Modulation instability in pulsed surface-wave sustained discharges

Experimental results showing development of modulation instability and tendency to soliton formation in pulsed gas discharges sustained by surface waves are presented. The measurements are performed in argon discharges at gas pressure 13-1.3[multiplied by][10.sup.3] Pa sustained by pulsed microwave power at 2.45 GHz. The changes along the discharge length of the shape of the pulses of the total light emission, which is an indication for the plasma density, and of the wave electric field creating the discharge, are registrated. The cases when the modulation instability arises from the level of fluctuations in the plasma and when it is forced by the applied signal producing the discharge are demonstrated. The obtained results are discussed in terms of weak nonlinearity superimposed on the mechanism of strong ionization nonlinearity responsible for the discharge creation itself. A separation of a solitary-like wave from the leading edge of the pulse is also reported as an experimental result. Index Terms - Ionization nonlinearity, modulation instability, pulsed microwave discharges, solitary waves, surface wave sustained discharges.