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2014
On MAST, compressional Alfven eigenmodes can be destabilized by the presence of a sufficiently large population of energetic particles in the plasma. This dependence was studied in a series of very similar discharges in which increasing amounts of hydrogen were puffed into a deuterium plasma. A simple method to estimate the isotopic ratio nH/nD usi…
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2014
A new coherence imaging Doppler spectroscopy diagnostic has been deployed on the UK’s Mega Amp Spherical Tokamak for scrape-off-layer and divertor impurity flow measurements. The system has successfully obtained 2D images of C III, C II, and He II line-of-sight flows, in both the lower divertor and main scrape-off-layer. Flow imaging has been obt…
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2014
An energy-principle-based dispersion relation is derived for the resistive wall mode, which incorporates both the drift kinetic resonance between the mode and energetic particles and the resistive layer physics. The equivalence between the energy-principle approach and the resistive layer matching approach is first demonstrated for the resistive pl…
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2014
The high pressure gradients in the edge of a tokamak plasma can lead to the formation of explosive plasma instabilities known as edge localised modes (ELMs). The control of ELMs is an important requirement for the next generation of fusion devices such as ITER. Experiments performed on the Mega Amp Spherical Tokamak (MAST) at Culham have shown that…
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2014
A key goal for fusion materials modelling research is the development of predictive simulation models and capabilities to assess material performance under the neutron irradiation conditions expected in near-plasma regions of fusion reactor tokamaks. This paper presents computational results from the modelling of neutron fields in the latest concep…
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2014
The simulation of neutron irradiation–induced transmutation using inventory codes is an important part of the research into materials in various nuclear environments, including fusion, fission, medical physics, nuclear security, and astrophysics. These simulations, even in their simplest form, such as the neutron irradiation of a single pure elem…
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2014
When resonant magnetic perturbations are applied in MAST, the plasma edge boundary experiences a three dimensional distortion, which can be a few percent of the minor radius in amplitude, in good agreement with ideal 3d equilibrium modelling. This displacement occurs in plasmas both with radial position feedback control applied, and without feedbac…
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2014
The power load to the divertor surfaces is a key concern for future devices such as ITER, due to the thermal limits on the material surface. One factor that characterises the heat flux to the divertor is the fall off length in the SOL, which recent empirical scalings have shown could be as small as 1 mm. These predictions are based on a multi-machi…
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2014
The type I ELMy H-mode is the baseline operating scenario for ITER. While it is known that the type I ELM ultimately results from the peeling-ballooning instability, there is growing experimental evidence that a mode grows up before the ELM crash that may modify the edge plasma, which then leads to the ELM event due to the peeling-ballooning mode. …
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2014
There is an increasing need to model plasma inter- action with complex engineered surfaces, notably to verify that power deposition rates are acceptable. The SMARDDA algorithm has been developed to meet this requirement, with particular reference to the neutral beam ducts that feed into the vacuum vessels of tokamaks. Application to limiters and di…
Showing 271 - 280 of 353 UKAEA Paper Results