脉冲等离子体推力器点火可靠性试验研究

为了得到PPT点火可靠性表征参量的内在联系及放电能量对其影响规律,开展了传统PTFE与掺碳PTFE两种工质的可靠性试验研究,通过记录点火故障率和分析放电延迟时间,得到了不同工质PPT的点火可靠性,为PPT点火可靠性分析提供了新的研究思路。研究结果表明:在不同放电电压下,PTFE工质PPT放电延迟时间随点火次数增加的变化规律明显不同。放电电压为1kV时,放电延迟时间在1μs～15μs内变化,在初始阶段时明显增加,然后在波动中上升,并伴随有点火故障发生;放电电压为1250V和1500V时,放电延迟时间在1μs～5μs之内波动,且没有点火故障发生。两种工质的放电延迟时间均随点火故障率增加呈非线性规律变化,掺碳PTFE的放电延迟阈值与放电电压之间呈指数函数规律变化。     

New results on planetary lightning

We present the latest observations from spacecraft and ground-based instruments in search for lightning activity in the atmospheres of planets in the solar system, and put them in context of previous research. Since the comprehensive book on planetary atmospheric electricity compiled by Leblanc et al. (2008), advances in remote sensing technology and telescopic optics enable detection of additional and new electromagnetic and optical emissions, respectively. Orbiting spacecraft such as Mars Express, Venus Express and Cassini yield new results, and we highlight the giant storm on Saturn of 2010/2011 that was probably the single most powerful thunderstorm ever observed in the solar system. We also describe theoretical models, laboratory spark experiments simulating conditions in planetary mixtures and map open issues.