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P: Fachverband Plasmaphysik
P 13: Magnetic Confinement IV & Helmholtz Graduate School IV
P 13.1: Invited Talk
Thursday, September 2, 2021, 14:00–14:30, H4
How turbulence sets boundaries for fusion plasma operation — •Peter Manz1, Thomas Eich2, and the ASDEX Upgrade Team2 — 1Institut für Physik, Universität Greifswald — 2Max-Planck-Institut für Plasmaphysik, Garching
The operational space for safe and efficient operation of a tokamak is limited by several constraints. Well known examples are the Greenwald density limit and the accessibility of high confinement. Their extrapolation to reactor machine size is based on empirical scalings. Both phenomena are related to turbulent transport. Large turbulent transport can lead to a transition to low confinement or trigger events finally leading to a disruption (the L-mode density limit). The strength of turbulent transport in the plasma edge depends on the competition between rather gentle drift-wave and the rather violent resistive ballooning turbulence. The operation boundaries are derived in terms of a combination of dimensionless parameters describing interchange-drift-Alfven turbulence without any free adjustable parameter. This way, the disruptive density limit is related to a transition from the electrostatic to the electromagnetic resistive ballooning regime. At the L-H transition, drift-wave dominated turbulence is suppressed by a combination of flow shear, diamagnetic and beta stabilization. The derived boundaries are compared to about 300 discharges and agreement within experimental error bars.