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Microwaves / Plasma

par Olivier Pigaglio - publié le , mis à jour le

The prevalence of studies that explicit plasmas also reflects the ambition to lay the foundations of a microwave / Plasma engineering. This undoubtedly represents a strong marker of the group that has been developed in recent years, in very close partnership with the LAPLACE-GREPHE group through the transverse action 3EP (Electromagnetism Electrodynamics Energy and Plasma).

Simulation tools dedicated

GRE participates in MACOPA ANR project (Asynchronous Methods for Combustion and Atmospheric Plasmas), associating IMFT, IRIT, LAPLACE and ONERA, the aim is to provide a Fortran 90 library able to simulate multiphysics problems and especially multi scales by using an approach known as "asynchronous" : the time step of the numerical scheme can differ from one cell to another of the spatial discretization of the computational domain. In this project, GRE is specifically involved in the development of modules for the Maxwell equations including the coupling with plasmas. These developments are being validated hoping to make a design support tool for some microwave / plasma devices that the group wants to develop.

Reconfigurable antennas and filters

In support with researchers from the LAPLACE-GREPHE team and a researcher at the ISAE, the Group has initiated a co-integration strategy to insert micro discharges in planar circuits. Topologies capable of magnifying the effect of the plasma were first identified to be further characterized in wide ranges of microwave parameters (frequency) and plasma parameters (gas composition, pressure). This work has significantly enhanced this interaction and propose to exploit it in the context of the very original insertion of antennal protection against HPM attacks (High Power Micro-wave). The feasibility has been demonstrated experimentally in the context of a thesis. The images below show successively electromagnetic configuration of transmission and reception, the confined and controlled environment under pressure and gas composition, activated antenna and the received power diagram based on the transmitted power, the discontinuity characterized the ignition of the plasma and the antenna protection.

Antennal protection against HPM attacks

With the kills acquired in the fields of surface waves and plasmas, an original strategy was proposed to carry out a leaky wave scanning antenna. By exploiting the control of the electron density offered by the plasma, it becomes indeed possible to scan a broad angular sector, as was shown by the modeling.

This same approach, research of frequency tuning for filters, which was motivated the use of plasma as material with controllable electrical properties. Initially oriented toward changing permittivity of the material, technological choices have stepped towards the use of plasma in its conducting phase. In this context, two types of devices have been developed :

  • pseudo-volume filters SIW whose topologies have been developed to minimize the impact of plasma losses, assumed significant, multi cavitary configuration. Simulated results are presented below ;

Filtre SIW accordable à plasma

Plasma tunable SIW filter
  • hybrid micro-switches (planar - SIW) that take advantage of both plasma conductivity (decrease of the coupling coefficient through the iris) and plasma losses to improve the dynamics of switch insulation. A line overview as well as the simulated results for off an on states of the plasma is presented below.

Micro-switch using plasma

Emerging technologies

To ensure both electrical performance and reconfigurability of devices we develop breakthrough technologies. Among these, plasma technologies, although difficult to implement, are at the heart of our concerns. They ensure control of physical parameters of the plasma and, therefore, a change in the behavior of the wave with which it interacts. Thus, we extend features such as micro-switches, antennas, tunable filters and multiplexers, which benefit from the switching speed of the plasma.

Prototype de démultiplexeur BIE - Plasma

Demultiplexer IBE - Plasma prototype

Filtre SIW accordable à plasma

SIW tunable filter with plasma