Four-Stage Linear Transformer Driver With Sharing Shell: EM Model, Simulation, and Performance

A four-stage fast linear transformer driver (LTD) with sharing shell was constructed as a fundamental component of China's next-generation Z-pinch driver CZ34. Separate metal rods replaced conventional independent cavity shells for the ease of installation and maintenance. SF6 was utilized for the first time as insulating medium instead of transformer oil. To investigate the electrical performance of the LTD module, a 3-D full-scale electromagnetic model was developed by field-circuit co-simulation method in Computer Simulation Technology Studio Suite. Fundamental discharging brick was modeled as a conductive current path in 3-D model, excitation was employed through exterior circuits coupled to the field model. The applicability of the simulation model was validated by primary experiments. Compared to circuit simulation, the field-circuit co-simulation modeled the impedances of transmission lines and load impedance accurately since specific structures were included. Annular liquid resistor in experiment configurations brought in extra load inductance, which influenced greatly on output voltage fluctuations in each stage due to the mismatch of load impedance. Simulation results were in good agreement with experiments, except that the switch performances were not entirely up to expectations. It was indicated that several switches showed notable delays according to calculations, leading to voltage and current loss in measurements.