(OV/2-3) Overview of Physics Results from MAST

B. Lloyd1), R.J. Akers1), F. Alladio2), Y. Andrew1), L.C. Appel1), D. Applegate1), K.B. Axon1), N. Ben Ayed3), C. Bunting1), R.J. Buttery1), P.G. Carolan1), I. Chapman1), D. Ciric1), J.W. Connor1), N.J. Conway1), M. Cox1), G.F. Counsell1), G. Cunningham1), A. Darke1), E. Delchambre1), R.O. Dendy1), J. Dowling1), B. Dudson4), M.R. Dunstan1), A.R. Field1), A. Foster5), S. Gee1), L. Garzotti1), M.P. Gryaznevich1), A. Gurchenko6), E. Gusakov6), N.C. Hawkes1), P. Helander1), T.C. Hender1), B. Hnat7), D.F. Howell1), N. Joiner8), D. Keeling1), A. Kirk1), B. Koch9), M. Kuldkepp10), S. Lisgo11), F. Lott8), G.P. Maddison1), R. Maingi12), A. Mancuso2), S.J. Manhood1), R. Martin1), G.J. McArdle1), J. McCone13), H. Meyer1), P. Micozzi2), A.W. Morris1), D.G. Muir1), M. Nelson14), M.R. O’Brien1), A. Patel1), S. Pinches1), J. Preinhaelter15), M.N. Price1), E. Rachlew10), C.M. Roach1), V. Rozhansky16), S. Saarelma1), A. Saveliev6), R. Scannell13), S.E. Sharapov1), V. Shevchenko1), S. Shibaev1), K. Stammers1), J. Storrs1), A. Surkov6), A. Sykes1), S. Tallents8), D. Taylor1), N. Thomas-Davies1), M.R. Turnyanskiy1), J. Urban15), M. Valovic1), R.G.L. Vann3), F. Volpe1), G. Voss1), M.J. Walsh1), S.E.V. Warder1), R. Watkins1), H.R. Wilson3), M. Wisse13)
1) EURATOM/UKAEA Fusion Association, Abingdon, United Kingdom of Great Britain and Northern Ireland
2)Associazione EURATOM-ENEA sulla Fusione, Frascati, Rome, Italy
3)University of York, Heslington, York, UK
4)Oxford University, Clarendon Laboratory, Oxford, UK
5)University of Strathclyde, Glasgow, UK
6)A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia
7)Department of Physics, Warwick University, UK
8)Imperial College of Science, Technology and Medicine, London, UK
9)Institut für Physik der Humboldt, Universität zu Berlin, Germany
10)Dept. of Physics, KTH, EURATOM -VR Association, Stockholm, Sweden
11)University of Toronto Institute for Aerospace Studies, Toronto, Canada
12)Oak Ridge National Laboratory, Oak Ridge, USA
13)University College, Cork, Association EURATOM-DCU Ireland
14)Queen’s University, Belfast, UK
15)EURATOM/IPP.CR Fusion Association, Prague, Czech Republic
16)St. Petersburg State Polytechnical University, St. Petersburg, Russia

Abstract.  Important advances have been made on MAST, aided by substantial developments to plasma control, diagnostics and heating systems. The parameter range of the MAST confinement database has been extended and it now also includes pellet-fuelled discharges. Co-ordinated studies on MAST and DIII-D provide a strong link between the aspect ratio and beta scaling of H-mode energy confinement, consistent with that obtained when MAST data were merged with a subset of the ITPA database. Efficient pellet fuelling has been observed in H-mode discharges and post-pellet losses are low. Electron and ion ITBs are readily formed and their evolution has been investigated. Electron and ion thermal diffusivities have been reduced to values close to the ion neoclassical level. Non-linear GS2 calculations predict transport from the ETG mode at mid-radius in MAST H-mode comparable with experimental values. Error field correction coils have been used to determine the locked mode threshold scaling which is comparable with that in conventional tokamaks. The impact of plasma rotation on sawteeth has been investigated with co- and counter-NBI and the results have been well-modelled using the MISHKA-F code. The supra-Alfvénic ion population in MAST leads to a rich variety of fast particle driven instabilities. Their characteristics, beta dependence and impact on the fast ion population have been investigated. Off-axis NBCD and heating has been studied. Measurements are consistent with classical fast ion modelling and indicate efficient heating and significant driven current. Electron Bernstein wave heating has been observed via the O-X-B mode conversion process. Further advances in non-solenoid start-up techniques have been made. High pedestal temperature plasmas have been produced with collisionalities one order of magnitude lower than in previous MAST experiments. Pedestal widths in these plasmas agree better with banana orbit scalings and ELM losses are increased, consistent with the broad mode structures predicted by stability analyses. New measurements clearly show that ELM filaments persist for 200 μs during which time their toroidal rotation slows down and they accelerate radially outwards. SOL flows have been studied using a Gundestrup probe and 2D imaging of toroidally symmetric impurity gas puffing and compared with predictions from the B2SOLPS5.0 code.

Full paper and slides available (PDF)