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2009
A Sub-Harmonic Arc Detection (SHAD) system has been installed on the transmission lines feeding the JET ICRF ITER-like-Antenna (ILA). Along with the commissioning of SHAD, extensive measurements of the RF field in the transmission lines were carried-out using fast sampling (125 Mb/s) oscilloscopes. The system is described, and the SHAD ability to d…
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2009
ITER and future superconducting fusion machines need efficient wall conditioning techniques for routine operation in between shots in the presence oi permanent high magnetic field for wall cleaning, surface isotope exchange and to control the in-vessel long term tritium retention. Ion Cyclotron Wall Conditioning (ICWC) based on the ICRF discharge i…
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2009
Over the past two decades, the increase in neutral-beam heating and particle production in magnetically confined fusion plasmas has led to an increase in energetic particle driven mode activity, much of which has an electromagnetic signature which can be detected by the use of external Mirnov coils. Typically, the frequency and spatial wave number …
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2009
Beam emission spectroscopy BES of the energetic deuterium D 0 heating beams can provide a means of characterizing the density turbulence in tokamak plasmas. First such measurements have been performed on the MAST spherical tokamak using a trial BES system, which shares the collection optics of the charge-exchange recombination spectroscopy system. …
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2009
The sawtooth control mechanism in plasmas employing off-axis toroidally propagating ion cyclotron resonance waves in tokamaks is reinvestigated. The radial drift excursion of energetic passing ions distributed asymmetrically in the velocity parallel to the magnetic field determines stability when the rational q 1/4 1 surface resides within a narrow…
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2009
Large tokamaks capable of fusion power production such as ITER, should avoid large edge localized modes (ELMs), thought to be triggered by an ideal magnetohydrodynamic instability due to current at the plasma’s separatrix boundary. Unlike analytical work in a cylindrical approximation, numerical work finds the modes are stable. The plasma’s sep…
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2009
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2009
Impurity ions with sufficiently high mass in toroidally-rotating tokamak plasmas are deeply trapped by a centrifugal potential well in the outer plasma midplane, with a bounce period that is shorter than both the bounce period of magnetically-trapped ions and the collision time. As a result trace impurity ions can undergo collisional transport at a…
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2009
A self-consistent, rigorous approach is proposed to study the synergistic effects of plasma flow, drift kinetic resonances and three-dimensional conducting structures on the resistive wall mode. This approach is based on coupling between the hybrid MHD-kinetic computation and the 3D electromagnetic eddy current computation via a specific boundary c…
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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…
Showing 361 - 370 of 507 UKAEA Paper Results