N.R.Walkden B.D.Dudson C.Ham F.Militello D.Moulton F.Riva J.T.Omotani
A firm grasp of transport processes perpendicular to the magnetic field line is required in order to understand and predict heat and particle fluxes to divertor components in tokamaks. Perpendicular transport from the hot core into the scrape-off layer (SOL) upstream impacts the SOL profile at the divertor via parallel streaming along the magnetic …
Preprint PurchaseBogdan Hnat Nick Walkden The MAST Team
We study the amplitude modulation of the radial electric field constructed from the Langmuir probe plasma potential measurements at the edge of MAST. The Empirical Mode Decomposition technique is applied, which allows us to construct fluctuations on temporal scales of plasma turbulence, the Geodesic Acoustic Mode and these associated with the res…
Preprint PublishedF. Riva F. Militello S. Elmore J. T. Omotani B. Dudson N. R. Walkden MAST team
The STORM module of BOUT++ [L. Easy et al., Phys. Plasmas 21, 122515 (2014)] is generalized to simulate plasma turbulence at the periphery of tokamak devices in diverted configuration and it is used to carry out three-dimensional nonlinear flux-driven simulations in double null configuration with realistic experimental par…
Preprint PublishedB. Cannas S. Carcangiu A. Fanni T. Farley F. Militello A. Montisci F. Pisano G. Sias N. Walkden
In the present magnetically confined plasmas, the prediction of particle loading on material surfaces is a primary concern in view of the protection of plasma facing components for next step devices. Thus, an understanding of filament dynamics is needed. In this context, this work aims to develop an automatic detector for filaments arising in the M…
Preprint PublishedN. R. Walkden B. Labit H. Reimerdes J. Harrison T. Farley P. Innocente F. Militello the TCV Team the MST1 Team
Tangentially viewing fast camera footage of the low-field side snowflake minus divertor in TCV is analysed across a four point scan in which the proximity of the two X-points is varied systematically. The apparent flow observed in the post-processed movie shows two distinct regions of the camera frame exhibiting differing flow patterns. One flow in…
Preprint PublishedD. Schwörer N. R. Walkden H. Leggate B. D. Dudson F. Militello T. Downes M. M. Turner
This paper presents the effect of self-consistent plasma backgrounds including plasma-neutral interactions, on the dynamics of filament propagation. The principle focus is on the influence of the neutrals on the filament through both direct interactions and through their influence on the plasma background. Both direct and indirect interactions infl…
Preprint PublishedF. Militello T. Farley K. Mukhi N. Walkden J.T. Omotani
A statistical framework was introduced in textit{Militello et al., Nucl. Fusion 56, 104004 (2016)} to correlate the dynamics and statistics of L-mode and inter-ELM plasma filaments with the radial profiles of thermodynamic quantities they generate in the Scrape Off Layer. This paper extends the framework to cases in which the filaments are emitted …
Preprint PublishedN. R. Walkden J. Harrison S. A. Silburn T. Farley S.S. Henderson A. Kirk F. Militello A.Thornton the MAST Team
Using high speed imaging of the divertor volume, the region close to the X-point in MAST is shown to be quiescent. This is confirmed by three different analysis techniques and the quiescent X-point region (QXR) spans from the separatrix to the N = 1.02 flux surface. Local reductions to the atomic density and effects associated with the camera vie…
Preprint PublishedJ.Leddy B. Dudson M. Romanelli B. Shanahan N. Walkden
Tokamak plasmas are confined by a magnetic field that limits the particle and heat transport perpendicular to the field. Parallel to the field the ionised particles can move freely, so to obtain confinement the field lines are “closed" (ie. form closed surfaces of constant poloidal flux) in the core of a tokamak. Towards, the edge, however, the …
Preprint PublishedN. R. Walkden A. Wynn F. Militello B. Lipschultz G. Matthews C.Guillemaut J. Harrison D. Moulton JET Contributors
This paper presents the use of a novel modelling technique based around intermittent transport due to filament motion, to interpret experimental profile and fluctuation data in the scrape-off layer (SOL) of JET during the onset and evolution of a density profile shoulder. Three cases are studied at different points in a density ramp experiment wher…
Preprint Published