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CCFE-PR(15)312015
New experiments in 2013-2014 have investigated the physics responsible for the decrease in H-mode pedestal confinement observed in the initial phase of JET-ILW operation (2012 Experimental Campaigns). The effects of plasma triangularity, global beta and neutrals on pedestal confinement and stability have been investigated systematically. The stabil…
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CCFE-PR(15)292015
ITER operations require effective fuelling of the core plasma for conditions in which neutral dynamics through the scrape-off layer (SOL) is expected to affect significantly the efficiency of gas penetration. On the basis of previous analysis for stationary conditions, pellets are foreseen to provide core fuelling of high-Q DT scenarios. In this pa…
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CCFE-PR(15)272015
The high-k (7 . k??i . 11) wavenumber spectrum of density fluctuations has been measured for the first time in MAST [B. Lloyd et al, Nucl. Fusion 43, 1665 (2003)]. This was accomplished with the first implementation of Doppler backscattering (DBS) for core measurements in a spherical tokamak. DBS has become a well-established and versatile diagnost…
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CCFE-PR(15)232015
Comparing with ITER, the experimental fusion machine under constraction, the next step test fusion power plant, DEMO will be characterized by very long pulse/steady-state operation and much higher plasma volume and fusion power. The substantially increased level of neutron and gamma fluxes will require reducing the physical access to the plant. It …
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CCFE-PR(15)092015
The replacement of the JET carbon wall (C-wall) by a Be/W ITER-like wall (ILW) has affected the plasma energy confinement. To investigate this, experiments have been performed with both the C-wall and ILW to vary the heating power over a wide range for plasmas with different shapes. It was found that the power degradation of thermal energy confinem…
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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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CCFE-PR(15)082015
Tokamak plasmas rotate even without external injection of momentum. A Doppler backscattering system installed at MAST has allowed this intrinsic rotation to be studied in Ohmic L-mode and Hmode plasmas, including the first observation of intrinsic rotation reversals in a spherical tokamak. Experimental results are compared to a novel 1D model, whic…
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CCFE-PR(15)1142015
The linear and quasi-linear plasma response to the n = 3 and n = 4 (n is the toroidal mode number) resonant magnetic perturbation (RMP) fields, produced by the in-vessel edge localized mode control coils, is numerically studied for an ITER 15MA H-mode baseline Scenario. Both single fluid and fluid-kinetic hybrid models are used. The inclusion of dr…
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2015
The H mode of confinement in Tokamaks is characterized by a thin region of high gradients, located at the edge of the plasma and called the Edge Transport Barrier. Even if various theoretical models have been proposed for the interpretation of the edge physics, the main empirical scaling laws of the plasma confinement time are expressed in terms of…
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CCFE-PR(17)162015
Recent JET-ILW [1,2] experiments reiterated the importance of tuning the plasma fuelling in order to optimize ion cyclotron resonance frequency (ICRF) heating in high power H-mode discharges. By fuelling the plasma from gas injection modules (GIMs) located in the midplane and on the top of the machine instead of adopting the more standardly used di…
Showing 171 - 180 of 266 UKAEA Paper Results