【作者】 欧阳佳；

【导师】 刘永贵；

【作者基本信息】 国防科学技术大学 ， 物理电子学， 2007， 博士

【摘要】 高功率微波的军事应用对脉冲功率技术提出新的要求是向小型化和高平均功率发展。折叠型平板Blumlein线作为向该方向发展的脉冲功率源候选者之一目前得到了广泛关注。本文在研究折叠型平板Blumlein传输线的工作机理和运行特性基础上,研制了一台紧凑的折叠型平板Blumlein传输线,并用它驱动高功率微波源产生了百兆瓦级高功率微波。本文的主要研究内容有以下几个方面。在系统深入地调研固体介质和液体介质的电特性和其它参数基础上,确定了使用Kapton膜作为折叠型平板Blumlein线的传输介质;使用优质纯净的变压器油作为传输线的填充介质。Kapton材料有非常高的介电强度(200kV/mm)、还有耐热、耐辐射、耐有机溶剂等性能,能够承受电晕放电,可以用比较小的厚度(继而减小装置体积)实现较大的耐高电压强度。变压器油有与Kapton薄膜相近的相对介电常数、很高的电阻率、较高的击穿场强和很小的介质损耗角正切,所以选择变压器油作为折叠线填充介质是非常合适的。对平板Blumlein线的工作机理进行了理论分析和电路模拟。利用无损耗传输线模型得到了平板Blumlein线的相关参数:特征阻抗、延迟时间和脉冲宽度、传输线电容、传输线击穿电场强度以及传输线总储能;在有损耗模型中增加了单位长度的电阻R和通过介质的单位长度电导G等参数。通过调整各种参数,利用有损耗模型模拟计算确定了折叠线介质厚度为5mm,铜板宽度20cm。采用电磁场分布模拟的方法确定了介质边缘宽度的最小值为3cm。对折叠型平板Blumlein线的折叠部分的色散特性进行了理论分析,计算表明在我们感兴趣的频率范围内折叠部分的色散影响可以忽略。采用保角变换等多种方法对折叠部分的特征阻抗进行了系统分析,得出折叠部分的特征阻抗与平板部分的特征阻抗相差不大的结论。采用电路分析和电场分布计算模拟相结合的方法,对折叠型平板Blumlein线的折叠部分的特征阻抗和传输电压波的影响进行了详细分析,综合考虑工程上的实现问题,选取了合适的折叠方式:回转180°,折叠内半径r=10mm。在理论计算基础上,设计制作了一个以Kapton薄膜为介质的折叠型平板Blumlein线(特征阻抗约为5Ω);还设计制作了一个尺寸为120cm×40cm×40cm的外箱盛放传输线主体、液体绝缘填充介质以及其它连接部件;研制了一个适合平板Blumlein线的多通道轨道开关,其具有体积小(φ60×300mm)和电感小(40nH)等优点。利用该折叠型平板Blumlein线装置在匹配负载上形成了电压600kV、脉宽100ns的电压波。设计制作了不同结构的水电阻作为折叠线的匹配负载,实验证明U形电阻最适合作为折叠型平板Blumlein线的匹配负载。利用研制的折叠型平板Blumlein线装置驱动强流电子束二极管产生了500kV、50kA、100ns的电子束;并以此驱动低阻抗的微波源(MILO)产生了高功率微波:实验表明,在二极管电压550kV,电流40kA,电压脉冲半高宽80ns时,利用该折叠型平板Blumlein线装置驱动C波段MILO输出了峰值功率达350MW,脉宽为40ns的高功率微波。所研制的折叠型平板Blumlein线装置与输出相同电功率的传输线相比不仅大大减小了体积和重量,而且它不需要附加液体循环系统和其它辅助设备,这样两个特点使折叠型平板Blumlein线有利于向模块化集成的方向发展,为脉冲功率装置的小型化和集成化提供了一个非常有意义的方法和途径,因此具有较高的应用价值。更多还原

【Abstract】 The military application of high power microwave requires that the pulsed power technology develops towards the direction of compactness and high average power. As one of the candidates meeting these requirements, the folded plate Blumlein line has attract extensive attention nowadays. In this dissertation, based on the calculation and analysis of the working mechanism and operation properties of folded plate Blumlein lines, a compact folded plate Blumlein line was designed and fabricated, and thereby used to drive a high power microwave source to produce several hundred megawatts high power microwave.This dissertation mainly consists of the following aspects.Based on the detailed investigation of the electric characteristics and other parameters of the solid and liquid dielectrics, the Kapton film has been chosen as the transmitting dielectric and the pure transformer oil as the insulating dielectric in the folded plate Blumlein line. Kapton material is of excellent breakdown voltage (200kV/mm), high endurance to heat, radiance, organic solvent and corona flashover which enables to withstand high voltage with comparably less thickness (thus may reduce the volume of the equipment). Transformer oil is of similar relative dielectric constants as the Kapton film, with high resistivity, high breakdown voltage and minor dielectric loss tangent. Therefore transformer oil of high quality and purity is very suitable to use as filling dielectric for this folded line.Theoretical analysis and electric circuit simulation of the working mechanics of the parallel plate Blumlein line are performed. Parameters such as characteristic resistance, time delay, pulse width, the capacitance, breakdown voltage and overall energy of the plate Blumlein line have been obtained from the non-loss transmission line model; the unit-length resistance R and the unit-length conductance G are involved in the loss transmission line model. By adjusting the parameters, the thickness of folded line dielectric and the copperplate width are optimized as 5mm and 20cm, respectively. And by means of the electromagnetic field distribution simulation, the minimum dielectric edge width is optimized as 3cm.The dispersive property of the folded part of folded Blumlein line is analyzed, calculating results show that dispersion effect of the folded part can be ignored under the present low frequency conditions. Systematic analysis on the characteristic resistance of the folded part of folded Blumlein line is carried out through various methods such as conformal mapping, which leads to the conclusion that there is no much difference between the characteristic resistances of folded part and plane part. Detailed analysis on the influence from characteristic resistance and transmitting voltage wave of the folded part of folded Blumlein line is conducted through the combination of electric circuit analysis and electric field distribution simulation. In consideration of the engineering issues in project realization, the appropriate folding manner with folding angle of 180°and inner radius r = 10mm is determined.Based on theoretical analyses, a folded Blumlein line with Kapton film as dielectric is designed and fabricated; a multi-channel rail switch with the advantage of small volume (Φ60×300mm) and low inductance (40nH), which especially suits for plate Blumlein lines, is developed; An outer-chamber in the size of 120cm×40cm×40cm is made up for holding the folded Blumlein line, liquid filling dielectric and other connection parts. Experiment conducted on this folded Blumlein line has provided a voltage pulse of 600kV and 100ns on a match load. Several water resistances with different constructers have been used for the match loads, but experimental results show that the U-shape resistance is more suitably used as the match load of the folded Blumlein line.Using the folded plate Blumlein line to drive an intense electron beam diode to produce an electron beam of 500kV, 50kA, 100ns when the diode load is matched with the transmission line and then it is used to drive a magnetically insulated line oscillator (MILO) to produce high power microwaves. Experiments have affirmed that with diode parameters of 550kV, 40kA and 80ns, microwave peak power of 350MW with 40ns pulse width can be output from C band MILO.Compared to other transmission lines with the same output power, the folded plate Blumlein line has advantages of small volume and weight, no need of cycle purifying system and other assistant apparatus; these advantages make it possible to develop towards the direction of compactness and integration. Therefore study on the folded plate Blumlein line is of significant application value.更多还原