S. C. Chapman R. O. Dendy T. N. Todd N. W. Watkins F. A. Calderon J. Morris JET Contributors
A global signature of the build-up to an intrinsic edge localized mode (ELM) is found in the temporal analytic phase of signals measured in full flux azimuthal loops in the divertor region of JET. Toroidally integrating, full flux loop signals provide a global measurement proportional to the voltage induced by changes in poloidal magnetic flux; the…
PublishedA. J. Webster J. Morris T. N. Todd S. Brezinsek P. Coad J. Likonen M. Rubel JET EFDA Contributors
A unique sequence of 120 almost identical plasmas in the Joint European Torus (JET) recently provided two orders of magnitude more statistically equivalent data than ever previously available. The purpose was to study movement of eroded plasma-facing material from JET’s new Beryllium wall, but it has allowed the statistical detection of otherwise…
PublishedS. C. Chapman R. O. Dendy T. N. Todd N. W. Watkins A. J. Webster F. Calderon J. Morris JET EFDA Contributors
A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in …
PublishedA.J. Webster R.O. Dendy F.A. Calderon S. C. Chapman E. Delabie D. Dodt R. Felton T. N. Todd F. Maviglia J. Morris V. Riccardo B. Alper S. Brezinsek P. Coad J. Likonen M. Rubel JET EFDA Contributors
For a two week period during the Joint European Torus (JET) 2012 experimental campaign, the same high confinement plasma was repeated 151 times. The dataset was analysed to produce a probability density function (pdf) for the waiting times between edge-localised plasma instabilities (“ELMs”). The result was entirely unexpected. Instead of a smo…
PublishedT. N. Todd
The diagnostic systems of DEMO that are mounted on or near the torus, whether intended for the monitoring and control functions of the engineering aspects or the physics behaviour of the machine, will have to be designed to suit the hostile nuclear environment. This will be necessary not just for their survival and correct functioning but also to s…
PublishedR.A. Bamford B. Kellett J. Bradford T.N. Todd M.G. Benton Sr R. Stafford-Allen E.P. Alves L. Silva C. Collingwood I.A. Crawford R. Bingham
If mankind is to explore the solar system beyond the confines of our Earth and Moon the problem of radiation protection must be addressed. Galactic cosmic rays and highly variable energetic solar particles are an ever-present hazard in interplanetary space. Electric and/or magnetic fields have been suggested as deflection shields in the past, but t…
PublishedT N Todd
Now that ITER is under construction, interest is increasing in the specification and design of the successor machine, a Demonstration Power Plant (DEMO), which in Europe is coordinated by the EFDA Power Plant Physics and Technology programme. This paper summarises the work carried out for EFDA in 2011-2012 on design issues pertinent to a pulsed ver…
PublishedA S Kaye H Altmann R Albanese D Ciric P Coad D Brennan F Durodie T Edlington D C Edwards R Felton T T C Jones A Lioure P Lomas J Mailloux I Monakhov M Nightingale J Pamela R Pearce V Riccardo J Rapp A Rolfe E Surrey S Rosanvallon T Todd, A Walden
JET supports ITER both in development of technology and in torus operations. The latter include the study of ITER-like scenarios, operation in tritium (a trace tritium campaign has recently been completed), mitigation of ELMs and disruptions, investigation of tritium retention, real time control of plasma parameters, and control of extreme plasma s…
PublishedColin George Windsor Thomas Noel Todd David Leonard Trotman Michael Edward Underhill Smith
The plasma position and shape on the COMPASS-D tokamak have been controlled simultaneously with a 75- kHz bandwidth, hard-wired, real-time neural network. The primary network operates with up to 48 selected magnetic inputs and has been used in the vertical position control loop to control the position of the upper edge of the plasma at the radius o…
PublishedA. W. Morris P. G. Carolan Fl Fitzpatrick T. C. Hender T. N. Todd
The question of the influence of nonaxisymmetric field perturbations on tokamaks is investigated. Recent experiments in the COMPASS-C tokamak [in Proceedings of the 15th Symposium on Fusion Technology, Utrecht (North-Holland, Amsterdam, 1989), Vol. 1, p. 3611 with externally applied helical fields reveal that magnetic islands do not appear until th…
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