A novel square wave generator based on unequal-capacitance form of Blumleinpulse forming network

Compared with many design solutions for square wave pulse generators, the Blumlein pulse forming network (PFN) is smaller in size and simpler in design. However, the quality of the output square wave is often affected by the loop inductance, stray inductance, stray capacitance, and load state in practical engineering applications. In this case, it will bring great engineering difficulties and funding wastage if the matching parameters of PFN are redesigned and adjusted. This paper proposes a novel idea of using unequal-capacitance form of Blumlein PFN to optimize the output waveform. The Blumlein PFN is divided into part A (LC loop) and part B (LCR loop). Among them, part A controls the transmission delay and potential drop, and part B directly determines the output. It is proved to obtain a faster front by decreasing the capacitance of part A to accelerate the potential drop and increasing the capacitance of part B to reduce the loss of voltage at the frontal moment. Besides, a single-gap multichannel PSS is developed as the main switch for a square wave pulse generator. To improve the output characteristics (hold-off voltage, lifetime, repetition frequency, and so on), some structural improvements have been made. For example, the flat anode with shielding is adopted to avoid the direct bombardment of the discharge plasma on the Al
2
O
3
ceramic support. Moreover, the multi-hole electrodes increase the current while reducing the single hole ablation. The principle prototype designed generates pulses with 25 kV voltage, 25 ns rise time, and 90 ns pulse width. Currently, it has been operating at 100 Hz repetition rate for 1 million shots without any significant degradation in output performance. Arguably, it may solve the practical problems faced by square wave generators, and provide a direction for the future design of such pulse generators.