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2012
The application of nonaxisymmetric resonant magnetic perturbations (RMPs) with a toroidal mode number n . 6 in the MAST tokamak produces a significant reduction in plasma energy loss associated with type-I edge localized modes (ELMs), the first such observation with n>3 . During the ELM mitigated stage clear lobe structures are observed in visible-…
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2012
Plasma equilibria reconstructed from the Mega-Amp Spherical Tokamak have sufficient resolution to capture plasma evolution during the short period between edge-localized modes (ELMs). Immediately after the ELM, steep gradients in pressure, P , and density, n e , form pedestals close to the separatrix, and they then expand into the core. Local gyrok…
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2012
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2011
Deconvolution of Thomson scattering (TS) profiles is required when the gradient length of the electron temperature ( T e ) or density ( n e ) are comparable to the instrument function length ( R ). The most correct method for deconvolution to obtain underlying T e and n e profiles is by consideration of scattered signals. However, deconvolution at …
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2011
Recent experiments show the impact of Resonant Magnetic Perturbations on the density [O Schmitz et al Plasma Phys. Control. Fusion 50 124029 (2008); T E Evans et al Nucl. Fusion 48 024002 (2008); A Kirk et al Nucl. Fusion 50 024002 (2008); Y Liang et al Phys. Rev. Lett. 98 265004 (2007)], leading to a so-called density pump-out. Previous comparison…
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2011
Pedestal profiles that span the ELM cycle have been obtained and used to test the idea that the pedestal pressure gradient in MAST is limited by the onset of Kinetic Ballooning Modes (KBMs). During the inter-ELM period of a regularly type I ELM-ing discharge on MAST, the pressure pedestal height and width increase together while the pressure gradie…
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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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2010
The radial propagation of type-I ELMs in ASDEX Upgrade has been measured using a number of techniques. The most reliable technique uses a filament probe to measure the time difference between two separated probes and yields a mean radial velocity obtained of ~1.5 kms -1 . The radial velocity calculated using a time of flight technique suffers from …
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