Abstract Details
Abstracts
Author: Jack Gabriel
Requested Type: Consider for Invited
Submitted: 2025-02-20 11:00:26
Co-authors: S. Mordijck, G. Wilkie
Contact Info:
William & Mary
411 Lewis Burwell Dr.
Williamsburg, Virginia 23185
USA
Abstract Text:
This talk seeks to validate our continuum kinetic neutral code, GUERNICA, through comparisons to analytic theory and benchmarking against DEGAS2. In fusion devices, neutral atoms and molecules play a crucial role by determining fueling efficiency and mitigating heat fluxes to the divertor [1, 2]. While kinetic Monte Carlo codes like DEGAS2 capture the full neutral dynamics, they suffer from statistical noise and high computational cost—particularly in large devices and/or in regimes with strong neutral density variations such as with divertor detachment—limiting their scalability [3, 4]. GUERNICA addresses these challenges by employing 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 [5, 6]. The code operates in 1X3V phase space and incorporates electron-impact ionization, charge exchange and neutral-neutral collisions via the BGK Boltzmann equation for atomic hydrogen. We validate ionization and charge exchange against analytic theory and benchmark them with DEGAS2. The BGK Boltzmann operator is tested through collisional relaxation and Sod shock test cases, demonstrating conservation properties and confirming the transition from the kinetic to the fluid regime, as it approaches the Euler equations solution in the high-collisionality limit. We also discuss ongoing efforts to integrate GUERNICA into the MFEM framework and leverage GPUs to enhance performance.
References
[1] S. Mordijck, Nucl. Fusion 60, 082006 (2020)
[2] P. C. Stangeby, The Plasma Boundary of Magnetic Fusion Devices (2000)
[3] I. Josepch et al, Nucl. Mater. Energy 12, 813-81 (2017)
[4] D. V. Borodin et al, Nucl. Fusion 62 086051 (2022)
[5] J. Hesthaven and T. Warburton, Nodal Discontinuous Galerkin Methods (2008)
[6] W. Su et al, Computers & Fluids 109, 123-136 (2015)
Work supported by US DOE under DE-SC0007880.
Characterization: 4.0
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