UKAEA Journals

Showing 21 - 30 of 35 Journals Results
2013

Sustained ELM mitigation has been achieved using RMPs with a toroidal mode number of n=4 and n=6 in lower single null and with n=3 in connected double null plasmas on MAST. The ELM frequency increases by up to a factor of eight with a similar reduction in ELM energy loss. A threshold current for ELM mitigation is observed above which the ELM freque…

Published
2012

The application of resonant magnetic perturbations (RMPs) with a toroidal mode number of n=4 or n=6 to lower single null plasmas in the MAST tokamak produces up to a factor of 5 increase in Edge Localized Mode (ELM) frequency and reduction in plasma energy loss associated with type-I ELMs. A threshold current for ELM mitigation is observed above wh…

Published
2012

The application of resonant magnetic perturbations with toroidal mode number n = 4 or n = 6 is observed to result in a significant increase in ELM frequency, despite a reduction in the edge pressure gradient. A picture for how type-I ELMs are mitigated, or destabilised, when magnetic perturbations are applied is proposed. Despite the magnetic pertu…

Published
2012

Electrostatic gyrokinetic analyses are presented for an L-mode discharge with an internal transport barrier, from the spherical tokamak, MAST. Local and global microstability analysis finds similar linear growth rates for ion temperature gradient (ITG) driven modes. When the electron response is assumed to be adiabatic, growth rates are found to be…

Published
2012

A stability analysis using equilibria from CORSICA transport simulations finds that the maximum stable pedestal pressure in ITER 15 MA baseline plasma is 110 kPa corresponding to a pedestal temperature of 5.9 keV. The height of the stable pedestal is robust for the assumption of the pedestal height varying only by about 10% if the width of the pede…

Published
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…

Published
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…

Published
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…

Published