A Genetic-Algorithm-Based In-Situ Diagnostic Method for Plasma with Non-Uniform Distribution Profile

The plasma sheath generated during the re-entry process of the hypersonic aircraft has a great impact on the electromagnetic radiation, transmission, and scattering problems. In this paper, an in-situ diagnostic method for non-uniformly distributed plasma sheath is proposed based on microwave reflection theory. Using the genetic algorithm, the electron density distribution and collision frequency of the plasma can be inferred from a set of broadband complex reflection coefficients. To mitigate the challenge of the multiple values in the inverse problem, an additional dimension of information can be involved into the reflection coefficients. Specifically, introducing static magnetic fields with varying intensities can help improve the inversion accuracy and robustness. Numerical experiment involving the diagnosis of a typical plasma profile subjected to double Gauss distribution demonstrate the accuracy and effectiveness of the proposed method.