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CCFE-PR(17)182016
Clear filamentary structures are observed at the edge of tokamak plasmas. These filaments are ejected out radially and carry plasma in the far Scrape Off Layer (SOL) region, where they are responsible for producing most of the transport. A study has been performed of the characteristics of the filaments observed in L-mode plasma on MAST, using visi…
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CCFE-PR(16)292016
Breaking the up-down symmetry of tokamaks removes a constraint limiting intrinsic momentum transport, and hence toroidal rotation, to be small. Using gyrokinetic theory, we study the effect of different up-down asymmetric flux surface shapes on the turbulent transport of momentum. This is done by perturbatively expanding the gyrokinetic equation in…
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CCFE-PR(16)182016
A subset of JET ITER-like wall (ILW) discharges, combining electron density and temperature as well as divertor heat flux measurements, has been collected for the validation of non-linear MHD simulations of Edge-Localised-Modes (ELMs). This permits a quantitative comparison of simulation results against experiments, which is required for the valida…
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CCFE-PR(16)462016
A summary of negative ion development work being presently undertaken at the Culham Centre for Fusion Energy (CCFE) is given. The Small Negative Ion Facility (SNIF) has an RF driven volume ion source with beam extraction at energies up to 30keV. The extracted beam of Hions has an associated co-extracted electron beam with an electron to ion ratio o…
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CCFE-PR(16)022016
There has been considerable controversy regarding the structure of TiBe12, which is variously reported as hexagonal and tetragonal. Lattice dynamics simulations based on density functional theory show the tetragonal phase space group I4/mmm to be more stable over all temperatures, while the hexagonal phase exhibits an imaginary phonon mode, which, …
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CCFE-PR(15)552015
Modelling of nuclide densities as a function of time within magnetic confinement fusion devices such as the JET, ITER and proposed DEMO tokamaks is performed using Monte-Carlo transport codes coupled with a Bateman equation solver. The generation of reaction rates occurs either through point-wise interpolation of energy dependent tracked particle …
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2015
Understanding the behaviour of solid solutions over wide ranges of temperature and pressure remains a major challenge to both theory and experiment. Here we report a detailed exchange Monte Carlo study using a classical ionic model of the model perovskite parascandolaite-neighborite (K,Na)MgF3 solid solution and its end-members for temperatures in …
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CCFE-PR(15)602015
The interaction between multiple filamentary plasma eruptions is investigated by modelling the non-linear ideal MHD ballooning mode envelope equation with a mixed Eulerian and Lagrangian characterisation of the boundary conditions. The study of multiple plasma filaments is performed in a specific slab equilibrium susceptible to Rayleigh-Taylor ins…
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CCFE-PR(15)582015
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…
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CCFE-PR(15)672015
Preferential ion heating in the solar wind, observed as the occurrence of an ion beam which drifts along the background magnetic field with a velocity close to the local Alfven speed, is still an open problem. Several mechanisms have been identified that might work together in the solar wind to drive the observed ion heating. These mechanisms resul…
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