Editing Plasma diagnostics (section)

=== Self Excited Electron Plasma Resonance Spectroscopy (SEERS) ===
Nonlinear effects like the [[I-V characteristic]] of the boundary sheath are utilized for Langmuir probe measurements but they are usually neglected for modelling of RF discharges due to their very inconvenient mathematical treatment. The Self Excited Electron Plasma Resonance Spectroscopy (SEERS) utilizes exactly these nonlinear effects and known resonance effects in RF discharges. The nonlinear elements, in particular the sheaths, provide harmonics in the discharge current and excite the plasma and the sheath at their series resonance characterized by the so-called geometric resonance frequency.

SEERS provides the spatially and reciprocally averaged electron plasma density and the effective electron collision rate. The electron collision rate reflects stochastic (pressure) heating and ohmic heating of the electrons.

The model for the plasma bulk is based on 2d-fluid model (zero and first order moments of Boltzmann equation) and the full set of the [[Maxwell's equations|Maxwellian]] equations leading to the [[Helmholtz equation]] for the magnetic field. The sheath model is based additionally on the [[Poisson equation]].