Hannover 2020 – scientific programme

The DPG Spring Meeting in Hannover had to be cancelled! Read more ...

Parts | Days | Selection | Search | Updates | Downloads | Help

P: Fachverband Plasmaphysik

P 15: Helmholtz Graduate School 3 and Magnetic confinement 3

P 15.1: Invited Talk

Wednesday, March 11, 2020, 14:00–14:30, b305

How turbulence sets boundaries for fusion plasma operation — •Peter Manz, Thomas Eich, and the ASDEX Upgrade Team — Max-Planck-Institut für Plasmaphysik, 85748 Garching, Germany

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 (the H-mode density limit) and also trigger a sequence of 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. In the electrostatic limit relevant for L-mode their relative strength depends on the collisionality only. In H-mode also electromagnetic effects are important. In order to develop a more physics based understanding of the operation boundaries turbulence control parameters have been measured at the separatrix in ASDEX Upgrade. Taking into account over a hundred discharges, different confinement regimes are mapped into a phase space of normalized collisionality and plasma beta. Thereby confinement regimes can be assigned to different regimes of plasma edge turbulence. The density limit occurs around the transition from drift-dominated to interchange dominated turbulence, the transition to improved confinement regimes is around the transition to finite-beta turbulence.