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2011
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2011
Resistive wall mode stability limits have been probed by MHD spectroscopy and numerical modelling. MAST plasmas have operated up to βN = 5.7, well above the predicted ideal kink no-wall limit or measured resonant field amplification limits due to a combination of rotation and kinetic damping. By varying the density, both the rotation and the fast …
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2011
We study the effects of the X-point configuration on ELM triggering peeling and ballooning modes by using fixed boundary equilibria and modifying the plasma shape to approach the limit of a true X-point. The current driven pure peeling modes are asymptotically stabilised by the X-point while the stabilising effect on ballooning modes depends on the…
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2011
Experiments have been performed on MAST using internal (n=3) resonant magnetic perturbation coils. The application of the RMPs to L-mode discharges has shown a clear density pump out when the field line pitch angle at the low field side of the plasma is sufficiently well aligned with the applied field. The application of the RMPs before the L-H tra…
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2011
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2011
Derek Robinson was a leading UK plasma physicist of his generation. After an early success in measuring the electron temperature in the ZETA plasma through the Thomson scattering of laser light, he became a key member of the team from Culham Laboratory sent to Moscow in 1968 to verify the high temperatures claimed by the Russians for their T3 tokam…
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2011
Access into H-mode is studied in the MAST tokamak when plasma is fuelled by cryogenic pellets. It is shown that pellet fuelling from the high field side allows access to Hmode in plasmas heated by neutral beams. Simple and two-stage L-H transitions are identified. The results of comparison of the L-H transitions with pellet injection with transitio…
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2010
The impact of Resonant Magnetic Perturbations (RMPs) on the edge of MAST L-mode plasmas is studied using a mid-plane reciprocating probe equipped with a Gundestrup probe head. A strong impact on the characteristics of the ion saturation current fluctuations is observed just inside the separatrix, with a broadening of the power spectrum and an asymm…
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2010
The retention of deuterium fuel during MAST discharges has been studied using the method of global gas balance. The results show that with inter-shot 4 He- GDC, the total number of particles retained for a discharge increases with total number of injected particles, and the total retention fraction stays very high, mostly around 80%, and can be alm…
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2010
Plasma rotation in tokamaks is of special interest for its potential stabilising effect on micro- and macro instabilities, leading to increased confinement. In MAST, the torque from Neutral Beam Injection (NBI) can spin the plasma to a core velocity ~ 300km.s -1 (Alfven Mach number ~ 0.3). Low density plasmas often exhibit a weakly non-monotonic sa…
Showing 81 - 90 of 103 UKAEA Paper Results