to 3600 s, as ITER itself. MITICA includes three functional components: the heating neutral beam injector plant system (HNB), which is the device under test; the auxiliary plant system (AUX), which includes all equipment to operate the HNB in the test facility (e.g. the local electric grid to feed the HNB power supplies), and MITICA supervisory system that is an electronics/informatics infrastructure to operate the facility. The paper introduces the requirements for the control and data acquisition systems of the experiments and proposes a preliminary design for both systems. SPIDER, which is preparatory to MITICA and will be developed on a shorter time scale, has no constraints coming from ITER CODAC, whereas MITICA includes the ITER neutral beam injector and therefore must be fully compatible with ITER CODAC.     

Actuator and diagnostic requirements of the ITER Plasma Control System

The ITER Plasma Control System (PCS) requires an extensive set of about 50 diagnostic systems to measure the plasma response and about 20 actuators to act on the plasma to carry out its control functions. The specifications and real limitations of the actuators and diagnostics are being assessed as part of the ongoing conceptual design of the PCS to understand the potential impact on plasma control. The actuators include magnetic coils (central solenoid (CS), poloidal field (PF), vertical stability (VS), edge localized mode (ELM), correction coils (CC)), heating and current drive (electron cyclotron (EC), ion cyclotron (IC), neutral beam injection (NBI), and possibly lower hybrid (LH)), glow discharge cleaning, fueling and impurity gas and pellet injection, vacuum pumping, and disruption mitigation systems. Diagnostic systems are prioritized according to their role in machine protection (MP), basic control (BC), advanced control (AC), and physics studies (PS). At the conceptual design phase, detailed control algorithms do not yet need to be specified, but conceptual solutions must be chosen that satisfy the PCS requirements for control within the real constraints of the diagnostics and actuators. The feasibility of the chosen solutions must be proven either through established control schemes on existing machines or through an R&D program to develop them before they will be required on ITER. The diagnostic and actuator requirements of the PCS will evolve from first plasma through the high performance DT phase. A comparison is made of the expected requirements to control vertical stability, sawteeth, neoclassical tearing modes (NTMs), edge localized modes (ELMs), error fields, resistive wall modes (RWMs), Alfvén eigenmodes, and disruptions with the ITER baseline actuator and diagnostic specifications.     

The J-TEXT CODAC system design and implementation

Inspired by the ITER COntrol, Data Access and Communication (CODAC) and ITER instrumentation and control system, J-TEXT tokamak has upgraded its control system with J-TEXT CODAC system. The J-TEXT CODAC system is based on Experimental Physics and Industrial Control System (EPICS). The J-TEXT CODAC system covers everything in the J-TEXT control system including both central and plant control systems, similar to the ITER I&C system. J-TEXT CODAC system is built around a single central control system called Central CODAC system. All the control functions including conventional control, interlock, safety and other common services are supervised by CCS. The J-TEXT CODAC system has been implemented and tested on J-TEXT. It not only tests some of the ideas in ITER CODAC in real life, but also explores the feasibility of new approaches that is unique in J-TEXT CODAC system.     

ITER prototype fast plant system controller

ITER CODAC Design identified the need for slow and fast control plant systems, based respectively on industrial automation technology with maximum sampling rates below 100 Hz, and on embedded technology with higher sampling rates and more stringent real-time requirements. The fast system is applicable to diagnostics and plant systems in closed-control loops whose cycle times are below 1 ms. Fast controllers will be dedicated industrial controllers with the ability to supervise other fast and/or slow controllers, interface to actuators and sensors and high performance networks (HPN).This contribution presents the engineering design of two prototypes of a fast plant system controller (FPSC), specialized for data acquisition, constrained by ITER technological choices. This prototyping activity contributes to the Plant Control Design Handbook (PCDH) effort of standardization, specifically regarding fast controller characteristics. The prototypes will be built using two different form factors, PXIe and ATCA, with the aim of comparing the implementations. The presented solution took into consideration channel density, synchronization, resolution, sampling rates and the needs for signal conditioning such as filtering and galvanic isolation. The integration of the two controllers in the standard CODAC environment is also presented and discussed. Both controllers contain an EPICS IOC providing the interface to the mini-CODAC which will be used for all testing activities. The alpha version of the FPSC is also presented.     

