Articles written in Pramana – Journal of Physics

    • A computer modelling and its partial experimental validation to study the attenuation of electromagnetic waves in plasma using CST MICROWAVE STUDIO®


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      There is a huge interest among the scientific fraternity to generate plasma that can selectively absorb or reflect the incident microwaves. Simulations have been carried out to study the absorption of microwaves in plasma using plane wave as a source. In real experiments, the source of microwaves is not always a plane waveand hence the exact simulated replication of the experiment cannot be done using a plane wave source. In order to generate the exact experimental conditions, a horn antenna has been designed and used as a source. A computermodel to study the attenuation of X-band (8–12) microwaves in a plasmamedium is prepared and partially validated using suitable initial experiments. The study can be extended to any target microwave frequency band. The presentwork discusses the preliminary simulations that are carried out to study the effect of plasma frequency (ω$_p$) and collisional frequency (υ$_c$) on attenuation of microwaves (MW) of 8–12GHz using CST®MWS®. The plasma istreated as a Drude dispersive material whose properties are governed by two plasma parameters, namely plasma frequency (ω$_p$) and collisional frequency (υ$_c$). The simulation is carried out on an array of plasma tubes enclosedin a housing made of teflon. This chamber is then illuminated with microwaves using a horn antenna unlike other simulations where the source of the signal is a plane wave. Using a horn antenna as the transmitter and receiverallows exact simulation of the experimental conditions in the laboratory. The amount of attenuation is measured by considering the difference in return losses with and without plasma. The attenuation of incident microwave isstudied by varying plasma frequency from 0.02GHz to 3GHz at a fixed collisional frequency of 10$^10$ S$^−1$. The simulation is also carried out by varying υc from 10$^8$ to 10$^11$ S$^−1$ at a constant ωp. An experiment to validate thesimulation is designed to validate the simulation results. For experimental purpose, fluorescent tube array (FTA), which is a series connection of commercially available tubes is excited using a high-frequency power supply ofsuitable voltage. The simulation and initial experimental results are compared and are in good agreement with each other. This model serves as a tool to study the attenuation of MW in plasma with given ω$_p$ and υ$_c$well before the experiment is carried out. This can also be used to select optimum working points for further experiments.

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