Experimental investigation of steady state power balance in double null and single null H mode plasmas in MAST Upgrade
Not Available
Lovell, J. (ORCID:0000000195653466)↗
Engineering topics
Patel, B. S.
Publications and source records attributed to Patel, B. S..
Benefits of the Super-X divertor configuration for scenario integration on MAST Upgrade
The integration of good core and edge/pedestal confinement with strong dissipation of heat and particles in the divertors is a significant challenge for the development of fusion energy. Alternative divertor configurations offer potential advantages by broadening the operational space where a device can operate with detached divertors and acceptable power exhaust. First results from MAST Upgrade are presented from high confinement mode experiments with outer divertors in the Super-X divertor configuration, showing that the outer divertors naturally detach when the Super-X is formed with no discernible impact on the plasma core and pedestal. These initial findings confirm predicted benefits of the Super-X configuration in terms of facilitating scenario integration.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
New linear stability parameter to describe low-β electromagnetic microinstabilities driven by passing electrons in axisymmetric toroidal geometry
In magnetic confinement fusion devices, the ratio of the plasma pressure to the magnetic field energy, β, can become sufficiently large that electromagnetic microinstabilities become unstable, driving turbulence that distorts or reconnects the equilibrium magnetic field. In this paper, a theory is proposed for electromagnetic, electron-driven linear instabilities that have current layers localised to mode-rational surfaces and binormal wavelengths comparable to the ion gyroradius. The model retains axisymmetric toroidal geometry with arbitrary shaping, and consists of orbit-averaged equations for the mode-rational surface layer, with a ballooning space kinetic matching condition for passing electrons. The matching condition connects the current layer to the large scale electromagnetic fluctuations, and is derived in the limit that β is comparable to the square root of the electron-to-ion-mass ratio. Electromagnetic fluctuations only enter through the matching condition, allowing for the identification of an effective β that includes the effects of equilibrium flux surface shaping. The scaling predictions made by the asymptotic theory are tested with comparisons to results from linear simulations of micro-tearing and electrostatic microinstabilities in MAST discharge #6252, showing excellent agreement. In particular, it is demonstrated that the effective β can explain the dependence of the local micro-tearing mode (MTM) growth rate on the ballooning parameter θ 0 – possibly providing a route to optimise local flux surfaces for reduced MTM-driven transport.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