  Ion cyclotron radio frequency range (ICRF) power plays an important role in
heating and current drive in fusion devices. However, experiments show that in
the ICRF regime there is a formation of a radio frequency (RF) sheath at the
material and antenna boundaries that influences sputtering and power
dissipation. Given the size of the sheath relative to the scale of the device,
it can be approximated as a boundary condition (BC). Electromagnetic field
solvers in the ICRF regime typically treat material boundaries as perfectly
conducting, thus ignoring the effect of the RF sheath. Here we describe
progress on implementing a model for the RF sheath based on a finite impedance
sheath BC formulated by J. Myra and D. A. D'Ippolito, Physics of Plasmas 22
(2015) which provides a representation of the RF rectified sheath including
capacitive and resistive effects. This research will discuss the results from
the development of a parallelized cold-plasma wave equation solver Stix that
implements this non-linear sheath impedance BC through the method of finite
elements in pseudo-1D and pseudo-2D using the MFEM library. The verification
and comparison of the sheath BC from Stix with results from H. Kohno and J.
Myra, Computer Physics Communications 220 129-142 (2017) will also be
discussed.
