Simulation Analysis of Transmission-Line Impedance Transformers Petawatt-Class Pulsed Power Accelerators

Based on the transmission line code TLCODE, a 1D circuit model for a transmission-line impedance transformer was developed and the simulation results were compared with those in the literature. The model was used to quantify the efficiencies of voltage-transport, energy-transport and power-transport for a transmission-line impedance transformer as functions of Psi (the ratio of the output impedance to the input impedance of the transformer) and Gamma (the ratio of the pulse width to the one-way transit time of the transformer) under a large scale of m (the coefficient of the generalized exponential impedance profile). Simulation results suggest that with the increase in Gamma, from 0 to infinity, the power transport efficiency first increases and then decreases. The maximum power transport efficiency can reach 90% or even higher for an exponential impedance profile (m = 1). With a consideration of dissipative loss in the dielectric and electrodes of the transformer, two representative designs of the water-insulated transformer are investigated for the next generation of petawatt-class z-pinch drivers. It is found that the dissipative losses in the electrodes are negligibly small, below 0.1%, but the dissipative loss in the water dielectric is about 1% to 4%.