M. Fitzgerald S.E. Sharapov P. Rodrigues D. Borba
We use the HAGIS code to compute the nonlinear stability of the Q=10 ITER baseline scenario to toroidal Alfveneigenmodes (TAE) and the subsequent effects of these modes on fusion alpha-particle redistribution. Our calculations build upon an earlier linear stability survey [Rodrigues, P. et al. (2015). Nuclear Fusion, 55(8), 083003] which provides a…
Preprint PublishedY. Liu S.A. Sabbagh I.T. Chapman S. Gerasimov Y. Gribov T.C. Hender V. Igochine M. Maraschek G. Matsunag M. Okabayashi E.J. Strait
The high-frequency noise measured by magnetic sensors, at levels above the typical frequency of resistive wall modes, is analyzed across a range of present tokamak devices including DIII-D, JET, MAST, ASDEX Upgrade, JT-60U, and NSTX. A high-pass filter enables identification of the noise component with Gaussian-like statistics that shares certain c…
Preprint PurchaseF. Militello J.T. Omotani
A theoretical framework is developed to link the density profiles in the Scrape Off Layer (SOL) with the fluctuations (filaments) that generate them. The framework is based on the dynamics of independent filaments and their statistical behaviour and can be used to rigorously understand the mechanisms that lead to attending and broadening of the SOL…
Preprint PublishedS.C. Chapman R.O. Dendy P.T. Lang N.W. Watkins F.A. Calderon
We focus on JET plasmas in which ELMs are triggered by pellets in the presence of ELMs which occur naturally. We perform direct time domain analysis of signals from fast radial field coils and toroidal full flux azimuthal loops. These toroidally integrating signals provide simultaneous high time resolution measurements of global plasma dynamics and…
Preprint PublishedS. Schmuck J. Fessey J. E. Boom L. Meneses P. Abreu E. Belonohy I. Lupelli
At the tokamak Joint European Torus (JET), the electron cyclotron emission spectra in O-mode and X-mode polarisations are diagnosed simultaneous in absolute terms for several harmonics with two Martin-Puplett interferometers. From the second harmonic range in X-mode polarisation, the electron temperature profile can be deduced for the outboard side…
Preprint PublishedT. D. Swinburne K. Arakawa H. Mori H. Yasuda M. Isshiki Kouji Mimura Masahito Uchikoshi Sergei L. Dudarev
Vacancy-mediated climb models cannot account for the fast, direct coalescence of dislocation loops seen experimentally. An alternative mechanism, self climb, allows prismatic dislocation loops to move away from their glide surface via pipe diffusion around the loop perimeter, independent of any vacancy atmosphere. Despite the known importance of se…
Preprint PublishedF. Militello N.R. Walkden T. Farley W.A. Gracias J. Olsen F. Riva L. Easy N. Fedorczak I. Lupelli J. Madsen A.H. Nielsen P. Ricci P. Tamain J. Young
Four numerical codes are employed to investigate the dynamics of Scrape-Off Layer filaments in tokamak relevant conditions. Experimental measurements were taken in the MAST device using visual camera imaging, which allows the evaluation of the perpendicular size and velocity of the filaments, as well as the combination of density and temperature as…
Preprint PublishedY. Zayachuk I. Tanyeli S. Van Boxel K. Bystrov T. W. Morgan S.G. Roberts
For tungsten exposed to low-energy hydrogen-plasmas, it has been thought that grains with surface normal are most susceptible to blistering while those with surface normal are virtually impervious to it. Here, we report results showing that non-uniformity of blister distribution depends on the state of the surface due to polishing. In e…
Preprint PublishedC.J. Ham R.G.J. Cramp S. Gibson S.A. Lazerson I.T. Chapman A. Kirk
The magnetic perturbations produced by the resonant magnetic perturbation (RMP) coils will be rotated in ITER so that the spiral patterns due to strike point splitting which are locked to the RMP also rotate. This is to ensure even power deposition on the divertor plates. VMEC equilibria are calculated for different phases of the RMP rotation. It i…
Preprint PublishedM.L. Jackson P.C.M. Fossati R.W. Grimes
Atomic scale molecular dynamics simulations of radiation damage have been performed on beryllium. Direct threshold displacement simulations along a geodesic projection of directions were used to investigate the directional dependence with a high spatial resolution. It was found that the directionally averaged probability of displacement increases f…
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