Two Methods on Pulse Shaping for a Series Coaxial Multilayered Film-Winded Pulse-Forming Line

A coaxial multilayered film-winded pulse-forming line (shortened as winded PFL) is a novel compact device to produce pulses with amplitude up to 100 kV and width longer than 10 ns, which was put forward by Su et al. [a coaxial multilayered film-winded PFL,laser, and particle beams, 36(1), 69-75(2017)]. A quasi-rectangular pulse with amplitude higher than 1 MV can be formed if several stages of this winded PFL are connected in series. However, the top of the output pulse of this PFL unit is not “flat”, with a “recess” about 10%. By analyzing the wave transmission process, it is found that this “recess” is due to a large local impedance in the series PFL unit. Two methods are put forward to decrease the local impedance of the series PFL unit in order to shape the output pulse. One is to fill a polymer insulator in the proper position in the series PFL unit; the other is to redesign the configuration of the outer conductor of the PFL unit. With the transient wave simulation method, it is found that the first method can reduce the recess to a level of 5.5%, and the second can reduce the recess to a level of 2.5%. In the end, the feasibility of the first method is verified by experiments.