Abstract of ELMU2 Project

Elmfire [1] is an electrostatic gyrokinetic particle code developed by TKK and VTT for simulating tokamak plasma microturbulence. Extensive work has been done to improve scaling of the code in collaboration with UNED and Åbo Akademi[2]. As a unique feature of Elmfire, the polarization operator is dynamically updated from the particle distribution for every time step. The computations associated with the polarization operator such as operator element stacking are one of the most computationally intensive
parts of the simulation, and as such, performance of interpolations and grid assignments are of crucial importance for performance both for the magnetic and electric fields. Currently a simplified geometry is employed for the discretization of the electric potential, and the model needs to be made more flexible to be able to handle more complicated geometries frequently encountered in tokamak experiments. Also related to this are the improvements to be made with respect to numerical accuracy and generality of interpolations, especially due to conservation requirements of total energy and momentum. The Elmfire code participates in the ITM IMP#4 benchmarking and transport model development project, and as part
of this project, improved diagnostics and CPO data structures are required.

[1] Heikkinen et al., J. Comp. Phys. 227 5582 (2008)
[2] Artur Signell et al., Comp. Phys. Comm. 179 5, 330-338 (2008)