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2008
We present the first derivation of the analytic expression for the Peierls-Nabarro potential for crowdion migration using the double sine-Gordon model. The analysis is guided by the group-specific trend in the shapes of the periodic lattice potentials calculated for the body-centered-cubic transition metals in groups 5B and 6B of the periodic table…
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2008
A full orbit test-particle approach is used to study the collisional transport of impurity (carbon) ions in spherical tokamak (ST) plasmas with transonic and subsonic toroidal flows. The efficacy of this approach is demonstrated by reproducing the results of classical transport theory in the large aspect ratio limit. The equilibrium parameters used…
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2008
A self-consistent kinetic model is developed to study the stability of the resistive wall mode in toroidal plasmas. This model is compared with other models based on perturbative approaches. The degree of the kinetic modification to the stability of the mode depends on the plasma configurations. Both stabilizing and destabilizing kinetic effects ar…
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2008
A prediction has been made of the Charpy ductile-brittle transition temperature at high irradiation levels from a dataset of 459 low-activation ferritic/martensitic steels. It follows a similar study of the yield stress of some 1811 similar alloys (Windsor et al , Modelling Simul. Mater. Sci. Eng. 16 (2008) 025005) Neural networks have previously b…
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2008
The need to understand and control the dynamics of reactor grade fusion plasmas requires the analysis of increasing amounts of data, which at JET can reach easily the level of several GBytes per shot. Therefore a series of new approaches are being pursued to store the data and to retrieve the required information. They range from loss less data com…
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2008
Charge exchange Recombination Spectroscopy (CXRS) plays a pivotal role in the diagnostics of hot fusion plasmas and is implemented currently in most of the operating devices. In the present report the main features of CXRS are summarized and supporting software packages encompassing "Spectral Analysis Code CXSFIT", "Charge Exchange Analysis Package…
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2008
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2007
The linear stability of dissipative drift electrostatic modes in tokamak plasmas is studied numerically with an extended version of the gyrokinetic code [Kinezero C. Bourdelle and et al. , Nucl. Fusion 42 , 892 (2002)] including a modified Krook collision operator to account for collisional effects on the trapped electron response. This new version…
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2007
The structural changes during the phase change between the amorphous and crystalline phase in Ge 2 Sb 2 Te 5 have been the subject of intense study due to the importance of Ge 2 Sb 2 Te 5 in phase change memory devices. In our study, the energetics of the transition between the crystalline and the amorphous phase of Ge 2 Sb 2 Te 5 is explored using…
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2007
Iron-chromium alloys are characterized by a complex phase diagram, by the small negative enthalpy of mixing at low Cr concentrations in the bcc -phase of Fe, and by the inversion of the short-range order parameter. We present Monte Carlo simulations of the binary Fe-Cr alloy based on the cluster expansion approximation for the enthalpy of the syste…
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