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Minisymposium Presentation
Modeling the Edge Physics of Magnetic Fusion Devices in a Tungsten Environment
Presenter
Dr. Julien Dominski is a staff research physicist in the theory department of the Princeton Plasma Physics Laboratory. He came at PPPL after completing his Ph.D. from EPFL Swiss Plasma Center during which he conducted gyrokinetic studies of the non-adiabatic response of passing electrons near rational surfaces of tokamaks. His current research focuses on gyrokinetic modeling of whole device plasma in the presence of tungsten impurities, as well as nonlinear physics occurring during explosive plasma events.He is currently developing advanced gyrokinetic models to be run on the new generation of exascale supercomputers. These models cover the whole volume of tokamaks by combining core delta-f and edge total-f models together, and they also use telescoping techniques to evolve the plasma profiles on the transport time scale. Finally, most advanced tokamak devices are contaminated by tungsten impurities that strongly affect the performance of the fusion plasma. The physics of tungsten, including atomic interaction, radiations, and sonic flows are thus implemented in the new gyrokinetic models.
Description
The construction of the ITER tokamak is motivating a whole field of research concerning the influence of the tungsten wall on the fusion plasma efficiency. Tungsten ions are sputtered from the plasma facing components and contaminate the plasma where they radiate a significant amount of its energy. This can lead to a radiative collapse, as observed in the WEST tokamak. Understanding this physics requires modeling the different ionization states and radiation levels of each species in the fusion device. Atomic interactions calculations, such as ionization and recombination, provides this information but the delta-f or total-f modeling of all the ionization states of the different impurity species is still out of computational capabilities, even on exascale supercomputers. Instead we introduced a bundling technique that regroups ions of similar charge together while accounting for their bundled atomic physics. This bundling technique has been implemented in a modular way to be integrated in different transport codes. Application to the WEST and ASDEX-U tokamak with the neoclassical transport code FACIT and with the 5D gyrokinetic code XGC will be presented. This includes the whole device simulation of ASDEX-U plasma with multiple low-Z impurities and bundles of tungsten ions.