Radio frequency signal propagation through a stagnant flow in a plasma facility for analysis of the communication blackout phenomenon

Abstract

During the atmospheric entry phase, the high levels of ionization on the plasma layer around a spacecraft can cause disruption of the communications, leading to a radio blackout phenomenon. This work, as part of the Horizon 2020 Magnetohydrodynamics Enhanced Entry System for Space Transportation (MEESST) project, presents experimental measurements of radio signal propagation through stagnant flows of air and CO2 plasmas, representative of Earth and Mars entry flows, to characterize the effect of the flow on the radio wave signal propagation. The measurements are conducted at the VKI plasma wind tunnel, the Plasmatron facility, using conical horn antennas in the Ka-band transmitting inside an optimally designed probe. The design and characterization of the probe, conducted at the UPC anechoic chamber, are also detailed. The measurements at the plasma wind tunnel show that the signal propagates almost undisturbed for low electric powers (and plasma frequencies), being its magnitude attenuated and its polarization rotated consecutively for higher electric powers. The dependency with pressure in air is seen to comply with experimental measurements of electron number densities in the facility found in literature. Similar behaviours for air and CO2 plasmas are observed.

Diana Luís research is funcled by a doctoral fellowship (2021.04930.BD) granted by Fundaçao para a Ciencia e Tecnologia (FCT Portugal). The MEESST project is funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No 899298.

Peer Reviewed

Postprint (author's final draft)