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2010
Plasma rotation in tokamaks is of special interest for its potential stabilising effect on micro- and macro instabilities, leading to increased confinement. In MAST, the torque from Neutral Beam Injection (NBI) can spin the plasma to a core velocity ~ 300km.s -1 (Alfven Mach number ~ 0.3). Low density plasmas often exhibit a weakly non-monotonic sa…
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2010
A major upgrade to the ruby Thomson scattering (TS) system has been designed and implemented on the Mega-ampere spherical tokamak (MAST). MAST is equipped with two TS systems, a Nd:YAG laser system and a ruby laser system. Apart from common collection optics each system provides independent measurements of the electron temperature and density profi…
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2010
In this work, the radial transport of tracers in an H-mode run in the CUTIE code [A. Thyagaraja et al. , Phys. Plasmas 12 , 090907 (2005)] is analyzed globally. Several techniques are applied to the study of the trajectories performed by the tracers, measuring the degree of self-similarity in the motion and searching for long range spatial and temp…
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2010
The COMPASS tokamak, a mid-sized flexible device with ITER-like shape, which can operate in H-mode, is starting its re-established operation at the Institute of Plasma Physics in Prague. A new 600 kW, 40 keV neutral beam injection (NBI) system is foreseen as a major upgrade. Reported here are predictive simulations with the ASTRA transport code, in…
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2010
Wepresentgeneralizedstructurefunction(GSF)analysisof magneticandvelocityfieldfluctuationsmeasured insituinthesolarwindat ~ 1 AUwiththeACEspacecraft.Wedecomposethefluctuationsintodirectionsparalleland perpendiculartothemeanlocalbackgroundmagneticfield.GSFplotsbasedonthesequantitiesareshowntoprovideaclear indicatorofthespectralbreakbetweentheinertial…
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2010
Frank-Read sources are among the most important mechanisms of dislocation multiplication, and their operation signals the onset of yield in crystals. We show that the critical stress required to initiate dislocation production falls dramatically at high elastic anisotropy, irrespective of the mean shear modulus. We hence predict the yield stress of…
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2010
Direct coupling between a transport solver and local, nonlinear gyrokinetic calculations using the multiscale gyrokinetic code TRINITY [M. Barnes, “TRINITY: A unified treatment of turbulence, transport, and heating in magnetized plasmas,” Ph.D. thesis, University of Maryland, (2008) eprint arXiv:0901.2868] is described. The coupling of the micr…
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2010
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 …
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2010
Massive amounts of data generated by fusion machines (such as JET) require developing automatic methods for data analysis. Edge-localized modes (ELMs) are instabilities occurring in the edge of H-mode plasmas. The aim of this work is to develop an automatic off-line method for identifying and locating ELMs. This method uses Universal Multi-Event Lo…
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2010
The sensitivity of the stability of the ideal n = 1 internal kink mode to variations in the plasma profiles is analysed both analytically and numerically in rotating tokamak plasmas. These stability analyses have been carried out including the centrifugal effects of toroidal plasma rotation upon the equilibrium, and also inconsistently when the equ…
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