Influence factors and mechanism of backscattering characteristics of electromagnetic waves in a single layer plasma tube array

Abstract

A single-row plasma tube array (PTA) experimental system is established to improve the backscattering attenuation of a metal plate covered by a plasma tube array. The backscattering test system is utilized in a microwave anechoic chamber to examine the effects of gas composition, pressure, tube diameter, and discharge power on the backscattering attenuation of a metal plate using a plasma tube array. The electron density is obtained via microwave diagnosis. The backscattering attenuation mechanism in different frequency bands is revealed via numerical simulation. The results show that the reasonable selection of PTA parameters achieves strong attenuation in different frequency bands. The strong attenuation frequency bands of Ar–Hg PTA are in low frequency (1.5–3.5 GHz) and high frequency (13–17 GHz), while that of Ne–Hg discharge is in medium frequency (6.4–11.7 GHz). When the pressure is 0.5 and 1 Torr, the PTA shows a low, medium, and high multi-band distribution for the backscattering strong attenuation region. The backscattering strong attenuation region shows a low and high dual-band distribution, while the pressure is 2–4 Torr. As the tube diameter increases, the strong attenuation region maintains the dual-band, but it changes from low and high frequency bands to medium frequency (6-12 GHz), where the backscattering attenuation mechanism is collisional absorption when the frequency of plasma electron oscillation is close to that of electro-magnetic waves. The backscattering attenuation mechanism in the low frequency band involves the periodic structure of PTA generating local surface plasmon to absorb electromagnetic waves.