S.M. Kaye J.W. Connor C.M. Roach
In this paper, we review the confinement and transport properties observed and predicted in low aspect ratio tokamaks, or spherical tokamaks (STs), which can depart significantly from those observed at higher aspect ratio. In particular, thermal energy confinement scalings show a strong, near linear dependence of energy confinement time on toroidal…
Preprint PurchaseNick Walkden Fabio Riva James Harrison Fulvio Militello Tom Farley John Omotani
Fusion power plant designs based on magnetic confinement, such as the tokamak design, offer a promising route to sustainable fusion power but require robust exhaust solutions capable of tolerating intense heat and particle fluxes from the plasma to material surfaces. Turbulent plasma transport in the divertor volume – the region where the plasma-…
Preprint PublishedN. VIANELLO N. WALKDEN M. DUNNE B. LOMANOWSKI E. WOLFRUM C. TSUI A. STAGNI M. GRIENER B. TAL T. EICH D. REFY D. BRIDA O. FÈVRIER M. AGOSTINI H. DE OLIVEIRA S. ALEIFERIS M. BERNERT J. BOEDO M. BRIX D. CARRALERO I. CARVALHO L. FRASSINETTI C. GIROUD A. HAKOLA A. HUBER J. KARHUNEN A. KARPUSHOV7 B. LABIT A. MEIGS V. NAULIN T. PEREIRA C. PEREZ VON THUN H. REIMERDES C. THEILER the ASDEXUpgrade Team the TCV team the EUROfusion MST1 Team and the JET Contributors
The evolution of SOL density profiles and fluctuations have been studied at different recycling levels in 3 different tokamaks, ASDEXUpgrade, TCV and JET, all operated in HMode. In all devices we clearly observe an increase of far SOL efolding length at high …
Preprint PublishedT. E. G. Nicholas J. Omotani F. Riva F. Militello B. Dudson
There exists a large body of previous work using reduced two-dimensional models of the SOL, which model fluctuations in the drift-plane but approximate parallel transport with effective loss terms. Full size three-dimensional simulations of SOL turbulence in experimental geometries are now possible, but are far more computationally expensive than …
Preprint PublishedE. Berger I. Pusztai S.L. Newton M. Hoppe O. Vallhagen A. Fil T. Fülöp
Understanding generation and mitigation of runaway electrons in disruptions is important for the safe operation of future tokamaks. In this paper we investigate runaway dynamics in reactor-scale spherical tokamaks. We study both the severity of runaway generation during unmitigated disruptions, as well as the effect that typical mitigation schem…
PreprintA R Field D Fajardo F J Casson C Angioni C D Challis J Hobirk A Kappatou Hyun-Tae Kim E Lerche A Loarte J Mailloux JET Contributors
Screening of high-Z (W) impurities from the confined plasma by the temperature gradient at the hot edge pedestal of fusion-grade H-mode plasmas has been demonstrated for the first time in the JET-ILW tokamak. Through careful optimisation of the hybrid-scenario, deuterium plasmas with sufficient heating power (≳ 32MW), high enough ion temperature …
PreprintHJ. Sun SA. Silburn IS. Carvalho C Giroud G Fishpool GF. Matthews DB. King RB. Henriques DL. Keeling FG. Rimini L. Garzotti D. Frigione D. Van Eester D Kos M-L. Mayoral J. Mailloux C. Maggi A. Huber D. Douai PJ. Lomas L Morten M. Maslov K. Kirov P. Jacquet CG. Lowry M. Baruzzo C. Stuart J. Mitchell L. Horvath DC. McDonald JET Contributors
Unusually high power loads on the Beryllium limiter caused by Neutral Beam re-ionisation, and much cooler divertor target surfaces were observed during the recent JET tritium campaign. As both phenomena are driven by scrape-off layer (SOL) physics, the SOL features of 72 tritium H-mode discharges and their deuterium references have been studied. …
PreprintH. J. Sun R. J. Goldston A. Huber X. Q. Xu J. Flanagan D. C. McDonald E. de la Luna M. Maslov J. R. Harrison F. Militello J. Fessey S. Cramp JET Contributors
A study of a dataset of JET H-mode plasma with the Be/W ITER-like wall (JET-ILW) shows that reaching the edge MHD ballooning limit leads to confinement degradation. However, unlike JET plasmas with a carbon wall (JET-C), the JET-ILW plasmas stay in a marginal dithering phase for a relatively long period, associated with a higher (20%) H-mode den…
Preprint PublishedH. G. Dudding F. J. Casson D. Dickinson B. Patel C. M. Roach E. A. Belli G. M. Staebler
A new quasilinear saturation model SAT3 has been developed for the purpose of calculating radial turbulent fluxes in the core of tokamak plasmas. The new model is shown to be able to better recreate the isotope mass dependence of nonlinear gyrokinetic fluxes compared to contemporary quasilinear models, including SAT2 [1], whilst performing at least…
Preprint PublishedK. Verhaegh B. Lipschultz J.R. Harrison N. Osborne A. Williams P Ryan J. Allcock J. Clark F. Federici B. Kool T. Wijkamp A. Fil D. Moulton O. Myatra A. Thornton T.O.S.J. Bosman C. Bowman B. Duval S. Henderson R. Scannell the MAST Upgrade team the EuroFusion MST1 team
In this paper we a first qualitative analysis of the atomic and molecular processes at play during detachment in the MAST-U Super-X divertor, using divertor spectroscopy data. Our analysis indicates a wide operational regime of detachment of the MAST-U super-X divertor, which can be roughly separated in four phases: 1) The ionisation front detac…
Preprint