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UKAEA-CCFE-CP(19)472019
Spherical Tokamaks (STs) could provide a route towards a compact fusion reactor due to advantageous properties such as high plasma beta. A GW-scale ST plasma is explored where Q=10 and R=2.5m. In this design 110 MW of NBI is needed to provide 9 MA of noninductive current, where the remaining 12 MA is pressure driven. To penetrate into the core a 1 …
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UKAEA-CCFE-CP(19)452019
Spherical Tokamaks offer a number of potential advantages for a future fusion power plant. They have a high ratio of thermal to magnetic field pressure (beta) and strong flows, either of which could result in reduced turbulence. Fewer Toroidal Field (TF) coils and a different geometry offers the potential for new methods of remote maintenance …
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UKAEA-CCFE-CP(19)442019
MAST has undergone a substantial upgrade [1], featuring among other things several new poloidal field coils mostly distributed around the new closed-throat divertor structure and an enlarged centre column. The considerable changes have required the plasma control software to be substantially re-written. The MAST digital plasma control system […
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UKAEA-CCFE-CP(19)402019
In magnetic confinement devices, boundary turbulence is responsible for transporting plasma and energy from the well-confined region towards the material surfaces where it can severely harm reactor relevant machines. It is therefore essential to develop a solid understanding of the mechanisms behind the transport in the edge of the plasma. Large fl…
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UKAEA-CCFE-CP(19)392019
In the present work, global, three-dimensional edge plasma turbulence simulations of a MAST L-mode attached plasma discharge are presented. Our study is based on the drift-reduced Braginskii equations, solved with the STORM module of BOUT++ for realistic MAST parameters in disconnected lower double null configuration. The plasma profiles are evolve…
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UKAEA-CCFE-CP(19)212019
A firm grasp of transport processes perpendicular to the magnetic field line is required in order to understand and predict heat and particle fluxes to divertor components in tokamaks. Perpendicular transport from the hot core into the scrape-off layer (SOL) upstream impacts the SOL profile at the divertor via parallel streaming along the magnetic …
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UKAEA-CCFE-PR(19)672019
Analysis of the L-H and H-L transition power thresholds (Pth) and pedestal parameters are presented for the Mega Ampere Spherical Tokamak (MAST). The dependencies of Pth on the average, core plasma electron density, X-point height and plasma current are described. Increasing X-point distance from the divertor floor over 10-12 cm, is found to inc…
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UKAEA-CCFE-PR(19)342019
Reduced models coupled to time-dependent axisymmetric vacuum field calculations are used to develop the prefill and feed-forward coil current targets required for reliable direct induction (DI) startup on the new MA-class spherical tokamaks, MAST-U and NSTX-U. The calculations are constrained by operational limits unique to each device, such as the…
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UKAEA-CCFE-PR(19)282019
We study the amplitude modulation of the radial electric field constructed from the Langmuir probe plasma potential measurements at the edge of MAST. The Empirical Mode Decomposition technique is applied, which allows us to construct fluctuations on temporal scales of plasma turbulence, the Geodesic Acoustic Mode and these associated with the res…
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UKAEA-CCFE-PR(19)162019
The STORM module of BOUT++ [L. Easy et al., Phys. Plasmas 21, 122515 (2014)] is generalized to simulate plasma turbulence at the periphery of tokamak devices in diverted configuration and it is used to carry out three-dimensional nonlinear flux-driven simulations in double null configuration with realistic experimental par…
Showing 81 - 90 of 302 UKAEA Paper Results