A modular nanosecond pulse generation system for plasma-assisted ignition

Abstract

Plasma-assisted ignition technology has been proposed to boost the combustion efficiency of scramjets during high speed flight. One technique utilizes high-voltage nanosecond-duration pulses, which can generate free radicals thereby initiating ignition earlier in the combustion chamber and improving fuel efficiency. A high-voltage nanosecond pulse generator is an integral part of the system. In this paper, a modular nanosecond pulse generation system, utilizing multiple high-speed, high-voltage MOSFETs, is developed and tested. The modular system can generate width-adjustable pulses (from 20 ns to 50 ns) with fast rise time (<; 6 ns), fast fall time (<; 6 ns) and variable amplitude using multiple switch cells. Employing the inductive voltage adder, the system is configured in two different ways: two switch cells coupled in parallel and two switch cells coupled in series. The parallel-coupled two-switch configuration increases the peak current capability of the system for a given MOSFET current rating. The increased distributed capacitance is a dominant factor, which leads to mismatch of the drain-to-source voltage at turn-off and increases the output pulse width. The series-coupled two switch configuration doubles the peak voltage of the output pulse. However, the increased leakage inductance is a major contributor to increased rise and fall time of the output pulse and this is demonstrated experimentally.