四级串联共用腔体MA级FLTD的设计与仿真

Fast Linear Transformer Drivers (FLTDs) can directly produce high-power pulse with the rise time 70-200 ns, which are based on magnetic coupling by many bricks connected in parallel in a circular annulus to output MA current and tens of cavities connected in series to output MV voltage. FLTDs are regarded as the next petawatt drivers for Z-pinch by international scientific community. At present, mega-ampere scale FLTD cavities need two or four triggering pulses with 100 kV and rise time of 25 ns in general, so the petawatt FLTD drivers consist of several thousand cavities require ten thousands of the triggering pulses and should be arrived the different position cavities at accurate sequences in order to realize the secondary pulses to superpose inductively and efficiently, which is the bottleneck of the FLTD development. The paper presents a creative FLTD module with four stages in series sharing induction cavity shell and a novel trigger method achieving nearly ideal IVA triggering sequence for each FLTD module. The FLTD module with mega-ampere current output consisting of 16-cavities in series is designed. The circuit model of the new structure of 16-stage FLTD is developed. The influences of the switches' prefire of main bricks, the triggering brick switches' closing sequences and jitter, and the secondary transmission line impedances are simulated based on the circuit model.