Showing 11 - 20 of 47 Journals Results
2014
H.J.C. Oliver S.E. Sharapov R. Akers I. Klimek M. Cecconello The Mast Team
Compressional Alfven and ion-ion hybrid waves excited by energetic beam ions are studied in plasmas with two ion species. In our experiment, a hydrogendeuterium (H-D) plasma is used to produce instabilities similar to those likely to be present in the burning deuterium-tritium plasmas of future tokamaks. Modes are suppressed in the deuterium cyclot…
Published2014
I.T. Chapman A. Kirk R.J. Akers C.J. Ham J.R. Harrison J. Hawke Y.Q. Liu K.G. McClements S. Pamela S. Saarelma R. Scannell A.J. Thornton The Mast Team
ELM mitigation has been demonstrated in MAST using resonant magnetic perturbations (RMPs) with toroidal mode number, n RM P = 2, 3, 4, 6. It has been observed that the mitigated ELM frequency increases with the amplitude of the applied field provided it is above a critical threshold. This threshold value depends on the mode number of the RMP, with …
Published2014
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…
Published2013
H. 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…
Published2013
M. 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…
Published2011
B. 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 …
Published2011
M 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…
Published2010
G. 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…
Published2010
M. 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 …
Published2010