The design of electrical pulse forming networks (PFN), using multiple coils and energy storage capacitors, has a profound effect on the intensity and temporal shape of the radiant flash emitted from a flashlamp. In addition, the geometrical dimensions of a flashlamp control its electrical impedance (i.e. its interaction with the PFN), and also its explosion energy (i.e. its lifetime expectancy). We present a simple, non iterative algorithm for optimizing the electrical and geometrical design of a bank of flashlamps connected to a high order (multi-section) PFN for use in thermal flash processes. We also describe a full scale 160 kJ system for flash annealing of 300 mm wafers, which was built in our laboratory according to the procedure presented here