O.M. Jones C.A. Michael K.G. McClements N.J. Conway B. Crowley R.J. Akers R.J. Lake S.D. Pinches The Mast Team
Using the recently-installed Fast-Ion Deuterium Alpha (FIDA) spectrometer, the effects of low-frequency (20 - 50 kHz) chirping energetic particle modes with toroidal mode number n = 1 on the NBI-driven fast-ion population in MAST plasmas are considered. Results from the FIDA diagnostic are presented and discussed in the light of the present theoret…
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…
PublishedM. Turnyanskiy C. D. Challis R. J. Akers M. Cecconello D. L. Keeling A. Kirk R. Lake S. D. Pinches S. Sangaroon I. Wodniak
Previous experiments on MAST and other tokamaks have indicated that the level of fast ion redistribution can exceed that expected from classical diffusion and that this level increases with beam power. In this paper we present a quantification of this effect in MAST plasmas using a recently commissioned scanning neutron camera. The observed fast io…
PublishedB. Lloyd R.J. Akers F. Alladio S. Allan Et Al
Major developments on MAST have enabled important advances in support of ITER and the physics basis of a spherical tokamak (ST) based component test facility (CTF), as well as providing new insight into underlying tokamak physics. For example, L-H transition studies benefit from high spatial and temporal resolution measurements of pedestal profile …
PublishedM Valovic L Garzotti C Gurl R Akers J Harrison C Michael G Naylor R Scannell The Mast Team
Access into H-mode is studied in the MAST tokamak when plasma is fuelled by cryogenic pellets. It is shown that pellet fuelling from the high field side allows access to Hmode in plasmas heated by neutral beams. Simple and two-stage L-H transitions are identified. The results of comparison of the L-H transitions with pellet injection with transitio…
PublishedG. Hommen M. De Baar P. Nuij G. Mcardle R. Akers M. Steinbuch
A new diagnostic is developed to reconstruct the plasma boundary using visible wavelength images. Exploiting the plasma’s edge localized and toroidally symmetric emission profile, a new coordinate transform is presented to reconstruct the plasma boundary from a poloidal view image. The plasma boundary reconstruction is implemented in MATLAB and a…
PublishedM. Cecconello M. Turnyanskiy S. Conroy G. Ericsson E. Ronchi S. Sangaroon R. Akers I. Fitzgerald A. Cullen M. Weiszflog
A prototype neutron camera has been developed and installed at MAST as part of a feasibility study for a multichord neutron camera system with the aim to measure the spatial and time resolved 2.45 MeV neutron emissivity profile. Liquid scintillators coupled to a fast digitizer are used for neutron/ gamma ray digital pulse shape discrimination. The …
PublishedIT Chapman M-D Hua SD Pinches RJ Akers AR Field JP Graves RJ Hastie CA Michael The Mast Team
MAST plasmas with a safety factor above unity and a profile with either weakly reversed shear, or broad low shear regions, regularly exhibit long-lived saturated ideal magnetohydrodynamic (MHD) instabilities. The toroidal rotation is flattened in the presence of such perturbations and the fast ion losses are enhanced. These ideal modes, distinguish…
PublishedA.Kirk E.Nardon R.Akers M.Bécouleta G.Detemmerman B.Dudsonb B.Hnatc Y.Q.Liu R.Martin P.Tamain D.Taylor The Mast Team
Experiments have been performed on MAST using both external (n=1,2) and internal (n=3) resonant magnetic perturbation coils. ELM suppression has not been achieved even though vacuum modelling shows that either set of coils can produce a region for which the Chirikov parameter is greater than 1 wider than that required to produce ELM suppression in …
PublishedH Meyer R J Akers F Alladio L C Appel K B Axon N Ben Ayed P Boerner R J Buttery P G Carolan D Ciric C D Challis I T Chapman Et Al
Several improvements to the MAST plant and diagnostics have facilitated new studies advancing the physics basis for ITER and DEMO, as well as for future spherical tokamaks. Using the increased heating capabilities PNBI ≤ 3.8 MWH-mode at Ip = 1.2 MA was accessed showing that the energy confinement on MAST scales more weakly with Ip and more strong…
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