A numerical study of the standard sheath model

Schabnam Naggary, Ralf Peter Brinkmann

DPG Früh­jahrs­ta­gung 2014, Berlin, Ger­ma­ny, 17 - 21 March


The characteristics of radio frequency (RF) modulated plasma boundary sheaths are studied within the so-called ”standard model”. This model assumes that the applied radio frequency ?RF is considerably larger than the plasma frequency of the ions but smaller than that of the electrons. It comprises a phase-averaged ion model – consisting of an equation of continuity (with ionization neglected) and an equation of motion (with collisional ion-neutral interaction taken into account)–, a phase resolved electron model – consisting of an equation of continuity and the assumption of Boltzmann equilibrium –, and Poisson’s equation for the electrical field. Previous investigations have studied the standard model under additional approximations, most notably the assumption of a step-like electron front [V.A. Godyak and Z.K. Ghanna, Sov. J. Plasma Phys. 6, 372 (1979)]. This manuscript presents an investigation and parameter study of the standard model which avoids any further assumptions. The resulting density profiles and overall charge-voltage characteristics are compared with those of the step-model based theories of Lieberman for the non-collisional [M.A. Lieberman, IEEE Trans. Plasma Sci. 16, 638 (1988)] and fully collisional [M.A. Lieberman, IEEE Trans. Plasma Sci. 17, 338 (1989)] limiting cases.

Tags: plasma, Sheath