Stuttgart 2012 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 10: Magnetischer Einschluss I
P 10.5: Vortrag
Dienstag, 13. März 2012, 15:30–15:45, V57.02
H-mode edge current density profiles and scaling — •Mike G. Dunne1, Elisabeth Wolfrum2, Philip A. Schneider2, and P.J. McCarthy1 — 1Department of Physics, University College Cork, Association Euratom-DCU, Cork, Ireland — 2Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-85748 Garching, Germany
An edge localised mode (ELM) is an instability which causes a large outflux of particles and energy in a tokamak device. These regularly (Δt ≈ 10 - 20 ms in ASDEX Upgrade) occurring events pose a significant issue for next generation devices due to a loss of confinement and large heat loads on plasma facing components. The current understanding of this phenomenon posits critical pressure gradient and current density limits in the edge of the plasma. While measuring the pressure gradient is standard at all tokamaks, measuring the local current density in these plasmas is rather difficult, as physical probes would melt and extremely high accuracy is required for polarimetry based measurements. In light of this, an equilibrium reconstruction of the plasma, based on magnetic measurements, Ampere’s law applied to an elongated toroidal plasma, and a requirement of force balance, is used as a quasi measurement of the plasma current density. First results from a database of these reconstructions are presented, including scalings of the peak edge current density with global plasma parameters. Comparisons of different drives of current density in a tokamak plasma are analysed with a view to differentiating ELM regimes and correlating different ELM period lengths.