
UKAEACCFEPR(23)1672023
A nonlinear 4dimensional drift island theory derived in (Imada et al 2019 Nucl. Fusion 59 046016 and references therein) provides qualitative predictions of the plasma response to a stationary neoclassical tearing mode (NTM) magnetic island in a low beta, large aspect ratio tokamak plasma. (Dudkovskaia et al 2021 Plasma Phys. Control. Fusion 63 05…

UKAEACCFEPR(22)872022
The neutral ionisation model proposed by R J Groebner et al. (Phys Plasmas 9 2134 (2002)) to determine the plasma density profile in the Hmode pedestal, extended to include charge exchange processes in the pedestal stimulated by the ideas of Mahdavi et al. ((Phys Plasmas 10 3984 (2003)). The model is then teste…

UKAEACCFEPR(22)402022
In this paper, we review the confinement and transport properties observed and predicted in low aspect ratio tokamaks, or spherical tokamaks (STs), which can depart significantly from those observed at higher aspect ratio. In particular, thermal energy confinement scalings show a strong, near linear dependence of energy confinement time on toroidal…

UKAEACCFEPR(21)812021
The impact of plasma shaping through magnetic well modifications on the stability of resistive ballooning modes in tokamaks is analysed, also including finite diamagnetic flows. Various limiting cases of the dispersion relation, obtained by matching the averaged ballooning equation across the ideal and resistive layers, are analysed. It is found th…

UKAEACCFECP(21)082021
The pedestal plays an important role in determining the confinement in tokamak Hmode plasmas. However, the steep pressure gradients in this transport barrier also lead to edge localized modes (ELMs) [1]. There is good understanding of the pedestal in type I ELM regimes [2], however, type I ELMs are known to damage plasma facing components and f…

UKAEACCFEPR(19)702019

UKAEACCFEPR(19)092018
Kinetic treatments of drift tearing modes that match an inner, resonant layer solution to an external MHD solution, can fail to match the ideal MHD boundary condition on the parallel electric field. In this paper we demonstrate how consideration of ion sound and ion Landau damping effects achieves this, placing the theory on a firm footing. The …

UKAEACCFEPR(18)412018
A new driftkinetic theory of the ion response to magnetic islands in tokamak plasmas is presented. Small islands are considered, with widths w much smaller than the plasma radius r, but comparable to the trapped ion orbit width ρ_bi. An expansion in w/r reduces the system dimensions from five down to four. In the absence of an electrostatic poten…

UKAEACCFEPR(18)202018
Starting from expressions in Connor et al. (1988), we derive a onedimensional tearing equation similar to the approximate equation obtained by Hegna & Callen (1994); Nishimura et al. (1998), but for more realistic toroidal equilibria. The intention is to use this approximation to explore the role of steep Hmode pedestals, bootstrap currents a…

CCFEPR(17)512017
A set of layer equations for determining the stability of semicollisional tearing modes in an axisymmetric torus, incorporating neoclassical physics, in the small ion Larmor radius limit is provided. These can be used as an inner layer module for inclusion in numerical codes that asymptotically match the layer to toroidal calculations of the teari…
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