Evaluation of the ATCA fast controller standard for ITER diagnostics

ITER project's long time span and the nature of the instrumentation and control (I&C) procurement procedures for the Plant Systems require that the ITER Organization defines and follows well recognized standards which are used both by the industry and in physics experiments. The ITER I&C standards are defined in the Plant Control Design Handbook (PCDH) [1]. The ITER Organization has selected PCI Express and Ethernet for IO intercommunication to be used for plant system instrumentation for fast controllers. The decision on the usage of serialized I/O bus protocols is based on the impressive performance and the commercial availability. The form factors that will be supported by CODAC include PXIe, MicroTCA, and AdvancedTCA platforms. While the PXIe form factor is already well established for instrumentation purposes through the PXI Systems Alliance (www.pxisa.org), the AdvancedTCA and MicroTCA platforms which were originally targeted for the telecommunications market (www.picmg.org) are currently optimized and specified for instrumentation use through the xTCA extensions for physics [2]. The objective of this study is the evaluation of an integrated ATCA controller design using only commercial components.     

基于EPICS的J-TEXT CODAC系统

J-TEXT装置是华中科技大学恢复建造的中型托卡马克装置,已于2007年放电运行,其控制系统采用分布式结构,由多个子系统组成。为提高子系统集成、维护和更新的效率,并有效地管理各子系统、控制装置的运行状态及保障设备和人员安全,J-TEXT装置参考ITER CODAC的设计思路,结合J-TEXT装置的需求设计了J-TEXT CODAC系统。J-TEXT CODAC系统为装置各子系统提供统一的设计模型和相关设计标准,使用EPICS软件作为通讯中间层,设计了全局控制系统、时序和同步控制系统、联锁保护系统,并将原有控制系统改造、集成到J-TEXT CODAC系统中。目前该系统已部署在J-TEXT装置上,在2012年春季以来的多轮实验中运行良好。     

Present status of the conceptual design of the EU test blanket systems

The EU Breeding Blanket Programme aims the testing of two blankets concept in ITER in form of Test Blanket Modules. In the equatorial port #16 the two EU TBMs – a solid and a liquid blanket concept – will be exposed to the plasma and the complex system of their auxiliary systems dedicated to heat and Tritium removal will be integrated in the surrounding ITER buildings. The development of the conceptual design of the EU TBM System is the main objective of the Grant F4E-2008-GRT-09 contract launched by F4E and assigned to a European Consortium. This paper presents an overview of the results after about 20 months of activities: namely, the design of the main sub-systems of the EU TBSs and a concept of integration in ITER.     

Design and application of an EPICS compatible slow plant system controller in J-TEXT tokamak

J-TEXT tokamak has recently implemented J-TEXT COntrol, Data Access and Communication (CODAC) system on the principle of ITER CODAC. The control network in J-TEXT CODAC system is based on Experimental Physics and Industrial Control System (EPICS). However, former slow plant system controllers in J-TEXT did not support EPICS. Therefore, J-TEXT has designed an EPICS compatible slow controller. And moreover, the slow controller also acts the role of Plant System Host (PSH), which helps non-EPICS controllers to keep working in J-TEXT CODAC system. The basic functionalities dealing with user defined tasks have been modularized into driver or plug-in modules, which are plug-and-play and configured with XML files according to specific control task. In this case, developers are able to implement various kinds of control tasks with these reusable modules, regardless of how the lower-lever functions are implemented, and mainly focusing on control algorithm. And it is possible to develop custom-built modules by themselves. This paper presents design of the slow controller. Some applications of the slow controller have been deployed in J-TEXT, and will be introduced in this paper.     

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

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 configuration-driven 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.     

Event generation and simulation of exception handling with the ITER PCSSP

The plasma control system simulation platform (PCSSP) for ITER shall support the analysis and development of methods to be used by the ITER plasma control system (PCS) for handling exceptions to optimize pulses and assist in machine protection. PCSSP will permit to investigate physical and technical events, such as component failures, control degradation, operation domain excess, plasma state bifurcation or instabilities, and interlock activity. Serving that purpose, the plasma, actuator, diagnostics and PCS simulation modules in PCSSP will be enhanced to compute nominal and off-normal data. Configured by an event schedule, an event generator will orchestrate the activation and manipulate the characteristics of such off-normal computation. In the simulated PCS exceptions will be handled in a pulse supervision layer operating on top of the pulse continuous control (PCC) feedback loops. It will monitor events, decide on which exceptions to respond, and compute new control references to modify PCC behavior. We discuss basic concepts for the event generation in PCSSP, and a preliminary architecture for exception handling in PCS, and show how these will be configured with event and pulse schedules.     

