Extending Continuum Kinetic Neutral Code GUERNICA to 2X3V for MAST-U Simulations

This poster presents the extension of our continuum kinetic neutral code, GUERNICA, to 2X3V phase space and its application to neutral transport simulations in a MAST-U cross-section. Neutral atoms influence fueling efficiency and divertor heat flux mitigation in fusion devices [1], but kinetic Monte Carlo codes like EIRENE, while accurate, suffer from statistical noise and high computational cost, particularly in large devices and detached divertor regimes with steep neutral density gradients [2]. GUERNICA addresses these challenges using the discontinuous Galerkin method in configuration space and the discrete velocity method in velocity space, achieving high-order accuracy, parallel scalability and improved handling of complex geometries [3]. Previously benchmarked with DEGAS2 for 1X3V, GUERNICA has now been integrated with the MFEM framework, enabling extensions to higher dimensions, unstructured grids and GPU acceleration. The 2X3V code is coupled to a static plasma in a MAST-U cross-section, with results compared against SOLPS-ITER to examine the impact of different collision operators used by GUERNICA and EIRENE. Ongoing efforts to parallelize the code and utilize GPU computing are discussed along with future efforts to incorporate molecular hydrogen and further extensions to 3X3V.

[1] S. Mordijck, Nucl. Fusion 60 (2020) 082006

[2] D. V. Borodin et al, Nucl. Fusion 62 (2022) 086051

[3] W. Su et al, Computers & Fluids 109 (2015) 123-136