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2009
The formation of neoclassical tearing modes (NTMs) severely limits the performance of a tokamak plasma by increasing the radial particle and heat fluxes from the core and can even lead to a plasma disruption. Indeed, NTMs are a serious consideration for the next step device, ITER. The appearance of a finite NTM magnetic island requires an initial …
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2009
Neo-classical tokamak plasma theory predicts poloidal rotation driven by the temperature gradient of order ~ few km/s. In conventional aspect ratio tokamak plasmas, e.g. on JET and DIII-D, poloidal velocities considerably in excess of the neo-classical values have been measured, particularly in the presence of internal transport barriers (ITBs), by…
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2009
Recently several tokamak experiments have been completed to try and elucidate the scaling of the confinement with the key dimensionless parameters ρ*, ν* and β. It has been shown theoretically that these 3 parameters are fundamental in determining the scaling of the energy confinement [1-3]. The experimental results, which consist of single scan…
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2009
Systematic analysis of the radiation fields throughout the ITER core LIDAR diagnostic system were performed to support the design optimisation and assessment process, aiming at achieving the required performance in terms of reliability, occupational safety and interface with neighboring systems. Neutron, photon, nuclear heat and material activation…
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2009
‘Advanced tokamak’ (AT) scenarios were developed with the aim of reaching tokamak steady-state operation. They are designed to optimise the self-generated current, whilst also reaching sufficiently high plasma pressure to achieve optimal fusion reaction rates. AT scenarios exhibit non-monotonic to flat safety factor profiles (q, a measure of th…
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2008
Impurity transport is an important topic for ITER as impurity density in tlie core has to stay below a relative concentration of 5 x 10~^ [1] to reach ignition conditions. The reasons for that is mainly impurity radiation leading to cooling. In the edge region on the other hand site, higher impurity densities, going along with radiation energy loss…
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2008
We present the main design options and implementation of an X -mode reflectometer developed and successfully installed at JET using an innovative approach. It aims to prove the viability of measuring density profiles with high spatial and temporal resolution using broadband reflectometry operating in long and complex transmission lines. It probes t…
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2008
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2008
Core localized Alfvén eigenmodes in DIII-D [J. L. Luxon, Nucl. Fusion 42 , 614 (2002)] and Joint European Torus JET [P. H. Rebut and B. E. Keen, Fusion Technol. 11 , 13 (1987)] plasmas are driven by deuterium neutral beam ions traveling well below the Alfvén speed. Modes are observed in reverse magnetic shear discharges with deuterium ion velocit…
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2008
Edge Localised Modes (ELMs) are periodic disturbances of the plasma periphery occurring in tokamaks with an H-mode edge transport barrier. As a result, a fraction of the plasma energy present in the confined hot edge plasma is transferred to the open field lines in the divertor region, ultimately appearing at the divertor target plates. These event…
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