Radio frequency wave interactions with a plasma sheath: the role of wave and plasma sheath impedances

The accompanying files contain digital data for figures in the article "Radio frequency wave interactions with a plasma sheath: the role of wave and plasma sheath impedances" by J.R. Myra and H. Kohno, to be submitted to the journal Physics of Plasmas.

Abstract:
RF sheaths form near surfaces where plasma and strong RF fields coexist. The effect of these RF sheaths on wave propagation near the boundary can be characterized by an effective sheath impedance that includes both resistive and capacitive contributions describing RF sheath rectification and RF power absorption in the sheath [J. R. Myra and D. A. D’Ippolito, Phys. Plasmas 22, 062507 (2015)].  Here we define a dimensionless parameter, the ratio of incoming wave impedance to the sheath impedance, which determines the characteristics of the interaction, ranging from quasi-conducting to quasi-insulating, or in the case of matched impedances, to a sheath-plasma resonance. A semi-analytical analysis is carried out for electrostatic slow waves in the ion cyclotron range of frequencies (ICRF). For the propagating slow wave case, where the incident wave is partially reflected, the fraction of power dissipated in the sheath is calculated.  For the evanescent slow wave case, which admits a sheath-plasma resonance, an amplification factor is calculated.  Using the impedance ratio approach, RF sheath interactions are characterized for a range of RF wave and plasma parameters including plasma density, magnetic field angle with respect to the surface, wave frequency and wave-vector components tangent to the surface. For a particularly interesting example case, results are compared with the rfSOL code [H. Kohno and J. R. Myra, Comput. Phys. Commun. 220, 129 (2017)]. Finally electromagnetic effects, absent from the semi-analytical analysis, are assessed.