Title : Simulations of plasma filaments in stellarator geometries with BSTING
Speaker Name: Brendan Shanahan
Speaker Institution : Max Planck Institut fur Plasmaphysik, Greifswald
Notes:Abstract : Wendelstein 7-X has exhibited novel edge and scrape-off-layer physics in the first experimental campaign. Edge filaments  and high frequency heat flux variations  are among many new observations which merit numerical investigation. While there are several edge fluid turbulence frameworks for tokamak geometries, the complicated nature of a stellarator edge and scrape-off-layer has as yet inhibited the development of a fluid turbulence framework for stellarator geometries. One of these simulation frameworks written for tokamak geometries, BOUT++ , is also able to simulate phenomena such as ELMs, magnetic reconnection, plasma transport and neutral interactions. The BSTING project  has extended BOUT++ to stellarator geometries, thereby providing the first nonlinear fluid simulation framework for non-axisymmetric geometries.
Here we outline recent developments in the BSTING project, including a newly implemented curvilinear grid system suitable for stellarator edge magnetic topology, and present simulations of plasma filaments in stellarator geometries . Results from simulations of filaments dynamics in non-uniform drive scenarios  and in regions of strongly-varying connection lengths, such as the view from the planned Gas Puff Imaging diagnostic on W7-X, are also included. Initial investigations of ablated pellet interaction using the Hermes  fluid turbulence model are presented. Finally, a discussion of the relevance and application of these methods to Wendelstein 7-X edge turbulence scenarios is provided.
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