Design of a high power long pulse folded coaxial spiral transmission line

Spiral and folded Pulse Forming Line (PFL) are the most effective methods to generate long pulse high power pulse. Combined these two methods together, a long pulse accelerator using water as the transmission dielectric, with two spiral pulse high power PFLs connected by a transition section to form a folded line, was designed. At the length of 1.2 m, high power pulse with pulse length 260 ns was designed. The wave process of the pulse modulator was analyzed. PSpice circuit was used to calculate the voltage, current at the dummy load. Factors affecting the waveform of the load were also studied. The result shows that the modulator can work with charging voltage greater than 1 MV without water breakdown. Experiments were done using high power coaxial line at the voltage of 30 kV; the results are in agreement with the theory and simulation. This technique can be used to increase the energy stored per unit length for a PFL of fixed impedance and pulse duration.