Remote participation infrastructure in the European Fusion Programme

The large experiments in the European Fusion community are increasingly run as shared facilities. This is following the lead of the JET (Joint European Torus) Facilities that have been run in this way since the beginning of 2000 under the European Fusion Development Agreement (EFDA). The Remote Participation Technical Infrastructure being put in place for the joint scientific exploitation of the JET Facilities serves as a blueprint for the future shared exploitation of several other large experiments. At the same time the scope of the remote access and remote collaboration is being extended from the purely scientific exploitation to include shared engineering design work for major JET enhancements that are conducted jointly by several laboratories, and for the next-step design work (ITER-FEAT) as well. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:3829.715695(01/18) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Time-frequency images of magnetohydrodynamic phenomena in tokamak plasmas using discrete-time Wigner distribution

A discrete-time Wigner distribution is used to yield a time-frequency representation of nonstationary magnetic activity at the edge of a tokamak plasma, thereby contributing to the magnetohydrodynamic analysis of the underlying phenomena, more precisely, to the identification of toroidal AlfvEn eigenmodes. (author)Available from British Library Document Supply Centre-DSC:3829.715695(01/11) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

A rational approach to remote handling equipment control system design

SIGLEAvailable from British Library Document Supply Centre-DSC:3829.715695(01/05) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Development of the MASCOT telemanipulator control system

SIGLEAvailable from British Library Document Supply Centre-DSC:3829.715695(01/06) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Helium partial pressure measurements using a Penning gauge A new approach

Future magnetic-confinement devices which produce significant power by the fusion of D-T nuclei will require an adequate removal rate of helium ash from the plasma core, in order to maintain core purity and the level of power production. Hence, the role of the divertor in removing helium is of crucial importance. At JET, several divertor configurations have been studied to characterise their efficacy at this task, under various operating conditions. The partial pressures of the deuterium and helium in the sub-divertor volume are measured using a Penning gauge, which is a well-established technique. In this paper, a new approach to the measurement is described, which is particularly useful for plasmas with high and varying concentrations of heliumAvailable from British Library Document Supply Centre-DSC:3829.15695(01/25) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Remote maintenance of an operational fusion experiment

SIGLEAvailable from British Library Document Supply Centre-DSC:3829.715695(01/04) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The effect of plasma shaping on the damping of low-n Alfven Eigenmodes in JET tokamak plasmas

SIGLEAvailable from British Library Document Supply Centre-DSC:3829.715695(01/02) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

From JET to ITER Preparing the next step in fusion research

An overview of fusion research in tokamak plasmas is presented: from the energy demands providing motivation, to basic fusion reactions, principles of magnetic confinement of plasmas and tokamaks. Major results from JET are presented. The Next Step device, ITER, is described: it shows the way towards the development of fusion reactors. (author)Available from British Library Document Supply Centre-DSC:3829.715695(01/16) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

The evolution of real-time control systems at JET

Real-time feedback control of the JET experiment is based upon a collection of diagnostics providing signals which are processed by various controllers that manipulate actuator parameters for plasma current, shape and heating. The real-time data network (RTDN) connects the diagnostic, controller and actuator systems to form a flexible feedback and protection system for plasma monitoring and control. The controllers are mainly VME systems based on the Motorola 680X0 (68K) processor with some computationally intensive systems utilising Texas Instruments TMS320C40 (C40) digital signal processors (DSP), though lately there has been a move towards PowerPC 750 based processors. The majority of 68K VME systems use VxWorks, a hard real time operating system. There is an ongoing requirement to improve the efficiency of the real-time control systems at JET. This is driven by a desire to either add more input signals, reduce the feedback cycle time or increase algorithm complexity. New technology has a major role to play in the upgrade of the real-time control systems but the novel redeployment of existing equipment can also be used to enhance performance. This paper examines the configuration of existing systems, both hardware and software, and how new technology can be gradually integrated without jeopardising the current functionality. The adoption of Asynchronous Transfer Mode (ATM) as the connection medium for the RTDN is key to the evolutional development of the control systems. The ATM network is extremely flexible to configure and benefits from low message latency and deterministic delivery time, essential properties for a real-time network. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:3829.715695(01/21) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

On the link between ExB sheared flows and rational surfaces in fusion plasmas

Experimental evidence of flattening in plasma profiles has been observed in the edge region of the JET tokamak. This observation has been interpreted in terms of the influence of rational surfaces on plasma profiles. In the framework of this interpretation, significant ExB sheared flows linked to rational surfaces have been identified. These ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes. These results can explain the link between the magnetic topology and the generation of transport barriers reported in fusion devices. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:3829.715701((00)05) / BLDSC - British Library Document Supply CentreGBUnited Kingdo