S. Queyreau J. Marian M. R. Gilbert B. D. Wirth
In the traditional picture of plasticity in bcc metals, edge dislocations have been assumed to play a minor role due to their high mobility with respect to screw dislocations, which then control plastic flow. 1 2 111{110} edge dislocations indeed fit this description, as it has been shown by way of numerous atomistic simulations. However, 1 2 111{1…
PublishedI.N.Chugunov V.G.Kiptily A.E.Shevelev D.B.Gin
Gamma-ray spectrometry provides diagnostics of fast ion behavior in plasmas of large tokamaks. Information acquiring with the gamma-ray diagnostics gives possibility to identify and distinguish simultaneously presence of fast alpha-particles and other ions (H, D, T, 3 He), to obtain its relative densities and also to perform tomographic radial prof…
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…
PublishedM. K.Lilley B.N.Breizman S.E.Sharapov
A fully nonlinear model is developed for the bump-on-tail instability including the effects of dynamical friction drag and velocity space diffusion on the energetic particles driving the wave. The results show that drag provides a destabilizing effect on the nonlinear evolution of waves. Specifically, in the early nonlinear phase of the instability…
PublishedR. Scannell M. Beurskens M. Kempenaars G. Naylor M. Walsh T. O’Gorman R. Pasqualotto
Absolute calibration of LIDAR Thomson scattering systems on large fusion devices may be achieved using rotational Raman scattering. The choice of calibrating gas molecule presents different options and design trade-offs and is likely to be strongly dependent on the laser wavelength selected. Raman scattering of hydrogenic molecules produces a very …
PublishedYueqiang Liu
The effects of the fusion born a particles on the stability of the RWM are numerically investigated for one of the advanced steady state Scenarios in ITER. The a contribution is found to be generally stabilising, compared to the thermal particle kinetic contribution alone. The same conclusion is achieved following both a perturbative and self-consi…
PublishedAnthony J. Webster
The surface or “skin” current that can flow at a perturbed interface between plasma and vacuum is considered in the approximation where a surface marks a sharp transition from plasma to vacuum. A short magnetohydrodynamic calculation gives an exact and general expression for the component perpendicular to the average of the magnetic field eithe…
PublishedM. Gelfusa A. Murari P. Gaudio A. Boboc M. Brombin F. P. Orsitto E. Giovannozzi JET EFDA Contributors
An equivalent model of JET polarimeter is presented, which overcomes the drawbacks of previous versions of the fitting procedures used to provide calibrated results. First of all the signal processing electronics has been simulated, to confirm that it is still working within the original specifications. Then the effective optical path of both the v…
PublishedL Garzotti L Baylor F Köchl B Pégourié M Valovic K B Axon J Dowling C Gurl G P Maddison H Nehme T O’Gorman A Patel M Price R Scannell M Walsh
Pellet material deposited in a tokamak plasma experiences a drift towards the low field side of the torus induced by the magnetic field gradient. Plasma fuelling in ITER relies on the beneficial effect of this drift to increase the pellet deposition depth and fuelling efficiency. It is therefore important to analyse this phenomenon in present machi…
Published