On Ohm's law in reduced plasma fluid models

TY - JOUR

T1 - On Ohm's law in reduced plasma fluid models

AU - Dudson, Benjamin Daniel

AU - Newton, Sarah

AU - Omotani, John Tomotaro

AU - Birch, Jack

PY - 2021/10/26

Y1 - 2021/10/26

N2 - Drift-reduced MHD models are widely used to study magnetised plasma phenomena, in particular for magnetically confined fusion applications, as well as in solar and astrophysical research. This letter discusses the choice of Ohm's law in these models, the resulting dispersion relations for the dynamics parallel to the magnetic field, and the implications for numerical simulations. We find that if electron pressure is included in Ohm's law, then both electromagnetic and finite electron mass effects must also be included in order to obtain physical dispersion relations. A simple modification to the plasma vorticity is also found which improves handling of low density regions, of particular relevance to the simulation of the boundary region of magnetised plasmas.

AB - Drift-reduced MHD models are widely used to study magnetised plasma phenomena, in particular for magnetically confined fusion applications, as well as in solar and astrophysical research. This letter discusses the choice of Ohm's law in these models, the resulting dispersion relations for the dynamics parallel to the magnetic field, and the implications for numerical simulations. We find that if electron pressure is included in Ohm's law, then both electromagnetic and finite electron mass effects must also be included in order to obtain physical dispersion relations. A simple modification to the plasma vorticity is also found which improves handling of low density regions, of particular relevance to the simulation of the boundary region of magnetised plasmas.

U2 - 10.1088/1361-6587/ac2af9

DO - 10.1088/1361-6587/ac2af9

M3 - Article

SN - 0741-3335

VL - 63

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

M1 - 125008

ER -