Optimizing design on the wide-band absorbing plasma using fluorescent lamps

Abstract

The plasma was generated using the fluorescent lamp array and the generating principle was the glow discharge mode. The electron density and angular frequency of the plasma could be adjusted with the electronic ballast by changing the lamp input power. The microwave measurement system was built to get the transmission parameter as a function of the lamp input power and the frequency. The transmission parameter expression as functions of the plasma electron density and the electron collision frequency was deduced, and the optimized function could be established. Then the electron density and the electron collision frequency could be fit using a nonlinear least square interpolation method in the MATLAB software kit. The effective permittivity and permeability of the equivalent plasma absorber could be calculated, the real permittivity decreased and the imaginary permittivity increased as the lamp power increased. As the lamps filled with plasma were aligned with different duty ratio, the reflection and transmission parameter could be simulated in the Computer Simulation Technology (CST) software, and the equivalent permittivity was calculated. Finally, the genetic algorithm was used to optimize the structure of the plasma in two cases (lamps aligned adjacently or dispersed with space) as the reflection loss (RL) was set less than −10 dB in 1–8 GHz. The results showed that as the lamps were distributed adjacently, the lamp powers were of two kinds and the total layer number was 28, the minimum RL was −47.1 dB at 5.1 GHz. While as the lamp power was the same 25 W and the lamp layer alignment was different, the minimum RL was −38.2 dB at 5.7 GHz, the total layer number was only 9 and much smaller than that in the first case.