FTU toroidal magnet power supply slow control using ITER CODAC Core System

FTU (Frascati Tokamak Upgrade) three-level slow control system has undergone several enhancements during its lifetime, involving essentially the supervisory and medium level, while the lower level is still mainly based on old Westinghouse Numalogic PLCs (Programmable Logic Controller). The legacy PLC controlling the toroidal magnet flywheel generator, named MFG1, is now being replaced with a more modern Siemens Simatic S7 PLC, because of its versatility an the ability to be integrated via standard networking protocol.The upgrade to this family of Siemens PLCs, which in the meantime has been selected as standard by ITER CODAC, has made MFG1 slow control an ideal candidate to deploy ITER CODAC software technologies and architecture to a running plant in an operating tokamak environment. A project has thus been started to port MFG1 control to ITER CODAC I&C architecture using the software package CODAC Core System to interface the PLC with the ITER standard systems for instrumentation and control, Plant System Host (PSH) and Mini-CODAC, developing dedicated HMI (Human–Machine Interface) and realizing the communication layer between MFG1 plant system and FTU supervisor.This paper will give a full account of the project and will report the results that have been obtained up to now, focusing also on the definite advantages provided by a distributed control architecture compared to the supervisor-dependent one still running at FTU, in view of future fusion devices.     

Overview of magnetic control in ITER

ITER is targeting Q = 10 with 500 MW of fusion power. To meet this target, the plasma needs to be controlled and shaped for a period of hundreds of seconds, avoiding contact with internal components, and acting against instabilities that could result in the loss of control of the plasma and in its disruptive termination.Axisymmetric magnetic control is a well-understood area being the basic control for any tokamak device. ITER adds more stringent constraints to the control primarily due to machine protection and engineering limits. The limits on the actuators by means of the maximum current and voltage at the coils and the few hundred ms time response of the vacuum vessel requires optimization of the control strategies and the validation of the capabilities of the machine in controlling the designed scenarios.Scenarios have been optimized with realistic control strategies able to guarantee robust control against plasma behavior and engineering limits due to recent changes in the ITER design. Technological issues such as performance changes associated with the optimization of the final design of the central solenoid, control of fast transitions like H to L mode to avoid plasma-wall contact, and optimization of the plasma ramp-down have been modeled to demonstrate the successful operability of ITER and compatibility with the latest refinements in the magnetic system design.Validation and optimization of the scenarios refining the operational space available for ITER and associated control strategies will be proposed. The present capabilities of magnetic control will be assessed and the remaining critical aspects that still need to be refined will be presented. The paper will also demonstrate the capabilities of the diagnostic system for magnetic control as a basic element for control. In fact, the noisy environment (affecting primarily vertical stability), the non-axisymmetric elements in the machine structure (affecting the accuracy of the identification of the plasma boundary), and the strong component of eddy current at the start-up (resulting in a poor S/N ratio for plasma reconstruction for I_p < 2 MA requiring a robust plasma control) make the ITER magnetic diagnostic system a demanding part of the magnetic control and investment protection systems. Finally the paper will illustrate the identified roles of magnetic control in the PCS (plasma control system) as formally defined in the recent first step of the design and development of the system.     

Overview of the COMPASS CODAC system

This paper presents an overview of the Control, Data Acquisition, and Communication system (CODAC) at the COMPASS tokamak: the hardware set-up, software implementation, and communication tools are described.The diagnostics and the data acquisition are tailored for high spatial and temporal resolution required by the COMPASS physics programme, which aims namely at studies of the plasma edge, pedestal, and Scrape-off-Layer (SOL). Studies of instabilities and turbulence are also an integral part of the programme. Therefore, the data acquisition consists of more than 1000 channels, sampled at rates from 500 kS/s up to 2 GS/s.Presently, the feedback system controls the plasma position and shape, plasma current, and density and it includes 32 analogue input channels as well as 1 digital input/output channel and 8 analogue outputs. The feedback control runs within the Multi-threaded Application Real-Time executor (MARTe) framework with two threads, a 500 μs cycle to control slow systems and a 50 μs cycle to control the fast feedback power supplies for plasma position control.In this paper, special attention is paid to the links between the systems, to the hardware and software connections, and to the communication. The hardware part is described, the software framework is addressed, and the particular implementation – the dedicated software modules, communication protocols, and links to the database are described.