Publications (5)11.94 Total impact
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Conference Proceeding: Neutral beam heating and current drive on MAST
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ABSTRACT: Heating and NBCD studies on MAST benefited from recent diagnostic upgrades such as T$_{i}$ and V$_{\phi }$ profiles on the ion Larmor radius scale by improved CXRS and bremsstrahlung imaging to measure $Z_{eff}$ profiles. The operational flexibility of MAST has also been improved by implementation of digital plasma control and real time optical edge detection and position control. These enhancements, combined with the access offered by the large MAST vessel, have been exploited for the study of off-axis heating and NBCD in vertically displaced SND plasmas. These had a neutron yield and stored energy comparable to up-down symmetric DND discharges with on-axis NBI. The extreme features of low aspect ratio devices can have a strong effect on the behaviour of fast ions, potentially influencing their heating and NBCD properties. The experimental results and modelling of off-axis NBI in SND (upper and lower) and on-axis NBI in DND will be presented and compared in terms of heating and NBCD.47th Annual Meeting of the Division of Plasma Physics, Denver, Colorado, USA; 10/2005 -
Article: L-H transition in the mega-amp spherical tokamak.
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ABSTRACT: H-mode plasmas have been achieved on the MAST spherical tokamak at input power considerably higher than predicted by conventional threshold scalings. Following L- H transition, a clear improvement in energy confinement is obtained, exceeding recent international scalings even at densities approaching the Greenwald density limit. Transition is accompanied by an order-of-magnitude increase in edge-density gradient, a marked decrease in turbulence, the efficient conversion of internal electron Bernstein waves into free space waves, and the onset and saturation of edge poloidal rotation.Physical Review Letters 02/2002; 88(3):035002. · 7.37 Impact Factor -
Conference Proceeding: Results from the MAST spherical tokamak
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ABSTRACT: The MAST (Mega-Amp Spherical Tokamak) experiment has been operational since Jan 2000. Results from MAST are important both in evaluating the potential of future ST fusion devices, and in developing understanding of processes relevant to conventional aspect ratio tokamaks. In this paper methods of initiating, ramping up, and sustaining the high plasma currents associated with ST fusion devices are discussed. New physics results, including the effectiveness of inboard gas puffing, the threshold power required for the L-H transition, and the 'natural' divertor configuration are given. Plans for improvements during 2002 are outlined.Fusion Engineering, 2002. 19th Symposium on; 02/2002 -
Article: First physics results from the MAST Mega-Amp Spherical Tokamak
Physics of Plasmas 01/2001; · 2.15 Impact Factor -
Article: High- performance of the START spherical tokamak
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ABSTRACT: Using additional heating provided by neutral-beam injection, the START spherical tokamak at UKAEA Fusion Culham has achieved high- (ratio of volume average plasma pressure to vacuum magnetic-field pressure) values of , more than twice the value previously obtained in a tokamak. These plasmas reach normalized beta values of at values of auxiliary heating power comparable to the ohmic power. Operation at high normalized current is observed, so that the plasma current exceeds the central rod toroidal-field current for the first time in a hot tokamak.Plasma Physics and Controlled Fusion 12/1998; 39(12B):B247. · 2.42 Impact Factor
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2001
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Culham Centre for Fusion Energy
Abingdon, ENG, United Kingdom
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