H. Tanabe T. Yamada T. Watanabe K. Gi K. Kadowaki M. Inomoto R. Imazawa M. Gryaznevich R. Scannell N. Conway B. Crowley K. G. McClements I. Fitzgerald C. Michael J. Harrison A. Meakins N. Hawkes T. OGorman F. Cheng Y. Ono The Mast Team
This paper describes a recent advances in merging/reconnection experiments in MAST, namely tomographic ion Doppler spectroscopy capability from 2013 which solves the problem of the absence of ion temperature profile measurement during the solenoid-less startup. Providing 32 channel line-integrated spectra from 0.25m< rtangential <1.1m are con…
PreprintB. Layden Z. S. Qu M. Fitzgerald M. J. Hole
A number of tools have recently been developed to study equilibrium and stability in tokamaks with pressure anisotropy. Here we apply these tools to a Mega Ampere Spherical Tokamak (MAST) discharge to calculate equilibrium, Alfven continua and eigenmodes, through to linear growth and nonlinear saturation of a toroidal Alfven eigenmode (TAE); this i…
Preprint PublishedM. Fitzgerald S.E. Sharapov P. Rodrigues D. Borba
We use the HAGIS code to compute the nonlinear stability of the Q=10 ITER baseline scenario to toroidal Alfveneigenmodes (TAE) and the subsequent effects of these modes on fusion alpha-particle redistribution. Our calculations build upon an earlier linear stability survey [Rodrigues, P. et al. (2015). Nuclear Fusion, 55(8), 083003] which provides a…
Preprint PublishedZ.S. Qu M.J. Hole M. Fitzgerald
Extending the ideal MHD stability code MISHKA, a new code, MISHKA-A, is developed to study the impact of pressure anisotropy on plasma stability. Based on full anisotropic equilibrium and geometry, the code can provide normal mode analysis with three fluid closure models: the single adiabatic model (SA), the double adiabatic model (CGL) and the inc…
Preprint PublishedZ.S. Qu M.J. Hole M. Fitzgerald
An unstable branch of energetic geodesic acoustic mode (EGAM) is found using the fluid theory with fast ions characterised by their narrow width in energy distribution and collective transit along field lines. This mode, with a frequency much lower than the thermal GAM frequency !GAM, is now confirmed as a new type of unstable EGAM : a reactive in…
Preprint PublishedH. Tanabe T. Yamada T. Watanabe K. Gi K. Kadowaki M. Inomoto R. Imazawa M. Gryaznevich C. Michael B. Crowley N. J. Conway R. Scannell J. Harrison I. Fitzgerald A. Meakins N. Hawkes K. G. McClements T. OGorman C. Z. Cheng Y. Ono The MAST Team
Electron and ion heating characteristics during merging reconnection startup on the MAST spherical tokamak have been revealed in detail using 130 channel YAG- and 300 channel Ruby-Thomson scattering system and a new 32 chord ion Doppler tomography diagnostic. Detailed 2D profile measurements of electron and ion temperature together with electron de…
Preprint PublishedM. Fitzgerald M. J. Hole Z. S. Qu
In this work, we generalise linear magnetohydrodynamic (MHD) stability theory to include equilibrium pressure anisotropy in the uid part of the analysis. A novel `single-adiabatic' (SA) uid closure is presented which is complementary to the usual `double-adiabatic' (CGL) model and has the advantage of naturally reproducing exactly the MHD spectrum …
Preprint PublishedT. D. Swinburne S. L. Dudarev S. P. Fitzgerald M. R. Gilbert A. P. Sutton
Isolated kinks on thermally fluctuating 1/2 111 screw, 100 edge, and 1/2 111 edge dislocations in bcc iron are simulated under zero stress conditions using molecular dynamics (MD). Kinks are seen to perform stochastic motion in a potential landscape that depends on the dislocation character and geometry, and their motion provides fresh insight …
PublishedS.P. Fitzgerald S. Aubry S.L. Dudarev W. Cai
Frank-Read sources are among the most important examples of dislocation sources in crystals, and their operation facilitates dislocation multiplication and hence yield and plastic flow. Iron is known to become highly elastically-anisotropic as the alpha - gamma transition at 912 degrees centigrage is approached, a temperature regime of critical imp…
Published