Shock Formation by Plasma Filaments of Microwave Discharge under Atmospheric Pressure

8th International Conference on Inertial Fusion Sciences and Applications

Takahashi, Masayuki^1 ; Ohnishi, Naofumi^1

Department of Aerospace Engineering, Tohoku University, Japan^1

关键词: Compressible fluids;    Diffusion effects;    Ionization process;    Microwave discharge;    Microwave propagation;    Microwave sources;    Propagation of electromagnetic waves;    Strong shock waves;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/688/1/012119/pdf
DOI  :  10.1088/1742-6596/688/1/012119

来源: IOP

【 摘 要 】

A one-dimensional compressible fluid calculation was coupled with a finite- difference time-domain code and a particle-in-cell code with collision to reproduce propagation of electromagnetic wave, ionization process of plasma, and shock wave formation in atmospheric microwave discharge. Plasma filaments are driven toward the microwave source at 1 atm, and the distance between each filament is one-fifth of the wavelength of the incident microwave. The strong shock wave is generated due to the high plasma density at the atmospheric pressure. A simple analysis of the microwave propagation into the plasma shows that cut-off density of the microwave becomes smaller with the pressure decrease in a collisional plasma. At the lower pressure, the smaller density plasma is obtained with a diffusive pattern because of the smaller cut-off density and the larger diffusion effect. In contrast with the 1-atm case, the weak shock wave is generated at a rarefied condition, which lowers performance of microwave thruster.