ORCID Profile
0000-0002-3105-2546
Current Organisation
University of York
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 12-2012
Publisher: IOP Publishing
Date: 26-09-2013
Publisher: IOP Publishing
Date: 15-10-2008
Publisher: IOP Publishing
Date: 05-06-2019
Publisher: IOP Publishing
Date: 20-06-2017
Publisher: AIP Publishing
Date: 02-09-2016
DOI: 10.1063/1.4961283
Abstract: The synthetic aperture microwave imaging diagnostic has been operating on the MAST experiment since 2011. It has provided the first 2D images of B-X-O mode conversion windows and showed the feasibility of conducting 2D Doppler back-scattering experiments. The diagnostic heavily relies on field programmable gate arrays to conduct its work. Recent successes and newly gained experience with the diagnostic have led us to modify it. The enhancements will enable pitch angle profile measurements, O and X mode separation, and the continuous acquisition of 2D DBS data. The diagnostic has also been installed on the NSTX-U and is acquiring data since May 2016.
Publisher: Informa UK Limited
Date: 05-2016
DOI: 10.13182/FST15-188
Publisher: IOP Publishing
Date: 10-09-2009
DOI: 10.1088/0029-5515/49/10/104017
Abstract: 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 (STs). Using the increased heating capabilities P NBI ⩽ 3.8 MW H-mode at I p = 1.2 MA was accessed showing that the energy confinement on MAST scales more weakly with I p and more strongly with B t than in the ITER IPB98( y , 2) scaling. Measurements of the fuel retention of shallow pellets extrapolate to an ITER particle throughput of 70% of its original designed total throughput capacity. The anomalous momentum diffusion, χ ϕ , is linked to the ion diffusion, χ i , with a Prandtl number close to P ϕ ≈ χ ϕ /χ i ≈ 1, although χ i approaches neoclassical values. New high spatial resolution measurements of the edge radial electric field, E r , show that the position of steepest gradients in electron pressure and E r (i.e. shearing rate) are coincident, but their magnitudes are not linked. The T e pedestal width on MAST scales with rather than ρ pol . The edge localized mode (ELM) frequency for type-IV ELMs, new in MAST, was almost doubled using n = 2 resonant magnetic perturbations from a set of four external coils ( n = 1, 2). A new internal 12 coil set ( n ⩽ 3) has been commissioned. The filaments in the inter-ELM and L-mode phase are different from ELM filaments, and the characteristics in L-mode agree well with turbulence calculations. A variety of fast particle driven instabilities were studied from 10 kHz saturated fishbone like activity up to 3.8 MHz compressional Alfvén eigenmodes. Fast particle instabilities also affect the off-axis NBI current drive, leading to fast ion diffusion of the order of 0.5 m 2 s −1 and a reduction in the driven current fraction from 40% to 30%. EBW current drive start-up is demonstrated for the first time in a ST generating plasma currents up to 55 kA. Many of these studies contributed to the physics basis of a planned upgrade to MAST.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Roddy Vann.