Investigation of the sheath effect on the resonance frequencies of a curling probe

The curling probe [1] is a recent innovative realization of the “active plasma resonance spectroscopy” (APRS) concept. If we model the medium around the curling probe only by a plasma region with negative permittivity, our previous researches show resonance frequencies on or near the electron plasma frequency ω_pe when the probe is excited with a low power RF signal (in the GHz range). However in reality a thin sheath layer is built in the vicinity of the probe surface which can change the resonance behavior of the probe.