Microwave Reflection from a Plasma Column in a Rectangular Waveguide

Abstract

The paper concerns the microwave reflection method suitable for the diagnostics of a plasma column placed transversely across a rectangular waveguide for a TE10 wave. VSWR and phase measurement results are presented regarding the complex reflection coefficient of a discharge Neon diode Philips K50A used as a positive column in the 2–11 Gc/s band. A reflection coefficient theory of cylindrical dielectric post having two coaxial layers of different dielectric permittivity, has also been presented and checked with measurements on calibrated dielectric rods. A numerical calculation of the complex coefficient of reflection performed in the 2–11 Gc/s band is presented for conventional plasma parameters along with a radial electron density distribution depending on a paraboloidal function. The computed values fit the measurement results within the experimental errors.

Ionization waves in plasma columns detected by microwaves

“…7 0 = 250 mA. Langmuir's electron frequencies for these plasmas were estimated by numerical calculation from the measured values of the complex reflexion coefficient (Cicconi et al 1973). The maximum value of II_ was found to be 38 GHzf for neon at maximum discharge current, and 20 GHz for argon, with uncertainties of the order of ±20%.…”

“…Here the modulation due to the Ionization waves 109 striations on the reflected and transmitted microwave fields showed enhancement and, consequently, the component amplitudes and the spectral extension reached their maximum values. The electron density was estimated by an exact numerical calculation of the reflexion coefficient of the plasma column in the waveguide assuming the Lorentz model for the plasma to be valid, and the electron density to have a parabolic radial profile (Cicconi et al 1973).…”

An approach to diagnostics along HF high pressure plasma columns by microwave reflectometer

“…The measured values of the complex reflection coefficient are compared to the calculated ones obtained by a numerical code (Benedetti and Poli 1975), which were first applied in plasma diagnostics by Cicconi er a1 (1973), and verified in measurements on dielectrics having a known dielectric permittivity (Cicconi and Rosatelli 1973). In this model, the plasma is confined in a dielectric cylindrical tube which is centred across the section of the rectangular waveguide, with the tube axis parallel to the electric field lines of the incident microwave propagating in the fundamental TE mode of the waveguide.…”

Cold plasma-induced effects on electromagnetic wave scattering in waveguides: a mode-matching analysis

“…A multiscale property in a Janus metastructure can be achieved by adjusting the incident angle of electromagnetic waves, by arranging the dielectrics asymmetrically, and by using the anisotropy of the plasma [21,22]. The scattering of microwaves from a plasma column in a rectangular waveguide has also been discussed [23,24].…”