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UKAEA-CCFE-CP(19)352019
In high-performance, ITER baseline-scenario pulses (3MA/2.7T) in JET-ILW with high levels (~ 32 MW) of heating power, typically ~ 20-40% of the input power is radiated, predominantly by W impurities, which are sputtered from the divertor targets and reach the confined plasma. Sustained ELMy H-mode operation at such high heating power in JET-ILW req…
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UKAEA-CCFE-PR(19)212019
The JET exploitation plan foresees D-T operations in 2020 (DTE2). With respect to the first D-T campaign in 1997 (DTE1), when JET was equipped with a carbon wall, the experiments will be conducted in presence of a beryllium-tungsten ITER-like wall (ILW) and will benefit from an extended and improved set of diagnostics and higher additional heating …
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UKAEA-CCFE-PR(19)132018
Multiple space and time scales arise in plasma turbulence in magnetic confinement fusion devices because of the smallness of the square root of the electron-to-ion mass ratio and the consequent disparity of the ion and electron thermal gyroradii and thermal speeds. Direct simulations of this turbulence that include both ion and electron space-ti…
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UKAEA-CCFE-PR(18)202018
Starting from expressions in Connor et al. (1988), we derive a one-dimensional tearing equation similar to the approximate equation obtained by Hegna & Callen (1994); Nishimura et al. (1998), but for more realistic toroidal equilibria. The intention is to use this approximation to explore the role of steep H-mode pedestals, bootstrap currents a…
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CCFE-PR(17)492017
In this work, using solutions from a local gyrokinetic flux-tube code combined with higher order ballooning theory, a new analytical approach is developed to reconstruct the global linear mode structure with associated global mode frequency. In addition to the isolated mode (IM), which usually peaks on the outboard mid-plane, the higher order ballo…
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CCFE-PR(16)482016
In electrostatic simulations of MAST plasma at electron-gyroradius scales, using the local flux-tube gyrokinetic code GS2 with adiabatic ions, we find that the longtime saturated electron heat flux (the level most relevant to energy transport) decreases as the electron collisionality decreases. At early simulation times, the heat flux quasisatura…
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CCFE-PR(16)172016
Measurements of local density and magnetic field fluctuations near the pedestal top, conditionally-averaged over the ELM cycle, have been made in MAST. A Doppler backscattering (DBS) system installed at MAST was used to measure intermediate-k (k ? _i _ 3 - 4) density fluctuations at the top of the pedestal. A novel diagnostic technique combining DB…
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CCFE-PR(15)482015
Carbon and nitrogen impurity transport coefficients are determined from gas puff experiments carried out during repeat L-mode discharges on the Mega-Amp Spherical Tokamak (MAST) and compared against a previous analysis of helium impurity transport on MAST. The impurity density profiles are measured on the lowfield side of the plasma, therefore this…
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2014
Solutions to a model 2D eigenmode equation describing micro-instabilities in tokamak plasmas are presented that demonstrate a sensitivity of the mode structure and stability to plasma profiles. In narrow regions of parameter space, with special plasma profiles, a maximally unstable mode is found that balloons on the outboard side of the tokamak. Th…
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2014
Observations of ion-scale density turbulence of relative amplitude are available on the Mega Amp Spherical Tokamak (MAST) using a 2D (8 radial × 4 poloidal channel) imaging Beam Emission Spectroscopy (BES) diagnostic. Spatial and temporal characteristics of this turbulence, i.e., amplitudes, correlation times, radial and perpendicular correlation …
Showing 21 - 30 of 49 UKAEA Paper Results