T D Swinburne
Through multiscale analysis of the adjoint Fokker-Planck equation, strict bounds are derived for the center of mass diffusivity of an overdamped harmonic chain in a periodic potential, often known as the discrete Frenkel-Kontorova model. Significantly, it is shown that the free energy barrier is a lower bound to the true finite temperature migratio…
PublishedYueqiang Liu Youwen Sun
The non-linear interplay between the resistive wall mode (RWM) and the toroidal plasma flow is numerically investigated in a full toroidal geometry, by simultaneously solving the initial value problems for the n¼1 RW and the n¼0 toroidal force balance equation. Here, n is the toroidal mode number. The neoclassical toroidal viscous torque is ident…
PublishedD Dickinson C M Roach J M Skipp H R Wilson
Solutions to a model global 2D eigenmode equation describing micro-instabilities in tokamak plasmas are presented that demonstrate a sensitivity of the mode structure and stability to plasma profiles. In narrow regions of parameter space, with special plasma profiles, a maximally unstable mode is found that balloons on the outboard side of the toka…
PublishedIT Chapman JP Graves O Sauter C Zucca O Asunta RJ Buttery S Coda T Goodman V Igochine T Johnson M Jucker RJ La Haye M Lennholm JET-EFDA Contributors
13MW of electron cyclotron current drive (ECCD) power deposited inside the q = 1 surface is likely to reduce the sawtooth period in ITER baseline scenario below the level empirically predicted to trigger neo-classical tearing modes (NTMs). However, since the ECCD control scheme is solely predicated upon changing the local magnetic shear, it is prud…
PublishedH. Meyer I.G. Abel R.J. Akers A. Allan S.Y. Allan L.C. Appel O. Asunta M. Barnes N.C. Barratt Et Al
New diagnostic, modelling and plant capability on the Mega Ampere Spherical Tokamak (MAST) have delivered important results in key areas for ITER/DEMO and the upcoming MAST Upgrade, a step towards future ST devices on the path to fusion currently under procurement. Micro-stability analysis of the pedestal highlights the potential roles of micro-tea…
PublishedF. A. Calderon R. O. Dendy S. C. Chapman A. J. Webster B. Alper et al.
Edge localised mode (ELM) measurements from reproducibly similar plasmas in the Joint European Torus (JET) tokamak, which differ only in their gas puffing rate, are analysed in terms of the pattern in the sequence of inter-ELM time intervals. It is found that the category of ELM defined empirically as type I—typically more regular, less frequent,…
PublishedJ. Hawke R. Scannell M. Maslov J. B. Migozzi JET-EFDA Contributors
This work isolated the cause of the observed discrepancy between the electron temperature (Te) measurements before and after the JET Core LIDAR Thomson Scattering (TS) diagnostic was upgraded. In the upgrade process, stray light filters positioned just before the detectors were removed from the system. Modelling showed that the shift imposed on the…
PublishedS.E. Sharapov
A general introduction is given to ideal magnetohydrodynamic (MHD) waves, using linear perturbations of ideal MHD equations. Subsequently the shear Alfvén waves are shown to form a discrete spectrum of Global Alfvén Eigenmodes in current-carrying cylindrical plasmas and Toroidal Alfvén Eigenmodes in toroidal plasmas. A comparison between theory …
PublishedLeonid E. Zakharov Sergei A. Galkin Sergei N. Gerasimov
This paper describes progress achieved since 2007 in understanding disruptions in tokamaks, when the effect of plasma current sharing with the wall was introduced into theory. As a result, the toroidal asymmetry of the plasma current measurements during vertical disruption event (VDE) on the Joint European Torus was explained. A new kind of plasma …
PublishedI. Balboa G. Arnoux T. Eich B. Sieglin S. Devaux et al.
For the new ITER-like wall at JET, two new infrared diagnostics (KL9B, KL3B) have been installed. These diagnostics can operate between 3.5 and 5 µ m and up to sampling frequencies of ~ 20 kHz. KL9B and KL3B image the horizontal and vertical tiles of the divertor. The divertor tiles are tungsten coated carbon fiber composite except the central til…
Published