V. Schmidt

Confinement studies on RFX

The results of the first year of operation of the experiment RFX are reported. Profiles of electron density, electron and ion temperature and impurity emission have been measured at plasma current I<0.7 MA. The energy confinement parameters at different density are reported, the best values ( tau E approximately 1ms, beta theta approximately 8%) being obtained operating at higher density. The role of the impurity content in determining the present performance of the experiment is discussed.

Remote participation at JET Task Force work: users’ experience

Abstract The Joint European Torus (JET) fusion experiment is now operated with strong involvement of physicists from outside research laboratories, which often requires remote participation in JET physics experiments. Users’ experience with tools for remote collaborative work is reported, including remote computer and data access, remote meetings, shared documentation and various other communication channels.

The technical infrastructure for Remote Participation in the European Fusion Programme

Abstract Remote Participation in European Fusion Research has now undergone a period of practical application with the C1–C4 Campaigns in the EFDA-JET Scientific Programme in 2000 and 2001. We report on the Technical Infrastructure established at a European level in the JET framework for the support of this type of approach. We present the five technical poles of the RP project: Remote Data Access, Remote Computer Access, Network Connectivity, Telecommunications, and Support/Documentation. Many of these subjects are covered in more depth in other papers at this conference. In each topic we describe the current state, but go on to address future progress, difficulties and open questions. We make recommendations for the future technical requirements, with a goal of a well established, closely bound “Virtual Fusion Association” for a combined European strategy, including the JET EP project, inter-Association collaborations, and the ITER project, in which physical location of scientific effort and support staff is expected to become less important than it is today.

Remote participation technical infrastructure for the JET facilities under EFDA

The new collaborative exploitation of the JET Facilities requires suitable technical tools and infrastructure measures to enable the Remote Participation of scientists from all European Fusion labs. Such measures are being gradually introduced. They comprise of a toolkit for Remote Data Access, Remote Computer Access and for teleconferencing, and of infrastructure measures that address network connectivity, network security, shared documentation and technical support.

INTEGRATION OF THE RFX ELECTROMAGNETIC CIRCUITS

The commissioning of the RFX power supplies and their integration with the machine windings were performed in steps of increasing complexity; the target was to start the experiments with plasma in the final configuration of all systems, tested up to the performances required for first operation. After a brief description of RFX circuits and operation, the final tests on the power supplies, their commissioning with the control, data acquisition and fast protection systems and the integration with the machine windings are presented. Indications on operation reliability following the first experimental phase are finally given.

THE GLOBAL FAST PROTECTION SYSTEM OF RFX

RFX is equipped with an original fast protection central system named SGPR, particularly designed to perform the fast protection of the device during the pulse phase. It is interfaced with all sub-systems in which dangerous faults for the machine integrity can arise and develop very quickly, namely within 2 ms. SGPR is a logic machine, including a central processing unit operating in HHL and all interconnecting lines implemented with plastic optic fibres. All internal and external lines are completely duplicated for redundancy. Protection functions are organized in four hierarchical levels. The central unit receives logic protection requests from all interfaced units, processes and coordinates such requests, also performing time conditioning, and produces protection commands for all protective devices. A number of features has been implemented to improve machine flexibility and reliability, in particular self-diagnostics functions.

Installation, Commissioning and Start Up of RFX

The Reverse Field Pinch experiment RFX has been operating since the end of 1991. The paper, after a brief description of the load assembly, presents the most significant aspects of the assembly phase and discusses methods and results of the final tests, carried out before producing the first plasma. Finally, the machine behaviour during the first experimental phase is described.

Teleconferencing for the EFDA laboratories

Abstract Since early 2000 the Joint European Torus (JET) has been operating as a shared facility; several other European fusion experiments will follow. This requires tools for Remote Participation and in particular for Teleconferencing in the widest sense. Similar requirements exist for the International Thermonuclear Experimental Reactor (ITER) and JET design and construction activities as well as for administrative and management areas. The 23 Associates of the European Fusion Development Agreement (EFDA) are now making significant use of such techniques. Many technical and scientific meetings are regularly organised as distributed meetings with audiences and speakers spread over several locations. While presentation (electronic slides) sharing has converged on a single approach based on the open-source vnc software, two different technologies have been adopted for Internet-based audio and video conferencing. Many labs in the JET collaboration are using the Virtual room videoconferencing system (VRVS) infrastructure, originally developed by the California Institute of Technology for the CERN Large Hadron Collider (LHC) community, with the open-source MBone tools VIC and RAT for video and audio. Several other labs have opted for the H.323 umbrella standards. The two systems are not fully interoperable. Hence, an EFDA working group has been created to explore and compare the two approaches, and to produce recommendations for the future. The paper presents the functional requirements for teleconferencing, taking into account the different application scenarios that are expected in the European Fusion community. It then describes technical solutions and the proposed approach, which reflect the uncertainties about the future standards development.

Synchronization in a PLC/VAX-based control and data-acquisition system of a nuclear-fusion experiment

Abstract This paper describes the concept and implementation details of the synchronization mechanisms used in the control and data-acquisition system of the RFX (Reversed-Field Experiment) nuclear-fusion experimental device, at present under construction in Padova, Italy, within the framework of the co-ordinated nuclear-fusion research programme of the European Communities. The system employs industrial PLCs for the “slow” control and monitoring functions, and a VAX-based CAMAC for the “fast” functions of trigger-signal generation and data acquisition during the experiment pulses. All subsystems communicative via Ethernet, using compatible software protocols. The operational sequence of the complete system is governed by a single state machine implemented on a PLC-based supervisor system. Equivalent “slave” state machines are implemented on all other subsystems (PLC-and VAX-based). These state machines are synchronized by means of the exchange of messages via Ethernet. This paper deals in detail with the following components which are involved in system synchronization: • - the Message Exchange System which implements the system-wide exchange of short messages; • - the Scheduler programs which implement the state machine on the various computing nodes, and which make use of the Message Exchange System.

INTEGRATION AND FIRST OPERATION OF THE RFX CONTROL AND DATA ACQUISITION SYSTEM

The RFX plant is functionally organized in local units and subsystems. The Control and Data Acquisition System (“SIGMA”) reflects this structure. It uses programmable controllers (PLCs) for slow signals and VAX based CAMAC for the fast data acquisition and timing tasks. The commissioning of SIGMA took about four months and followed the functional structure of the plant: independent commissioning of local units, subsystem-wide integration, system-wide integration. SIGMA was completely operational at the end of the power supply integration phase of RFX (June 1991). The integrated machine commissioning and first operation phases of RFX were indistinguishable for SIGMA. RFX produced first plasma in November 1991 under fully remote computer control. The paper gives a short description of the procedures and discusses the features of SIGMA which contributed to this fast and smooth commissioning.