高功率微波窗内外表面闪络击穿流体模拟研究

发布时间：2018-03-16 22:17

本文选题：高功率微波输出窗　切入点：沿面闪络击穿　出处：《物理学报》2014年18期 　论文类型：期刊论文

【摘要】：建立理论模型,将电磁场时域有限差分方法与等离子体流体模型结合,编制一维电磁场与等离子流体耦合程序,数值研究了3 GHz高功率微波窗内外表面闪络击穿的不同物理过程.研究结果表明:外表面闪络击穿中,输出微波脉宽缩短(未完全截止),窗体前均方根场强呈驻波分布,波节与波腹位置不变,窗体外表面形成有一层高密(约10~(21)·m~(-3)量级)极薄(约mm量级)等离子体(扩散缓慢),入射波可部分透过该薄层等离子体,脉宽缩短主要源于等离子体吸收效应;降低初始等离子体密度、厚度、入射波场强及缩短入射波脉宽等方式,可不同程度地改善输出脉宽缩短效应.内表面闪络击穿中,窗体前均方根场强亦出现驻波分布f但波节与波腹位置随时间变化),等离子体向波源方向运动;强释气下,输出脉宽缩短(未完全截止),形成多丝状高密(约10~(21)·m~(-3)量级)极薄(约mm量级)等离子体区域(扩散缓慢),间距1/4微波波长,脉宽缩短主要源于等离子体吸收效应;弱释气、低场强下,脉宽缩短有所改善(但最终截止),形成多带状致密(约10~(18)·m~(-3)量级)略厚(mm-cm量级)等离子体区域(扩散较快),间距1/4波长,脉宽缩短主要源于等离子体吸收效应;弱释气、高场强下,脉宽缩短严重(很快截止),形成块状高密(约10~(21)·m~(-3)量级)较厚(约cm量级)等离子体区域(扩散迅速),脉宽缩短主要源于等离子体反射效应.
[Abstract]:In this paper, a theoretical model is established, the finite difference time-domain (FDTD) method of electromagnetic field is combined with the plasma fluid model, and a one-dimensional electromagnetic field and plasma fluid coupling program is developed. The different physical processes of external surface flashover breakdown in 3 GHz high power microwave window are numerically studied. The results show that the output microwave pulse width is shortened (incomplete cut-off) and the RMS field intensity in front of the form is distributed as standing wave in the external surface flashover breakdown. The position of the nodal and the wave-belly is invariant, and the outer surface of the form is formed with a layer of high density (about 10 ~ 21) 路mf-1 ~ (-3)) thin plasma (about mm order of magnitude) (diffusing slowly), and the incident wave can partly penetrate the thin layer of plasma. The shortening of the pulse width is mainly due to the absorption effect of the plasma, and the reduction of the initial plasma density, the thickness, the intensity of the incident wave and the shortening of the pulse width of the incident wave can improve the shortening effect of the output pulse width in varying degrees. In front of the form, the root mean square field strength also appears standing wave distribution f, but the position of wave nodal and wave belly changes with time, and the plasma moves towards the wave source. The output pulse width is shortened (not completely cut off, forming polyfilamentous high density (about 10 ~ 21) 路m ~ (-1) -3) plasma region (diffusing slowly, spacing 1/4 microwave wavelength). The shortening of pulse width is mainly due to the absorption effect of plasma, weak gas release, At low field intensity, the pulse width shortening has been improved (but finally cut off, forming multi-band density (about 10 ~ (18) 路m ~ (-1) -3)) the plasma region (diffusion is faster, the spacing is 1/4 wavelength, the pulse width shortening is mainly due to the plasma absorption effect), the plasma region is a little thicker (about 10 ~ (18) ~ (18) 路m ~ (-1) 路m ~ (-3)). Under weak gas release and high field intensity, the pulse width shortens seriously (quickly cut off, forming block high density (about 10 ~ 21 ~ 21 路m ~ (-1) ~ (-3))) thick (about cm) plasma region (diffusion is rapid, pulse width shortening is mainly due to plasma reflection effect).
【作者单位】：北京应用物理与计算数学研究所;
【基金】：国家重点基础研究发展计划(批准号:2013CB328904) 国家自然科学基金(批准号:11305015,11105018,61201113,11371067) 中国工程物理研究院科学技术发展基金(批准号:201280402064)资助的课题~~
【分类号】：O441

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