Line Glass Ceramic Solid State Pulse Form

High power pulse system based on pulse forming lines for pulse forming and transmission, has been widely applied in the domains of controlled thermonuclear fusion, high power laser, railgun, ultra-wideband technology(UWB), industrial materials processing and dielectric wall accelerator(DWA). As the compact high power system is demanded in these domains, composite materials with high energy density become promising materials in solid-state transmission line because of portability, maintainability and compatibility.In this thesis, glass-ceramic material with high energy density and plate transmission line is combined to construct solid-state pulse forming line. The bulk breakdown characteristic and transmission characteristic of plate transmission lines made of glass-ceramic are studied, in order to verify the feasibility of which using glass-ceramic as the dielectric material, and to summarize the laws of this kind of plate transmission’s characteristics with different parameters.In the study, a high voltage narrow pulse modulator is used to get a high voltage pulse conveniently, and through a simple discharge circuit and copper electrode,19glass-ceramic slice samples with different materials, thickness, relative permittivity or electrode processing are experimented to bulk breakdown. It is found that, the field enhancement effect at the three realms points is more obvious when the relative permittivity difference between samples and transformer oil is greater. Under the same conditions, samples with lower relative permittivity has higher bulk breakdown field strength. Samples with larger scale can resistant higher voltage, but the probability of its own defect is greater too, so thicker samples has lower bulk breakdown field strength. In the experiments, all bulk breakdown happened at the edge of the electrode, the naked samples has higher bulk breakdown field strength than those with electrodes, which prove that, glass-ceramic has a high voltage resistance capability and the bottleneck to improve this capability is the electrode processing. By coating ZnO semiconductor glass glaze at the edge of the electrode, the bulk breakdown field strength is successfully improved, especially for B2O3glass-ceramic, which has higher bulk breakdown field strength than niobate or PbBa glass-ceramic. Based on the phased results, a B2O3glass-ceramic sample with lmm thick,20relative permittivity, ZnO semiconductor glass glaze coated at the edge of the electrode is prepared. It got a filed strength resistance as high as46.9kV/mm without breakdown in the experiments.Based on the electromagnetic wave propagation characteristics on uniform lossless transmission line and the plate transmission line structure, a positive mismatch single transmission line pulse forming line circuit is designed. By measuring charging voltage, main pulse amplitude, sub-pulse amplitude, pulse width and line length, the relative permittivity and characteristic impedance of the transmission line can be calculated. In this way, niobate glass-ceramic plate transmission lines with different thickness and B2O3glass-ceramic plate transmission lines with different relative permittivity and electrode width are experimented. The results show that both of these two kinds of glass-ceramic materials are good for solid-state pulse forming line. The output pulse waves have good rising-edge and flat-top. It is proved that the characteristic impedance of plate transmission line is a function of the ratio of electrode width W and dielectric thickness d, rather than the two independent impact. In the experiments, the characteristic impedance of plate transmission line with Wld from0.6to3.5is close to the empirical formula.In order to verify the correctness of the method and the accuracy of the results, finite difference time domain numerical simulations for single plate transmission line pulse forming process are applied on XFDTD software. The simulation results show that, as same as the experimental results, plate transmission line with the same relative permittivity and Wld ranged from0.6to3.5, the characteristic impedance is only related to W/d, rather than W and d independently.