Influence of moderate pressure nanosecond discharge on the structure of detonation wave

The effect of a volumetric nanosecond discharge on detonation cell size was demonstrated ex- perimentally in a detonation tube test rig. The experiments were performed in CH₄:O₂ :Ar=1:2:2 mixture, at initial pressure 180 mbar and ambient temperature. The detonation wave was initiated in a 3.6-m long, 50 x 50-mm² square cross section tube, and entered the measuring section where the electrode system was installed to produce a double-pulse discharge ahead of the detonation front. The triggering of the discharge was synchronized with the arrival of the detonation front to the diagnostic chamber. The plasma was generated by two consecutive pulses of -50 and -32 kV amplitude on the high-voltage electrode and 25 ns pulse duration. It was shown that the plasma fills the entire interelectrode space. The analysis of the detonation cell size with and without plasma generation was performed via sooted-plate technique. Production of atoms and radicals in the discharge triggered combustion chemistry decreasing the ignition delay time. As a result, the detonation cell size was reduced by a factor of 1.5-2, while passing through the region of the discharge.