Theoretical Study On Compact Broadband Marx Generator

This paper reviews the research achievements at home and abroad on the compact Marx generator, its working principle is theoretical derived and experimental simulation are consistent with the expected results, and the inter-turn voltage analysis of internal final stage inductor of Marx generator is presented. The thesis focuses on the working principle of Marx generator, and the theoretical analysis of its charging and discharging circuit are also carried out. The value of main circuit parameters including inductance, capacitance are derived. What’s more, with OrCAD pspice circuit simulation software, the simulation results of the different loads, inductance, and capacitance values impact on Marx generator output waveform were compared with the theoretical analysis and the final value of the circuit parameters are determined based on the simulation waveform.We need to pay special attention to the inductance coil by spiral winding and its dispersion characteristics. When the inductor works in greater than 1 MHz band, at this time the inductance of high frequency dispersion characteristics will greatly influence on distribution parameters. At low frequency, the analysis of the inductance coil adopts the theory of static magnetic field, however when the inductance coil is used as isolated inductance in high frequency, such as Marx generator(for a few MHz to several hundred MHz), the large inductance value of low frequency at this time will be reduced to a small value, causing the failure of Marx generator.In addition, the general input voltage of the pulse power modulation system for the dozens of kV, and input current up to hundreds of kA, and output voltage requires several hundred kV, pulse width width are only a few nanoseconds. Thus, Marx generator working in extremely high field, and withstand voltage waveform is very steep. In a short pulse width, high amplitude of the voltage, the coil winding itself form a non-uniform field, considering the high frequency effect of various parameters such as interturn capacitance and the capacitance to ground, if the winding insulation structure is improper designed, once exerted impact gradient voltage, it is easy to produce strong distortion electric field among the windings, the turn-to-turn inductance and capacitance to the ground cannot slow down the fast rise of transient voltage, causing the winding of generator interturn breakdown. Therefore, in order to design pulse generator of high voltage working in high repetition frequency, we need focus on the insulation problem of generator. The issue using the finite element analysis software ANSYS Maxwell to build two-dimensional model of the coil based on the internal coil winding inductor structure of Marx generator, and the values of distribution parameters were calculated by electromagnetic field analysis, then the values were substituted into multi-conductor transmission line equations so that we can obtain the voltage to ground and the voltage distribution of each turn, the results provide a strong basis for the internal insulation of Marx generator. Through exerting high impulse voltage between the windings to simulate the real working condition, according to the experiment results preliminarily summarizes the voltage distribution characteristics of Marx generator winding.