【作者】 高景明；

【导师】 刘永贵；

【作者基本信息】 国防科学技术大学 ， 电子科学与技术， 2009， 博士

【摘要】 国防和工业应用的需要推动脉冲功率技术向高平均功率和紧凑化的方向发展。陡化前沿Marx发生器(Wave Erection Marx Generator)是该方向发展的重要候选方案之一,在国外已受到广泛关注,而国内尚无研究报道。本文在对陡化前沿Marx发生器进行深入细致的理论分析、电路模拟和实验设计的基础上,研制出一台10级陡化前沿Marx发生器,并开展了初步的应用研究与重频运行实验研究。本文的研究方法和研究结果对于此类脉冲功率发生器的研制具有重要的指导意义,为此类脉冲发生器向更高的性能指标推进和开展更广泛的应用研究奠定了基础。论文的研究内容主要包括以下几个方面:对陡化前沿Marx发生器进行了细致的理论研究。通过对单元回路中影响气体火花开关过电压因素的分析,发现消除充电隔离元件自身的分散电容与增大开关电极对地分散电容有利于陡化前沿脉冲波形的建立。建立了N级陡化前沿Marx发生器的放电等效回路方程组,通过数值求解发现在单元结构参数确定后,发生器存在最佳级数使输出波形同时具有陡化前沿和近似平顶。综合考虑阻抗与充电均匀性等方面的影响最终确定发生器的级数为10,并针对10级陡化前沿Marx发生器对相关参量进行了分析。分析结果表明,单元回路的电感对发生器输出波形的变化趋势影响不大,但较大的回路电感会降低输出脉冲的幅值,增加输出脉冲的宽度,同时在一定程度上增加脉冲前沿时间;开关电极对地分散电容对陡化前沿脉冲波形的建立起到关键作用,此分散电容应具备一定的数值以实现陡化前沿脉冲波形的建立;此外,计算结果表明开关的顺序导通对陡化前沿脉冲波形的建立非常关键。利用PSpice软件建立了基于自击穿开关模型的10级陡化前沿Marx发生器全电路模型,电路模拟结果与理论计算结果基本一致。基于理论分析结果,采用3 nF低电感高压脉冲电容器与无容性的大功率金属电阻分别作为储能元件和隔离元件,研制了一台10级电阻隔离型陡化前沿Marx发生器。该发生器直径0.22 m,长度1.6 m,当充电40 kV时,在90Ω大功率低电感金属膜电阻负载上,输出电压约210 kV,上升前沿约5 ns,脉宽(FWHM)约40 ns,此类型发生器与性能指标在国内为首次报道。通过实验研究发现,同轴结构对陡化前沿Marx发生器的设计与诊断非常重要;在相邻火花开关之间不存在紫外光耦合的情况下,所研制的10级陡化前沿Marx发生器依靠对单元回路中开关过电压方面的合理设计,实现了开关的顺序快速导通,建立了快前沿高压脉冲,如果将来在改进结构中引入紫外光耦合可能会使发生器的性能得到进一步的提高;大功率金属膜电阻负载集成了金属膜电阻的无容性和变阻抗线结构可减少反射两大优点,配合电容分压器使用,相对于硫酸铜水溶液电阻负载能够更好地完成对快前沿高压脉冲信号的测量;通过定义两种阻抗——发生器的集总参数阻抗Z0和分散参数所形成的等效传输线阻抗ZN,对实验结果进行了分析,提出了发生器进一步改进的方案。对所研制的10级陡化前沿Marx发生器开展了初步的应用研究。在作为高压触发源的实验中,发现此发生器适应系统同步性要求较高的触发要求;在直接驱动强流场发射二极管的实验中,发现此发生器可以初步完成变压器与传输线相结合的功能,证实了这种发生器用作强流电子束加速器脉冲功率平台的可行性,由于陡化前沿Marx发生器不需要外部储能大电容及液体循环系统等辅助设备,从而为实现强流电子束加速器的小型化探索了一条经济可靠的技术路线;在作为ns量级水击穿脉冲功率平台的实验中,发现该10级陡化前沿Marx发生器适合作为基于水介质传输线的强流电子束加速器电水锤效应研究的缩比实验平台,并得到了一定实验条件下电脉冲能量与冲击波能量之间的转换系数。由以上应用研究可以看出,陡化前沿Marx发生器具备较好的应用前景。将10级陡化前沿Marx发生器由原来的电阻隔离型改造为电感隔离型,进而利用恒流充电平台开展了陡化前沿Marx发生器重复频率运行的初步实验研究。实验结果表明,在不对内部开关吹气的情况下,当充电30 kV时,发生器在8.2 Hz重频下稳定工作,输出脉冲的一致性较好,输出电压约为150 kV,电流约为1.8 kA。更多还原

