The crucial role of molecular ions in the radial contraction of argon microwave-sustained plasma jets at atmospheric pressure

Ar2+ normalized energy resolved ion fluxes (IEDF) as a function of discharge radii. Power of 50 W and flux of 2.5 slm (contracted discharge) and 5.0 slm (diffuse discharge). In the diffuse discharge the plots of the IEDFs for r = 0, 200, 500 and 750 μm are superimposed.