Shock Formation by Plasma Filament of Microwave Discharge under Atmospheric Pressure
Shock Formation by Plasma Filament of Microwave Discharge under Atmospheric Pressure
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大气压下微波放电等离子体丝形成激波
DOI：
10.1088/1742-6596/688/1/012119
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Naofumi Ohnishi
中科院分区：
文献类型：
--
作者：
Masayuki Takahashi;Naofumi Ohnishi
一维可压缩流体计算与有限差分时域代码和碰撞粒子内粒子代码相结合，再现了电磁波的传播、等离子体的电离过程以及大气微波放电中冲击波的形成。等离子体细丝在 1 个大气压下被驱动向微波源，每个细丝之间的距离是入射微波波长的五分之一。强烈的冲击波是由于大气压下等离子体密度高而产生的。对微波在等离子体中传播的简单分析表明，随着碰撞等离子体中压力的降低，微波的截止密度变小。在较低的压力下，由于较小的截止密度和较大的扩散效应，可以获得具有扩散图案的较小密度的等离子体。与1-atm情况相比，微弱的冲击波是在稀薄的条件下产生的，这降低了微波推进器的性能。
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.