【Abstract】 Driven by national defense and industrial applications, pulsed power technology has been advancing towards higher average power and more compact structure. A wave erection Marx generator is one of the important candidates for these development trends. It has been well developed by foreign researchers, whereas domestic reports have not been found yet in literature. In this dissertation, a 10-stage wave erection Marx generator is developed based on detailed theoretical analysis, total circuit simulations and experimental design. Preliminary researches are also made on its potential applications and repetitive operation characteristics. These efforts are instructive for the further development of this kind of pulse generator, and also set a good foundation for the realization of higher performance as well as more extensive applications.This dissertation mainly consists of the following aspects.The wave erection Marx generator is investigated theoretically in detail. Through the analysis of the factors influencing the amplitude of over voltage across gas spark gap in a single stage, it is found that eliminating the coupling stray capacitance between stages and increasing the stray capacitance between the electrode and the ground are favorable for the formation of erected waveform of the Marx generator. Equations describing the equivalent discharging circuit of an N-stage wave erection Marx generator are established and numerically calculated. The results show that under the specific structure parameters of the single stage, the generator has an optimum number of stages to obtain an output pulse with both a fast rise time and a quasi-square waveform. Considering the impedance and the charging uniformity synthetically, the optimum number of stages is chosen to be 10 at last. The effects of parameters on performance of the 10-stage wave erection Marx generator are analyzed. The analysis results show that the single stage circuit inductance slightly affects the variation trend of output voltage waveforms, however a larger inductance will reduce the pulse amplitude, and increase both the pulse width and the rise time; while the stray capacitance between the electrode and the ground is the critical component and it should be of a proper value to form a high voltage pulse with fast rise time on the load. Calculation results also show that the switch-closing in order is very important for the wave erection process. A total circuit model of the 10-stage wave erection Marx generator is developed via PSpice software and detailed simulations are performed based on the model. The simulation results agree well with the above calculation results.Based on the theoretical analysis results, a resistively isolated 10-stage wave erection Marx generator is designed and constructed with 3 nF high voltage low inductance capacitors and 50 k? high power solid resistors, respectively, as its energy storage and isolation components. The dimension of this generator isΦ0.22 m×1.6 m. At a 40 kV charging voltage, the generator can deliver a high voltage pulse with amplitude of ~210 kV, rise time of ~5 ns, and pulse width (FWHM) of ~40 ns to the 90Ωmetal film resistor load. It is the first domestic report on this type of pulse generator with such performance. Through experiments it is found that a coaxial structure is important for both the design and the diagnostics of the wave erection Marx generator. Due to proper design with respect to the over voltage across spark gap to realize the spark gaps closing rapidly in order, the generator can produce a fast rise time and high voltage pulse even without the help of ultraviolet (UV) coupling between stages; however its performance may be enhanced with UV coupling introduced by further modification of the generator structure. Compared to the copper sulphate solution load, the metal film resistor load combines such two virtues that nearly without stray capacitance and adopting an impedance tapering structure to reduce wave reflection, thus it can make a more precise measurement in cooperation with a capacitive divider. The output performance of the generator has been analyzed through defining two kinds of impedances, Z0, the lumped impedance of the generator, and ZN, the impedance raised from the effective transmission line formed by stray parameters of the generator. Then a further improvement suggestion of the generator is put forward.Preliminary research is made on the application of the 10-stage wave erection Marx generator. When applied as a high voltage trigger, it is found to be suitable for triggering the systems where strict synchronization is required. The generator is successfully utilized to drive a field-emission diode directly, which accomplishes the joint function of a transformer and a pulse forming line (PFL) and verifies the possibility to drive an intense relativistic electron beam (REB) accelerator. This result indicates that the wave erection Marx generator driven REB accelerator may open a new economical and reliable route for the minimization of the REB generators. The 10-stage wave erection Marx generator is also found to be applicable for producing ns range underwater shockwave to simulate the electric water hammer effect of the water transmission line based REB generator in operation. The energy transformation rate of electrical pulse and shockwave is obtained under certain conditions. All the above applications show that the wave erection Marx generator has a promising future.The 10-stage wave erection Marx generator is modified from a resistively isolated configuration to an inductively isolated configuration for the investigation on its repetitive operation characteristics. The experimental results show that at a 30 kV charging voltage, the 10-stage wave erection Marx generator can operate stably at 8.2 Hz repetition rate without gas blow-off from the internal spark gaps, producing an output pulse of 150 kV and 1.8 kA.更多还原