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2011
Magnetohydrodynamic equilibrium states with a three-dimensional helical core are computed to model the MAST spherical tokamak and the RFX-mod reversed field pinch. The boundary is fixed as axisymmetric. The MAST equilibrium state has the appearance of an internal kink mode and is obtained under conditions of weak reversed central shear. The RFX-mod…
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2011
The aim of the Tore Supra tokamak is to address physics and technology issues of long pulse discharges. For this purpose, Tore Supra is equipped with two actively cooled Lower Hybrid Current Drive (LHCD) antennas (f = 3.7GHz), designed to operate in 1000s long pulses. One of these is the recently installed passive active multijunction (PAM) antenna…
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2011
The sawtooth instability in tokamak plasmas results in a periodic reorganization of the core plasma. A typical sawtooth cycle consists of a quiescent period, during which the plasma density and temperature increase, followed by the growth of a helical magnetic perturbation, which in turn is followed by a rapid collapse of the central pressure. The …
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2010
A long wavelength range infrared camera (LWIR) has been installed on MAST to compliment the existing medium wave infrared system. Simultaneous LWIR/MWIR temperature measurements have been made in the lower and upper divertors of MAST. As expected, the LWIR system is less sensitive to disturbances from hot spots on the surface. A thorough correction…
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2010
In this work, the radial transport of tracers in an H-mode run in the CUTIE code [A. Thyagaraja et al. , Phys. Plasmas 12 , 090907 (2005)] is analyzed globally. Several techniques are applied to the study of the trajectories performed by the tracers, measuring the degree of self-similarity in the motion and searching for long range spatial and temp…
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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
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 â…
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2009
Several improvements to the MAST plant and diagnostics have facilitated new studies advancing the physics basis for ITER and DEMO, as well as for future spherical tokamaks. Using the increased heating capabilities PNBI ≤ 3.8 MWH-mode at Ip = 1.2 MA was accessed showing that the energy confinement on MAST scales more weakly with Ip and more strong…
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2009
One of the main operational aims of the MAST experiment [1] and the proposed MAST upgrade is to investigate possible mechanisms to control the q-profile and drive off-axis current. Experiments were carried out to determine the extent to which the q-profile may be modified using two different approaches, transient and steady-state. Transient effects…
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2008
A new infrared Thomson scattering system has been designed for the MAST tokamak. The system will measure at 120 spatial points with 10 mm resolution across the plasma. Eight 30 Hz 1.6 J Nd:YAG lasers will be combined to produce a sampling rate of 240 Hz. The lasers will follow separate parallel beam paths to the MAST vessel. Scattered light will b…
Showing 91 - 100 of 139 UKAEA Paper Results