Characterization of a Corona Discharge Initiator Using Detonation Tube Impulse Measurements

Experiments were carried out to determine the effectiveness of a transient plasma, i.e, corona discharge, to initiate a detonation in a short tube. A high-voltage pulse generator used a pseudo-spark switch to discharge a capacitor through a transformer connected to electrodes in the combustion initiator section. The resulting voltage pulse (90 kV for 50 ns) produced a plasma discharge consisting of many radial streamers. The transient plasma initiated low-speed combustion, a deflagration, which can transition to detonation if the mixture is sufficiently sensitive. In some tests, turbulence-generating obstacles were used within the detonation tube to promote the transition from deflagration to detonation. The corona discharge was slightly more effective than a standard internal combustion engine spark plug initiating combustion that will transition to detonation. In all cases, the use of turbulence-generating obstacles significantly improved the effectiveness of detonation initiation as had been found previously in Cooper et al., J. Propulsion Power 18(5), 10331041, 2002. The corona discharge was an excellent method to achieve very rapid combustion of the region near the electrodes but additional means appeared to be needed to accelerate the resulting flame to a detonation for mixtures with greater than 40% nitrogen dilution.