Comparing notes with the international fusion community

The ITER plasma control system (PCS) will have a key role in the operation of the ITER Tokamak. The plasma control system will consist essentially of a sophisticated computer program running within the CODAC environment, which will handle the many interfaces between the plasma control system and the ITER systems. Its function will be to control simultaneously many aspects of the ITER plasma—the plasma current, position and shape, the density, the fusion power level, the exhaust power flowing onto the divertor, and so on—so as to keep the plasma producing fusion power at the desired level for many hundreds, or even thousands of seconds.

It will also provide the first level of "exception handling" to provide a controlled response to "off-normal" events. It will make use of inputs from many of the ITER diagnostic systems and will send control signals out to the systems involved in producing and maintaining the plasma, ranging from the power supplies for the superconducting magnets, through the heating and current drive systems, to the plasma fuelling systems.

Over the past year the Fusion Science & Technology (FST) Department has been responsible for developing the system requirements for the plasma control system, and thoughts are now turning to the development of the system's conceptual design. Operational experience in present tokamaks will have a significant impact on our thinking about the structure and functionality of the ITER plasma control system. An ITER Plasma Control Workshop has therefore been organized at the Cadarache Château during next week, 8-12 December, to bring together some of the world's leading experts in this area and to review their experience in operating plasma control systems on the world's major magnetic fusion devices.

The workshop will be an opportunity for the ITER experts to present our current ideas on what the ITER system should do and how it should operate, and to hear from the international experts what their own experience has been in developing and running the complex plasma control systems which are at the heart of today's major experiments. At the end of the workshop we expect to be able to draw up guidelines for launching the conceptual design activities for the plasma control system.

Another opportunity for a major interaction with the international fusion community will occur during the following week in Daejeon, Korea, when the National Fusion Research Institute hosts the 8th International Energy Agency (IEA) Large Tokamak Workshop. This workshop will bring together the leadership of the International Tokamak Physics Activity (ITPA) community and program leaders from the major fusion research facilities in the ITER Members to review and agree on proposals made by the ITPA Topical Groups for collaborative studies in support of ITER's main physics R&D issues. Joint experimental work, in which coordinated experiments on key questions in fusion physics are conducted in several tokamak facilities, has proven to be a powerful tool for advancing our understanding of tokamak plasmas.

During the two-day meeting, the IEA and ITPA experts will review the progress which has been made in conducting experiments across a wide range of issues, including disruption mitigation, ELM control and studies of ITER plasma operating scenarios. The major output from the meeting will be an agreement among the program leaders on the priorities for operational time for joint experiments in 2010.

A third major area of international collaboration which FST has been developing relates to the integrated modelling program. An Integrated Modelling Expert Group (IMEG), involving experts nominated by the ITER Domestic Agencies from the Members' fusion communities, met for the first time in June 2009 to review the ITER Organization's proposal for an integrated modelling activity on fusion plasmas, and it has now issued its report.

Not surprisingly, the report highlights the need for a proper balance between standards and guidelines and the available resources. The integrated modelling program is now moving to the implementation stage with a call for tender for the definition and development of an integrated modelling infrastructure. IMEG and FST will work together to prepare a revised program proposal incorporating IMEG's comments and recommendations.